Identification of non-muscle myosin heavy chain as a substrate for Cdk5 and tool for drug screening

<p>Abstract</p> <p>Background</p> <p>Deregulated activation of cyclin-dependent kinase-5 (Cdk5) is implicated in neurodegenerative disorders such as Alzheimer's disease. One of the restricting factors for developing specific Cdk5 inhibitors is the lack of reproducible and well-characterized cellular in vitro assay systems.</p> <p>Methods</p> <p>HEK293 cells were transfected with Cdk5 and its activator p25 as a starting point for an assay to screen for Cdk5 kinase inhibitors. To identify suitable substrates for Cdk5 we utilized an antibody that recognizes phospho serine in a consensus motif for Cdk substrates.</p> <p>Results</p> <p>Western blot analysis of transfected cells detected a 200 kDa band that was identified, by mass spectrometry, as non-muscle myosin heavy chain, type B (NMHC-B). Phosphorylation of NMHC-B was evident only in cells that were double transfected with Cdk5/p25 and was dose-dependently inhibited by Roscovitine and other Cdk5 inhibitors. Cdk5 was found to phosphorylate NMHC-B also in the human neuroblastoma SH-SY5Y cell line.</p> <p>Conclusion</p> <p>A novel Cdk5 substrate NMHC-B was identified in this study. A cellular assay for screening of Cdk5 inhibitors was established using NMHC-B phosphorylation as a read-out in Cdk5/p25 transfected HEK293 cells. A novel Cdk5 inhibitor was also pharmacologically characterized in this assay system.</p

On Generation and Recombination in Cu(In,Ga)Se2 Thin-Film Solar Cells

The solar cell technology based on Cu(In,Ga)Se2 (CIGS) thin-films provides a promising route to cost competitive solar electricity. The standard device structure is ZnO:Al/ZnO/CdS/CIGS/Mo films on a glass substrate, where the first three layers are n-type semiconductors with wide bandgaps, forming a pn-junction with the p-type CIGS absorber layer; the Mo layer serves as a back contact. This thesis deals with analysis of the generation and recombination of electron-hole pairs throughout the device. These processes determine the maximum output power: generation limits the current; recombination limits the voltage. The generation is calculated with an optical model based on complex refractive indices determined for the individual layers. The main features of the optical response of the solar cell can be reproduced with a specular model neglecting scattering. A model including ideally Lambertian scattering at the front and back surface of the CIGS absorber layer is introduced to investigate the possibility to maintain a high current generation with thin absorber layers. The result highlights the relatively poor optical performance of the Mo back contact. TiN and ZrN are explored as alternatives, and improved optical performance is experimentally demonstrated for both materials. The recombination analysis emphasizes that, in general, more than one recombination path of comparable magnitude are operative in parallel. For cells with absorber bandgap increasing from 1.0 eV (CuInSe2) to 1.7 eV (CuGaSe2), a relative increase of interface recombination is found. When these cells are subject to accelerated ageing, degradation is smallest for intermediate bandgaps; an explanation involving different sensitivity to decreased absorber band bending and activation of grain boundaries is suggested. The optical gain with ZrN back contacts is counteracted by increased back contact recombination and contact resistance, but an intermediate layer of MoSe2 is shown to alleviate these problems, allowing for an overall improved efficiency

On Generation and Recombination in Cu(In,Ga)Se2 Thin-Film Solar Cells

The solar cell technology based on Cu(In,Ga)Se2 (CIGS) thin-films provides a promising route to cost competitive solar electricity. The standard device structure is ZnO:Al/ZnO/CdS/CIGS/Mo films on a glass substrate, where the first three layers are n-type semiconductors with wide bandgaps, forming a pn-junction with the p-type CIGS absorber layer; the Mo layer serves as a back contact. This thesis deals with analysis of the generation and recombination of electron-hole pairs throughout the device. These processes determine the maximum output power: generation limits the current; recombination limits the voltage. The generation is calculated with an optical model based on complex refractive indices determined for the individual layers. The main features of the optical response of the solar cell can be reproduced with a specular model neglecting scattering. A model including ideally Lambertian scattering at the front and back surface of the CIGS absorber layer is introduced to investigate the possibility to maintain a high current generation with thin absorber layers. The result highlights the relatively poor optical performance of the Mo back contact. TiN and ZrN are explored as alternatives, and improved optical performance is experimentally demonstrated for both materials. The recombination analysis emphasizes that, in general, more than one recombination path of comparable magnitude are operative in parallel. For cells with absorber bandgap increasing from 1.0 eV (CuInSe2) to 1.7 eV (CuGaSe2), a relative increase of interface recombination is found. When these cells are subject to accelerated ageing, degradation is smallest for intermediate bandgaps; an explanation involving different sensitivity to decreased absorber band bending and activation of grain boundaries is suggested. The optical gain with ZrN back contacts is counteracted by increased back contact recombination and contact resistance, but an intermediate layer of MoSe2 is shown to alleviate these problems, allowing for an overall improved efficiency

Synthesis, properties and applications of chalcogen-containing antioxidants

In the first part, the preparation and properties of chalcogen-containing vitamin E analogues are described. The sulfur compound 3,3,4,6,7-pentamethyl-2,3-dihydrobenzo[b]thiophene-5-ol was prepared by two different routes using ionic and radical chemistry. Interesting rearrangements were observed in the two synthetic pathways. A new methodology for the synthesis of dihydroselenophene and dihydrotellurophene derivatives is described. In the preparation of the vitamin E analogues 2,3-dihydrobenzo[b]selenophene-5-ol and 2,3-dihydrobenzo[b]tellurophene-5-ol a tellurium-mediated tandem SRN1/SHi sequence was suggested to be operative. 2,3-Dihydrobenzo[b]thiophene-5-ol and the vitamin E-like selenide 2-methyl-2-(4,8,12-trimethyl-tridecyl)-selenochroman-6-ol were prepared via intramolecular homolytic substitution at sulfur and selenium, respectively. The first rate constant for intramolecular homolytic substitution at tellurium is also reported (5x108 s-1 at 25 °C). The antioxidant profile for 2,3-dihydrobenzo[b]furan-5-ol and its 1-thio, 1-seleno, and 1-telluro analogues is described. By means of pulse radiolysis, it was shown that the one-electron reduction potentials (ArO·/ArO-) were independent of the chalcogen (0.49-0.52 V vs NHE). The O-H bond dissociation enthalpies for the compounds were also estimated to be similar (336-340 kJ mol-1). The pKa values and the oxidation potentials were also determined for these compounds. For some compounds the rate of hydrogen atom donation to tert-butoxyl radicals was determined by means of laser flash photolysis. Using a two-phase lipid peroxidation model, it was demonstrated that the selenium and tellurium analogues could be regenerated in the presence of a stoichiometric amount of a reducing agent. The organotellurium analogue also acted as a good glutathione-peroxidase mimic and as a potent inhibitor of lipid peroxidation in liver microsomes. In the second part of the thesis the stabilizing capacity of bis[4-(dimethylamino)phenyl]telluride was investigated in the thermoplastic elastomer PACREL®. It was demonstrated that the addition of 0.17-0.50 % of the telluride significantly improved the tensile strength and elongation at break of the polymer. Chemiluminescence measurements showed that the organotellurium compound prolonged the induction period of thermo-oxidation and reduced the total luminescence intensity of the material

Upplevelsen av arbetslöshet bland ungdomar : -En kvalitativ studie om arbetslöshet, stigmatisering och diskriminering

Denna sociologiska uppsats behandlar den subjektiva upplevelsen av arbetslöshet bland ungdomar. Arbetslösheten i denna grupp är hög och syftet är att visa på vilken ställning ungdomarna har gentemot sin situation, samt hur denna upplevs. En extra tyngd har lagts på etnisk diskriminering för att belysa om detta upplevs förekomma bland ungdomar med ett utländskt efternamn. Det är en kvalitativ studie som bygger på semistrukturerade intervjuer med nio arbetslösa ungdomar under 25 år, samt två intervjuer med tjänstemän som representerade arbetsförmedlingen. Ungdomarna beskriver återkommande sin situation med frustration och utsatthet, samt att viss diskriminering kan tänkas förekomma. Studien har utgått från en hermeneutisk ansats och bygger mycket på tidigare forskning, samt på sociologiska teorier. Uppsatsen vill besvara följande frågor:   Hur upplever ungdomarna arbetslösheten? -Hur upplever ungdomarna att de blir bemötta av olika samhällsinsatser och arbetsgivare? -Hur upplever ungdomarna sin vardag? Är upplevelsen av arbetslöshet förenad med diskriminering och stigmatisering? -Hur upplever ungdomarna att omgivningen reagerar på arbetslösheten? -Upplever ungdomarna med utländskt efternamn att de blir stigmatiserade eller diskriminerade på grund av sitt efternamn

Brandsäkerhet - Grundläggande kunskap om brandskydd i småhus

Back in the days it was considered that it was your own problem if your property burned down. It continued to the 1950 when the department of housing came out guides to building code which are the foundation of the new Swedish building code. 1960 came the first collected building code that contained laws and rules about firesafety. In 1987 they accepted PBL and in 1994 it was drastically changed because we entered EU. PBL is setting the standard of laws by describing the function, properties and how the government, local authorities, companies and individuals are going to relate to building constructions in Sweden. It is not just PBL that decides what you are allowed to do and not to do, there are other law that they need to follow. We have choose to describe “The regulation about preventing accidents” and “The law about flammable and explosive goods”. In the fifth chapter in BBR can you find all the things you need to know of building construction in Sweden, but there can be harder codes depending on where your building are placed, what your are attending to use it for and its design. It is necessary to have all knowledge about the building constructions codes. Especially when you are renovating, redevelopments, and are planning the neighborhood rescue operation. They who study this problem need to be involved early in the project to prevent accidents in an economical way. The Swedish building code states different classifications according to the properties to the whole construction. Regulations can be sat on the constructions resistance, ability to prevent smoke and diathermancy to the other rooms