| 1. |
- Barth, Henrik, et al.
(författare)
-
A new model for in vitro testing of vitreous substitute candidates
- 2014
-
Ingår i: Graefe's Archives for Clinical and Experimental Ophthalmology. - Hedidelberg, Germany : Springer. - 0721-832X .- 1435-702X. ; 252:10, s. 1581-1592
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: To describe a new model for in vitro assessment of novel vitreous substitute candidates.Methods: The biological impact of three vitreous substitute candidates was explored in a retinal explant culture model; a polyalkylimide hydrogel (Bio-Alcamid (R)), a two component hydrogel of 20 wt.% poly (ethylene glycol) in phosphate buffered saline (PEG) and a cross-linked sodium hyaluronic acid hydrogel (Healaflow (R)). The gels where applied to explanted adult rat retinas and then kept in culture for 2, 5 and 10 days. Gel-exposed explants were compared with explants incubated under standard tissue culture conditions. Cryosections of the specimens were stained with hematoxylin and eosin, immunohistochemical markers (GFAP, Vimentin, Neurofilament 160, PKC, Rhodopsin) and TUNEL.Results: Explants kept under standard conditions as well as PEG-exposed explants displayed disruption of retinal layers with moderate pyknosis of all neurons. They also displayed moderate labeling of apoptotic cells. Bio-Alcamid (R)-exposed explants displayed severe thinning and disruption of retinal layers with massive cell death. Healaflow (R)-treated explants displayed normal retinal lamination with significantly better preservation of retinal neurons compared with control specimens, and almost no signs of apoptosis. Retinas exposed to Healaflow (R) and retinas kept under standard conditions showed variable labeling of GFAP with generally low expression and some areas of upregulation. PEG-exposed retinas showed increased GFAP labeling and Bio-Alcamid (R)-exposed retinas showed sparse labeling of GFAP.Conclusions: Research into novel vitreous substitutes has important implications for both medical and surgical vitreoretinal disease. The in vitro model presented here provides a method of biocompatibility testing prior to more costly and cumbersome in vivo experiments. The explant culture system imposes reactions within the retina including disruption of layers, cell death and gliosis, and the progression of these reactions can be used for comparison of vitreous substitute candidates. Bio-Alcamid (R) had strong adverse effects on the retina which is consistent with results of prior in vivo trials. PEG gel elicits reactions similar to the control retinas whereas Healaflow (R) shows protection from culture-induced trauma indicating favorable biocompatibility.
|
|
| 2. |
- Helmfors, Henrik
(författare)
-
Cell-penetrating peptides : an uptake mechanism & a new endosomolytic peptide
- 2013
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Peptide-based drugs have slowly begun migrating from laboratories into pharmacies and now there are several on the market. However, currently only one gene based therapy that is relies on a viral delivery vector has been approved. The long-term goal of our research is to leverage the cell-penetrating peptide (CPP) technology into a potent, safe and simple delivery vector for oligonucleotide (ON) based therapies.Cell-penetrating peptides have been actively researched for more than 20 years, and many CPPs have been discovered. However, it is not fully understood how the peptides are able to enter cells. In this thesis we present a novel receptor for CPP:ON complexes. Pharmacological inhibition and siRNA knockdown of the class A scavenger receptors (SCARAs) demonstrate that these receptors are the main pathway by which CPP:ON complexes are taken up. As the intracellular fate of particles taken up by (receptor mediated) endocytosis is entrapment in endosomes this thesis also presents a new peptide for ON delivery that has endosomolytic properties. Additionally this new peptide (PepFect 15) is also taken up via receptor-mediated endocytosis by the SCARAs.
|
|
| 3. |
- Malm, Henrik, et al.
(författare)
-
Biologically inspired enhancement of dim light video
- 2012
-
Ingår i: Frontiers in Sensing: From Biology to Engineering. - Vienna : Springer Vienna. - 9783211997499 - 9783211997482 ; , s. 71-85
-
Bokkapitel (refereegranskat)abstract
- In this chapter a technology for the enhancement of video data obtained at low light levels is presented. The method was inspired by the way in which nocturnal animals adaptively sum intensities, spatially and temporally, to improve vision at night. Due to the low photon count under these conditions the visual input is dark and unreliable, which leads to noisy low contrast images. The noise becomes very apparent when we try to enhance the contrast and, by this, amplify the intensities in the darkest regions of the images. By constructing spatio-temporal smoothing kernels that automatically adapt to the three dimensional intensity structure at every point, the noise can be considerably reduced, with fine spatial detail being preserved and enhanced without added motion blur. For color image data, the chromaticity is restored and demosaicing of raw RGB input data can be performed simultaneously with the noise reduction. The method is a very generally applicable one, contains only few user-defined parameters and has been developed for efficient parallel computation using a graphics processing unit (GPU). The technique has been applied to image sequences with various degrees of darkness and noise levels. Results from some of these tests, and comparisons to related work, are presented here.
|
|
| 4. |
- Ulvenblad, Pia, 1961-, et al.
(författare)
-
Agricultural business model innovation in Swedish food production : The influence of self-leadership and lean innovation
- 2014
-
Konferensbidrag (refereegranskat)abstract
- This conceptual paper focuses on the need for knowledge in leadership, organization and innovative thinking that exist in primary production throughout the value chain from the farm to the final consumer. There are also needs in terms of improving and developing the entire value chain from the farm to the final consumer. Self-leadership and lean innovation is in this paper proposed to enhance the possibilities for business model innovation in the food production. The aims of the paper are two folded; Firstly, the aim is to present a framework containing self-leadership and lean innovation and how these theoretical approaches can facilitate and shape business model innovation in the agricultural sector. Secondly, the aim is to show a way of working with this problem area in order to meet these needs in the agricultural sector. A framework for business model innovation is presented as well as an interactive research design addressing the problem area in terms of action research in which learning networks is an important concept. The paper concludes with suggestions for future research challenges.
|
|
