| 1. |
- Hibar, Derrek P., et al.
(författare)
-
Novel genetic loci associated with hippocampal volume
- 2017
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (r(g) = -0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Krasnou, I., et al.
(författare)
-
Permeability of water and oleic acid in composite films of phase separated polypropylene and cellulose stearate blends
- 2016
-
Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617. ; 152, s. 450-458
-
Tidskriftsartikel (refereegranskat)abstract
- Cellulose esters with long carbon side chains (e.g. stearate) were produced via a homogenous reaction in ionic liquids. The degree of substitution was calculated to approximately 2. The melt rheology was studied for the pure cellulose esters but also combinations of the esters and polypropylene to study the processability of a blended composite material. It was shown that the compatibility between the two components was weak, which resulted in a phase-separated composite material. The morphology and permeability of water and oleic acid of the composite films were studied and it was shown that the water permeability decreased upon addition of the cellulose ester to the polymer. The permeability of oleic acid was however unchanged, which is most probable a result of high solubility in the cellulose ester rich domains of the composites. Also, the following hypothesis is stated: cellulose stearate influence the polypropylene crystallization process by decreasing the size of spherulites. (C) 2016 Elsevier Ltd. All rights reserved.
|
|
| 5. |
- Makhubela, B. C. E., et al.
(författare)
-
Hydroformylation of 1-octene using low-generation Rh(I) metallodendritic catalysts based on a tris-2-(2-pyridyliminoethyl)amine scaffold
- 2012
-
Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 41:35, s. 10715-10723
-
Tidskriftsartikel (refereegranskat)abstract
- The synthesis and characterization of low-generation pyridylimine Rh(I) metallodendrimers is described. These metallodendrimers were obtained via a Schiff base condensation of tris-2-(aminoethyl) amine with 2-pyridinecarboxaldehyde to afford the tris-2-(2-pyridylimine ethyl) amine ligand (1). Subsequent complexation reactions with [RhCl(CO)(2)](2) and [RhCl(COD)](2) yielded the corresponding metal-containing dendrimers containing RhCl(CO) and Rh(COD) moieties on the periphery. These new rhodium metallodendrimers (2 and 3) and their precursor ligand (1) are thermally stable and have been characterized using H-1 NMR, C-13 NMR, P-31 NMR, FT-IR spectroscopy, elemental analysis as well as mass spectrometry. The Rh(I) metallodendrimers are highly active and chemo- and regioselective in the hydroformylation of 1-octene. Aldehydes were favoured at moderate to high temperatures (95 degrees C and 75 degrees C) and pressure (30 bars), while more iso-octenes were formed at low temperature (55 degrees C) and pressures (5 and 10 bars). The mononuclear analogues (5 and 6) also produced more aldehydes (albeit showing catalyst decomposition at 95 degrees C and 75 degrees C, 30 bars) and these aldehydes were mostly branched.
|
|
| 6. |
- Karlsson, E., et al.
(författare)
-
In silico and in vitro studies of the reduction of unsaturated alpha,beta bonds of trans-2-hexenedioic acid and 6-amino-trans-2-hexenoic acid - Important steps towards biobased production of adipic acid
- 2018
-
Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 13:2
-
Tidskriftsartikel (refereegranskat)abstract
- The biobased production of adipic acid, a precursor in the production of nylon, is of great interest in order to replace the current petrochemical production route. Glucose-rich lignocellulosic raw materials have high potential to replace the petrochemical raw material. A number of metabolic pathways have been proposed for the microbial conversion of glucose to adipic acid, but achieved yields and titers remain to be improved before industrial applications are feasible. One proposed pathway starts with lysine, an essential metabolite industrially produced from glucose by microorganisms. However, the drawback of this pathway is that several reactions are involved where there is no known efficient enzyme. By changing the order of the enzymatic reactions, we were able to identify an alternative pathway with one unknown enzyme less compared to the original pathway. One of the reactions lacking known enzymes is the reduction of the unsaturated a,6 bond of 6-amino-trans-2-hexenoic acid and trans-2-hexenedioic acid. To identify the necessary enzymes, we selected N-ethylmaleimide reductase from Escherichia coli and Old Yellow Enzyme 1 from Saccharomyces pastorianus. Despite successful in silico docking studies, where both target substrates could fit in the enzyme pockets, and hydrogen bonds with catalytic residues of both enzymes were predicted, no in vitro activity was observed. We hypothesize that the lack of activity is due to a difference in electron withdrawing potential between the naturally reduced aldehyde and the carboxylate groups of our target substrates. Suggestions for protein engineering to induce the reactions are discussed, as well as the advantages and disadvantages of the two metabolic pathways from lysine. We have highlighted bottlenecks associated with the lysine pathways, and proposed ways of addressing them.
|
|
| 7. |
|
|
| 8. |
- Zhao, Yadong, 1985-
(författare)
-
Towards Large-scale and Feasible Exploitation of Tunicate Cellulose and Cellulose Nanocrystals for Different Applications
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tunicates are a group of filter-feeding animals that live in the ocean. They are widely distributed throughout the world and are a major contributor to the fouling problem in aquaculture. In addition to their natural abundance, large-scale farming will further render them readily available in high quantities, and they should instead be providing us food, energy, chemicals and materials. As tunicates are the sole known animal group synthesizing cellulose, the primary target for this bioresources exploitation should be cellulose preparation and application. Moreover, cellulose exploitation should be conducted in both a technically and economically feasible manner.Among the tunicates, Ciona intestinalis (termed Ciona hereafter) is one of the most abundant species in Norwegian and Swedish coastal waters. Upon comprehensive quantification of the principal chemical compositions, cellulose has been confirmed to exist as cellulose-protein fibrils cemented by non-cellulose glycans and lipids and is almost exclusively present in the Ciona tunic fraction. Using the tunic as raw material, Ciona cellulose was prepared following a unique prehydrolysis-kraft cooking-bleaching sequence with a yield of 21.64% and by a modified Updegraff method with a yield of 23.65% on a dried ash-free mass basis. To improve the Ciona cellulose dispersibility and processability, Ciona cellulose nanocrystals (CNs) were prepared using different processes, namely acid hydrolysis, 2,2,6,6‑tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation and enzymatic hydrolysis as well as acid hydrolysis followed by TEMPO-mediated oxidation. The CN preparation yield was 30.0-73.4%, depending on the process applied.By conducting comprehensive characterizations, it was found that the Ciona cellulose was nearly 100% pure, with a large weight average degree of polymerization (DPw=4200), a high surface area (133 m2/g), a large aspect ratio (length of several micrometres and diameter of ~16 nm), a high crystallinity (89%) in the form of nearly pure Iβ crystals, and a good thermal stability (onset degradation temperature of 226 ºC). When obtained in membrane form, the cellulose preserved the native interwoven microfibril network structure in the original tunic. It had a high ductility (tensile strain of 19.24%) in the wet state and good mechanical strength (tensile strength of 41.19 MPa and Young’s Modulus of 1.98 GPa) when dried. The CNs obtained were smaller in DPw, shorter in morphological size (length), similar or higher in crystallinity and more thermally stable than the starting cellulose to different extents and with different charged structures and charge contents dependent on the method/procedure used.Several applications have been examined. First, the Ciona cellulose in pulp form was utilized in the fabrication of sponge cloth to replace cotton, and the product obtained was of similar quality to the commercial one made from cotton. Second, the Ciona cellulose in membrane form was tested in the cultivation of human umbilical vein endothelial cells and mouse NIH‑3T3 cells for evaluations of cell proliferation performance and medical application potential. The performance was very positive. Third, the Ciona cellulose membrane and two CNs were applied as the matrix for high-quality zinc-blende CdSe/CdS core/shell nanocrystal quantum dots (QDs) for the development of mechanically strong and high-performance fluorescent material. The QDs were firmly attached to the Ciona CNs with uniform monolayer distribution and a high packing density. The obtained composites preserved both the high-quality optical properties from the QDs and the matrix morphology and thus expectedly the excellent mechanical properties from the cellulose. Finally, the Ciona CNs were processed to composite films cemented by konjac glucomannan for material development. Newly introduced hydrogen bonds between these two compatible polysaccharides and thus strong cementing effects were observed. The composite films showed excellent mechanical properties in addition to improved transparency, thermal stability and hydrophobicity compared with the CN’s neat films.Feasible tunicate cellulose exploitation demands the sound large-scale farming of Ciona for the highest possible cellulose content in the farmed animal, the exploitation of species other than Ciona, the complete utilization of fractions other than the tunic used and the value-added productions of other by-products. Composition quantification of the adult Ciona specimens collected from different farms showed that the carbohydrate content was linearly correlated with the body weight, which in turn was affected by the farm location, deployment time and sub-sea depth of the settling structures. Through analysing the Ciona intestinal content, it was found that both eukaryotes and prokaryotes contributed to the diet of the animal, and their quantities were positively correlated with the animal size (body weight). The tunics of three other tunicate species, Halocynthia roretzi, Styela plicata, and Ascidia sp., have been examined for tunicate cellulose preparation following the prehydrolysis-kraft cooking‑bleaching procedure. They were all found to be good sources for similar quality tunicate cellulose exploitation, thus verifying the universal applicability of the procedure. Based on more detailed chemical composition analyses, all the fractions other than the tunic, termed the inner body tissues fraction, from all four tunicate species were found to have excellent nutritional values: a high protein content with good quality amino acids and high contents of omega-3 (n-3) fatty acids and essential elements. Their toxic element contents were under the regulated limits for human food. They should therefore all be explored as human food sources. Furthermore, many different chemical structures, many of which were found for the first time, were present in the tunicate animals studied, ranging from collagens, glycosaminoglycans, and sterols to phospholipids. These structures should be explored as various bioactive by‑products during tunicate cellulose exploitation. For example, the prepared Ciona lipids had a high content of n-3 fatty acids, which presented mainly in the form of phospholipids. They should be an excellent alternative to markedly high value fish oils, but with a higher bioavailability.The techniques and knowledge obtained by this study will provide a basis for the promising large-scale and feasible exploitation of tunicate cellulose and cellulose nanocrystals for different applications.
|
|
