No description available.

This thesis describes the improvement of two radically different cellulose materials, paper and artificial blood vessels, constructed from two diverse cellulose sources, wood pulp and Acetobacter xylinum. The improvement of both materials was possible due to the natural affinity of the hemicellulose xyloglucan for cellulose. Chemical and mechanical pulps were treated with xyloglucan in the wet-end prior to hand sheet formation or by spray application of dry hand sheets, loading a comparable amount of xyloglucan. The tensile strength increases for the wet-end treatment and spray application were 28% and 71% respectively for bleached soft wood, compared to untreated sheets (20.7 Nm/g). The corresponding strength increases for hand sheets made of thermo-mechanical pulp were 6% and 13% respectively compared to untreated sheets (42.4 Nm/g). The tendency for chemical pulp to be superior to mechanical pulp with respect to strength increase was valid even for tear strength and Scott-Bond. These results suggest, in agreement with other studies, that adhesion of xyloglucan to wood fibres is dependent on their degree of surface lignification. Also, a method was developed to increase the blood compatibility of artificial blood vessels constructed of bacterial cellulose. Xyloglucan was covalently linked to the endothelial cell adhesion motif (Arg-Gly-Asp). To obtain this, new solid-phase coupling chemistry was developed. Xyloglucan oligosaccharides (XGO) were transformed into XGO-succinamic acid via the corresponding XGO--NH2 derivative prior to coupling with the N-terminus of the solid-phase synthesised Gly-Arg-Gly-Asp-Ser peptide. The resin-bound glyco-peptide was then cleaved and enzymatically re-incorporated into high molecular weight xyloglucan. The glyco-peptide was further adsorbed onto bacterial cellulose scaffolds, increasing the adhesion and proliferation of endothelial cells and therefore blood compatibility. / QC 20101102

Enzymes are successfully employed in the synthesis of different types of polymers. Candida antarctica lipase B is a highly efficient catalyst for the synthesis of polyesters by ring opening polymerization. ω-Pentadecalactone is an interesting lactone due to the unique proprieties of its polymer (poly-pentadecalactone). These polymers have not been applied in any industrial application due to the difficulties to reach them by chemical polymerization. Enzymatically, poly-pentadecalactone macromonomers can be obtained to high conversion. In this investigation we synthesized difunctionalized poly-pentadecalactone with different functional groups. Taking advantage of the selectivity of Candida antarctica lipase B, we introduced different functional end groups. α,ω-Difunctionalized poly-pentadecalactone macromonomers with two thiol ends, two (meth)acrylate ends or with one thiol and one acrylate end were obtained with a high degree of functional ends. We have improved the difunctionalization procedure to a single-step route for the synthesis of α,ω-functionalized poly-pentadecalactones. This procedure has a great potential for industrial applications due to the simplicity of the process and the clean products afforded. Macromonomers with functionalized ends can be used to obtain new polymer architectures with novel proprieties. We also show how the use of enzymes could have some limitations when using an initiator with a cleavable ester bond. 2-Hydroxyethyl methacrylate (HEMA) was used as initiator for the ring opening polymerization (eROP) of ε-caprolactone and ω-pentadecalactone aiming for methacrylate functional polyester. However, the lipase catalyzed not only the ring opening polymerization but also the cleavage of the HEMA moiety resulting in a mixture of polymer products with various end groups. A kinetics study of the eROP and the transesterification processes when using HEMA showed that the transesterification processes occurs at moderate frequency at low monomer concentration, it becomes dominant at longer reaction times. We showed that fully difunctionalized polymers can be obtained when using HEMA as initiator for the eROP of lactones by adding a proper end capper. / QC 20101124

As life expectancy increases globally, so does the prevalence of age-related diseases, some of which are more difficult to adapt to and accommodate for than others. In particular, neurodegenerative disorders are among those for which adaptations are more complex, often requiring long-term care. Alzheimer’s disease is a neurodegenerative disorder linked with atrophy of certain cognition related brain regions, causing severe memory, and cognitive function loss. A major hypothesis behind Alzheimer’s disease, upon which most pharmaceutical therapies are based, proposes its cause as the degeneration of cholinergic neurons. Nerve growth factor is a biomolecule found to stimulate the generation, protection, and regeneration of cholinergic neurons. Synthesis of nerve growth factor has been found to be promoted by hericenones and erinacines, bioactive compounds originally extracted from the mycelium of the Lion’s Mane Mushroom (Hericium erinaceus); however, direct supplementation with H. erinaceus has also yielded positive results. In animal models H. erinaceus has enhanced Nerve growth factor levels, increased neuronal survival, promoted hippocampal neurogenesis, decreased amyloid plaque build-up, and improved behavioural outcomes. Human trials showed improvements in cognitive function scores, short-term memory, and visual contrast sensitivity. Phytotherapeutic remedies such as these have long been used across a multitude of cultures, however, now with quantitative scientific evidence supporting their benefits, their implementation into clinical therapies is being explored. Though there is still room for further research, H. erinaceus shows a promising future as a potential pharmaceutical therapy for Alzheimer’s disease and other cognitive impairments.

No description available.

The aim of this work was to determine if the protein Majastridin found in the proteobacterium Rhodobacter blasticus has a functional relative in the hypothetical protein Q1U8S3/ B3XNV1 found in Lactobacillus reuteri. To be able to study the protein, it was overexpressed in  E. coli-cells and purified. As a starting material, the L. reuteri Q1U8S3 gene previously cloned into a pET SUMO vector from Invitrogen was used. The produced protein will be a fusion protein containing a His6-tag, a SUMO-protein and the protein of interest. A nickel column in combination with a gel filtration column was used to purify the protein and after purification, crystallization experiments were set up using standardized kits.

Mechanisms involved in the clearance of chylomicrons and aspects of the interactions at the vascular endothelium were studied in the rat. The poly-anion heparin, known to release lipoprotein lipase (LPL) from the vascular endothelium, enhanced the clearance of chylomicrons. Five minutes after heparin injection, the clearance of chylomicron triglycerides and retinyl esters was markedly accelerated. The rapid initial clearance was followed by a slower clearance of heavily lipolyzed chylomicrons. In contrast, one hour after heparin the clearance of both triglycerides and retinyl esters was retarded. This decreased removal of chylomicrons coincided with a decrease in the heparin releasable LPL activity, indicating that the previous release to plasma by heparin had resulted in net loss of functional LPL in the tissues. The poly-cation protamine released hepatic lipase and some LPL from their binding sites to plasma. One hour after protamine, plasma triglyceride levels were increased, indicating that chylomicron removal was impeded. It has been speculated that protamine inactivates LPL in vivo, but this was not the case. Ten minutes after injection of protamine normal amounts of LPL could be released by heparin. Thus, the accumulation of plasma triglycerides was not due to a rapid inactivation of LPL by protamine. LPL has specificity for sn-1,3-ester bonds. To investigate if this specificity is important in vivo, a lipid emulsion containing medium-chain fatty acids (MCFA) in the sn-1,3-position and long-chain fatty acids (LCFA) in the sn-2-position was synthesized, as well as an emulsion containing MCFA-TG mixed with LCFA-TGs (MMM/LLL). In vitro experiments showed large differences in the hydrolysis of the emulsions, but in vivo there were only small differences in the metabolism. To further study if lipid emulsions are cleared by the same mechanisms as chylomicrons, an emulsion was made by the same formulation as Intralipid® with addition of 3H-triolein and ,4C-cholesteryl ester. As measured by the removal of cholesteryl esters, the emulsion was cleared at the same rate as was chylomicrons. The triglyceride label was, however, removed more slowly from the emulsion droplets than from chylomicrons. Together with the lower recirculation of labeled free fatty acids (FFA) in plasma, this suggests that there was less lipolysis of the emulsion. The current view that removal of lipid emulsions in vivo is mainly dependent on LPL-mediated hydrolysis might thus not be correct. To further analyze the metabolism of chylomicrons, a compartmental model was developed. In this process, the distribution volume for chylomicrons was shown to be larger than the blood volume, a model for the metabolism of FFA in the rat was validated, and the full tissue distribution of injected chylomicrons was determined. According to the model, about half of the triglyceride label was removed from the circulation together with the core label while for the emulsion this number was about 80 %. In fasted rats all labeled fatty acids appeared to mix with the plasma FFA pool, while in fed rats about one-fifth of the fatty acids did not mix with the FFA but was apparently channeled directly to tissue metabolism. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1995, härtill 5 uppsatser.</p> / digitalisering@umu.se

Apis mellifera, otherwise known as the common honey bee, is an incredibly important social animal. Their important role in the world makes studying them of great importance. Their stomachs can be divided into three parts, the foregut, the midgut and the hindgut. The mouth and crop are located in the foregut, the midgut encompasses the ventriculus and the hindgut is made up of the ileum and rectum. Each part of a honey bee intestine hosts a different community of bacteria that vary in proportion with age, caste and season. These microbiota are essential for a honey bees mood, development and overall health. No two authors agree completely as to what the a honey bee’s gut microbiota is. In this thesis study the intestinal tract microbiome of four bee colonies, two of which belonging to the Apis mellifera carnica subspecies and two to the Apis mellifera buckfast subspecies, were sequenced. All four are from the same region in Sweden, Uddevalla. Many issues were found during this project, including one sick colony, but through them a more thorough and guaranteed method to sequence these honey bee intestinal bacteria was developed. The results of the sequencing showed that there is indeed a major difference in these intestinal communities even in bees from the same region or from the same subspecies. A possible culprit for the diseased colony was found.

Ribonucleotide reductase (RNR) is a key enzyme in the de novo biosynthesis and homeostatic maintenance of all four DNA building blocks by being able to make deoxyribonucleotides from the corresponding ribonucleotides. It is important for the cell to control the production of a balanced supply of the dNTPs to minimize misincorporations in DNA. Because RNR is the rate-limiting enzyme in DNA synthesis, it is an important target for antimicrobial and antiproliferative molecules. The enzyme RNR has one of the most sophisticated allosteric regulations known in Nature with four allosteric effectors (ATP, dATP, dGTP, and dTTP) and two allosteric sites. One of the sites (s-site) controls the substrate specificity of the enzyme, whereas the other one (a-site) regulates the overall activity.  The a-site binds either dATP, which inhibits the enzyme or ATP that activates the enzyme. In eukaryotes, ATP activation is directly through the a-site and in E. coli it is a cross-talk effect between the a and s-sites. It is important to study and get more knowledge about the overall activity regulation of RNR, both because it has an important physiological function, but also because it may provide important clues to the design of antibacterial and antiproliferative drugs, which can target RNR. Previous studies of class I RNRs, the class found in nearly all eukaryotes and many prokaryotes have revealed that the overall activity regulation is dependent on the formation of oligomeric complexes. The class I RNR consists of two subunits, a large α subunit, and a small β subunit. The oligomeric complexes vary between different species with the mammalian and yeast enzymes cycle between structurally different active and inactive α6β2 complexes, and the E. coli enzyme cycles between active α2β2 and inactive α4β4 complexes. Because RNR equilibrates between many different oligomeric forms that are not resolved by most conventional methods, we have used a technique termed gas-phase electrophoretic macromolecule analysis (GEMMA). In the present studies, our focus is on characterizing both prokaryotic and mammalian class I RNRs. In one of our projects, we have studied the class I RNR from Pseudomonas aeruginosa and found that it represents a novel mechanism of overall activity allosteric regulation, which is different from the two known overall activity allosteric regulation found in E. coli and eukaryotic RNRs, respectively.  The structural differences between the bacterial and the eukaryote class I RNRs are interesting from a drug developmental viewpoint because they open up the possibility of finding inhibitors that selectively target the pathogens. The biochemical data that we have published in the above project was later supported by crystal structure and solution X-ray scattering data that we published together with Derek T. Logan`s research group. We have also studied the effect of a novel antiproliferative molecule, NSC73735, on the oligomerization of the human RNR large subunit. This collaborative research results showed that the molecule NSC73735 is the first reported non-nucleoside molecule which alters the oligomerization to inhibit human RNR and the molecule disrupts the cell cycle distribution in human leukemia cells.

Zona pellucida glycoproteins (ZP) are important proteins for maturation of the oocytes in eukaryotes, these proteins are encoded by cluster of zp genes. zp2.3 and zp3.5 genes are expressed during the developing and maturation of the oocytes in zebrafish ovaries. Both of the gens have a CCAAT box in their promoter regions, playing a big role in the expression of the both genes in zebrafish oocytes. The transcription of the genes in the eukaryotes requires transcription factors to initiate and promote the transcription, the transcription factors can bind to the promoter region and initiate the transcription process. The nuclear factor y (NFY) regulates the genes by binding to the CCAAT boxes in their promoter regions, it consist from many subunit such as NF-YA and NF-YB. Here in this study we characterize the expression pattern of NF-YA and NF-YB by screening these genes expression in several organs and tissues, also to determine its roles in the expression of the zp2.3 and zp3.5 genes in the adultzebrafish ovary.