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  • General Chemistry  (32)
  • Life and Medical Sciences  (10)
  • Analytical Chemistry and Spectroscopy  (6)
  • 68.55.+b
  • 1985-1989  (32)
  • 1980-1984  (16)
  • 1930-1934  (1)
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Keywords
Publisher
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Photoluminescence of AlxGa1−xAs/GaAs quantum well heterostructures grown by molecular beam epitaxy (1984)
    Springer
    Applied physics 33 (1984), S. 97-105 
    Details
    ISSN: 1432-0630
    Keywords: 78.65.-s ; 71.70.-d ; 68.55.+b
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Low-temperature photoluminescence measurements on nominally undoped AlxGa1−xAs/GaAs quantum well heterostructures (QWHs) grown by molecular beam epitaxy (MBE) exemplified the exclusivelyintrinsic free-exciton nature of the luminescence under moderate excitation conditions. Neither any spectroscopic evidence for alloy clustering in the AlxGa1−xAs barriers nor any extrinsic luminescence due to recombination with residual acceptors has been detected in single and double QWHs when grown at 670 °C under optimized MBE growth conditions. Carrier confinement in AlxGa1−xAs/GaAs QWHs starts at a well width ofL z≌30 nm when x≌0.25. The minor average well thickness fluctuation ofΔL z=4×10−2nm as determined from the excitonic halfwidth allowed the realization of well widths as low asL z=1 nm and thus a shift of the free-exciton line as high as 2.01 eV which is close to the conduction band edge of the employed Al0.43Ga0.57As confinement layer. The measurements further revealed a strongly enhanced luminescence efficiency of the quantum wells as compared to bulk material which is caused by the modified exciton transition probabilities due to carrier localization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00617615
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  • 2
    Electronic Resource
    Electronic Resource
    Organizational forms of actin in 13762 ascites mammary tumor cell microvilli (1983)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 491-500 
    Details
    ISSN: 0886-1544
    Keywords: actin ; microfilaments ; oligomers ; transmembrane glycoprotein ; microvilli ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The organization of microvillus actin and its associated proteins have been investigated in sublines of mammary ascites tumors (MAT) with mobile (MAT-B1) and immobile (MAT-C1) cell surface receptors. Microvilli isolated from these sublines differ in morphology (branched for MAT-C1 versus unbranched for MAT-B1) and the presence of a 58,000-dalton polypeptide (58K). 58K is found associated with MAT-C1 microvilli, microvillar cytoskeletons obtained by nonionic detergent extractions, and microvillar membranes prepared under conditions which depolymerize actin microfilaments. By extraction with actin-stabilizing buffers (isotonic Triton-Mg-ATP) microvillar actin can be fractionated into four forms. About 40% of the actin is sedimented at low speed (7,500g, 15 min). The pellets contain microfilaments; actin and α-actinin are the predominant proteins. High-speed pellets from these low-speed supernates contain about 10% of the actin as a transmembrane complex with a cell surface glycoprotein (cytoskeleton-associated glycoprotein, [CAG] 75-80,000 daltons) in MAT-B1 cells or with CAG and 58K in MAT-C1 cells. Transmembrane complexes can be purified from MAT-B1 and MAT-C1 microvillar membranes in Triton-containing buffer by gel filtration or sucrose density gradient centrifugation. The presence of only CAG and actin in the MAT-B1 transmembrane complex strongly suggests the direct interaction of actin and a cell surface component. The high-speed supernates contain soluble actin. By gel filtration or rate-zonal sucrose density gradient centrifugation about 30% of the microvillar actin is found as small oligomers and about 10% as G-actin in this extraction buffer. We suggest that the actin-containing transmembrane complexes may serve as membrane-association sites for oligomeric actin segments and microfilaments and as initiation sites for actin polymerization.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970030516
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  • 3
    Electronic Resource
    Electronic Resource
    Ein einfaches Verfahren zur Darstellung von reinem, trocknem Bromwasserstoff (1933)
    Weinheim : Wiley-Blackwell
    Zeitschrift für die chemische Industrie 46 (1933), S. 279-279 
    Details
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ange.19330462003
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  • 4
    Electronic Resource
    Electronic Resource
    Structure-function studies on Acanthamoeba myosins IA, IB, and II (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 36 (1988), S. 37-50 
    Details
    ISSN: 0730-2312
    Keywords: actomyosin ; cell motility ; phosphorylation ; filaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Myosins IA and IB are globular proteins with only a single, short (for myosins) heavy chain (140,000 and 125,000 daltons for IA and IB, respectively) and are unable to form bipolar filaments. The amino acid sequence of IB heavy chain shows 55% similarity to muscle myosins in the N-terminal 670 residues, which contain the active sites, and a unique 500-residue C-terminus highly enriched in proline, glycine, and alanine. The C-terminal region contains a second actin-binding site which allows myosins IA and IB to cross-link actin filaments and support contractile activity. Myosins IA and IB are regulated solely by phosphorylation of one serine on the heavy chain positioned between the catalytic site and the actin-binding site that activates ATPase.Myosins II is a more conventional myosin in composition (two heavy chains and two pairs of light chains), heavy chain sequence (globular head 45% identical to muscle myosins and a coiled-coil helical tail), and structure (bipolar filaments). The tail of myosin II is much shorter than that of other conventional myosins, and it contains a 25 amino acid sequence in which helical structure is predicted to be weak or absent. The position of this sequence corresponds to the position of a bend in the monomer. Myosin II heavy chains also have a 29-residue nonhelical tailpiece which contains three regulatory, phosphorylatable serines. Phosphorylation at the tip of the tail regulates ATPase activity in the globular head apparently through an effect on filament structure.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240360105
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  • 5
    Electronic Resource
    Electronic Resource
    Protamine inhibits platelet derived growth factor receptor activity but not epidermal growth factor activity (1984)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 26 (1984), S. 205-220 
    Details
    ISSN: 0730-2312
    Keywords: PDGF ; EGF ; receptor ; oncogenes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Protamine sulfate blocked 125I-PDGF binding to its specific physiological receptor on Swiss mouse 3T3 cells. Reduced 125I-PDGF binding in the presence of protamine sulfate correlated directly with a protamine sulfate dose-dependent decrease in the PDGF-dependent incorporation of [3H]-thymidine into 3T3 cells and a decreased PDGF-stimulated tyrosine-specific protein kinase activity in isolated membrane preparations of 3T3 cells. Protamine sulfate blocked 125I-PDGF binding to simian sarcoma virus transformed cells (SSV-NIH 3T3 and SSV-NPl cells) and to nontransformed cells in a manner qualitatively identical to unlabelled PDGF. In contrast, protamine sulfate enhanced the specific binding of 125I-EGF by increasing the apparent number of EGF receptors on the cell surface. The increase in 125I-EGF receptor binding was not prevented by cycloheximide nor by actinomycin D. Protamine sulfate did not affect 125I-EGF binding to membranes from 3T3 cells or the EGF-stimulated 3T3 cell membrane tyrbsinc specific protein kinase activity, suggesting that protamine sulfate may have exposed a population of cryptic EGF receptors otherwise not accessible. Protamine sulfate was fractionated into four active fractions by Sephadex G-50 gel filtration columns; the half maximum inhibition concentration of 125I-PDGF binding to 3T3 cells of protamines I and II (MW ∼ 11,000 daltons and 7,000 daltons, respectively) is ∼ 0.4 μM. Protamine II (MW ∼ 4,800 daltons) was equally active (half maximum inhibition concentration ∼ 0.4 μM); protamine IV (MW ∼ 3,300 daltons) was substantially less active (half maximum inhibition concentration ∼ 2.8 μM).These investigations have extended previous observations that protamine sulfate is a potent inhibitor of PDGF binding and establish that protamine sulfate blocks PDGF binding at the physiological receptor, preventing PDGF initiated biological activities. Protamine sulfate can be used as a reagent to separate the influence of PDGF and EGF on cells with high specificity and has been used to demonstrate that the receptors on simian sarcoma virus transformed 3T3 cells qualitatively respond identically to protamine sulfate as to unlabelled PDGF and are likely identical to those on nontransformed 3T3 cells.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240260402
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  • 6
    Electronic Resource
    Electronic Resource
    Actin-associated cell-surface glycoprotein from ascites cell microvilli: A disulfide-linked multimer (1985)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 28 (1985), S. 243-252 
    Details
    ISSN: 0730-2312
    Keywords: cell surface ; glycoprotein ; actin ; disulfide ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Isolated microvilli of the MAT-Cl subline of the 13762 rat mammary adenocarcinoma contain a transmembrane complex composed of a cell surface, cytoskeleton-associated glycoprotein (CAG), actin, and a 58,000-dalton polypeptide (58K). The behavior of CAG has been studied by differential centrifugation and velocity sedimentation gradient centrifugation of detergent extracts of microvilli. CAG can be pelleted along with a fraction of the microvillar actin even in the presence of ionic detergents and under microfilament-depolymerizing conditions. By velocity sedimentation analysis CAG in Triton/PBS extracts sediments as a large, hetero-geneous species (sedimentation coefficient 〉 25S). In Sarkosyl and sodium dodecyl sulfate (SDS) the size and heterogeneity are somewhat reduced. In SDS CAG sediments as a 20S species in the absence of mercaptoethanol and as a 5S species in the presence of mercaptoethanol. These results indicate that CAG is a disulfide-linked multimer in the microvillus membrane. We suggest that the stable multimeric structure of CAG permits it to act as the membrane association site for several microfilaments and plays an important role in the formation and stabilization of the microvillus structure.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240280402
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  • 7
    Electronic Resource
    Electronic Resource
    Treatment of a fatal transplantable erythroleukemia by procedures that lower endogenous erythropoietin (1986)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 30 (1986), S. 311-318 
    Details
    ISSN: 0730-2312
    Keywords: leukemia ; antihormone therapy ; hormone-associated therapy ; erythropoietin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The in vitro growth of primary erythroleukemia cells has been examined in the presence and absence of the hormone erythropoietin (EPO). Although these leukemic cells had previously been considered to be hormone-independent, addition of EPO was found to be essential for maximum growth in culture. Erythroid colonies that grew in the presence of EPO were leukemogenic when returned to mice. Influence of EPO on the in vivo growth of leukemic cells was indicated by our findings that (1) administration of the hormone caused a more severe leukemia and rapid death, and (2) transfusion of red blood cells, which lowers endogenous EPO, led to decreased spleen size and increased survival of leukemic mice. We suggest from our results that hormone-associated therapy might be efficacious in the treatment of this and, perhaps, other leukemias.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240300404
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  • 8
    Electronic Resource
    Electronic Resource
    Modulation of the epidermal growth factor receptor by brain-derived growth factor in Swiss mouse 3T3 cells (1988)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 36 (1988), S. 209-221 
    Details
    ISSN: 0730-2312
    Keywords: receptor modulation ; internalization ; EGF receptor ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Incubation of Swiss mouse 3T3 cells at 37°C with bovine brain-derived growth factor (BDGF) decreased the cell surface 125I-EGF binding activity of these cells by 70-80%. This down-modulation of the EOF receptor by BDGF was time, temperature, and dose dependent Scatchard plot analysis indicated that BDGF binding led to a selective decrease in the number of high-affinity EGF receptors. The BDGF-induced down-modulation of the EGF receptor was completely blocked by protamine, a potent inhibitor of receptor binding and mitogenic activities of BDGF.BDGF down-modulated the EGF receptor in phorbol myristic acetate (PMA)-pretreated cells, as well as in control cells. Furthermore, PMA-pretreated cells responded mitogenically to BDGF, whereas PMA itself failed to stimulate the mitogenic response of PMA-pretreated cells. This BDGF-induced down-modulation of the EGF receptor in PMA-desensitized cells suggests that BDGF down-regulates the EGF receptor by a mechanism distinct from that of PMA.Incubation of cells with compounds which are known to inhibit pinocytosis blocked the down-modulation induced either by BDGF or by platelet-derived growth factor (PDGF) but had no effect on the PMA-induced down-modulation. Incubation of cells with inhibitors of receptor recycling enhanced the BDGF-induced down-modulation of the EGF receptor. These results suggest that BDGF and PDGF induce down-modulation of the EGF receptor by increasing the internalization of cell surface high-affinity receptors and that the internalization process may not be required for down-modulation induced by PMA.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240360303
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  • 9
    Electronic Resource
    Electronic Resource
    Cytochalasin B binding by human platelets (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 113 (1982), S. 320-323 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Intact human platelets bind cytochalasin B (CB) with a capacity of 100- 120 p mols CB/mg protein or approximately 7 × 104 molecules/cell and dissociation constants (KD) ranging from 2 × 10-8 to 10-6 M. Up to 85% of this saturable binding is displaced by 10-5 M cytochalasin E (CE). This CE-sensitive binding also appears heterogeneous with KD similar to those of the overall binding. The CE-insensitive binding, however, appears as a single component with KD ≌ 4 × 10-7 M. The sedimentable constituents from frozen, thawed, and washed cells also bind CB with KD ranging from 2.4 × 10-8 to 1.5 × 10-6 M and a total capacity of approximately 39 p mols/mg protein which accounts for only 4% of the ligand binding to the intact cell. The major portion (60-80%) of this CB binding is displaceable by 500 mM D-glucose and has a KD of 1.5 × 10-6M, while only 10-15% is CE-sensitive with a KD of 2.4 ± 10-8 M. It is concluded that 95% of the saturable CB binding in platelets is associated with the cytosol of which 80-85% is sensitive to CE and that only 3% of the cellular binding is glucose sensitive, membrane-associated binding. If the CE-sensitive binding associated with the cytosol is entirely to actin, the stoichiometry of this binding is approximately one CB to 30 actin monomers, which is greater by an order of magnitude than that for CB binding to muscle actin.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041130221
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  • 10
    Electronic Resource
    Electronic Resource
    The osmotic response of human erythrocytes and the membrane cytoskeleton (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 122 (1985), S. 266-272 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The volumes of human erythrocytes suspended in solutions of varying concentrations of sodium chloride and sucrose were measured by a Coulter Channelyzer® Model H4 with appropriate corrections. The cells showed greatly restricted volume changes at osmolarities between 200-700 mOsm. At osmolarities outside this limit, on the other hand, the cells showed nonrestricted volume changes following essentially the predictions of an ideal osmometer. This unexpected volume response was not spuriously due to changes in shape or to a changing orientation of the cells as they traversed the aperture. The restricted volume change observed was abolished when the cells had previously been treated with diamide or had been heated for 60 minutes at 50°C, conditions that are known to disturb the spectrin-actin network. The possibility must be considered that the osmotic behavior of human erythrocytes may be nonideal and that this nonideal behavior is primarily due to mechanical restriction provided by the spectrin-actin network of the membrane cytoskeleton.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041220216
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