| 1. |
- Aguda, Adeleke H., 1969-
(författare)
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Structural Study of the WH2 Family and Filamin: Implications for Actin Cytoskeleton Regulation
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cellular processes like motility, chemotaxis, phagocytosis and morphogenesis are dependent on the dynamic regulation of the actin cytoskeleton. This cytoskeleton system is tightly controlled by a number of diverse actin-binding proteins (ABPs) by various mechanisms described as nucleation, polymerization, capping, severing, depolymerization and sequestration. The ABPs are grouped based on sequence identity as in the Wiskott-Aldrich Syndrome protein homology domain 2 (WH2), and the calponin homology domain (CH) containing proteins.In this work, we elucidate the crystal structures of hybrids of gelsolin domain 1 with thymosin β4, ciboulot domain 2, and the second WH2 domain of N-WASP each bound to actin. We show that the single WH2 motif containing protein thymosin β4 in part sequesters actin by binding its pointed end via a C-terminal helix. This interaction prevents the addition of bound actin protomers to the barbed end of the filament. We propose that sequence variations in some WH2 motifs conferred F-actin binding ability to multiple repeat-containing proteins. These F-actin binding domains interact with the barbed end of a filament and the adjacent WH2 motifs are then freed to add their bound actin to the growing filament end. We demonstrate the binding of ciboulot domains 2 and 3 to both G- and F-actin and that full length ciboulot is capable of binding two actin monomers simultaneously. We have also cloned, expressed, purified and crystallized rod domains 14-16 from the actin crosslinking protein a-filamin. Preliminary X-ray crystallography data gives us hope that we shall be able to solve the structure of this triple domain repeat.
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| 2. |
- Cervenka, Simon, et al.
(författare)
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Associations between dopamine D2-receptor binding and cognitive performance indicate functional compartmentalization of the human striatum
- 2008
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Ingår i: NeuroImage. - : ACADEMIC PRESS INC ELSEVIER SCIENCE. - 1053-8119 .- 1095-9572. ; 40:3, s. 1287-1295
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Tidskriftsartikel (refereegranskat)abstract
- Based on pharmacological, neuroanatomical, and lesion studies in animals, a functional compartmentalization of the striatal complex has been proposed. However, this has not been convincingly demonstrated in human subjects. Most functions ascribed to the striatum have been linked to its dense dopaminergic innervation, from motor control to higher-order brain functions ( e. g., cognition), making the dopamine system a suitable probe for striatal function. Limbic striatum, a region involved in reward processing, has recently been implicated also in episodic memory function. Here we examined striatal dopamine D2-receptor binding in 16 healthy subjects using PET and the radioligand [C-11] raclopride, in relation to cognitive performance. Receptor availability in limbic striatum was related to performance in tests of episodic memory, but not to tests of verbal fluency and general knowledge. By contrast, D2 binding in associative and sensorimotor striatum was less strongly related to episodic memory, but showed associations to the non-episodic tasks. These findings provide biochemical evidence for a functional compartmentalization of human striatum, and serve as a starting point for a more detailed investigation of striatal biomarkers in the normal brain as well as in neurodegenerative disorders. (c) 2008 Elsevier Inc. All rights reserved.
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| 3. |
- Robertsson, Joacim, et al.
(författare)
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Folding of Spectrin's SH3 Domain in the Presence of Spectrin Repeats
- 2005
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Ingår i: Cellular & Molecular Biology Letters. ; 10, s. 595-612
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Tidskriftsartikel (refereegranskat)abstract
- The multifunctional protein spectrin contains several different structural motifs, such as spectrin repeats and a SH3 domain. Both triple-helix spectrin repeats and the SH3 domain are believed to form independent structural entities. In a-spectrins the SH3 domain is localized to repeat 9, where it is positioned between helix B and helix C in the repeat unit. The presence of SH3 in repeat 9 decreases the thermal stability considerably of this repeat unit while another insert in helix C does not seem to affect the stability. Addition of one or two adjacent repeat units increases the thermal stability from ca 25°C to ~41 and ~48°C, respectively. Despite the differences in thermal stability, the folding properties of peptides comprising the SH3 domain only or together with one or more repeats are more or less the same.
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| 4. |
- Backman, Anders, et al.
(författare)
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easyADL – Wearable Support System for Independent Life despite Dementia
- 2006
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Ingår i: ACM CHI 2006 Workshop onDesigning Technology for People with Cognitive Impairments.
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Konferensbidrag (refereegranskat)abstract
- This position paper outlines the easyADL project, a two-year project investigating the possibility of using wearable technology to assist people suffering the dementia disease in performing Activities of Daily Living (ADL). An introduction to the egocentric interaction modeling framework is provided and the virtual reality based development methodology is discusssed.
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| 5. |
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| 6. |
- Backman, Lars
(författare)
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Calmodulin—Alias: Cyclic Nucleotide Phosphodiesterase Activator, Ca2+-Dependent Regulatory Protein
- 2007
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Ingår i: Calcium Binding Proteins. - 1554-8643 .- 1554-8651. ; 2:1, s. 1-3
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Calmodulin is an important intracellular receptor for calcium signals. Calcium-activated calmodulin interacts with a large number of targets, thereby transducing the signal to many cellular processes. Calmodulin is also the archetype for proteins binding calcium by the EF-hand motif.
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| 7. |
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| 8. |
- Backman, Torbjorn, et al.
(författare)
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Video-assisted gastrostomy in infants less than 1 year.
- 2006
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Ingår i: Pediatric Surgery International. - : Springer Science and Business Media LLC. - 1437-9813 .- 0179-0358. ; 22:3, s. 243-246
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Tidskriftsartikel (refereegranskat)abstract
- The objectives of this study were to report our experience with the laparoscopic video-assisted gastrostomy technique in infants operated during their first year of life. A total of 53 infants (35 males, 18 females) aged 6 +/- 3 months, varying from 3 weeks to 11 months, underwent video-assisted gastrostomy. They were prospectively followed up. Included are infants with neurological dysfunction, chromosomal anomalies, metabolic disorders, cardiac anomalies or respiratory insufficiency. All the infants were operated under general and local anaesthesia. Gastrostomy tube feeding began within 4 h after the operation. The infants were followed with a scheduled control at 1 and 6 months postoperatively documenting complications and weight gain. The main outcome measure was the number and type of complications as well as weight gain using the age-adjusted Z-score of weight to normalize the data relative to a reference population. The weight before and 6 months after the video-assisted gastrostomy was 5.5 +/- 1.6 and 8.5 +/- 1.6 kg, respectively. The Z-score increased significantly (P < 0.001) from -2.7 +/- 1.5 to -1.7 +/- 1.0. This illustrates the postoperative weight gain and catch-up. Short and long-term complications included minor local wound infection, leakage around the gastrostomy tube and granuloma, but no severe complications. Our results encourage the use of video-assisted gastrostomy as a safe technique to provide a route for long-term nutritional support even in infants less than 1 year.
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| 9. |
- Capablo, Joaquin, et al.
(författare)
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Ash properties of alternative biomass
- 2009
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 23, s. 1965-1976
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Tidskriftsartikel (refereegranskat)abstract
- The ash behavior during suspension firing of 12 alternative solid biofuels, such as pectin waste, mash from a beer brewery, or waste from cigarette production have been studied and compared to wood and straw ash behavior. Laboratory suspension firing tests were performed on an entrained flow reactor and a swirl burner test rig, with special emphasis on the formation of fly ash and ash deposit. Thermodynamic equilibrium calculations were performed to support the interpretation of the experiments. To generalize the results of the combustion tests, the fuels are classified according to fuel ash analysis into three main groups depending upon their ash content of silica, alkali metal, and calcium and magnesium. To further detail the biomass classification, the relative molar ratio of Cl, S, and P to alkali were included. The study has led to knowledge on biomass fuel ash composition influence on ash transformation, ash deposit flux, and deposit chlorine content when biomass fuels are applied for suspension combustion.
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| 10. |
- Chumnarnsilpa, Sakesit, 1967-
(författare)
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The Structural Basis of the Control of Actin Dynamics by the Gelsolin Superfamily Proteins
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Rearrangement of the actin cytoskeleton occurs in a variety of cellular processes and structures and involves a wide spectrum of proteins. Among these, the gelsolin superfamily proteins (GSPs) control actin organization by severing filaments, capping filament ends and bundling filaments. Structural changes within the GSPs are key in controling their functions. This thesis is aimed in understanding the activation mechanisms of the C-terminal halves of GSPs through investigating the atomic structures of gelsolin, adseverin and villin. X-ray crystallography was used to determine the structures of C-terminal fragments of these 3 proteins. The results demonstrate that: 1) The structure of the activated form of the C-terminal half of gelsolin displays an open conformation, with the actin-binding site on gelsolin domain 4 (G4) fully exposed and all three type-II calcium binding sites (CBS) occupied. Neither actin nor the type-I calcium, which is normally sandwiched between actin and G4, is required to achieve this conformation. 2) Calcium ions at both type-I and type-II CBSs of gelsolin were exchangable within the crystals. Extraction of calcium ions from the CBSs triggered local conformation changes which we speculate are the initial steps toward restoration of the arrangement of domains found in the calcium-free inactive form of gelsolin in solution. 3) The long helix of G6 in the calcium-bound structure is similar to the helix of calcium-free isolated villin domain 6 (V6). 4) The conformation of the C-terminal half of adseverin in the active state is similar to that of gelsolin. These results suggest that the C-terminal halves of GSPs are activated before forming a complex with actin. The activation involves straightening the helix of domain 6 which is a key component in the global conformation changes of C-terminal halves of these proteins. The results also suggest that a calcium ion may bind to the type-I CBS on domain 4 of the active conformation of GSPs concurrently with forming the complex with actin, hence, stabilizing the GSP:actin complex.
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