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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: We have studied the effect of long-term treatment with hydrocortisone on the expression of acetylcholine receptors (AChRs) at the neuromuscular junctions of human muscle cultured in monolayer and innervated de novo by fetal rat spinal cord motoneurons. Hydrocortisone increased accumulation of junctional AChRs in a dose-and time-dependent fashion. This increase was due to both decreased degradation and increased synthesis of AChRs. Other glucocorticoids, dexamethasone and prednisolone, exerted similar effects. Our study demonstrates a novel action of glucocorticoids on human junctional AChRs.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 54 (1990), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Increased accumulation of muscle-specific isozyme (MSI) of creatine kinase (CK), lactate dehydrogenase (LDH), glycogen phosphorylase (GP), and phosphoglycerate mutase (PGAM) occurs with development and indicates muscle fiber maturation. The expression of MSIs of those four enzymes is greatly enhanced in innervated-contracting as compared to noninnervated and noncontracting cultured human muscle fibers. We have now studied the effect of contractile activity on developmental accumulation of MSIs in innervated-contracting, innervated-paralyzed (2 μM tetrodotoxin for 30 days), and noninnervated-noncontracting cultured human muscle fibers. Muscle acetylcholinesterase (AChE) and total enzyme activities were also studied under the same conditions. We observed a different dependency on contractile activity between total enzymatic activities of CK., LDH, and AChE, which were substantially reduced after paralysis, and GP and PGAM, which were unchanged. The expression of MSIs of CK, GP, PGAM, and LDH was always significantly increased in innervated as compared to noninnervated fibers. While the expression of MSIs of GP and PGAM was the same in contracting-innervated and paralyzed-innervated muscle fibers, the expression of MSIs of CK and LDH in paralyzed-innervated muscle fibers was very slightly decreased as compared to their contracting-innervated controls. Our studies demonstrate that in human muscle: (1) total enzymatic activities and the expression of MSIs of GP and PGAM are regulated by neuronal effect(s); (2) total enzymatic activities of CK, LDH, and AChE depend mainly on muscle contractile activity; and (3) MSIs of CK and LDH are regulated predominantly by neuronal factors and to a much lesser degree by muscle contractile activity.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 62 (1994), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: We have characterized the structural properties of heparan sulfates from brain and other tissues after de-polymerization with a mixture of three heparin and heparan sulfate lyases from Flavobacterium heparinum. The resulting disaccharides were separated by HPLC and identified by comparison with authentic standards. In rat, rabbit, and bovine brain, 46–69% of the heparan sulfate disaccharides are N-acetylated and unsulfated, and 17–21% contain a single sulfate residue in the form of a sulfoamino group. In rabbit, bovine, and 1-day postnatal rat brain, disaccharides containing both a sulfated uronic acid and N-sulfate account for an additional 10–14%, together with smaller and approximately equall proportions (5–9%) of mono-, di-, and trisulfated disaccharides having sulfate at the 6-position of the glucosamine residue. Kidney and lung heparan sulfates are distinguished by high concentrations of disaccharides containing 6-sulfated N-acetylglucosamine residues. In chromaffin granules, the catecholamine-and peptide-storing organelles of adrenal medulla, where heparan sulfate accounts for a minor portion (5–10%) of the glycosaminoglycans, we have determined that bovine chromaffin granule membranes contain heparan sulfate in which almost all of the disaccharides are either unsulfated (71 %) or monosulfated (18%). In sympathetic nerves, norepinephrine is stored in large densecored vesicles that in biochemical composition and properties closely resemble adrenal chromaffin granules. However, in contrast to chromaffin granules, heparan sulfate accounts for ∼ 75% of the total glycosaminoglycans in large dense-cored vesicles and more closely resembles heparin, insofar as it contains only 21 % unsulfated disaccharides, 10% mono-and disulfated disaccharides, and 69% trisulfated disaccharides. Our results therefore reveal significant differences among heparan sulfates from different sources, supporting other evidence that structural variations in heparan sulfate may be related to specific biological functions, such as the switching in the neural response from fibroblast growth factor-2 to fibro-blast growth factor-1 resulting from developmental changes in the glycosaminoglycan chains of a heparan sulfate proteoglycan.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1520-4812
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1520-4804
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 6075-6077 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In situ polar Kerr-effect measurements have been used to study the magnetic anisotropy of MBE-grown Au(111)/Co/X and Pd(111)/Co/X sandwiches, where X is the nonmagnetic metal Ag, Au, Cu, and Pd or the insulator MgO. For the metals it was recently found that the magnitude of the Co/X perpendicular interface anisotropy is strongly peaked at ∼1 atomic layer (1.5–2.5 A(ring)) coverage. To investigate structural influences on the anisotropy, reflection high-energy electron diffraction (RHEED) and low-energy electron diffraction (LEED) have been used to measure changes resulting from overlayer coverage. Analysis of digitized RHEED images captured every ∼1 A(ring) during metal overlayer coverage shows no abrupt change of the in-plane lattice constant. The out-of-plane lattice spacing has also been investigated as a function of nonmagnetic metal coverage by measuring LEED I-V curves along the (0,0) rod. In the case of Cu, where the LEED behavior is nearly kinematic, no evidence was seen of any abrupt structural changes at ∼1 atomic layer coverage. These results suggest the observed peak in magnetic anisotropy is not structural in origin. To further study this phenomenon, the influence of an insulating overlayer, MgO, on the perpendicular magnetic properties has been measured.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 6959-6961 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have grown epitaxial superconductor/spin-glass multilayers, Nb/CuMn, as well as complimentary nonmagnetic Nb/Cu multilayers by molecular beam epitaxy. To probe the interaction of superconductivity and magnetism, we measured the resistivity and ac susceptibility as a function of temperature for multilayers of nominally constant Nb thickness and varying normal-metal thickness. The reduction of the transition temperature of the Nb/Cu multilayers with increasing Cu thickness is in excellent agreement with the de Gennes–Werthamer proximity effect theory. The inclusion of Mn in the Cu causes a significant additional suppression of the transition temperatures relative to the Nb/Cu multilayers. The extension of the de Gennes–Werthamer theory to include the effects of random magnetic impurities agrees well with the data from the Nb/CuMn multilayers for small CuMn layer thicknesses. However, deviations occur at the largest CuMn thicknesses studied. These deviations between the data and theory may be due to a decoupling of the Nb layers, as a result of the spin-glass ordering, causing a three-dimensional to two-dimensional crossover.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 3623-3626 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The etching of Si(100) with hyperthermal beams of atomic and molecular chlorine has been studied in the temperature range between 130 and 200 K. The dominant etch product, SiCl4, is evolved in two parallel reaction pathways, only one of which is thermally activated. It is shown that the nonactivated pathway, which has an appreciable rate only when hyperthermal chlorine atoms are incident upon the surface, is due to collision-induced desorption of weakly bound SiCl4. By increasing the normal component of the chlorine incident translational energy, the efficiency of converting incident Cl into SiCl4 can be increased to 0.6% in the nonthermal channel, at temperatures for which the thermal etching rate is negligible. The normal energy scaling and the observed energy threshold suggest that this process should result in highly anisotropic etching.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 5919-5924 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We calculate resonance energies, wave functions, and widths by propagating wave packets on a grid. A collinear model of a symmetric triatomic molecule is studied and the results are compared to those obtained from a time-independent complex scaling calculation.
    Type of Medium: Electronic Resource
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