ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Design and fabrication of well confined uniform magnetic field exposure systems (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 15 (1994), S. 563-577 
    Details
    ISSN: 0197-8462
    Keywords: magnetic fields ; exposure system ; stray fields ; Merritt coils ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Exposure systems that provide good magnetic field uniformity, minimum stray fields, and minimal heating, vibration, and hum, as well as capability for true sham exposure in which current flows in the coils, are needed to determine rigorously the biological effects of weak magnetic fields. Designs based on acrylic polymer coil support structures and twisted pair bifilary coil windings were employed to fabricate several different systems for the exposure of laboratory animals and cell cultures to magnetic fields. These systems exhibit excellent performance characteristics in terms of exposure field uniformity, stray field containment, and exposure field cancellation in the sham exposure mode. A custom-written computer program was used to determine the best arrangement for coils with regard to field uniformity in the exposure volume and stray field containment. For in vivo exposures, modules were made up of four Merritt four-coil sets, built into a single structure and positioned to form an octapole with fields directed in the horizontal plane. For in vitro applications, two different coil configurations were selected to produce the vertical fields required. A quadrupole system, comprising modules consisting of two Merritt four-coil sets arranged side by side to limit stray fields, was built as a prototype. In the second configuration, one Merritt four-coil set was positioned inside the other to form a concentric coil set. In both in vitro systems, exposure chambers were connected to remote commercial incubators in order to reduce ambient magnetic fields in the exposure volume. An active field cancellation circuit was developed for reducing ambient AC magnetic fields in the in vitro sham exposure chamber, when necessary. These design and fabrication approaches provide systems that offer uniform field exposures and excellent stray field containment when needed and are portable, washable, and relatively inexpensive. © 1994 Wiley-Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250150610
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Colchicine-binding sites of brain tubulins from an Antarctic fish and from a mammal are functionally similar, but not identical: Implications for microtubule assembly at low temperature (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 21 (1992), S. 272-280 
    Details
    ISSN: 0886-1544
    Keywords: cold-stable microtubules ; cold adaptation ; cytoskeleton ; antimitotic drugs ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The tubulins of Antarctic fishes possess adaptations that favor microtubule for mation at low body temperatures (Detrich et al.: Biochemistry 28:10085-10093, 1989). To determine whether some of these adaptations may be present in a domain of tubulin that participates directly or indirectly in lateral contact between microtubule protofilaments, we have examined the energetics of the binding of colchicine, a drug thought to bind to such a site, to pure brain tubulins from an Antarctic fish (Notothenia gibberifrons) and from a mammal (the cow, Bos taurus), At temperatures between 0 and 200C, the affinity constants for colchicine binding to the fish tubulin were slightly smaller (1.5-2.6-fold) than those for bovine tubulin. van't Hoff analysis showed that the standard enthalpy changes for colchicine binding to the two tubulins were comparable (δH° = + 10.6 and + 7.4 kcal mol-1 for piscine and bovine tubulins, respectively), as were the standard entropy changes (δS° = +61.3 eu for N. gibberifrons tubulin, +51.2 eu for bovine tubulin). At saturating concentrations of the ligand, the maximal binding stoichiometry for each tubulin was ∼ 1 mol colchicine/mol tubulin dimer. The data indicate that the colchicine-binding sites of the two tubulins are similar, but probably not identical, in structure. The apparent absence of major structural modifications at the colchicine site suggests that this region of tubulin is not involved in functional adaptation for low-temperature polymerization. Rather, the colchicine site of tubulin may have been conserved evolutionarily to serve in vivo as a receptor for endogenous molecules (i.e., “colchicine-like” molecules or MAPs) that regulate microtubule assembly.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970210403
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Actin in the merozoite of the malaria parasite, Plasmodium falciparum (1993)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 25 (1993), S. 43-48 
    Details
    ISSN: 0886-1544
    Keywords: malaria ; Plasmodium falciparum ; merozoite ; actin ; ubiquitin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Merozoites of the human malaria parasite, Plasmodium falciparum, when treated with cytochalasin B, will attach irreversibly to red cells with formation of a vestigial internal (parasitophorous) vacuole, but they are inhibited from moving into the cell. The existence of an actin-based motile mechanism is implied. Immunoblotting, peptide mapping and the DNase inhibition assay have been used to show that the merozoite contains actin. It makes up an estimated 0.3% of the total parasite protein and is partitioned in the ratio of about 1:2 between the cytosolic and particulate protein fractions. In the former it is unpolymerised and in the latter filamentous. Most of the anti-actin-reactive protein in the soluble fraction and about 20% of that in the pellet has an apparent molecular weight of 55,000 and reacts with an anti-ubiquitin antibody; it is thus evidently ubiquitinyl actin, or arthrin, which has so far been detected only in insect flight muscle. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970250106
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Disruption of the golgi apparatus with brefeldin a does not destabilize the associated detyrosinated microtubule network (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 20 (1991), S. 289-300 
    Details
    ISSN: 0886-1544
    Keywords: stable microtubules ; detyrosinated α-tubulin ; microtubule organizing center ; trans Golgi network ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Stable subsets of microtubules (MTs) are often enriched in detyrosinated α-tubulin. Recently it has been found that the Golgi apparatus is associated with a subset of relatively stable MTs and that detyrosinated MTs colocalize spatially and temporally with the Golgi apparatus in several cell lines. To determine whether the Golgi apparatus actively stabilizes associated MTs and thus allows their time-dependent detyrosination, we have used the drug brefeldin A (BFA) to disrupt the Golgi apparatus and have monitored changes in the Golgi apparatus and MT populations using simultaneous immunofluorescence and fluorescent lectin microscopy. We found that although BFA caused the Golgi apparatus to completely redistribute to the endoplasmic reticulum (ER), the detyrosinated MTs were not disrupted and remained in a juxtanuclear region. By Western blot analysis we found that even after 6 h of continuous exposure of cells to BFA, there was no detectable reduction in the level of detyrosinated α-tubulin. Simultaneous treatment with nocodazole and BFA led to a complete disruption of all MTs and normal Golgi structure/organization. Upon removal of nocodazole in the continued presence of BFA, we found that the detyrosinated MTs reformed in a compact juxtanuclear location in the absence of an intact Golgi complex. Finally, we found that the detyrosinated MTs colocalized precisely with a BFA-resistant structure that binds to the lectin, wheat germ agglutinin. We conclude that the juxtanuclear detyrosinated MTs are not actively stabilized by association with BFA-sensitive Golgi membranes. However, another closely associated structure which binds wheat germ agglutinin may serve to stabilize the juxtanuclear MTs. Alternatively, the MT organizing center (MTOC) and/or MT-associated proteins (MAPs) may organize and stabilize the juxtanuclear detyrosinated MTs.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970200405
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    A component of the interphase cytoskeleton is cyclically recruited into spindle poles during mitosis (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 19 (1991), S. 80-90 
    Details
    ISSN: 0886-1544
    Keywords: centrosomes ; microtubules ; sea urchin embryos ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: During the transition from interphase to mitosis, proteins are recruited into forming spindle poles [Leslie, Cell Motil. Cytoskeleton 16:225-228, 1990]. Antibodies which recognize these recruited components clearly label spindle poles during mitosis but the location and character of such proteins during interphase remain a mystery. Competition assays using an antibody to a recruited spindle pole protein show that in its disperse form the spindle pole protein is a highly insoluble component of the Cytoskeleton which is dispersed to such an extent during interphase that it is difficult to identify by immunolocalization. The function of recruited spindle pole proteins is unknown but the aggregation/dispersion cycle and the antigen are highly conserved, appearing in sea urchin embryos and tissue culture cells.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970190203
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Space shuttle flight (STS-45) of L8 myoblast cells results in the isolation of a nonfusing cell line variant (1994)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 55 (1994), S. 530-544 
    Details
    ISSN: 0730-2312
    Keywords: muscle ; myogenesis ; Space Shuttle ; cell culture ; microgravity ; neoplastic transformation ; cartridge ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Myoblast cell cultures have been widely employed in conventional (1g) studies of biological processes because characteristics of intact muscle can be readily observed in these cultured cells. We decided to investigate the effects of spaceflight on muscle by utilizing a well characterized myoblast cell line (L8 rat myoblasts) as cultured in the recently designed Space Tissue Loss Flight Module “A” (STL-A). The STL-A is a “state of the art,” compact, fully contained, automated cell culture apparatus which replaces a single mid-deck locker on the Space Shuttle. The L8 cells were successfully flown in the STL-A on the Space Shuttle STS-45 mission. Upon return to earth, reculturing of these spaceflown L8 cells (L8SF) resulted in their unexpected failure to fuse and differentiate into myotubes. This inability of the L8SF cells to fuse was found to be a permanent phenotypic alteration. Scanning electron microscopic examination of L8SF cells growing at 1g on fibronectin-coated polypropylene fibers exhibited a strikingly different morphology as compared to control cells. In addition to their failure to fuse into myotubes, L8SF cells also piled up on top of each other. When assayed in fusion-promoting soft agar, L8SF cells gave rise to substantially more and larger colonies than did either preflight (L8AT) or ground control (L8GC) cells. All data to this point indicate that flying L8 rat myoblasts on the Space Shuttle for a duration of 7-10 d at subconfluent densities results in several permanent phenotypic alterations in these cells. © 1994 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240550412
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Structure-function studies of FGF-1: Dissociation and partial reconstitution of certain of its biological activities (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 39 (1994), S. 56-61 
    Details
    ISSN: 1040-452X
    Keywords: Receptor binding ; Growth factor ; Wild-type transfectants ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: We reported previously that the mitogenic activities of FGF-1 (acidic FGF) could be dissociated from its receptor-binding activities by site-directed mutagenesis of lysine 132 to a glutamic acid. Although the mutant FGF-1 protein binds to the high-affinity tyrosinekinase receptors, stimulates tyrosine-kinase activity, and promotes expression of immediate-early genes, it is not mitogenic for a variety of tested cell lines. Interestingly, the mutant FGF-1 is capable of other functions associated with the wild-type protein such as promotion of mesoderm formation in Xenopus animal caps. The mutant exhibits a reduced apparent affinity for heparin-Sepharose compared to the wild-type protein. The relationship between the reduced heparin affinity and lack of mitogenic activity of this mutant is not clear. Recent data indicates the relationship is not as simple as reduced stability of the protein. When NIH 3T3 cells are transfected with expression vectors encoding either wild-type or mutant FGF-1, a transformed phenotype can be seen in cells overexpressing the wild-type FGF-1, whereas cells overexpressing mutant FGF-1 appear normal. Analysis of lysates of these cells indicates that a tyrosine-kinase cascade, distinct from that associated with the high-affinity cell surface receptors, has been activated in the wild-type transfected cells but not in the mutant transfected cells. Although both transfected cell lines contain FGF-1 cell surface receptors as judged by crosslinking studies, the wild-type transfects are refractory to exogenous FGF-1, whereas the mutant transfectants respond normally. Together these results support an intracellular role of wild-type FGF-1 in mediating certain of its functions. In addition, they demonstrate that certain functions of the growth factor can be dissociated at the structural level. Additional mutagenesis studies have resulted in the identification of mutants with heparin-binding or mitogenic deficiencies that do not correlate as well as those of the 132 mutant. It appears that the inactivity of the lysine 132 mutant is related, in part, to cysteine 131. © 1994 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080390110
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Understanding the neostriatal microcircuitry: High-voltage electron microscopy (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 29 (1994), S. 368-380 
    Details
    ISSN: 1059-910X
    Keywords: EM tomography ; Dendritic spines ; Axonal arborizations ; Reconstruction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: High voltage electron microscopy (HVEM) and HVEM tomography of selectively stained cell processes in the neostriatum have offered an alternative to serial thin section reconstruction for accurate 3-D visualization and measurement of axons, dendrites, and dendritic spines. Tissue preparation is simple and rapid, allowing examination of large numbers of specimens required for quantitation of neuronal morphology. The resolution of the images exceeds that available from any light microscopic technique and is appropriate for measurement of the finest axons and dendritic spine necks. HVEM tomography allows the direct measurement of dendritic surface area, required for computational modeling of synaptic integration. © 1994 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070290507
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Selective etching of ALAs for preparation of III-V semiconductor thin foils (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 25 (1993), S. 291-296 
    Details
    ISSN: 1059-910X
    Keywords: Transmission electron microscopy ; Planar sections ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A new method of thin section preparation of III--V semiconductors and multilayers for transmission electron microscopy (TEM) is presented that exhibits considerable advantages over conventional methods such as ion beam milling and jet thinning. GaAs thin films and multilayers of GaAs/InxGa1-xAs/GaAs are grown over an etch release layer of AlAs on GaAs substrates by molecular beamepitaxy (MBE). Planar TEM sections prepared by selective etching from these samples show improved ability to image film morphology and dislocation arrangements, and the resulting large thin electron transparent areas facilitate dislocation density measurements and detection of spatial variations. Avoidance of radiation effects and wedge shaping, both common to ion milled samples, allows this method to be used to prepare uniform thickness standards of single layer GaAs films for EDS analysis or lattice imaging. © 1993 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070250405
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Structure-function studies of heparin-binding (acidic fibroblast) growth factor-1 using site-directed mutagenesis (1991)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 45 (1991), S. 131-138 
    Details
    ISSN: 0730-2312
    Keywords: proto-oncogene expression ; nuclear translocation ; mitogenesis ; tyrosine kinase ; angiogenesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The heparin-binding or fibroblast growth factors (HBGFs) modulate cell growth and migration, angiogenesis, wound repair, neurite extension, and mesoderm induction. Relatively little is known regarding the precise mechanism of action of these growth factors or the structural basis for their action. A better understanding of the structural basis for the different activities of these proteins should lead to the development of agonists and antagonists of specific HBGF-1 can be dissociated from the receptor-binding activities of the growth factor by site-directed mutagenesis of a single lysine residue. Thus, the mutant HBGF-1 has normal receptor-binding activity and is capable of stimulating tyrosine kinase activity and proto-oncogene expression but is not able to elicit a mitogenic response. A similar dissociation of early events such as proto-oncogene expression from the mitogenic response is observed when the human wild-type HBGF-1 is used in the absence of added heparin. These results indicate that intracellular sites of action by the growth factor may be required to complete the mitogenic response. Further evidence for this idea is provided by transfection experiments where NIH 3T3 cells are engineered to produce large quantities of wild-type or mutant HBGF-1. Production of wild-type induces a transformed phenotype, whereas over-production of the mutant does not. The majority of both forms of the protein is found in the nuclear fraction of the transfected cells. Additional site-directed mutagenesis of putative nuclear translocation sequences in the wild-type protein do not affect mitogenic activity. Thus, the role of nuclear translocation in the mechanisms of action of HBGF-1 remains unclear.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240450203
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...