| 1. |
- Beausang, Angela, et al.
(författare)
-
"Möjligheten att rädda några av dessa kvinnors liv har inte vägts in"
- 2014
-
Ingår i: Dagens Medicin. - : Dagens Medicin.
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Namnet på Socialstyrelsens vägledning lyder: Hur upptäcka våldsutsatthet? Ja, det kan man verkligen fråga sig efter att ha läst detta föga vägledande dokument, skriver ett stort antal kritiska debattörer.
|
|
| 2. |
- Berghard, Anna, et al.
(författare)
-
Lhx2-dependent specification of olfactory sensory neurons is required for successful integration of olfactory, vomeronasal, and GnRH neurons
- 2012
-
Ingår i: The FASEB Journal. - : Federation of American Society of Experimental Biology (FASEB). - 0892-6638 .- 1530-6860. ; 26:8, s. 3464-3472
-
Tidskriftsartikel (refereegranskat)abstract
- Inactivation of the LIM-homeodomain 2 gene (Lhx2) results in a severe defect in specification of olfactory sensory neurons (OSNs). However, the ramifications of lack of Lhx2-dependent OSN specification for formation of the primary olfactory pathway have not been addressed, since mutant mice die in utero. We have analyzed prenatal and postnatal consequences of conditionally inactivating Lhx2 selectively in OSNs. A cell-autonomous effect is that OSN axons cannot innervate their target, the olfactory bulb. Moreover, the lack of Lhx2 in OSNs causes unpredicted, non-cell-autonomous phenotypes. First, the olfactory bulb shows pronounced hypoplasia in adults, and the data suggest that innervation by correctly specified OSNs is necessary for adult bulb size and organization. Second, absence of an olfactory nerve in the conditional mutant reveals that the vomeronasal nerve is dependent on olfactory nerve formation. Third, the lack of a proper vomeronasal nerve prevents migration of gonadotropin-releasing hormone (GnRH) cells the whole distance to their final positions in the hypothalamus during embryo development. As adults, the conditional mutants do not pass puberty, and these findings support the view of an exclusive nasal origin of GnRH neurons in the mouse. Thus, Lhx2 in OSNs is required for functional development of three separate systems.—Berghard, A., Hägglund, A.-C., Bohm, S., and Carlsson, L. Lhx2-dependent specification of olfactory sensory neurons is required for successful integration of olfactory, vomeronasal, and GnRH neurons.
|
|
| 3. |
|
|
| 4. |
- Carlsson, Anna-Carin, 1976, et al.
(författare)
-
Solvent Effects on Halogen Bond Symmetry
- 2013
-
Ingår i: CrysteEngComm. - 1466-8033. ; 15:16, s. 3087-3092
-
Tidskriftsartikel (refereegranskat)abstract
- The symmetric arrangement of the iodine and bromine centred 3-center–4-electron halogen bond is revealed to remain preferred in a polar, aprotic solvent environment. Acetonitrile is unable to compete with pyridine for halogen bonding; however, its polarity weakly modulates the energy of the interaction and influences IPE-NMR experiments.
|
|
| 5. |
- Carlsson, Anna-Carin, 1976, et al.
(författare)
-
Symmetric Halogen Bonding is Preferred in Solution
- 2012
-
Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 134, s. 5706-5715
-
Tidskriftsartikel (refereegranskat)abstract
- Halogen bonding is a recently rediscovered secondary interaction that shows potential to become a complementary molecular tool to hydrogen bonding in rational drug design and in material sciences. Whereas hydrogen bond symmetry has been the subject of systematic studies for decades, the understanding of the analogous three-center halogen bonds is yet in its infancy. The isotopic perturbation of equilibrium (IPE) technique with 13C NMR detection was applied to regioselectively deuterated pyridine complexes to investigate the symmetry of [N−I−N]+ and [N−Br−N]+ halogen bonding in solution. Preference for a symmetric arrangement was observed for both a freely adjustable and for a conformationally restricted [N−X−N]+ model system, as also confirmed by computation on the DFT level. A closely attached counterion is shown to be compatible with the preferred symmetric arrangement. The experimental observations and computational predictions reveal a high energetic gain upon formation of symmetric, three-center four-electron halogen bonding. Whereas hydrogen bonds are generally asymmetric in solution and symmetric in the crystalline state, the analogous bromine and iodine centered halogen bonds prefer symmetric arrangement in solution.
|
|
| 6. |
- Carlsson, Anna-Carin, 1976
(författare)
-
Symmetry of Halonium Complexes in Solution
- 2012
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis the symmetry of two interaction types involving electropositive halogens have been studied in solution; the N-X+-N halogen bond (X = Br or I), and the C-X+-C interaction of previously characterised, cyclic, 1,2-bridged halonium ions (X = Cl or Br), respectively. The three N-X+-N model structures included are bispyridine, 1,2-bis(pyridine-2-ylethynyl)benzene and 1,2-bis((4-methylpyridin-2-yl)ethynyl)benzene halonium triflate complexes. Model structures representing the C-X+-C interaction are the dimethylethylene- and ethylenehalonium ions. All structures included in this thesis are comprised of symmetrically arranged atoms, but have the possibility to exist as either a static, symmetric structure, or as two asymmetric, fast equilibrating tautomers. For a symmetric structure, the positive halogen is positioned with equal distances to the electron donor nitrogens/carbons. In asymmetric structures, the halogen is always closer to one of the nitrogens/carbons, and is consistently jumping between the two nitrogens/carbons. In this investigation the NMR spectroscopic method Isotopic Perturbation of Equilibrium (IPE) has been applied for distinguishing a single symmetric structure from rapidly, interconverting tautomers. The technique measures 13C NMR isotope shifts, nobs, resulting from unsymmetrical introduction of deuterium isotopes in the molecule for which the symmetry is in doubt. Based on the magnitudes, signs, and temperature-dependency of nobs obtained from 13C NMR spectra of a mixture of non-labelled and deuterium labelled molecules, the symmetry of the molecule being considered can be determined. The IPE NMR experiments revealed that all bis(pyridine)based halonium complexes were best represented as static, symmetric structures in dichloromethane. The symmetric N-X+-N arrangement was also shown to be independent of environmental factors, such as increased solvent polarity and tight binding of the counter ion. Thus, these observations indicated that the formation of a symmetric N-X+-N halogen bond is energetically favourable. The 15N and 13C chemical shifts of the pyridine rings revealed significantly stronger N-X+-N interaction for the iodonium complexes than for the corresponding bromonium complexes, suggesting a covalent character of the N-I+-N interaction and an ionic character of the N-Br+-N interaction. Strongest interaction was observed for the bispyridine halonium complexes, in which the N-N distances are freely adjustable to provide the most favourable interaction. Ionisation of 2,3-dihalobutane or 1,2-dihaloethane precursors in SbF5-SO2 at -80 C were attempted for generation of the desired ethylenehalonium ions. Both bromonium ions were characterised as asymmetric, equilibrating structures; the dimethylethylenebromonium ions from their nobs values, and the ethylenebromonium ion from the dynamic behaviour, typical for asymmetric structures in a slow equilibrium, of the signals shown in its 1H and 13C NMR spectra. The 1H NMR spectral pattern of the ethylenechloronium ion was also consistent with asymmetric structures in a slow equilibrium. The symmetry of the dimethylethylenechloronium ions could not be determined, as they, if formed at all, immediately rearranged. SO2 was revealed to be sufficiently nucleophilic to add to the cations formed. Hence, the source of the asymmetry observed is ascribed the labile addition of SO2 to either cyclic halonium ions or open beta-halocarbenium ions.
|
|
| 7. |
- Carlsson, Anna-Carin, 1976, et al.
(författare)
-
Symmetry of [N-X-N]+ Halogen Bonds in Solution
- 2012
-
Ingår i: Chemical Communications. - 1364-548X .- 1359-7345. ; 48:10, s. 1458-1460
-
Tidskriftsartikel (refereegranskat)abstract
- The first investigation of halogen bond symmetry is presented. In contrast to related hydrogen bonds, the iodous halogen bond is symmetric in solution and in the crystal. The bromous analogue is symmetric in solution, but shows asymmetry in the solid state. NMR results are in agreement with DFT predictions.
|
|
| 8. |
- Hägglund, Anna-Carin, et al.
(författare)
-
Canonical Wnt/beta-Catenin Signalling Is Essential for Optic Cup Formation
- 2013
-
Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 8:12, s. e81158-
-
Tidskriftsartikel (refereegranskat)abstract
- A multitude of signalling pathways are involved in the process of forming an eye. Here we demonstrate that beta-catenin is essential for eye development as inactivation of beta-catenin prior to cellular specification in the optic vesicle caused anophthalmia in mice. By achieving this early and tissue-specific beta-catenin inactivation we find that retinal pigment epithelium (RPE) commitment was blocked and eye development was arrested prior to optic cup formation due to a loss of canonical Wnt signalling in the dorsal optic vesicle. Thus, these results show that Wnt/beta-catenin signalling is required earlier and play a more central role in eye development than previous studies have indicated. In our genetic model system a few RPE cells could escape beta-catenin inactivation leading to the formation of a small optic rudiment. The optic rudiment contained several neural retinal cell classes surrounded by an RPE. Unlike the RPE cells, the neural retinal cells could be beta-catenin- negative revealing that differentiation of the neural retinal cell classes is beta-catenin-independent. Moreover, although dorsoventral patterning is initiated in the mutant optic vesicle, the neural retinal cells in the optic rudiment displayed almost exclusively ventral identity. Thus, beta-catenin is required for optic cup formation, commitment to RPE cells and maintenance of dorsal identity of the retina.
|
|
| 9. |
- Hägglund, Anna-Carin, et al.
(författare)
-
Lhx2 is required for patterning and expansion of a distinct progenitor cell population committed to eye development
- 2011
-
Ingår i: PLOS ONE. - San Francisco, CA : Public Library of Science. - 1932-6203. ; 6:8, s. e23387-
-
Tidskriftsartikel (refereegranskat)abstract
- Progenitor cells committed to eye development become specified in the prospective forebrain and develop subsequently into the optic vesicle and the optic cup. The optic vesicle induces formation of the lens placode in surface ectoderm from which the lens develops. Numerous transcription factors are involved in this process, including the eye-field transcription factors. However, many of these transcription factors also regulate the patterning of the anterior neural plate and their specific role in eye development is difficult to discern since eye-committed progenitor cells are poorly defined. By using a specific part of the Lhx2 promoter to regulate Cre recombinase expression in transgenic mice we have been able to define a distinct progenitor cell population in the forebrain solely committed to eye development. Conditional inactivation of Lhx2 in these progenitor cells causes an arrest in eye development at the stage when the optic vesicle induces lens placode formation in the surface ectoderm. The eye-committed progenitor cell population is present in the Lhx2(-/-) embryonic forebrain suggesting that commitment to eye development is Lhx2-independent. However, re-expression of Lhx2 in Lhx2(-/-) progenitor cells only promotes development of retinal pigment epithelium cells, indicating that Lhx2 promotes the acquisition of the oligopotent fate of these progenitor cells. This approach also allowed us to identify genes that distinguish Lhx2 function in eye development from that in the forebrain. Thus, we have defined a distinct progenitor cell population in the forebrain committed to eye development and identified genes linked to Lhx2’s function in the expansion and patterning of these progenitor cells.
|
|
| 10. |
- Karim, Alavi, 1986, et al.
(författare)
-
The nature of [N-Cl-N]+ and [N-F-N]+ halogen bonds in solution
- 2014
-
Ingår i: Chemical Science. - 2041-6520 .- 2041-6539. ; 5, s. 3226-3233
-
Tidskriftsartikel (refereegranskat)abstract
- Halonium ions are synthetically useful, transient species that may be stabilized by attachment to two electron donors. Whereas studies of [C–X–C]+-type ions have greatly contributed to the fundamental understanding of chemical bonding and reaction mechanisms, investigations of the corresponding [N–X–N]+ halogen bond complexes are only at an early stage. Herein we present solution NMR spectroscopic and theoretical evidence for the nature of [N–Cl–N]+ and [N–F–N]+ complexes, and we discuss their geometries and stabilities in comparison to their iodine and bromine-centered analogues as well as the corresponding three-center [N–H–N]+ hydrogen bond. We show the chlorine-centered halogen bond to be weaker but yet to resemble the symmetric geometry of the three-center bond of heavier halogens. In contrast, the [N–F–N]+ bond is demonstrated to prefer asymmetric geometry analogous to the [N–H–N]+ hydrogen bond. However, the [N–F–N]+ system has a high energy barrier for interconversion, and due to entropy loss, its formation is slightly endothermic.
|
|
