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  • 1
    Electronic Resource
    Electronic Resource
    Multistability of the current-voltage characteristics in doped GaAs-AlAs superlattices (1994)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 65 (1994), S. 1808-1810 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electric-field domain formation in doped semiconductor superlattices leads to sharp discontinuities in the current-voltage (I-V) characteristic. The successive expansion of the high-field region with increasing bias voltage through the periodic heterostructure manifests itself in a regular sequence of stable current branches. The current shows a complex hysteretic behavior. We observe two, three, and more stable current levels for fixed bias voltages. Calculations of the I-V characteristic based on a microscopic model support the experimentally observed multistability. © 1994 American Institue of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.112850
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  • 2
    Electronic Resource
    Electronic Resource
    Electric field domains in intentionally perturbed semiconductor superlattices (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 626-628 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Simulations based on a rate equation model for high-field transport through a doped semiconductor superlattice are presented for the case that one barrier is chosen significantly wider than the others. The distinct impact of that local perturbation on the overall shape of the current–voltage characteristic is discussed and related to the spatial field distribution. The measured current–voltage characteristic of a superlattice, which was intentionally grown with one thicker barrier, confirms the strong asymmetry predicted by the model calculations. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117928
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  • 3
    Electronic Resource
    Electronic Resource
    In Vitro Production and Characterization of Partly Assembled Human CD3 Complexes (2002)
    Oxford, UK : Blackwell Science Ltd
    Scandinavian journal of immunology 56 (2002), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Pairwise assembly of human CD3 chains takes place in the endoplasmic reticulum of T cells. Subsequently, the CD3 heterodimers form complexes with Tiα and Tiß chains forming hexameric TiαβCD3γεδε complexes. Finally, association with the ζ2 homodimer occurs in Golgi apparatus before the fully assembled T-cell receptor is transported to the cell surface. To study the structural properties of the human CD3 chains, we have developed new methods to produce and fold the extracellular domains of CD3γ, CD3δ and CD3ε. Proteins were expressed in Escherichia coli as denatured chains and de novo folded in vitro. CD3γ and CD3ε folded as soluble monomers, whereas CD3δ did not yield any soluble proteins. When folding the chains pairwise, soluble CD3γε and CD3δε heterodimers could be isolated, whereas CD3γδ heterodimers were not produced. Using antibodies as structural probes, we identified two different types of antigenic epitopes that were dependent on heterodimerization. Our data indicate that CD3ε undergoes a conformational change after dimerization with CD3γ or CD3δ. Furthermore, we demonstrated that the CD3γε heterodimer could be purified using immunoaffinity chromatography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3083.2002.01151.x
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  • 4
    Electronic Resource
    Electronic Resource
    T-Cell Receptor Downregulation by Ceramide-Induced Caspase Activation and Cleavage of the ζ Chain (2001)
    Oxford, UK : Blackwell Science Ltd
    Scandinavian journal of immunology 53 (2001), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Regulation of T-cell receptor (TCR) cell surface expression levels is probably an important mechanism by which T-cell responsiveness is controlled. Previously, two distinct pathways for TCR downregulation have been described. One is dependent on protein kinase C (PKC) and the leucine-based receptor-sorting motif (l-based motif) of the CD3γ chain but independent of tyrosine kinases, whereas the other is dependent on the tyrosine kinase activation but independent of the PKC and the CD3γl-based motif. In this study, we describe a new pathway for TCR downregulation distinct from both the PKC/CD3γl-based motif-dependent and the tyrosine kinase-dependent pathways. This pathway is dependent on ceramide-induced activation of caspases and correlate with caspase-mediated cleavage of the ζ chain. Thus, a 10–15% downregulation of the TCR was induced following the treatment of the T cells with ceramide for 4 h. A close correlation between TCR downregulation, caspase activation, and cleavage of the ζ chain was found. Furthermore, the caspase inhibitors abolished the cleavage of the ζ chain and TCR downregulation in parallel with the inhibition of the caspase activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-3083.2001.00852.x
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  • 5
    Electronic Resource
    Electronic Resource
    A Simplified Cytokine Immunoassay Using Magnetic Polymer Particles (2004)
    Oxford, UK; Malden, USA : Blackwell Science Ltd
    Scandinavian journal of immunology 60 (2004), S. 0 
    Details
    ISSN: 1365-3083
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Accurate detection of cytokines is essential for understanding their biological role in the immune system. Various methods to detect cytokines have been developed, including sandwich enzyme-linked immunosorbent assay (ELISA) and flow cytometry-based methods. All of the currently available methods have limitations, however. These limitations include time and extensive handling in standard sandwich ELISAs and the need for specialized equipment in flow cytometry-based assays. We have developed a magnetic polymer cytokine immunoassay and demonstrate that this assay is rapid and simple, needs less handling and offers better dynamic range, compared to standard sandwich ELISA. Furthermore, it does not require flow cytometry equipment, which is often used in microparticle-based polymer immunoassays. The magnetic polymer cytokine immunoassay described in this study is as sensitive as a standard sandwich ELISA. Because the method is not limited to the use of magnetic polymer particles, it is versatile and compatible with a number of different solid matrixes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0300-9475.2004.01484.x
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  • 6
    Electronic Resource
    Electronic Resource
    Diurnal variations in lower leg subcutaneous blood flow rate in patients with chronic venous leg ulcers (1991)
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 125 (1991), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary The blood flow rate in subcutaneous adipose tissue was measured on the lower legs of 11 patients with chronic lower-leg venous insufficiency and ulceration and in eight age-matched control subjects for 12–20 h, under ambulatory conditions, using the 133Xe wash-out technique with portable Cadmium telluride (CdTe(Cl)) detectors. In both groups, the change from an upright to a supine position at the beginning of the night period elicited an instantaneous increment in the blood flow rate of 30–40% with a decrease in the central and local postural sympathetic vasoconstrictor activity. After approximately 1 h of sleep, a considerable increase in blood flow rate was seen in both patient and control groups which persisted for nearly 100 min. In the patient group, the mean increase was 137% compared to a mean increase of 68% in the control group (P〈0·01). The blood flow then returned to the same level as at the beginning of the night and remained stable until the subjects woke in the morning. The differences between this nocturnal hyperaemic phase and the adjacent phases were highly significant in both groups (P 〈0·0001 and P 〈 0·005, respectively). The blood flow levels measured on the second day were of the same magnitude as those registered on the first day. The mean values of the wash-out rate constants (k) of the two groups were of the same magnitude in all phases of subcutaneous blood flow level, except in the hyperaemic phase, where it was significantly higher in the patient group (P〈0·01).The pattern of the nocturnal blood flow rate corresponded to that described previously in a younger healthy population, but with quantitative differences, which suggests that the abnormality occurs in the neural, humoral or metabolic factors involved in the nocturnal hyperaemic response.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2133.1991.tb14768.x
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  • 7
    Electronic Resource
    Electronic Resource
    Crystallization and molecular replacement solution of human heparin binding protein (1996)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 52 (1996), S. 1222-1223 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The highly glycosylated protein, human heparin binding protein, has been crystallized in the primitive orthorhombic space group P212121 with cell dimensions a = 39.0, b = 66.2 and c = 101.4 Å. Ethanol was used as precipitant and glycerol as additive. A full data set has been collected to 3.1 Å and diffraction was observed to at least 2.3 Å. A molecular replacement solution using human neutrophile elastase as a search model was obtained, showing one molecule per asymmetric unit. The crystal packing showed no bad contacts and the R factor was 44.8% after ten cycles of rigid-body refinement.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444996010086
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  • 8
    Electronic Resource
    Electronic Resource
    X-ray Structure of the 154-Amino-Acid Form of Recombinant Human Basic Fibroblast Growth Factor. Comparison with the Truncated 146-Amino-Acid Form (1997)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 160-168 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The crystal structure of the 154-amino-acid form of human basic fibroblast growth factor (hbFGF154), probably representing the intact form of hbFGF as deduced from the open reading frame of hbFGF cDNA, was determined by X-ray crystallography and refined to a crystallographic residual of 19.0% for all data between 20.0 and 2.0 Å resolution. Crystals were obtained from recombinant hbFGF154 expressed in E. coli. hbFGF154 has the same overall structure as the N-terminus truncated 146-amino-acid form. The structure has a Kunitz-type fold and is built of 12 β-strands of which six antiparallel strands form a β-sheet barrel. In the structure it was possible to locate two additional residues at the N terminus and the last three C-terminal amino-acid residues, which seem to be disordered in all but one of the reported structures of the truncated form of hbFGF. The C-terminal amino-acid residues are part of the last β-strand through the formation of a hydrogen bond between the main-chain amide group of Ala152 and the carbonyl O atom of Pro28. An apparent phosphate ion is bound within the basic region on the surface of the molecule and has as ligands the side chains of Asn35, Arg128 and Lys133 and two water molecules. A slightly different hydrogen-bonding pattern to the phosphate ion is observed as compared with the sulfate ions in the truncated forms [Eriksson, Cousens & Matthews (1993). Protein Sci. 2, 1274–1284; Zhang, Cousens, Barr & Sprang (1991). Proc. Natl Acad. Sci. USA, 88, 3446–3450]. One molecule of β-mercaptoethanol forms a disulfide bridge to Cys77.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444996012711
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  • 9
    Electronic Resource
    Electronic Resource
    Human plasminogen binding protein tetranectin: crystallization and preliminary X-ray analysis of the C-type lectin CRD and the full-length protein (1997)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 108-111 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The recombinant human plasminogen binding protein tetranectin (TN) and the C-type lectin CRD of this protein (TN3) have been crystallized. TN3 crystallizes in the tetragonal space group P42212 with cell dimensions a = b = 64.0, c = 75.7 Å and with one molecule per asymmetric unit. The crystals diffract X-rays to at least 2.0 Å resolution. A complete diffraction data set has been collected to 2.7 Å resolution. The crystals of TN, obtained by the vapour-diffusion reverse salting-in method at 280 K, are rhombohedral, space group R3, with the hexagonal axes a = b = 89.1, c = 75.8 Å, and diffract to at least 2.5 Å. A full data set has been collected to 3.0 Å. The asymmetric unit contains one monomer of TN. Molecular replacement solutions for TN3 and TN have been obtained using the structure of the C-type lectin CRD of rat mannose-binding protein as search model. The rhombohedral space group indicates that trimers of TN are formed in accordance with the observation of trimerization in solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444996011493
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  • 10
    Electronic Resource
    Electronic Resource
    Impaired autoregulation of blood flow in subcutaneous tissue of long-term Type 1 (insulin-dependent) diabetic patients with microangiopathy: an index of arteriolar dysfunction (1985)
    Springer
    Diabetologia 28 (1985), S. 711-717 
    Details
    ISSN: 1432-0428
    Keywords: Autoregulation ; diabetic microangiopathy ; subcutaneous blood flow ; Type 1 diabetes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Autoregulation of blood flow in subcutaneous tissue was studied at the level of the lateral malleolus in eight long-term Type 1 (insulin-dependent) diabetic patients with clinical microangiopathy, eight short-term Type 1 diabetic patients without clinical microangiopathy and seven healthy control subjects. Blood flow was measured by the local 133Xenon washout technique. Mean arterial blood pressure was reduced by a maximum of 23 mmHg by elevating the limb above heart level and elevating to a maximum of 70 mmHg by head-up tilt; in the latter position venous pressure was kept constant and low by activation of the leg muscle vein pump (heel raising). Mean arterial blood pressure was thus varied between 60 and 160 mmHg. In normal and short-term diabetic subjects blood flow remained within 10% of control values during the changes in arterial blood pressure. In six of the eight Type 1 diabetic patients with clinical microangiopathy, autoregulation of blood flow was impaired, blood flow changing ap proximately 20% per 10 mmHg change in arterial blood pressure; the slope of the autoregulation curves was significantly higher compared with the two control groups (p〈0.02). Resting mean arterial blood pressure was significantly elevated in long-term diabetic patients (median: 107 mmHg) compared with short-term diabetic (median: 85 mmHg) and control subjects (median: 91 mmHg) (p〈0.01 and p〈0.02, respectively). No correlation was, however, demonstrated between resting mean arterial blood pressure and the degree of disturbed autoregulation, but a relationship was demonstrated between the degree of disturbed autoregulation and the amount of periodic acid Schiff positive material in the terminal arteriolar walls of the investigated area (p〈0.05).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00265016
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