| 1. |
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| 2. |
- Medina, LMP, et al.
(författare)
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Targeted plasma proteomics reveals signatures discriminating COVID-19 from sepsis with pneumonia
- 2023
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Ingår i: Respiratory research. - : Springer Science and Business Media LLC. - 1465-993X. ; 24:1, s. 62-
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundCOVID-19 remains a major public health challenge, requiring the development of tools to improve diagnosis and inform therapeutic decisions. As dysregulated inflammation and coagulation responses have been implicated in the pathophysiology of COVID-19 and sepsis, we studied their plasma proteome profiles to delineate similarities from specific features.MethodsWe measured 276 plasma proteins involved in Inflammation, organ damage, immune response and coagulation in healthy controls, COVID-19 patients during acute and convalescence phase, and sepsis patients; the latter included (i) community-acquired pneumonia (CAP) caused by Influenza, (ii) bacterial CAP, (iii) non-pneumonia sepsis, and (iv) septic shock patients.ResultsWe identified a core response to infection consisting of 42 proteins altered in both COVID-19 and sepsis, although higher levels of cytokine storm-associated proteins were evident in sepsis. Furthermore, microbiologic etiology and clinical endotypes were linked to unique signatures. Finally, through machine learning, we identified biomarkers, such as TRIM21, PTN and CASP8, that accurately differentiated COVID-19 from CAP-sepsis with higher accuracy than standard clinical markers.ConclusionsThis study extends the understanding of host responses underlying sepsis and COVID-19, indicating varying disease mechanisms with unique signatures. These diagnostic and severity signatures are candidates for the development of personalized management of COVID-19 and sepsis.
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| 3. |
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| 4. |
- Bhattacharya, S, et al.
(författare)
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Public health. The cholera crisis in Africa.
- 2009
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Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 324:5929
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Forskningsöversikt (refereegranskat)abstract
- Long-lasting cholera outbreaks in Africa suggest limitations in the current strategy of disease control.
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| 5. |
- Darenberg, J, et al.
(författare)
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Intravenous immunoglobulin G therapy in streptococcal toxic shock syndrome : A European randomized, double-blind, placebo-controlled trial
- 2003
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Ingår i: Clinical Infectious Diseases. - : Oxford University Press (OUP). - 1058-4838 .- 1537-6591. ; 37, s. 333-
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Tidskriftsartikel (refereegranskat)abstract
- The efficacy and safety of high-dose intravenous polyspecific immunoglobulin G (IVIG) as adjunctive therapy in streptococcal toxic shock syndrome (STSS) were evaluated in a multicenter, randomized, double-blind, placebo-controlled trial. The trial was prematurely terminated because of slow patient recruitment, and results were obtained from 21 enrolled patients (10 IVIG recipients and 11 placebo recipients). The primary end point was mortality at 28 days, and a 3.6-fold higher mortality rate was found in the placebo group. A significant decrease in the sepsis-related organ failure assessment score at days 2 (P = .02) and 3 (P = .04) was noted in the IVIG group. Furthermore, a significant increase in plasma neutralizing activity against superantigens expressed by autologous isolates was noted in the IVIG group after treatment (P = .03). Although statistical significance was not reached in the primary end point, the trial provides further support for IVIG as an efficacious adjunctive therapy in STSS.
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| 6. |
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| 7. |
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| 8. |
- Carroll, A. M., et al.
(författare)
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Synthetic and mechanistic studies in enantioselective allylic substitutions catalysed by palladium complexes of a modular class of axially chiral quinazoline-containing ligands
- 2020
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Ingår i: Tetrahedron. - : Elsevier BV. - 0040-4020. ; 76:1
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Tidskriftsartikel (refereegranskat)abstract
- The application of palladium complexes of a modular series of axially chiral phosphinamine ligands, the Quinazolinaps, to the enantioselective alkylation of 1,3-diphenyl-2-propenyl acetate with dimethyl malonate and methyl dimethyl malonate is described. Complete conversions and enantiomeric excesses of up to 91% were obtained. To elucidate the solution structure of these complexes and their dynamic behaviour, 2D COSY and NOESY NMR experiments were carried out. An X-ray crystal structure of a palladacycle derived from 2-phenylQuinazolinap which possesses two Pd3Cl5 units is shown. Computational studies were also undertaken to allow qualitative predictions of diastereomeric ratios. The observed enantioselectivity was then rationalised in terms of combined spectroscopic and theoretical data. The catalytic results obtained are best interpreted by the reaction proceeding with nucleophilic attack on the allyl trans to the phosphorus donor atom of the major diastereomeric intermediate. (C) 2019 Elsevier Ltd. All rights reserved.
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| 9. |
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| 10. |
- Dupont, Chris L., et al.
(författare)
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Functional Tradeoffs Underpin Salinity-Driven Divergence in Microbial Community Composition
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:2, s. e89549-
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial community composition and functional potential change subtly across gradients in the surface ocean. In contrast, while there are significant phylogenetic divergences between communities from freshwater and marine habitats, the underlying mechanisms to this phylogenetic structuring yet remain unknown. We hypothesized that the functional potential of natural bacterial communities is linked to this striking divide between microbiomes. To test this hypothesis, metagenomic sequencing of microbial communities along a 1,800 km transect in the Baltic Sea area, encompassing a continuous natural salinity gradient from limnic to fully marine conditions, was explored. Multivariate statistical analyses showed that salinity is the main determinant of dramatic changes in microbial community composition, but also of large scale changes in core metabolic functions of bacteria. Strikingly, genetically and metabolically different pathways for key metabolic processes, such as respiration, biosynthesis of quinones and isoprenoids, glycolysis and osmolyte transport, were differentially abundant at high and low salinities. These shifts in functional capacities were observed at multiple taxonomic levels and within dominant bacterial phyla, while bacteria, such as SAR11, were able to adapt to the entire salinity gradient. We propose that the large differences in central metabolism required at high and low salinities dictate the striking divide between freshwater and marine microbiomes, and that the ability to inhabit different salinity regimes evolved early during bacterial phylogenetic differentiation. These findings significantly advance our understanding of microbial distributions and stress the need to incorporate salinity in future climate change models that predict increased levels of precipitation and a reduction in salinity.
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| 11. |
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| 12. |
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Linner, A, et al.
(författare)
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Reply to Arends and Harkisoen
- 2015
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Ingår i: Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. - : Oxford University Press (OUP). - 1537-6591. ; 60:2, s. 324-5
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 18. |
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| 19. |
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| 20. |
- Norrby, T, et al.
(författare)
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Synthesis, structure, and photophysical properties of novel ruthenium(II) carboxypyridine type complexes
- 1997
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Ingår i: INORGANIC CHEMISTRY. - 0020-1669. ; 36:25, s. 5850-5858
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Tidskriftsartikel (refereegranskat)abstract
- A series of Ru(II) compounds and salts have been synthesized: [Ru(6-carboxylato-bpy)(2)] (5), [Ru(6-carboxylato-bpy)(tpy)]PF6 (9), [Ru(tpy)(2)](PF6)(2) (8), and [Ru(bpy)(2)(Pic)]PF6 (11), where 6-carboxy-bpy (1) 6-carboxy-2,2'-bipyridine, tpy (2) = 2,2':6
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| 21. |
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| 22. |
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| 23. |
- Rastad, AA, et al.
(författare)
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Management of infections caused by respiratory syncytial virus
- 2001
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Ingår i: Scandinavian Journal of Infectious Diseases. - 0036-5548 .- 1651-1980. ; 33:5, s. 323-328
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Tidskriftsartikel (refereegranskat)abstract
- This is a consensus document compiled by the Medical Products Agency in Sweden and the Swedish Reference Group for Antiviral Therapy on management of respiratory syncytial virus (RSV) infections. Prophylaxis against RSV infections using palivizumab, a commercially available humanized monoclonal IgG, antibody preparation, is recommended for children <2 y of age with chronic respiratory diseases requiring continuous treatment (oxygen and/or inhalations and/or steroids) during the previous 6 months and children 6 months old who were born before gestational week 26. Ribavirin inhalation treatment may be considered in high-risk infants with clinical symptoms indicating a serious course of an RSV infection. Treatment with ribavirin in combination with intravenous polyclonal immunoglobulin should be considered in patients who have received an allogenic stem cell transplantation or organ transplantation with >1 episode of rejection treatment and who have mild or moderate RSV pneumonia. Evidence-based documentation for treatment of other groups of patients is lacking.
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| 24. |
- Stanton, G. R., et al.
(författare)
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Chelation-Controlled Addition of Organozincs to alpha-Chloro Aldimines
- 2012
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 134:42, s. 17599-17604
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Tidskriftsartikel (refereegranskat)abstract
- Nucleophilic additions to alpha-chiral alpha-halo carbonyl derivatives are well-known to generate Cornforth-Evans products via a nonchelation pathway. What was unprecedented before this report is C-X bonds reversing the diastereoselectivity through coordination to metals during C-C bond-forming reactions (chelation control). Herein we describe chelation control involving C-X bonds in highly diastereoselective additions of organozinc reagents to a variety of alpha-chloro aldimines. The unique ability of alkylzinc halide Lewis acids to coordinate to the Cl, N, and O of alpha-chloro sulfonyl imine substrates is supported by computational studies.
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| 25. |
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| 26. |
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| 27. |
- Thanert, R, et al.
(författare)
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Molecular profiling of tissue biopsies reveals unique signatures associated with streptococcal necrotizing soft tissue infections
- 2019
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Ingår i: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 10:1, s. 3846-
-
Tidskriftsartikel (refereegranskat)abstract
- Necrotizing soft tissue infections (NSTIs) are devastating infections caused by either a single pathogen, predominantly Streptococcus pyogenes, or by multiple bacterial species. A better understanding of the pathogenic mechanisms underlying these different NSTI types could facilitate faster diagnostic and more effective therapeutic strategies. Here, we integrate microbial community profiling with host and pathogen(s) transcriptional analysis in patient biopsies to dissect the pathophysiology of streptococcal and polymicrobial NSTIs. We observe that the pathogenicity of polymicrobial communities is mediated by synergistic interactions between community members, fueling a cycle of bacterial colonization and inflammatory tissue destruction. In S. pyogenes NSTIs, expression of specialized virulence factors underlies infection pathophysiology. Furthermore, we identify a strong interferon-related response specific to S. pyogenes NSTIs that could be exploited as a potential diagnostic biomarker. Our study provides insights into the pathophysiology of mono- and polymicrobial NSTIs and highlights the potential of host-derived signatures for microbial diagnosis of NSTIs.
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| 28. |
- Wahlers, J., et al.
(författare)
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Proofreading experimentally assigned stereochemistry through Q2MM predictions in Pd-catalyzed allylic aminations
- 2021
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- The palladium-catalyzed enantioselective allylic substitution by carbon or nitrogen nucleophiles is a key transformation that is particularly useful for the synthesis of bioactive compounds. Unfortunately, the selection of a suitable ligand/substrate combination often requires significant screening effort. Here, we show that a transition state force field (TSFF) derived by the quantum-guided molecular mechanics (Q2MM) method can be used to rapidly screen ligand/substrate combinations. Testing of this method on 77 literature reactions revealed several cases where the computationally predicted major enantiomer differed from the one reported. Interestingly, experimental follow-up led to a reassignment of the experimentally observed configuration. This result demonstrates the power of mechanistically based methods to predict and, where necessary, correct the stereochemical outcome. A predictive model has been created for a stereoselective palladium-catalysed allylic amination reaction. Derived only from quantum chemical data, the method is accurate enough to reveal multiple erroneous assignments in literature experiments.
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| 29. |
- Wramner, Lars, 1955, et al.
(författare)
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Impaired kidney graft survival is associated with the TNF-alpha genotype
- 2004
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Ingår i: Transplantation. - 0041-1337. ; 78:1, s. 117-21
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The TNF2 allele at position -308 of the tumor necrosis factor (TNF)-alpha gene is associated with high TNF production. The purpose was to study the association of this gene polymorphism with rejection episodes and graft survival after kidney transplantation. METHODS: A retrospective analysis of transplant outcomes of patients who only had been treated with one single form of immunosuppression consisting of cyclosporine, azathioprine, and prednisolon was performed. RESULTS: We found that 115 (73%) patients had the TNF1/TNF1 genotype, whereas 42 (27%) were TNF2 positive. There was no difference in the overall acute rejection frequency between these two groups (50% in each), but our data showed a non-significant tendency towards a higher frequency of steroid resistant rejections in the TNF2 positive group (57% vs. 40%). There was no significant difference in graft survival between the two genotype groups, although an early tendency towards worse survival was seen in TNF2 recipients. However, the TNF2 positive recipients with rejection episodes had far worse graft survival compared with the TNF1/TNF1 recipients with rejection episodes (P<0.02). No difference was seen between the two genotype groups in patients without rejection episodes. CONCLUSION: Our data propose that potentially high TNF producers with the TNF2 allele do not have an increased risk for rejection episodes, but if rejection episodes occur, they have a significantly increased risk for early graft loss. TNF production may intensify rejection, but is not a primary factor for the induction of such acute immune activation.
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| 30. |
- Abrahamsson, Maria, et al.
(författare)
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A new strategy for the improvement of photophysical properties in ruthenium(II) polypyridyl complexes. Synthesis and photophysical and electrochemical characterization of six mononuclear ruthenium(II) bisterpyridine-type complexes
- 2005
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 44:9, s. 3215-3225
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis and characterization of six ruthenium(II) bistridentate polypyridyl complexes is described. These were designed on the basis of a new approach to increase the excited-state lifetime of ruthenium(II) bisterpyridine-type complexes. By the use of a bipyridylpyridyl methane ligand in place of terpyridine, the coordination environment of the metal ion becomes nearly octahedral and the rate of deactivation via ligand-field (i.e., metal-centered) states was reduced as shown by temperature-dependent emission lifetime studies. Still, the possibility to make quasi-linear donor-ruthenium-acceptor triads is maintained in the complexes. The most promising complex shows an excited-state lifet me of tau = 15 ns in alcohol solutions at room temperature, which should be compared to a lifetime of tau = 0.25 ns for [Ru(tpy)(2)](2+). The X-ray structure of the new complex indeed shows a more octahedral geometry than that of [Ru(tpy)(2)](2+). Most importantly, the high excited-state energy was retained, and thus, so was the potential high reactivity of the excited complex, which has not been the case with previously published strategies based on bistridentate complexes.
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| 31. |
- Ankerst, J., et al.
(författare)
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Induction of mammary fibroadenomas in rats by adenovirus type 9
- 1974
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 13:3, s. 286-290
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Tidskriftsartikel (refereegranskat)abstract
- After inoculation of adenovirus type 9 into newborn Wistar/Furth rats, seven out of seven females developed one or several mammary fibroadenomas within 14–25 weeks after virus inoculation. No tumours were observed in male rats inoculated with the same virus or in untreated controls. Neonatal inoculations of adenovirus type 5, produced on the same HeLa cells, gave negative results in both sexes. The results indicate that benign mammary tumours can be induced in rats by a virus and that mammary fibroadenomas are induced by adenovirus type 9, previously known to be capable of transforming cells in vitro but not of inducing tumours in vivo.
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| 32. |
- Berggren, U, et al.
(författare)
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Subsensitive alpha-2-adrenoceptor function in male alcohol-dependent individuals during 6 months of abstinence.
- 2000
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Ingår i: Drug and alcohol dependence. - 0376-8716. ; 57:3, s. 255-60
-
Tidskriftsartikel (refereegranskat)abstract
- Postsynaptic alpha-2-receptor function, as assessed by growth hormone (GH) response to clonidine (CLON), has been shown to be downregulated in patients investigated in acute but also in late withdrawal after heavy alcohol intake. The results are however sometimes conflicting. The question whether this changed receptor function is a trait or state marker is not fully investigated so far. A total of seven male patients with alcohol dependence according to DSM-IV were assessed for the postsynaptic alpha-2-receptor function with the CLON/GH test (2.0 microg/kg body weight; i.v.) starting immediately after a period of heavy drinking. Neuroendocrine tests were repeated after 7 days, 2 and 6 months. A total of six healthy males were used as controls. The maximum GH responses to CLON were significantly lower on all four test occasions in the patient group as compared to the controls. Furthermore, in the patient group all neuroendocrine test results showed blunted GH responses to CLON. Thus, patients with downregulated alpha-2-receptor function during acute withdrawal after heavy alcohol intake showed similar subsensitive receptor function abnormality after a prolonged period of abstinence. The findings in this study indicate that alcohol dependent individuals have a persistent subsensitive alpha-2-adrenoceptor function which may constitute a trait factor for alcohol dependence.
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| 33. |
- Biosca, M., et al.
(författare)
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An Improved Class of Phosphite-Oxazoline Ligands for Pd-Catalyzed Allylic Substitution Reactions
- 2019
-
Ingår i: Acs Catalysis. - : American Chemical Society (ACS). - 2155-5435. ; 9:7, s. 6033-6048
-
Tidskriftsartikel (refereegranskat)abstract
- A method for generation of Pd/phosphite-oxazoline catalysts containing an alkyl backbone chain has been successfully applied to Pd-catalyzed allylic substitution reactions. By carefully selecting the substituents at both the alkyl backbone chain and the oxazoline of the ligand, as well as the configuration of the biaryl phosphite group, high activities (TOF > 8000 mol substrate X (mol Pd X h)(-1)) and excellent enantioselectivities (ee's up to 99%) have been achieved for many hindered and unhindered substrates with a wide range of C-, O-, and N-nucleophiles (73 substitution products in total). Moreover, DFT and NMR studies of the key Pd-allyl complexes allowed us to better understand the origin of the excellent enantioselectivities observed experimentally. The useful application of the Pd/phosphite-oxazoline catalysts was demonstrated by the syntheses of many chiral carbobicycles, with multiples stereocenters, by simple sequential reactions involving Pd-allylic substitution and either 1,6-enyne cyclization or Pauson-Khand enyne cyclization.
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| 34. |
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| 35. |
- Bäcktorp, Carina, 1964, et al.
(författare)
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Mechanisms of Air Oxidation of Ethoxylated Surfactants - Computational Estimations of Energies and Reaction Behaviors
- 2008
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Ingår i: Chemistry - A European Journal. - : Wiley. - 0947-6539 .- 1521-3765. ; 14:31, s. 9549-9554
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Tidskriftsartikel (refereegranskat)abstract
- Pathways for formation of previously observed autoxidation products of ethoxylated surfactants have been studied by DFT (B3LYP). In addition to the established radical-chain reaction, several mechanistic possibilities for intramolecular fragmentation of the intermediate radicals have been characterized concerning reaction barriers and energies of transition states. The results can rationalize the formation of previously observed autoxidation products, including several, which have been implicated as strongly allergenic.
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| 36. |
- Caldeweyher, Eike, et al.
(författare)
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Hybrid Machine Learning Approach to Predict the Site Selectivity of Iridium-Catalyzed Arene Borylation
- 2023
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 145:31, s. 17367-17376
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Tidskriftsartikel (refereegranskat)abstract
- The borylation of aryl and heteroaryl C–H bonds is valuable for the site-selective functionalization of C–H bonds in complex molecules. Iridium catalysts ligated by bipyridine ligands catalyze the borylation of the C–H bond that is most acidic and least sterically hindered in an arene, but predicting the site of borylation in molecules containing multiple arenes is difficult. To address this challenge, we report a hybrid computational model that predicts the Site of Borylation (SoBo) in complex molecules. The SoBo model combines density functional theory, semiempirical quantum mechanics, cheminformatics, linear regression, and machine learning to predict site selectivity and to extrapolate these predictions to new chemical space. Experimental validation of SoBo showed that the model predicts the major site of borylation of pharmaceutical intermediates with higher accuracy than prior machine-learning models or human experts, demonstrating that SoBo will be useful to guide experiments for the borylation of specific C(sp2)–H bonds during pharmaceutical development.
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| 37. |
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| 38. |
- Delaine, Tamara, 1981, et al.
(författare)
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Epoxyalcohols: bioactivation and conjugation required for skin sensitization.
- 2014
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Ingår i: Chemical research in toxicology. - : American Chemical Society (ACS). - 1520-5010 .- 0893-228X. ; 27:10, s. 1860-70
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Tidskriftsartikel (refereegranskat)abstract
- Allylic alcohols, such as geraniol 1, are easily oxidized by varying mechanisms, including the formation of both 2,3-epoxides and/or aldehydes. These epoxides, aldehydes, and epoxy-aldehydes can be interconverted to each other, and the reactivity of them all must be considered when considering the sensitization potential of the parent allylic alcohol. An in-depth study of the possible metabolites and autoxidation products of allylic alcohols is described, covering the formation, interconversion, reactivity, and sensitizing potential thereof, using a combination of in vivo, in vitro, in chemico, and in silico methods. This multimodal study, using the integration of diverse techniques to investigate the sensitization potential of a molecule, allows the identification of potential candidate(s) for the true culprit(s) in allergic responses to allylic alcohols. Overall, the sensitization potential of the investigated epoxyalcohols and unsaturated alcohols was found to derive from metabolic oxidation to the more potent aldehyde where possible. Where this is less likely, the compound remains weakly or nonsensitizing. Metabolic activation of a double bond to form a nonconjugated, nonterminal epoxide moiety is not enough to turn a nonsensitizing alcohol into a sensitizer, as such epoxides have low reactivity and low sensitizing potency. In addition, even an allylic 2,3-epoxide moiety is not necessarily a potent sensitizer, as shown for 2, where formation of the epoxide weakens the sensitization potential.
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| 39. |
- Donoghue, Patricks J, et al.
(författare)
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Development of a Q2MM Force Field for the Asymmetric Rhodium Catalyzed Hydrogenation of Enamides
- 2008
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Ingår i: J.Chem.Theory Comput. - : American Chemical Society (ACS). ; 4, s. 1313-1323
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Tidskriftsartikel (refereegranskat)abstract
- The rhodium catalyzed asymmetric hydrogenation of enamides to generate amino acid products and derivatives is a widely used method to generate unnatural amino acids. The choice of a chiral ligand is of utmost importance in this reaction and is often based on high throughput screening or simply trial and error. A virtual screening method can greatly increase the speed of the ligand screening process by calculating expected enantiomeric excesses from relative energies of diastereomeric transition states. Utilizing the Q2MM method, new molecular mechanics parameters are derived to model the hydride transfer transition state in the reaction. The new parameters were based off of structures calculated at the B3LYP/LACVP** level of theory and added to the MM3* force field. The new parameters were validated against a test set of experimental data utilizing a wide range of bis-phosphine ligands. The computational model agreed with experimental data well overall, with an unsigned mean error of 0.6 kcal/mol against a set of 18 data points from experiment. The major errors in the computational model were due either to large energetic errors at high e.e., still resulting in qualitative agreement, or cases where large steric interactions prevent the reaction from proceeding as expected.
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| 40. |
- Donoghue, Patrick J, et al.
(författare)
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Prediction of enantioselectivity in rhodium catalyzed hydrogenations.
- 2009
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 131:2, s. 410-1
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Tidskriftsartikel (refereegranskat)abstract
- Using the Q2MM method, new molecular mechanics parameters were developed to perform initial screening of a chiral library to focus the experimental screening for the rhodium catalyzed hydrogenation of enamides. Computational predictions agree very well with experimental data.
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| 41. |
- Eastoe, Julian, et al.
(författare)
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Interrogation of a dynamic multi-catalyst ensemble in asymmetric catalysis
- 2010
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Ingår i: Faraday Discussions. - : Royal Society of Chemistry (RSC). - 1359-6640. ; 145, s. 27-47
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Tidskriftsartikel (refereegranskat)abstract
- The Trost Standard Ligand (2) is a chiral diphosphine ligand that distinguishes itself by the high selectivity it induces in the Pd-catalysed reactions of allylic substrates that generate slim cyclic or small linear intermediates. However, a range of unusual features, including memory effects, inverse dependence of selectivity and rate on catalyst concentration, high sensitivity to counter-ion, particularly chloride, and decreasing enantioselectivities at lower temperatures, are often encountered, thus requiring considerable optimisation of reaction conditions to attain optimum selectivity. These features can be accounted for by a model involving a dynamic multi-catalyst ensemble. To gain evidence for this model, the manner in which diphosphine 2 interacts with Pd–allyl cations, and in particular the higher-order systems it generates, has been investigated by use of NMR, isotopic labelling, polarimetry, UV, neutron scattering, X-ray crystallography and molecular modeling. Ligand 2 coordinates to Pd–allyl cations to generate a mononuclear P,P-chelate. This is found to readily form non-chelate oligomers, present in a range of forms, including rings, for which high homochiral selectivity in oligomerisation is demonstrated by the technique of pseudoenantiomers. All of these species are in relatively rapid equilibrium, with half-lives for interconversion in the range 2–6 s. Higher-order aggregation is also detected, and thus at even moderate concentrations (>50 mM) large rod-like aggregates are formed.
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| 42. |
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| 43. |
- Emgard, J, et al.
(författare)
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MAIT Cells Are Major Contributors to the Cytokine Response in Group A Streptococcal Toxic Shock Syndrome
- 2019
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 116:51, s. 25923-25931
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcal toxic shock syndrome (STSS) is a rapidly progressing, life-threatening, systemic reaction to invasive infection caused by group A streptococci (GAS). GAS superantigens are key mediators of STSS through their potent activation of T cells leading to a cytokine storm and consequently vascular leakage, shock, and multiorgan failure. Mucosal-associated invariant T (MAIT) cells recognize MR1-presented antigens derived from microbial riboflavin biosynthesis and mount protective innate-like immune responses against the microbes producing such metabolites. GAS lack de novo riboflavin synthesis, and the role of MAIT cells in STSS has therefore so far been overlooked. Here we have conducted a comprehensive analysis of human MAIT cell responses to GAS, aiming to understand the contribution of MAIT cells to the pathogenesis of STSS. We show that MAIT cells are strongly activated and represent the major T cell source of IFNγ and TNF in the early stages of response to GAS. MAIT cell activation is biphasic with a rapid TCR Vβ2-specific, TNF-dominated response to superantigens and a later IL-12- and IL-18-dependent, IFNγ-dominated response to both bacterial cells and secreted factors. Depletion of MAIT cells from PBMC resulted in decreased total production of IFNγ, IL-1β, IL-2, and TNFβ. Peripheral blood MAIT cells in patients with STSS expressed elevated levels of the activation markers CD69, CD25, CD38, and HLA-DR during the acute compared with the convalescent phase. Our data demonstrate that MAIT cells are major contributors to the early cytokine response to GAS, and are therefore likely to contribute to the pathological cytokine storm underlying STSS.
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| 44. |
- Engel, J., et al.
(författare)
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Mechanistic Insights into the Iridium-Catalyzed Hydrogenations of alpha,beta-Unsaturated Ketones
- 2016
-
Ingår i: Chemcatchem. - : Wiley. - 1867-3880. ; 8:19, s. 3099-3106
-
Tidskriftsartikel (refereegranskat)abstract
- The highly enantioselective hydrogenation of linear enones catalyzed by Ir complexes that bear a chiral P,N ligand have been investigated computationally. Compared to the results of previous studies, the mechanism is different because of the coordination of the substrate. In the favored pathway Ir stays in the +3 oxidation state throughout the entire catalytic cycle, the olefinic group is coordinated trans to the ligand N atom, and the carbonyl group binds trans to a spectator hydride. After migratory insertion, a H-2 coordinates and delivers the second H atom by sigma-metathesis. The calculated path rationalizes the observed enantioselectivities and allows the development of a predictive quadrant model for this class of substrate-ligand combination.
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| 45. |
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| 46. |
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| 47. |
- HAMMARSTROM, Leif, 1964-, et al.
(författare)
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MECHANISMS OF TRANSMEMBRANE ELECTRON-TRANSFER - DIFFUSION OF UNCHARGED REDOX FORMS OF VIOLOGEN, 4,4'-BIPYRIDINE, AND NICOTINAMIDE WITH LONG ALKYL CHAINS
- 1993
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY. - : American Chemical Society (ACS). - 0022-3654 .- 1541-5740. ; 97:39, s. 10083-10091
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Tidskriftsartikel (refereegranskat)abstract
- Transmembrane electron transfer in lecithin (phosphatidylcholine) vesicles was studied by pulse radiolysis. Upon reduction, cetylmethylviologen (N-hexadecyl-N'-methyl-4,4'-bipyridinium CMV), cetylbipyridine (4-(N-hexadecylpyridinium-4-yl)pyridine, CB), and cetylnicotinamide (N-hexadecyl-3-(aminocarbonyl)pyridinium, CNA) transferred electrons from the bulk water phase to Fe(CN)63- in the internal water phase of the vesicles. The transmembrane electron transfer was found in all cases to proceed through diffusion of uncharged forms of the redox mediators (CMV0, CB0, and CNA0, respectively) but the kinetic behavior varied considerably. The mechanisms for CB and CNA were simple, the reaction following first-order kinetics, and the transmembrane diffusion was rate limiting (k = (1.5 +/- 0.3) x 10(3) S-1 for CB and k = 3.2 +/- 0.5 s-1 for CNA). The mechanism for CMV was more complicated, and the reaction followed second-order kinetics. The rate-determining step was proposed to be the disproportionation of two viologen radicals formed by the radiation pulse (2CMV+ double-line arrow pointing left and right CMV0 + CMV2+), followed by rapid transmembrane diffusion of CMVO and its subsequent reoxidation by Fe(CN)63-. In pulse radiolysis, and in phosphorescence quenching experiments with Pt2(P2O5)4H84-, CB0 and CB+ were used as models in order to obtain the rates of transmembrane diffusion of CMV0 and CMV+, respectively. Our results exclude the possibility of electron tunneling between viologens on opposite sides of the membrane, and they provide strong arguments against transmembrane diffusion of viologen radical (CMV+).
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| 48. |
- Hammarstrom, Leif, et al.
(författare)
-
Two-dimensional emission quenching and charge separation using a Ru(II)-photosensitizer assembled with membrane-bound acceptors
- 1997
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Ingår i: JOURNAL OF PHYSICAL CHEMISTRY B. - : AMER CHEMICAL SOC. - 1089-5647. ; 101:38, s. 7494-7504
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Tidskriftsartikel (refereegranskat)abstract
- Novel syntheses of the bipyridine ligand 1, dcHb (dcHb = 4,4'-dicarboxy-2,2'-bipyridine), by anionic oxidation of 4,4'-dimethyl-2',2-bipyridine (dmb) using molecular oxygen (4 atm), and of the sensitizer precursor 4, tris(4,4'-diethoxycarbonyl-2,2'-bipyri
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| 49. |
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| 50. |
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