| 1. |
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| 2. |
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| 3. |
- Cutas, Daniela, 1978, et al.
(author)
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Legal imperialism in the regulation of stem cell research and therapy: the problem of extraterritorial jurisdiction
- 2010
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In: Capps BJ & Campbell AV (eds.). CONTESTED CELLS: Global Perspectives on the Stem Cell Debate. - London : Imperial College Press. - 9781848164376 ; , s. 95-119
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Book chapter (other academic/artistic)abstract
- Countries worldwide have very different national regulations on human embryonic stem (ES) cell research, informed by a range of ethical values. Some countries find reason to extend the applicability of their regulations on such research to its citizens when they visit other countries. Extraterritorial jurisdiction has recently been identified as a potential challenge towards global regulation of ES cell research. This chapter explores the implications and impact of extraterritorial jurisdiction and global regulation of ES cell research on researchers, clinicians and national health systems, and how this may affect patients. The authors argue that it would make ethical sense for ES cell restrictive countries to extend its regulations on ES cell research beyond its borders, because, if these countries really consider embryo destruction to be objectionable on the basis on the status of the embryo, then they ought to count it morally on par with murder (and thus have a moral imperative to protect embryos from the actions of its own citizens). However, doing so could lead to a legal situation that would result in substantial harm to central values in areas besides research, such as health care, the job market, basic freedom of movement, and strategic international finance and politics. Thus, it seems that restrictive extraterritorial jurisdiction in respect to ES cell research would be deeply problematic, given that the ethical permissibility of ES cell research is characterised by deep and wide disagreement.
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| 4. |
- Munthe, Christian, 1962
(author)
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The Price of Precaution and the Ethics of Risk
- 2011
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Book (other academic/artistic)abstract
- Since a couple of decades, the notion of a precautionary principle plays a central and increasingly influential role in international as well as national policy and regulation regarding the environment and the use of technology. Urging society to take action in the face of potential risks of human activities in these areas, the recent focus on climate change has further sharpened the importance of this idea. However, the idea of a precautionary principle has also been problematised and criticised by scientists, scholars and policy activists, and been accused of almost every intellectual sin imaginable: unclarity, impracticality, arbitrariness and moral as well as political unsoundness. In that light, the very idea of precaution as an ideal for policy making rather comes out as a dead end. On the basis of these contrasting starting points, Christian Munthe undertakes an innovative, in-depth philosophical analysis of what the idea of a precautionary principle is and should be about. A novel theory of the ethics of imposing risks is developed and used as a foundation for defending the idea of precaution in environmental and technological policy making against its critics, while at the same time avoiding a number of identified flaws. The theory is shown to have far-reaching consequences for areas such as bio-, information- and nuclear technology, and global environmental policy in areas such as climate change. The author argues that, while the price we pay for precaution must not be too high, we have to be prepared to pay it in order to act ethically defensible. A number of practical suggestions for precautionary regulation and policy making are made on the basis of this, and some challenges to basic ethical theory as well as consumerist societies, the global political order and liberal democracy are identified
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| 5. |
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| 6. |
- Rems, Lea, et al.
(author)
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Cell electrofusion using nanosecond electric pulses
- 2013
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In: Scientific Reports. - : Macmillan Publishers Ltd.. - 2045-2322. ; 3
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Journal article (peer-reviewed)abstract
- Electrofusion is an efficient method for fusing cells using short-duration high-voltage electric pulses. However, electrofusion yields are very low when fusion partner cells differ considerably in their size, since the extent of electroporation (consequently membrane fusogenic state) with conventionally used microsecond pulses depends proportionally on the cell radius. We here propose a new and innovative approach to fuse cells with shorter, nanosecond (ns) pulses. Using numerical calculations we demonstrate that ns pulses can induce selective electroporation of the contact areas between cells (i.e. the target areas), regardless of the cell size. We then confirm experimentally on B16-F1 and CHO cell lines that electrofusion of cells with either equal or different size by using ns pulses is indeed feasible. Based on our results we expect that ns pulses can improve fusion yields in electrofusion of cells with different size, such as myeloma cells and B lymphocytes in hybridoma technology.
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| 7. |
- Cardemil, Carina, et al.
(author)
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Strontium-doped calcium phosphate and hydroxyapatite granules promote different inflammatory and bone remodelling responses in normal and ovariectomised rats.
- 2013
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In: PLosOne. - : Public Library of Science (PLoS). - 1932-6203. ; 8:12
-
Journal article (peer-reviewed)abstract
- The healing of bone defects may be hindered by systemic conditions such as osteoporosis. Calcium phosphates, with or without ion substitutions, may provide advantages for bone augmentation. However, the mechanism of bone formation with these materials is unclear. The aim of this study was to evaluate the healing process in bone defects implanted with hydroxyapatite (HA) or strontium-doped calcium phosphate (SCP) granules, in non-ovariectomised (non-OVX) and ovariectomised (OVX) rats. After 0 (baseline), six and 28d, bone samples were harvested for gene expression analysis, histology and histomorphometry. Tumour necrosis factor-α (TNF-α), at six days, was higher in the HA, in non-OVX and OVX, whereas interleukin-6 (IL-6), at six and 28d, was higher in SCP, but only in non-OVX. Both materials produced a similar expression of the receptor activator of nuclear factor kappa-B ligand (RANKL). Higher expression of osteoclastic markers, calcitonin receptor (CR) and cathepsin K (CatK), were detected in the HA group, irrespective of non-OVX or OVX. The overall bone formation was comparable between HA and SCP, but with topological differences. The bone area was higher in the defect centre of the HA group, mainly in the OVX, and in the defect periphery of the SCP group, in both non-OVX and OVX. It is concluded that HA and SCP granules result in comparable bone formation in trabecular bone defects. As judged by gene expression and histological analyses, the two materials induced different inflammatory and bone remodelling responses. The modulatory effects are associated with differences in the spatial distribution of the newly formed bone.
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| 8. |
- Ušaj, Marko, et al.
(author)
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Electrofusion of B16-F1 and CHO cells: the comparison of the pulse first and contact first protocols
- 2013
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In: Bioelectrochemistry. - : Elsevier BV. - 1567-5394 .- 1878-562X. ; 89, s. 34-41
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Journal article (peer-reviewed)abstract
- High voltage electric pulses induce permeabilisation (i.e. electroporation) of cell membranes. Electric pulses also induce fusion of cells which are in contact. Contacts between cells can be established before electroporation, in so-called contact first or after electroporation in pulse first protocol. The lowest fusion yield was obtained by pulse first protocol (0.8%±0.3%) and it was only detected by phase contrast microscopy. Higher fusion yield detected by fluorescence microscopy was obtained by contact first protocol. The highest fusion yield (15%) was obtained by modified adherence method whereas fusion yield obtained by dielectrophoresis was lower (4%). The results are in agreement with current understanding of electrofusion process and with existing electrochemical models. Our data indicate that probability of stalk formation leading to fusion pores and cytoplasmic mixing is higher in contact first protocol where cells in contact are exposed to electric pulses. Another contribution of present study is the comparison of two detection methods. Although fusion yield can be more precisely determined with fluorescence microscopy we should note that by using this detection method single coloured fused cells cannot be detected. Therefore low fusion yields are more reliably detected by phase contrast microscopy.
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| 9. |
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| 10. |
- Martinez Avila, Hector, 1985, et al.
(author)
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Biocompatibility evaluation of densified bacterial nanocellulose hydrogel as an implant material for auricular cartilage regeneration
- 2014
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In: Applied Microbiology and Biotechnology. - : Springer Science and Business Media LLC. - 1432-0614 .- 0175-7598. ; 98:17, s. 7423-7435
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Journal article (peer-reviewed)abstract
- Bacterial nanocellulose (BNC), synthesized by the bacterium Gluconacetobacter xylinus, is composed of highly hydrated fibrils (99 % water) with high mechanical strength. These exceptional material properties make BNC a novel biomaterial for many potential medical and tissue engineering applications. Recently, BNC with cellulose content of 15 % has been proposed as an implant material for auricular cartilage replacement, since it matches the mechanical requirements of human auricular cartilage. This study investigates the biocompatibility of BNC with increased cellulose content (17 %) to evaluate its response in vitro and in vivo. Cylindrical BNC structures (48 Au 20 mm) were produced, purified in a built-in house perfusion system, and compressed to increase the cellulose content in BNC hydrogels. The reduction of endotoxicity of the material was quantified by bacterial endotoxin analysis throughout the purification process. Afterward, the biocompatibility of the purified BNC hydrogels with cellulose content of 17 % was assessed in vitro and in vivo, according to standards set forth in ISO 10993. The endotoxin content in non-purified BNC (2,390 endotoxin units (EU)/ml) was reduced to 0.10 EU/ml after the purification process, level well below the endotoxin threshold set for medical devices. Furthermore, the biocompatibility tests demonstrated that densified BNC hydrogels are non-cytotoxic and cause a minimal foreign body response. In support with our previous findings, this study concludes that BNC with increased cellulose content of 17 % is a promising non-resorbable biomaterial for auricular cartilage tissue engineering, due to its similarity with auricular cartilage in terms of mechanical strength and host tissue response.
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| 11. |
- Skiöld, Sara, et al.
(author)
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Radiation-induced stress response in peripheral blood of breast cancer patients differs between patients with severe acute skin reactions and patients with no side effects to radiotherapy
- 2013
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In: Mutation research. Genetic toxicology and environmental mutagenesis. - : Elsevier BV. - 1383-5718 .- 1879-3592. ; 756:1-2, s. 152-157
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Journal article (peer-reviewed)abstract
- The aim of the study was to compare the radiation-induced oxidative stress response in blood samples from breast cancer patients that developed severe acute skin reactions during the radiotherapy, with the response in blood samples from patients with no side effects. Peripheral blood was collected from 12 breast cancer patients showing no early skin reactions after radiotherapy (RTOG grade 0) and from 14 breast cancer patients who developed acute severe skin reactions (RTOG grade 3-4). Whole blood was irradiated with 0, 5 and 2000 mGy gamma-radiation and serum was isolated. The biomarker for oxidative stress, 8-oxo-dG, was analyzed in the serum by a modified ELISA. While a significant radiation-induced increase of serum 8-oxo-dG levels was observed in serum of the RTOG 0 patients, no increase was seen in serum of the RTOG 3-4 patients. The radiation induced increase in serum 8-oxo-dG levels after 5 mGy did not differ significantly from the increase observed for 2000 mGy in the RTOG 3-4 cohort, thus no dose response relation was observed. A receiver operating characteristic (ROC) value of 0.97 was obtained from the radiation-induced increase in 8-oxo-dG indicating that the assay could be used to identify patients with severe acute adverse reactions to radiotherapy. The results show that samples of whole blood from patients, classified as highly radiosensitive (RTOG 3-4) based on their skin reactions to radiotherapy, differ significantly in their oxidative stress response to ionizing radiation compared to samples of whole blood from patients with no skin reactions (RTOG 0). Extracellular 8-oxo-dG is primarily a biomarker of nucleotide damage and the results indicate that the patients with severe acute skin reactions differ in their cellular response to ionizing radiation at the level of induction of oxidative stress or at the level of repair or both.
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| 12. |
- Metreveli, Giorgi, et al.
(author)
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A Size-Exclusion Nanocellulose Filter Paper for Virus Removal
- 2014
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In: Advanced Healthcare Materials. - : Wiley. - 2192-2640 .- 2192-2659. ; 10:3, s. 1546-1550
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Journal article (peer-reviewed)abstract
- This is the first time a 100% natural, unmodified nanofibrous polymer-based membrane is demonstrated capable of removing viruses solely based on the size-exclusion principle, with log10 reduction value (LRV) ≥ 6.3 as limited by the assay lower detection limit and the feed virus titre, thereby matching the performance of industrial synthetic polymer virus removal filters.
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| 13. |
- Jönsson, Håkan, 1979-, et al.
(author)
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Tröpfchen-Mikrofluidik für die Einzelzellanalyse
- 2012
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In: Angewandte Chemie. - : Wiley Online Library. - 0044-8249 .- 1521-3757. ; 124:49, s. 12342-12359
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Journal article (peer-reviewed)abstract
- Die tröpfchenbasierte Mikrofluidik dient der Isolierung und Manipulation von einzelnen Zellen und Reagentien innerhalb von monodispersen, pikolitergroßen Flüssigkapseln bei einem Umsatz von tausenden Tröpfchen pro Sekunde. Diese Qualitäten machen die Tröpfchen‐Mikrofluidik geeignet für viele Anforderungen der Einzelzellanalyse. Durch die Monodispersität lässt sich die Konzentration in den Tröpfchen quantitativ einstellen. Die Tröpfchen bieten der Zelle und ihrer unmittelbaren Umgebung ein isoliertes Kompartiment, und bei einem Durchsatz von tausenden Tröpfchen pro Sekunde ist es möglich, zehntausende bis millionen verkapselte Zellen zu prozessieren. Heterogene Zellpopulationen lassen sich somit exakt beschreiben oder seltene Zellarten identifizieren. Das kleine Volumen der Tröpfchen macht auch sehr große Screenings ökonomisch machbar. Dieser Aufsatz gibt einen Überblick über den aktuellen Stand der Einzelzellanalyse durch die Tröpfchen‐Mikrofluidik und nennt Beispiele, bei denen sie biologische Vorgänge besser verstehen hilft.
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| 14. |
- Cardemil, Carina
(author)
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Effects of antiresorptive agents on inflammation and bone regeneration in different osseous sites - experimental and clinical studies
- 2014
-
Doctoral thesis (other academic/artistic)abstract
- The biological mechanisms involved in bone regeneration in osteoporotic bone and the effect of antiresorptive drugs in relation to surgically inserted biomaterials are not fully understood. Improved osseointegration of titanium implants but also adverse effects of antiresorptive therapies, such as osteonecrotic jaw have been described in the literature. The aims of this research project were, firstly, to investigate and to understand the biological events determining bone regeneration and implant integration, after administration of antiresorptive agents; secondly, to determine the cellular and molecular patterns of bone regeneration at implants and synthetic bone substitutes under osteoporotic conditions and, thirdly, to determine how different skeletal sites are affected. The present research included a study of jawbone morphology and gene expression in patients treated with systemic bisphosphonates. When compared to controls, higher gene expression levels of IL-1β was observed in bisphosphonate treated patients with osteonecrosis while bisphosphonate treated patients without necrosis showed lower expression levels of caspase 8, an apoptosis marker involved in the immune response. In ovariectomised rats, zoledronic acid resulted in site-specific differences in the rate of osseointegration and also of gene expression involved in bone healing and regeneration. Strontium-doped calcium phosphate inserted in the rat femur induced lower expression of osteoclastic markers compared to hydroxyapatite and higher bone formation in the periphery of the defects. Whereas major structural changes were demonstrated in the long bones of the ovariectomised rat, less structural alterations were shown in the mandible. However, ovariectomy resulted in lower expression of genes coding for bone formation and angiogenesis in the mandible. In conclusion, the present study shows that the mandible is differently affected by experimentally induced estrogen deficiency than the long bones. Bisphosphonates, administered systemically to estrogen deficient animals, impair osseointegration in the mandible, at least partly related to a downregulation of genes important for the osteogenic process. These observations may have implications for understanding the mechanisms involved in the deranged bone healing observed in the jawbone of bisphosphonate treated patients.
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| 15. |
- Lindahl, Anders, 1954, et al.
(author)
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Cartilage and Bone Regeneration
- 2014
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In: Tissue Engineering: Second Edition. - Amsterdam : Elsevier, Inc.. ; , s. 529-582
-
Book chapter (peer-reviewed)abstract
- This chapter deals with the tissue engineering aspects of one of the mesenchymal tissues-cartilage. It includes a brief description of the different cartilage types and their embryonal origin. Tissue structures including chondrocyte and extracellular matrix components are described in detail. The disease aspect of hyaline cartilage with emphasis on cartilage injuries and the tissue engineering approach to cartilage regeneration with the autologous chondrocyte implantation technique is described in depth. The future aspects of cartilage regeneration techniques with potential cell types other than autologous chondrocytes as well as new promising scaffold techniques are described. © 2015 Elsevier Inc. All rights reserved.
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| 16. |
- Mapelli, Valeria, 1978, et al.
(author)
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Biotechnology for production of bioactive seleno compounds and study of their influence on mouse metabolome
- 2011
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In: Natural Products Chemistry, Biology and Medicine IV Aug 28 - Sept 2, Acquafredda di Maratea, Italy.
-
Conference paper (other academic/artistic)abstract
- Organic seleno compounds are recognized as effective anti-oxidant agents and their bioactive role in prevention of certain forms of cancer has been suggested via in vitro studies and clinical trials. Among these compounds, Seleno-methyselenocysteine (SeMCys) and γ-glutamyl-SeMCys (γ-glu-SeMCys) are the most bioactive and the latter is the preferred storage form of selenium in Se-accumulator plants thanks to their Se-methyltransferase. Therefore, Se-accumulator edible plants such as Brassicaceae and Allioideae are the main source of SeMCys and γ-glu-SeMCys in the human diet. However, seasonal and environmental factors highly affect the content and the bioavailability of these bioactive compounds. A strategy to by-pass this problem and prevent selenium shortage in human diet is the production of Se-enriched yeast (Se-yeast) to be used as food supplement. In this work we show a biotechnological approach for production Se-yeast featured by higher content of SeMCys and γ-glu-SeMCys. Coupling of metabolic engineering and bioprocess optimization resulted in a Se-yeast with 24-fold increase of SeMCys levels, compared to commercial Se-yeast. The actual effect of the produced yeast has been evaluated in an animal study. In particular, as specific Se-compounds are known to activate phase II enzymes via the electrophile-responsive element (EpRE), this response was studied in transgenic mice expressing the luciferase gene under EpRE control. We observed no effect on regulation of EpRE, either overall or hepatic, by the different Se-supplements. Paradoxically, a decrease was observed in intestinal EpRE transactivation upon supplementation of the Se-yeast produced. The overall effect of the diet supplemented with Se-yeast on mouse metabolism is currently being evaluated by metabolome analysis of liver samples from the transgenic mice.
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| 17. |
- Hoffmann, Karolina, 1980
(author)
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Gliadin-Blocking Peptides In vitro assessment of their potential to alleviate celiac disease development
- 2010
-
Doctoral thesis (other academic/artistic)abstract
- This thesis work aimed to investigate the potential of synthetic peptides as agents to block wheat prolamins (gliadins) that trigger the development of symptoms in celiac disease. The first step of this investigation included selection and synthesis of peptides with high affinity to gliadins and assessment of the potential of these so-called blocking peptides to limit gliadin reactivity in vitro. Wheat proteins targeted by blocking peptides were characterized, and peptides ability to reduce gliadin recognition was evaluated in in vitro assays. It was tested whether blocking peptides could reduce gliadin processing by tissue transglutaminase, and its recognition by anti-gliadin antibodies. The digestive stability of complexes formed by gliadin and blocking peptides was also studied. Finally, their potential to reduce a negative non-immunological effect of gliadin on intestinal mucosal cells was assessed in vitro in a Caco-2 cell line model. A large pool of 12-mer peptides with a high affinity to gliadins was selected with the phage display technology, and two peptides denoted P61, and P64, were chosen for experiments. Blocking peptides expressed an affinity to a broad spectrum of gliadin proteins and to α-amylase/trypsin inhibitors, wheat allergenic proteins that are involved in eliciting an immune response in baker’s asthma. Both blocking peptides significantly reduced the tissue transglutaminase processing of intact gliadin and partially reduced its recognition by anti-gliadin antibodies. The blocking peptides also partially reduced the negative non-immunological effect that gliadin had on a Caco-2 cell line. However, complexes of blocking peptides with gliadin were only partially stable after the pancreatic phase of in vitro digestion, with P64 complex with gliadin being more stable than that of P61. The two chosen blocking peptides, P61 and P64, have proven the potential to bind to gliadin and to partially prevent its toxicity and recognition in in vitro assays. In order to be used in celiac disease therapy, however, more efficient gliadin blocking peptide complexes need to be explored. The large pool of 12-mer peptides obtained during selection with the phage display will further be screened in a search for the most effective peptides.
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| 18. |
- Härd, Torleif, et al.
(author)
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Inhibition of Amyloid Formation
- 2012
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In: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 421, s. 441-465
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Journal article (peer-reviewed)abstract
- Amyloid is aggregated protein in the form of insoluble fibrils. Amyloid deposition in human tissue-amyloidosis-is associated with a number of diseases including all common dementias and type II diabetes. Considerable progress has been made to understand the mechanisms leading to amyloid formation. It is, however, not yet clear by which mechanisms amyloid and protein aggregates formed on the path to amyloid are cytotoxic. Strategies to prevent protein aggregation and amyloid formation are nevertheless, in many cases, promising and even successful. This review covers research on intervention of amyloidosis and highlights several examples of how inhibition of protein aggregation and amyloid formation has been achieved in practice. For instance, rational design can provide drugs that stabilize a native folded state of a protein, protein engineering can provide new binding proteins that sequester monomeric peptides from aggregation, small molecules and peptides can be designed to block aggregation or direct it into non-cytotoxic paths, and monoclonal antibodies have been developed for therapies towards neurodegenerative diseases based on inhibition of amyloid formation and clearance. (c) 2012 Elsevier Ltd. All rights reserved.
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| 19. |
- Zirk, Katrin, et al.
(author)
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Vectorization of splice-correcting oligonucleotides with cell-penetrating peptides
- 2013
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In: Chimica oggi. - 0392-839X .- 1973-8250. ; 31:2, s. 12-15
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Journal article (peer-reviewed)abstract
- Personalized medicine approaches based on different gene therapy settings have gained much attention lately. In order to enforce successful gene therapy, genetic material needs to be delivered into cells. Nucleic acids and their analogues are unable to do so and thus require assistance to reach their site of action residing in the cytoplasm or nucleus. Here we give a short review on recent advancements in cell-penetrating peptide mediated delivery of splice-correcting oligonucleotides. We report on different cell-penetrating peptides applied for vectorization of splice-correcting oligonucleotides using both covalent conjugation and non-covalent nanoparticle formation approach. While covalent conjugation has gained extensive interest, there have also been great advances in non-covalent complex formation.
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| 20. |
- Kashfi, Pariya, 1980
(author)
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Towards Usable openEHR-aware Clinical Decision Support: A User-centered Design Approach
- 2011
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Licentiate thesis (other academic/artistic)abstract
- Nowadays, the use of computerized approaches to support health care processesin order to improve quality of health care is widespread in the clinical domain.Electronic health records (EHR) and clinical decision support (CDS) are consideredto be two complementary approaches to improve quality of health care.It is shown that EHRs are not able to improve quality of health care withoutbeing supported by other features such as CDS. On the other hand, one of thesuccess factors of CDS is its integration into EHR, and since there are variousinternational EHR standards (such as openEHR) being developed, it is crucialto take these standards into consideration while developing CDS.Various clinical decision support systems (CDSS) are developed but unfortunatelyonly a few of them are being used routinely. Two of the reasons for unacceptability of CDSSs among their users, i.e. clinicians, are shown to be their separation from EHRs and poor usability of the user interfaces. Besides integration into underlying information framework, i.e. EHR systems, consideration of human-computer interaction (HCI) in designing and evaluating CDS isone of the success factors that developers of these systems should keep in mind.This thesis addresses the question of how usable openEHR-aware clinical decision support can be designed and developed in order to improve the quality of health care. To answer this research question, several sub-questions were identified and investigated. This included analyzing \state of the art" in two different aspects of design and development and evaluation of CDS and also investigating application of a customized user-centered design (UCD) process in developing openEHR-based clinical applications.Analysis of state of the art in interplay between HCI and CDS and also the intersection between CDS and EHR revealed that consideration of both HCI and integration of CDS into EHR is more appreciated in theory than in practice and there is still a long way to go before reaching an acceptable level in these two success factors of CDS.Moreover, the experience in designing an openEHR-based clinical application revealed that apart from benefits offered by openEHR approach, such as specifying different roles and involvement of domain experts in defining domain concepts, there are various shortcomings that need to be improved, for instance the limited support for openEHR application developers. Additionally, this study revealed that there are characteristics of the domain, tasks and users in the domain that developers should be informed about while applying UCD methods.
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| 21. |
- Andersson, Helene, 1983, et al.
(author)
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Effects of molecular weight on permeability and microstructure of mixed ethyl-hydroxypropyl-cellulose films
- 2013
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In: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 48:1-2, s. 240-248
-
Journal article (peer-reviewed)abstract
- Films of ethyl cellulose (EC) and water-soluble hydroxypropyl cellulose (HPC) can be used for extended release coatings in oral formulations. The permeability and microstructure of free EC/HPC films with 30% w/w HPC were studied to investigate effects of EC molecular weight. Phase separation during film spraying and subsequent HPC leaching after immersion in aqueous media cause pore formation in such films. It was found that sprayed films were porous throughout the bulk of the films after water immersion. The molecular weight affected HPC leaching, pore morphology and film permeability; increasing the molecular weight resulted in decreasing permeability. A model to distinguish the major factors contributing to diffusion retardation in porous films showed that the trend in permeability was determined predominantly by factors associated with the geometry and arrangement of pores, independent of the diffusing species. The film with the highest molecular weight did, however, show an additional contribution from pore wall/permeant interactions. In addition, rapid drying and increasing molecular weight resulted in smaller pores, which suggest that phase separation kinetics affects the final microstructure of EC/HPC films. Thus, the molecular weight influences the microstructural features of pores, which are crucial for mass transport in EC/HPC films.
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| 22. |
- Fleetwood, Filippa, et al.
(author)
-
Simultaneous targeting of two ligand-binding sites on VEGFR2 using biparatopic Affibody molecules results in dramatically improved affinity
- 2014
-
In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 4, s. 7518-
-
Journal article (peer-reviewed)abstract
- Angiogenesis plays an important role in cancer and ophthalmic disorders such as age-related macular degeneration and diabetic retinopathy. The vascular endothelial growth factor (VEGF) family and corresponding receptors are regulators of angiogenesis and have been much investigated as therapeutic targets. The aim of this work was to generate antagonistic VEGFR2-specific affinity proteins having adjustable pharmacokinetic properties allowing for either therapy or molecular imaging. Two antagonistic Affibody molecules that were cross-reactive for human and murine VEGFR2 were selected by phage and bacterial display. Surprisingly, although both binders independently blocked VEGF-A binding, competition assays revealed interaction with non-overlapping epitopes on the receptor. Biparatopic molecules, comprising the two Affibody domains, were hence engineered to potentially increase affinity even further through avidity. Moreover, an albumin-binding domain was included for half-life extension in future in vivo experiments. The best-performing of the biparatopic constructs demonstrated up to 180-fold slower dissociation than the monomers. The new Affibody constructs were also able to specifically target VEGFR2 on human cells, while simultaneously binding to albumin, as well as inhibit VEGF-induced signaling. In summary, we have generated small antagonistic biparatopic Affibody molecules with high affinity for VEGFR2, which have potential for both future therapeutic and diagnostic purposes in angiogenesis-related diseases.
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| 23. |
- Honarvar, Hadis, et al.
(author)
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Position for site-specific attachment of a DOTA chelator to synthetic affibody molecules has a different influence on the targeting properties of 68Ga-Compared to 111in-labeled conjugates
- 2014
-
In: Molecular Imaging. - : SAGE Publications. - 1535-3508 .- 1536-0121. ; 13:10
-
Journal article (peer-reviewed)abstract
- Affibody molecules, small (7 kDa) scaffold proteins, are a promising class of probes for radionuclide molecular imaging. Radiolabeling of Affibody molecules with the positron-emitting nuclide 68Ga would permit the use of positron emission tomography (PET), providing better resolution, sensitivity, and quantification accuracy than single-photon emission computed tomography (SPECT). The synthetic anti-HER2 ZHER2:S1 Affibody molecule was conjugated with DOTA at the N-terminus, in the middle of helix 3, or at the Cterminus. The biodistribution of 68Ga-and 111In-labeled Affibody molecules was directly compared in NMRI nu/nu mice bearing SKOV3 xenografts. The position of the chelator strongly influenced the biodistribution of the tracers, and the influence was more pronounced for 68Ga-labeled Affibody molecules than for the 111In-labeled counterparts. The best 68Ga-labeled variant was 68Ga-[DOTA-A1]-ZHER2:S1, which provided a tumor uptake of 13 ± 1 %ID/g and a tumor to blood ratio of 39 ± 12 at 2 hours after injection. 111In-[DOTA-A1]-ZHER2:S1 and 111In-[DOTA-K58]-ZHER2:S1 were equally good at this time point, providing a tumor uptake of 15 to 16 %ID/g and a tumor to blood ratio in the range of 60 to 80. In conclusion, the selection of the best position for a chelator in Affibody molecules can be used for optimization of their imaging properties. This may be important for the development of Affibody-based and other protein-based imaging probes.
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| 24. |
- Srivastava, Vaibhav, et al.
(author)
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OnPLS integration of transcriptomic, proteomic and metabolomic data shows multi-level oxidative stress responses in the cambium of transgenic hipI- superoxide dismutase Populus plants
- 2013
-
In: BMC Genomics. - : BioMed Central. - 1471-2164. ; 14
-
Journal article (peer-reviewed)abstract
- BACKGROUND: Reactive oxygen species (ROS) are involved in the regulation of diverse physiological processes in plants, including various biotic and abiotic stress responses. Thus, oxidative stress tolerance mechanisms in plants are complex, and diverse responses at multiple levels need to be characterized in order to understand them. Here we present system responses to oxidative stress in Populus by integrating data from analyses of the cambial region of wild-type controls and plants expressing high-isoelectric-point superoxide dismutase (hipI-SOD) transcripts in antisense orientation showing a higher production of superoxide. The cambium, a thin cell layer, generates cells that differentiate to form either phloem or xylem and is hypothesized to be a major reason for phenotypic perturbations in the transgenic plants. Data from multiple platforms including transcriptomics (microarray analysis), proteomics (UPLC/QTOF-MS), and metabolomics (GC-TOF/MS, UPLC/MS, and UHPLC-LTQ/MS) were integrated using the most recent development of orthogonal projections to latent structures called OnPLS. OnPLS is a symmetrical multi-block method that does not depend on the order of analysis when more than two blocks are analysed. Significantly affected genes, proteins and metabolites were then visualized in painted pathway diagrams.RESULTS: The main categories that appear to be significantly influenced in the transgenic plants were pathways related to redox regulation, carbon metabolism and protein degradation, e.g. the glycolysis and pentose phosphate pathways (PPP). The results provide system-level information on ROS metabolism and responses to oxidative stress, and indicate that some initial responses to oxidative stress may share common pathways.CONCLUSION: The proposed data evaluation strategy shows an efficient way of compiling complex, multi-platform datasets to obtain significant biological information.
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| 25. |
- Sul, Young-Taeg, 1960, et al.
(author)
-
A novel in vivo method for quantifying the interfacial biochemical bond strength of bone implants
- 2010
-
In: Journal of the Royal Society Interface. - London, United Kingdom : Royal Society. - 1742-5689 .- 1742-5662. ; 7:42, s. 81-90
-
Journal article (peer-reviewed)abstract
- Quantifying the in vivo interfacial biochemical bond strength of bone implants is a biological challenge. We have developed a new and novel in vivo method to identify an interfacial biochemical bond in bone implants and to measure its bonding strength. This method, named biochemical bond measurement (BBM), involves a combination of the implant devices to measure true interfacial bond strength and surface property controls, and thus enables the contributions of mechanical interlocking and biochemical bonding to be distinguished from the measured strength values. We applied the BBM method to a rabbit model, and observed great differences in bone integration between the oxygen (control group) and magnesium (test group) plasma immersion ion-implanted titanium implants (0.046 versus 0.086 MPa, n=10, p=0.005). The biochemical bond in the test implants resulted in superior interfacial behaviour of the implants to bone: (i) close contact to approximately 2 μm thin amorphous interfacial tissue, (ii) pronounced mineralization of the interfacial tissue, (iii) rapid bone healing in contact, and (iv) strong integration to bone. The BBM method can be applied to in vivo experimental models not only to validate the presence of a biochemical bond at the bone–implant interface but also to measure the relative quantity of biochemical bond strength. The present study may provide new avenues for better understanding the role of a biochemical bond involved in the integration of bone implants.
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| 26. |
- Kandušer, Maša, et al.
(author)
-
Cell electrofusion: past and future perspectives for antibody production and cancer cell vaccines
- 2014
-
In: Expert Opinion on Drug Delivery. - : Taylor & Francis. - 1742-5247 .- 1744-7593. ; 11:12, s. 1885-1898
-
Journal article (peer-reviewed)abstract
- Introduction: In the past few decades, new methods for drug and gene delivery have been developed, among which electroporation and electrofusion have gained noticeable attention. Lately, advances in the field of immunotherapy have enabled new cancer therapies based on immune response, including monoclonal antibodies and cell vaccines. Efficient cell fusion is needed for both hybridoma production and cell vaccine preparation, and electrofusion is a promising method to achieve this goal.Areas covered: In the present review, we cover new strategies of cancer treatment related to antibody production and cell vaccines. In more detail, cell electroporation and electrofusion are addressed. We briefly describe principles of cell electroporation and focus on electrofusion and its influential factors, with special attention on the fusogenic state of the cell membrane, contact formation, the effect of electrofusion media and cell viability. We end the review with an overview of the very promising field of microfluidic devices for electrofusion.Expert opinion: In our opinion, electrofusion can be a very efficient method for hybridoma and cell vaccine production. Advances in the development of microfluidic devices and a better understanding of the underlying (biological) mechanisms will overcome the current limitations.
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| 27. |
- Koppisetty, Ashok Krishna Chaitanya, 1982, et al.
(author)
-
Computational studies on the interaction of ABO-active saccharides with the norovirus VA387 capsid protein can explain experimental binding data
- 2010
-
In: Journal of Computer-Aided Molecular Design. - : Springer Science and Business Media LLC. - 0920-654X .- 1573-4951. ; 24:5, s. 423-431
-
Journal article (peer-reviewed)abstract
- Norovirus strains are known to cause recurring epidemics of winter vomiting disease. The crystal structure of the capsid protein of VA387, a representative of the clinically important GII.4 genocluster, was recently solved in complex with histo-blood group A- and B-trisaccharides. However, the VA387 strain is known to bind also to other natural carbohydrates for which detailed structural information of the complexes is not available. In this study we have computationally explored the fit of the VA387 with a set of naturally occurring carbohydrate ligands containing a terminal alpha 1,2-linked fucose. MD simulations both with explicit and implicit solvent models indicate that type 1 and 3 extensions of the ABO-determinant including ALe(b) and BLe(b) pentasaccharides can be well accommodated in the site. Scoring with Glide XP indicates that the downstream extensions of the ABO-determinants give an increase in binding strength, although the alpha 1,2-linked fucose is the single strongest interacting residue. An error was discovered in the geometry of the GalNAc-Gal moiety of the published crystal structure of the A-trisaccharide/VA387 complex. The present modeling of the complexes with histo-blood group A-active structures shows some contacts which provide insight into mutational data, explaining the involvement of I389 and Q331. Our results can be applicable in structure-based design of adhesion inhibitors of noroviruses.
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| 28. |
- Engberg, GR, et al.
(author)
-
Transplantation of autologous minced bladder mucosa for a one-step reconstruction of a tissue engineered bladder conduit
- 2013
-
In: BioMed research international. - : Hindawi Limited. - 2314-6141 .- 2314-6133. ; 2013, s. 212734-
-
Journal article (peer-reviewed)abstract
- Surgical intervention is sometimes needed to create a conduit from the abdominal wall to the bladder for self-catheterization. We developed a method for tissue engineering a conduit for bladder emptying withoutin vitrocell culturing as a one-step procedure. In a porcine animal model bladder, wall tissue was excised and the mucosa was minced to small particles. The particles were attached to a tube in a 1 : 3 expansion rate with fibrin glue and transplanted back by attaching the tube to the bladder and through the abdominal wall. Sham served as controls. After 4-5 weeks, conduits were assessed in respect to macroscopic and microscopic appearance in 6 pigs. Two pigs underwent radiology before termination. Gross examination revealed a patent conduit with an opening to the bladder. Histology and immunostaining showed a multilayered transitional uroepithelium in all cases. Up to 89% of the luminal surface area was neoepithelialized but with a loose attachment to the submucosa. No epithelium was found in control animals. CT imaging revealed a patent channel that could be used for filling and emptying the bladder. Animals that experienced surgical complications did not form conduits. Minced autologous bladder mucosa can be transplanted around a tubular mold to create a conduit to the urinary bladder withoutin vitroculturing.
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| 29. |
- Erlöv, Tobias, et al.
(author)
-
A fast 2D tissue motion estimator based on the phase of the intensity enables visualization of the propagation of the longitudinal movement in the carotid artery wall
- 2013
-
In: 2013 IEEE International Ultrasonics Symposium (IUS). - 9781467356855 ; , s. 1761-1764
-
Conference paper (peer-reviewed)abstract
- A fast 2D motion estimator has been developed and evaluated. The method does not utilize block-matching or iterative solutions and is thus more computationally efficient and suitable for real-time motion estimation over the entire image. The method has been evaluated on 1) phantom measurements and 2) in vivo on the carotid artery wall of 17 subjects, where measurements of the longitudinal displacement of the intima-media complex were compared to our previously validated method. The mean error of the phantom measurements was 2.0 +/- 3.3% (velocities between 2-15 mm/s; approx. 60 million estimations). In the in vivo measurements the mean difference (validated-proposed) was 18 +/- 44 mu m. Further the method has enabled visualization of the propagation of the longitudinal movement in the carotid artery wall. Several different phases of the longitudinal propagation, which seem to be connected to the multi-phasic pattern of the longitudinal movement, can be seen. All phases of the longitudinal propagation seem to originate from the direction of the heart.
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| 30. |
- Evertsson, Maria, et al.
(author)
-
Magnetomotive Ultrasound Imaging Of Rat Lymph Nodes In Situ: Assessment Of Imaging Parameters
- 2013
-
In: 2013 IEEE International Ultrasonics Symposium (IUS). - 9781467356855 ; , s. 600-603
-
Conference paper (peer-reviewed)abstract
- Detection and removal sentinel lymph nodes (SLN) is important in the diagnosis and treatment of breast cancer and malignant melanoma. The SLN is the first regional lymph node draining the cancer tumor and if the cancer has spread it is most likely to find cancer cells in the SLN. In this study we have been able to detect multimodal superparamagnetic iron oxide nanoparticles (SPIO-NP) in rat SLNs in situ using magnetomotive ultrasound imaging (MMUS). In MMUS a time-varying external magnetic field acts to move the NPs and, thus, the NP-laden tissue. This movement can be detected by proper processing of ultrasound data. We have recently developed an MMUS algorithm, based on quadrature detection and phase gating at the frequency of NP displacement, and this is the first study where the algorithm is evaluated in animals. For both higher NP-concentration, as well as smaller NPs, we found that the MMUS data showed a larger displacement (1.56 +/- 0.43 and 1.94 +/- 0.54 times larger, respectively). The MMUS displacement also increased with a lower excitation frequency (1.95 +/- 0.64 times larger for 5 Hz compared to 15 Hz) and higher excitation voltage (2.95 +/- 1.44 times larger for 30V compared to 10V). The results from this study show that the MMUS technique has potential to be used as bedside guidance during SLN surgery, well as being used as standalone technique in a number of other applications such as stem cell tracking and cardiovascular research.
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| 31. |
- Persson, Mikael, 1959, et al.
(author)
-
Microwave-Based Stroke Diagnosis Making Global Prehospital Thrombolytic Treatment Possible
- 2014
-
In: IEEE Transactions on Biomedical Engineering. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9294 .- 1558-2531. ; 61:11, s. 2806-2817
-
Journal article (peer-reviewed)abstract
- Here, we present two different brain diagnostic devices based on microwave technology and the associated two first proof-of-principle measurements that show that the systems can differentiate hemorrhagic from ischemic stroke in acute stroke patients, as well as differentiate hemorrhagic patients from healthy volunteers. The system was based on microwave scattering measurements with an antenna system worn on the head. Measurement data were analyzed with a machine-learning algorithm that is based on training using data from patients with a known condition. Computer tomography images were used as reference. The detection methodology was evaluated with the leave-one-out validation method combined with a Monte Carlo-based bootstrap step. The clinical motivation for this project is that ischemic stroke patients may receive acute thrombolytic treatment at hospitals, dramatically reducing or abolishing symptoms. A microwave system is suitable for prehospital use, and therefore has the potential to allow significantly earlier diagnosis and treatment than today.
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| 32. |
- Nielsen, Jens B, 1962
(author)
-
Production of biopharmaceutical proteins by yeast Advances through metabolic engineering
- 2013
-
In: Bioengineered Bugs. - : Informa UK Limited. - 2165-5979 .- 2165-5987. ; 4:4, s. 207-211
-
Research review (peer-reviewed)abstract
- Production of recombinant proteins for use as pharmaceuticals, so-called biopharmaceuticals, is a multi-billion dollar industry. Many different cell factories are used for the production of biopharmaceuticals, but the yeast Saccharomyces cerevisiae is an important cell factory as it is used for production of several large volume products. Insulin and insulin analogs are by far the dominating biopharmaceuticals produced by yeast, and this will increase as the global insulin market is expected to grow from USD12B in 2011 to more than USD32B by 2018. Other important biopharmaceuticals produced by yeast are human serum albumin, hepatitis vaccines and virus like particles used for vaccination against human papillomavirus. Here is given a brief overview of biopharmaceutical production by yeast and it is discussed how the secretory pathway can be engineered to ensure more efficient protein production. The involvement of directed metabolic engineering through the integration of tools from genetic engineering, systems biology and mathematical modeling, is also discussed.
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| 33. |
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| 34. |
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| 35. |
- Borde, Annika, 1979
(author)
-
Design of solid dosage forms for mucosal vaccination - Investigations on the influence of excipients on product performance
- 2012
-
Doctoral thesis (other academic/artistic)abstract
- Most vaccines today are liquid formulations for parental administration. However, there are several drawbacks connected to these vaccines. Since injectable vaccines only induce systemic antibody responses, they are not effective against the various pathogens that affect mucosal surfaces with poor permeability for serum-derived antibodies, e.g. the small intestine. Further disadvantages of liquid injectable vaccines are the need for medical personnel for the administration, cold chain requirements and large packaging sizes, which all are especially negative factors in developing countries. Solid and preferably mucoadhesive vaccine formulations that are administered via mucosal surfaces would offer a good alternative to many of these problems. The aim of this thesis was therefore to study the influence of excipients in the design of such formulations regarding i) formulation-related properties (mucoadhesion and antigen release) and ii) antigen-functionality preservation during freeze-dying.Mechanistic and immunological investigations using mucoadhesive hydrophilic matrix tablets as potential formulations for sublingual immunization were performed. The effect of osmotic pressure differences on the adhesiveness of hydrophilic swelling matrix tablets was investigated and it was found that a decrease in the osmotic pressure difference resulted in a decrease in the adhesive force, i.e. the force required to detach the tablet from a wet surface. Release of the model antigen ovalbumin from hydrophilic matrix tablets and a fast releasing formulation was characterized. The Bradford Assay used for the protein quantification was found to be disturbed by the hydrophilic polymer Carbopol and a correction method was set up. Sublingual immunizations in BALB/c mice indicated a poor potential of all ER tablets to evoke intestinal immune responses, whereas an immediate release resulted in high antibody titres. Thus it was concluded that the latter formulation type should be preferred in sublingual immunization. In the second part of the thesis the stabilizing potential of different excipients during freeze-drying was tested on killed whole-cell Vibrio cholerae bacteria as a model vaccine for pathogens causing mucosal infections. Sucrose showed great potential to avoid bacterial aggregation, preserve important antigen structures and to maintain the immunogenicity of the bacteria.Hopefully, the presented findings are a help and inspiration for formulators and immunologists to develop mucosal vaccine formulations so that diseases for which today no vaccines exist can be prevented in all parts of the world.
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| 36. |
- Gustafsson, Anki, et al.
(author)
-
Pichia pastoris-produced mucin-type fusion proteins with multivalent O-glycan substitution as targeting molecules for mannose-specific receptors of the immune system
- 2011
-
In: Glycobiology. - : Oxford University Press (OUP). - 0959-6658 .- 1460-2423. ; 21:8, s. 1071-1086
-
Journal article (peer-reviewed)abstract
- Mannose-binding proteins like the macrophage mannose receptor (MR), the dendritic cell-specific intercellular adhesion molecule-3 grabbing non-integrin (DC-SIGN) and mannose-binding lectin (MBL) play crucial roles in both innate and adaptive immune responses. Immunoglobulin fusion proteins of the P-selectin glycoprotein ligand-1 (PSGL-1/mIgG2b) carrying mostly O-glycans and, as a control, the a1-acid glycoprotein (AGP/mIgG2b) carrying mainly N-linked glycans were stably expressed in the yeast Pichia pastoris. P. pastoris-produced PSGL-1/mIgG2b was shown to carry O-glycans that mediated strong binding to mannose-specific lectins in a lectin array and were susceptible to cleavage by a-mannosidases including an a1,2- but not an a1,6-mannosidase. Electrospray ionization - ion trap mass spectrometry (ESI-MS) confirmed the presence of O-glycans containing up to 9 hexoses with the penta- and hexasaccharides being the predominant ones. a1,2- and a1,3-linked, but not a1,6-linked, mannose residues were detected by 1H-nuclear magnetic resonance (1H-NMR) spectroscopy confirming the results of the mannosidase cleavage. The apparent equilibrium dissociation constants for binding of PNGase F-treated mannosylated PSGL-1/mIgG2b to MR, DC-SIGN and MBL were shown by surface plasmon resonance to be 126, 56 and 16 nM, respectively. In conclusion, PSGL-1/mIgG2b expressed in P. pastoris carried O-glycans mainly comprised of a-linked mannoses and with up to nine residues. It bound mannose-specific receptors with high apparent affinity and may become a potent targeting molecule for these receptors in vivo.
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| 37. |
- Forsgren, Johan, et al.
(author)
-
Co-loading of bisphosphonates and antibiotics to a biomimetic hydroxyapatite coating.
- 2011
-
In: Biotechnology letters. - : Springer Science and Business Media LLC. - 1573-6776 .- 0141-5492. ; 33:6, s. 1265-8
-
Journal article (peer-reviewed)abstract
- We have incorporated bisphosphonates and antibiotics simultaneously into a biomimetic hydroxyapatite implant coating aiming to use the interaction between drug-molecules and hydroxyapatite to enable local release of the two different substances to obtain a dual biological effect. A sustained release over for 43h of antibiotics (cephalothin) was achieved without negative interference from the presence of the bisphosphonate (clodronate) which, in turn, successfully bonded to the coating surface. To our knowledge, this is the first study that indicates the possibility to simultaneously incorporate both antibiotics and bisphosphonates to an implant coating, a strategy that is believed to improve implant stability and reduce implant-related infections.
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| 38. |
- Lundin, Sverker, 1982-
(author)
-
Methods to Prepare DNA for Efficient Massive Sequencing
- 2012
-
Doctoral thesis (other academic/artistic)abstract
- Massive sequencing has transformed the field of genome biology due to the continuous introduction and evolution of new methods. In recent years, the technologies available to read through genomes have undergone an unprecedented rate of development in terms of cost-reduction. Generating sequence data has essentially ceased to be a bottleneck for analyzing genomes instead to be replaced by limitations in sample preparation and data analysis. In this work, new strategies are presented to increase both the throughput of library generation prior to sequencing, and the informational content of libraries to aid post-sequencing data processing. The protocols developed aim to enable new possibilities for genome research concerning project scale and sequence complexity.The first two papers that underpin this thesis deal with scaling library production by means of automation. Automated library preparation is first described for the 454 sequencing system based on a generic solid-phase polyethylene-glycol precipitation protocol for automated DNA handling. This was one of the first descriptions of automated sample handling for producing next generation sequencing libraries, and substantially improved sample throughput. Building on these results, the use of a double precipitation strategy to replace the manual agarose gel excision step for Illumina sequencing is presented. This protocol considerably improved the scalability of library construction for Illumina sequencing. The third and fourth papers present advanced strategies for library tagging in order to multiplex the information available in each library. First, a dual tagging strategy for massive sequencing is described in which two sets of tags are added to a library to trace back the origins of up to 4992 amplicons using 122 tags. The tagging strategy takes advantage of the previously automated pipeline and was used for the simultaneous sequencing of 3700 amplicons. Following that, an enzymatic protocol was developed to degrade long range PCR-amplicons and forming triple-tagged libraries containing information of sample origin, clonal origin and local positioning for the short-read sequences. Through tagging, this protocol makes it possible to analyze a longer continuous sequence region than would be possible based on the read length of the sequencing system alone. The fifth study investigates commonly used enzymes for constructing libraries for massive sequencing. We analyze restriction enzymes capable of digesting unknown sequences located some distance from their recognition sequence. Some of these enzymes have previously been extensively used for massive nucleic acid analysis. In this first high throughput study of such enzymes, we investigated their restriction specificity in terms of the distance from the recognition site and their sequence dependence. The phenomenon of slippage is characterized and shown to vary significantly between enzymes. The results obtained should favor future protocol development and enzymatic understanding.Through these papers, this work aspire to aid the development of methods for massive sequencing in terms of scale, quality and knowledge; thereby contributing to the general applicability of the new paradigm of sequencing instruments.
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| 39. |
- Fink, Helen, 1978, et al.
(author)
-
Bacterial cellulose modified with xyloglucan bearing the adhesion peptide RGD promotes endothelial cell adhesion and metabolism--a promising modification for vascular grafts.
- 2011
-
In: Journal of tissue engineering and regenerative medicine. - : Hindawi Limited. - 1932-7005 .- 1932-6254. ; 5:6, s. 454-63
-
Journal article (peer-reviewed)abstract
- Today, biomaterials such as polytetrafluorethylene (ePTFE) are used clinically as prosthetic grafts for vascular surgery of large vessels (>5 mm). In small diameter vessels, however, their performance is poor due to early thrombosis. Bacterial-derived cellulose (BC) is a new promising material as a replacement for blood vessels. This material is highly biocompatible in vivo but shows poor cell adhesion. In the native blood vessel, the endothelium creates a smooth non-thrombogenic surface. In order to sustain cell adhesion, BC has to be modified. With a novel xyloglucan (XG) glycoconjugate method, it is possible to introduce the cell adhesion peptide RGD (Arg-Gly-Asp) onto bacterial cellulose. The advantage of the XG-technique is that it is an easy one-step procedure carried out in water and it does not weaken or alter the fiber structure of the hydrogel. In this study, BC was modified with XG and XGRGD to asses primary human vascular endothelial cell adhesion, proliferation, and metabolism as compared with unmodified BC. This XG-RGD-modification significantly increased cell adhesion and the metabolism of seeded primary endothelial cells as compared with unmodified BC whereas the proliferation rate was affected only to some extent. The introduction of an RGD-peptide to the BC surface further resulted in enhanced cell spreading with more pronounced stress fiber formation and mature phenotype. This makes BC together with the XG-method a promising material for synthetic grafts in vascular surgery and cardiovascular research.
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| 40. |
- Johansson, Kristin, et al.
(author)
-
The effects of coating structure and water-holding capacity on the oxygen-scavenging ability of enzymes embedded in the coating layer
- 2013
-
In: TAPPI Journal. - : TAPPI Press. - 0734-1415. ; 12:6, s. 43-52
-
Journal article (peer-reviewed)abstract
- Enzymes catalyzing oxygen scavenging were embedded in latex-based coatings with and without barrier kaolin clay to produce material for active packages. The clay was used to create a porous structure, and the closed-structure matrix consisted of a biopolymer comprising either starch or gelatin to increase the water uptake of the coating. The effects of the porous open structure and of the water uptake of the coated layer on the oxygen-scavenging ability of the embedded enzymes were examined at both 75% and 100% relative humidity. The results showed that the porous clay structure led to higher oxygen-scavenging capacity than that of a closed structure at both test conditions by enabling a high diffusion rate for oxygen and glucose to the active sites of the enzymes. The addition of a water-holding biopolymer did not always significantly affect the oxygen-scavenging capacity. However for a less-porous layer at 100% relative humidity, an increase in the amount of biopolymer resulted in an increase in oxygen-scavenging capacity. The results were treated statistically using multiple-factor analysis where the most important factor for the oxygen-scavenging ability was found to be the addition of clay. The coatings were also characterized with respect to water vapor uptake, overall migration, porosity, and scanning electron microscopy images.
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| 41. |
- Johansson, Staffan, 1978-, et al.
(author)
-
A MEMS-based passive air flow regulator for handheld breath diagnostics
- 2014
-
In: Sensors and Actuators A-Physical. - : Elsevier. - 0924-4247 .- 1873-3069. ; 215, s. 65-70
-
Journal article (peer-reviewed)abstract
- This paper reports on a passive MEMS-based flow regulator designed to maintain a steady flow during asthma diagnostics. A prototype consisting of six in-plane moving pistons that restrict the flow through six flow orifices has been fabricated from three wafers using standard silicon micromachining. The in-plane design enables relatively large flows and tuning of the flow and pressure range to specific application requirements by changing a wafer thickness. In particular, for FENO asthma monitoring, regulatory guidelines specifies that measurements should be made at steady flow of approximately 50 ml/s and within a pressure range of 1–2 kPa. Experimental evaluation of the prototype shows that the flow rate is controlled within a dynamic pressure range of 770 Pa compared to only 430 Pa for a dummy structure and that it can be achieved on a chip measuring only 2 mm × 2 mm × 4 mm. The evaluation also showed that condensation of exhaled air that expectedly occurs in the flow regulator at room temperature can be eliminated by local heating of the device to 40◦C.
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| 42. |
- Johansson, Staffan, 1978-, et al.
(author)
-
A MEMS-based passive hydrocephalus shunt with adaptive flow characteristics
- 2013
-
In: 2013 Transducers & Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS & EUROSENSORS XXVII). - : IEEE conference proceedings. - 9781467359818 ; , s. 1671-1674
-
Conference paper (peer-reviewed)abstract
- This paper reports a novel MEMS valve with adaptive flow characteristics for improved treatment of hydrocephalus, a disease that is characterized by elevated pressure in the cerebrospinal fluid (CSF) that surrounds the brain and spinal cord. In contrast to conventional valves with two ports, the valve presented here features a third port, called compensation port, which utilizes hydrostatic pressure to adapt CSF drainage based on body position. A prototype has been fabricated using standard MEMS manufacturing processes and the experimental evaluation successfully showed that the flow rate was adjustable with a varying hydrostatic pressure on the compensation port. Extracted data shows that flow rate was at near ideal values at both standing and laying body position showing an effective adaptation to body position. This is the first passive hydrocephalus valve intended for body position dependent CSF pressure regulation.
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| 43. |
- Anasontzis, George E, 1980, et al.
(author)
-
Constitutive homologous expression of phosphoglucomutase and transaldolase increases the metabolic flux of Fusarium oxysporum
- 2014
-
In: Microbial Cell Factories. - : Springer Science and Business Media LLC. - 1475-2859. ; 13:1
-
Journal article (peer-reviewed)abstract
- Background: Fusarium oxysporum is among the few filamentous fungi that have been reported of being able to directly ferment biomass to ethanol in a consolidated bioprocess. Understanding its metabolic pathways and their limitations can provide some insights on the genetic modifications required to enhance its growth and subsequent fermentation capability. In this study, we investigated the hypothesis reported previously that phosphoglucomutase and transaldolase are metabolic bottlenecks in the glycolysis and pentose phosphate pathway of the F. oxysporum metabolism.Results: Both enzymes were homologously overexpressed in F. oxysporum F3 using the gpdA promoter of Aspergillus nidulans for constitutive expression. Transformants were screened for their phosphoglucomutase and transaldolase genes expression levels with northern blot. The selected transformant exhibited high mRNA levels for both genes, as well as higher specific activities of the corresponding enzymes, compared to the wild type. It also displayed more than 20 and 15% higher specific growth rate upon aerobic growth on glucose and xylose, respectively, as carbon sources and 30% higher biomass to xylose yield. The determination of the relative intracellular amino and non-amino organic acid concentrations at the end of growth on glucose revealed higher abundance of most determined metabolites between 1.5- and 3-times in the recombinant strain compared to the wild type. Lower abundance of the determined metabolites of the Krebs cycle and an 68-fold more glutamate were observed at the end of the cultivation, when xylose was used as carbon source.Conclusions: Homologous overexpression of phosphoglucomutase and transaldolase in F. oxysporum was shown to enhance the growth characteristics of the strain in both xylose and glucose in aerobic conditions. The intracellular metabolites profile indicated how the changes in the metabolome could have resulted in the observed growth characteristics. © 2014 Anasontzis et al.; licensee BioMed Central Ltd.
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| 44. |
- Sjöblom, Magnus, et al.
(author)
-
Secretion and expression dynamics of a GFP-tagged mucin-type fusion protein in high cell density Pichia pastoris bioreactor cultivations
- 2012
-
In: Advances in Bioscience and Biotechnology. - : Scientific Research Publishing, Inc.. - 2156-8456 .- 2156-8502. ; 3:3, s. 238-248
-
Journal article (peer-reviewed)abstract
- The methanol inducible alcohol oxidase 1 promoter and the Saccharomyces cerevisiae alpha-factor prepro secretion signal were used to drive expression and secretion of a mucin-type fusion protein by Pichia pastoris in 1 L scale bioreactors. The aim of the study was to understand how varying expression rates influenced the secretion dynamics of the fusion protein in terms of intracellular- and extracellular concentrations. Endoplasmic reticulum (ER) folding stress was assessed by the relative expression of the unfolded protein response controlled KAR2 gene. Three predefined methanol feeding models were applied to control the fusion protein synthesis rate. To track the fusion protein synthesis in a non-invasive manner and to follow its intracellular distribution, its C-terminal was linked to the green fluorescent protein. Under all conditions the fusion protein was found to partially accumulate intracellularly, where the major fraction was an insoluble, fluorescent full-sized protein. The high degree of glycosylation of the insoluble fusion protein indicated a secretory bottle-neck in the Golgi-system. This result was consistent with low ER folding stress as quantified by the relative expression of the KAR2 gene. Reduction of recombinant protein synthesis rate, by using lower feed rates of methanol, enhanced extracellular concentrations from 8 to 18 mg·L–1 and reduced the rate of intracellular accumulation. This clearly demonstrates the importance of tuning the synthesis rate with secretory bottle-necks to maintain secretion.
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| 45. |
- Bjursten, Lars Magnus, et al.
(author)
-
Titanium dioxide nanotubes enhance bone bonding in vivo.
- 2010
-
In: Journal of biomedical materials research. Part A. - : Wiley. - 1552-4965 .- 1549-3296. ; 92:3, s. 1218-24
-
Journal article (peer-reviewed)abstract
- Implant topography is critical to the clinical success of bone-anchored implants, yet little is known how nano-modified implant topography affects osseointegration. We investigate the in vivo bone bonding of two titanium implant surfaces: titanium dioxide (TiO(2)) nanotubes and TiO(2) gritblasted surfaces. In previous in vitro studies, the topography of the TiO(2) nanotubes improved osteoblast proliferation and adhesion compared with gritblasted titanium surfaces. After four weeks of implantation in rabbit tibias, pull-out testing indicated that TiO(2) nanotubes significantly improved bone bonding strength by as much as nine-fold compared with TiO(2) gritblasted surfaces. Histological analysis confirmed greater bone-implant contact area, new bone formation, and calcium and phosphorus levels on the nanotube surfaces. It is anticipated that further studies will contribute to a better understanding of the effect of implant nanotopography on in vivo bone formation and bonding strength.
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| 46. |
- Ghareh Baghi, Ghareh Baghi
(author)
-
Assessment of Valvular Aortic Stenosis by Signal Analysis of the Phonocardiogram
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Aortic stenosis (AS) is one of the most prevalent valvular heart diseases in elderly people. According to the recommendations of both the American Heart Association and the European Society of Cardiology, severity assessment of AS is primarily based on echocardiographic findings. The experience of the investigator here play important roles in the accuracy of the assessment, and therefore in the disease management. However, access to the expert physicians could be limited, especially in rural health care centers of developing countries.This thesis aims to develop processing algorithms tailored for phonocardiographic signal with the intension to obtain a noninvasive diagnostic tool for AS assessment and severity grading. The algorithms employ a phonocardiogram as input signal and perform analysis for screening and diagnostics. Such a decision support system, which we call “the intelligent phonocardiography”, can be widely used in primary healthcare centers.The main contribution of the thesis is to present innovative models for the phonocardiographic analysis by taking the segmental characteristics of the signal into consideration. Three novel methodologies are described, based on the presented models, to perform robust classification. In the first attempt, a novel pattern recognition framework is presented for screening of AS-related murmurs. The framework offers a hybrid model for classifying cyclic time series in general, but is tailored to detect the murmurs as a special case study. The time growing neural network is another method that we use to classify short time signals with abrupt frequency transition. The idea of the growing frames is extended to the cyclic signals with stochastic properties for the screening purposes. Finally, a combined statistical and artificial intelligent classifier is proposed for grading the severity of AS.The study suggests comprehensive statistical validations not only for the evaluation and representation of systolic murmurs but also for setting the methodology design parameters, which can be considered as one of the significant features of the study. The resulting methodologies can be implemented by using web and mobile technologies to be utilized in distributed healthcare system.
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| 47. |
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| 48. |
- Wallin, Patric, 1985
(author)
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Creating cell microenvironments in vitro
- 2012
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Licentiate thesis (other academic/artistic)abstract
- Stem cells have a great potential to bring about advancements in fields like developmental biology, drug discovery, cancer biology and tissue engineering. In order to be able to use stem cells to their full potential, it is important to have control over their behavior. In vivo cellular fate processes are controlled by the microenvironment around them and the many different factors in it. Cells communicate with their surrounding environment and shape it actively via cell-cell, cell-matrix and cell-liquid interactions. These interactions often happen on the cellular and subcellular length scale in defined time dependent sequences. Consequently, it is important to have systems that can provide different molecular cues with a high spatial and temporal resolution, in order to mimic cell microenvironments in vitro and study cells under controlled conditions. This thesis focuses on cell-matrix and cell-liquid interactions and different ways to create cell niches in cell culture systems. The focus is on designing and characterizing microfluidic cell culture platforms and, in particular, systems that are capable of forming molecular gradients. Flow-based and diffusion-based microfluidic gradient generators were combined with substrates coated with biofunctionalized gold nano dots, chemical active molecules, or electrospun microfibers. Thus, it was possible to provide cells with topographical cues and a defined surface chemistry, as well as soluble molecular cues in a gradient manner, simultaneously. COMSOL Multiphysics simulations were used to assist the design process and characterization of the microfluidic systems, and also to study cell receptor binding interactions in great detail. The developed toolbox of COMSOL modeling, a liquid handling system, a variety of microfluidic networks, surface modification techniques and molecular gradients allows the formation of multifactorial microenvironments to now study induction of cellular fate process of different cell types in vitro.
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| 49. |
- Hofström, Camilla, 1979-
(author)
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Engineering of Affibody molecules for Radionuclide Molecular Imaging and Intracellular Targeting
- 2013
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Doctoral thesis (other academic/artistic)abstract
- Affibody molecules are small (7 kDa) affinity proteins of non-immunoglobulin origin that have been generated to specifically interact with a large number of clinically important molecular targets.In this thesis, Affibody molecules have been employed as tracers for radionuclide molecular imaging of HER2- and IGF-1R-expressing tumors, paper I-IV, and for surface knock-down of EGFR, paper V. In paper I, a tag with the amino acid sequence HEHEHE was fused to the N-terminus of a HER2-specific Affibody molecule, (ZHER2), and was shown to enable facile IMAC purification and efficient tri-carbonyl 99mTc-labeling. In vivo evaluation of radioactivity uptake in different organs showed an improved biodistribution, including a 10-fold lower radioactivity uptake in liver, compared to the same construct with a H6-tag. In paper II, it was further shown that an N-terminally placed HEHEHE-tag on ZHER2 provided lower unspecific uptake of radioactivity in liver compared to its H6-tagged counterpart even when radiolabeling was at the C-terminus using alternative chemistries to attach 99mTc, 111In or 125I. In paper III, the H6-tag’s composition and position was varied with regards to charge, hydrophobicity and its C- or N-terminal placement on ZHER2. Among the ten variants investigated, it was found that an N-terminal HEHEHE-tag provided the most favorable overall biodistribution profile and that introduction of hydrophobic and positively charged amino acids provoked liver uptake of radioactivity. In paper IV, the HEHEHE-tag was shown to enable IMAC purification and tri-carbonyl 99mTc-labeling of an IGF-1R-specific Affibody molecule and improved its overall biodistribution when compared to the same construct with a H6-tag. In paper V, the aim was to develop an intracellular receptor-entrapment system to reduce the surface levels of EGFR. An EGFR-specific Affibody molecule was expressed as a fusion to different mutants of an intracellular transport protein in SKOV-3 cells, resulting in a collection of cell lines with 50%, 60%, 80% and 96% reduced surface level of EGFR. Analysis of the proliferation rate of these cell lines showed that a modest reduction (15%) in proliferation occurs between 60% and 80% reduction of the surface level of EGFR.
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| 50. |
- Härd, Torleif
(author)
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Protein engineering to stabilize soluble amyloid beta-protein aggregates for structural and functional studies
- 2011
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In: FEBS Journal. - : Wiley. - 1742-464X. ; 278, s. 3884-3892
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Research review (peer-reviewed)abstract
- The molecular biology underlying protein aggregation and neuronal death in Alzheimer's disease is not yet completely understood, but small soluble nonamyloid aggregates of the amyloid beta-protein (A beta) have been shown to play a fundamental neurotoxic role. The composition and biological action of such aggregates, known as oligomers and protofibrils, are therefore areas of intense study. However, research is complicated by the multitude of different interconverting aggregates that A beta can form in vitro and in vivo, and by the inhomogeneity and instability of in vitro preparations. Here we review recent studies in which protein engineering, and in particular disulfide engineering, has been applied to stabilize different A beta aggregates. For example, several techniques now exist to obtain stable and neurotoxic protofibrillar forms of A beta, and engineered A beta dimers, or larger aggregates formed by these, have been shown to specifically induce neuronal damage in a way that mimics Alzheimer's disease pathology. Disulfide engineering has also revealed structural properties of neurotoxic aggregates, for instance that A beta in protofibrils and globular oligomers adopts a beta-hairpin conformation that is similar to, but topologically distinct from, the conformation of A beta in mature amyloid fibrils. Protein engineering is therefore a workable strategy to address many of the outstanding questions relating to the structure, interconversion and biological effects of oligomers and protofibrils of A beta.
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