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  • 1
    Electronic Resource
    Electronic Resource
    A structural basis for R- and T-banding: a scanning electron microscopy study (1986)
    Springer
    Chromosoma 94 (1986), S. 395-402 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The structure of reverse (R)-banded and telomeric (T)-banded chromosomes was studied by examination of the same chromosomes first in the light microscope (LM) followed by the scanning electron microscope (SEM). This procedure demonstrated a structural basis to both the R- and T-banding techniques. A direct correlation was shown between the LM staining patterns and the structural patterns observed in the SEM. In the R-banded chromosomes the positively stained R-bands, viewed by LM, corresponded to highly fibrous three-dimensional regions in the SEM. The negatively stained R-interbands corresponded to flatter regions from which material appeared to have been extracted. These structural observations strongly support the suggestion that chromosomal material is preferentially lost from the R-interbands with aggregation of fibres in the R-bands. T-banded chromosomes showed a similar structure to the R-banded chromosomes. The positively stained T-bands located at the telomeres corresponded to regions of highly aggregated fibres. The remainder of the chromosome, corresponding to the negatively stained area, had a flattened and extracted appearance. These similarities in morphology between the T- and R-banded chromosomes support the view that T-bands result from a progressive breakdown of the R-banded chromosome structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00328640
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  • 2
    Electronic Resource
    Electronic Resource
    The structural basis for C-banding (1985)
    Springer
    Chromosoma 91 (1985), S. 363-368 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The same C-banded human polymorphic chromosomes were observed in the light microscope (LM) and then in the scanning electron microscope (SEM) to investigate the structural changes produced by the C-banding technique. C-banded regions, which stained positively in LM, were highly condensed with tightly packed chromatin fibres, resembling non-banded chromosomes. In striking contrast, adjacent non-C-banded regions were represented by loosely arranged fibres, resembling G-banded chromosomes. The significance of these observations in relation to current theories on the effects of C-banding on chromosome structure is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00291009
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  • 3
    Electronic Resource
    Electronic Resource
    Cell mediated calcification in collagen gel cultures of fetal rat calvaria cells. Loss of gap junctions precedes calcification (1989)
    Springer
    Journal of bone and mineral metabolism 7 (1989), S. 6-17 
    Details
    ISSN: 1435-5604
    Keywords: Intercellular communication ; Gap junction ; Calcification ; Collagen gel ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To analyze the mechanism of initiation of cell-mediated calcification in hard tussue and its relationship to the frequency of gap junctions, enzymatically isolated cells from fetal rat calvaria cultured in collagen gels were observed ultrastructurally over a time course. Calcification was observed at 2–3 weeks after the initiation of culture when the seeding cellularity and the concentration of β-glycerophosphate were sufficiently high. In the collagen gels, round cells (R), spindle or stellate cells (S), and fat cells (F) were characterised morphologically. The ultrastructural features of initial calcification could be classified into 4 subtypes: 1) a large mass greater than 10 µm in diameter (Type I), 2) deposition associated with dead R cells or matrix vesicles (Type II), 3) intracellular deposition (Type III), and 4) other than Types I–III (Type IV). Type II was the most frequent (44.5%) and Type III was the least (6.8%). Gap junction was observed frequently between 1) R cells, 2) S cells, 3) between R cells and S cells. The frequency of gap junctions in collagen gels decreased statistically (X2-test; p〈0.001), when calcification was initiated. This cell culture system can be regarded as a useful model to analyze the initiation of cell mediated calcification in hard tissue. Gap junctions might function in cell communication and a decrease in their numbers could lead to cell death and, subsequently to calcification.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02399048
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  • 4
    Electronic Resource
    Electronic Resource
    Advances in gas permeability measurements (1987)
    Weinheim : Wiley-Blackwell
    Chemical Engineering & Technology - CET 10 (1987), S. 86-92 
    Details
    ISSN: 0930-7516
    Keywords: Chemistry ; Industrial Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The Carman-Arnell equation relates the rate of flow of a fluid through a packed bed to the pressure drop across the bed. This equation is the basis for surface area determination by permeametry. It is found that the surface area measured at sub-atmospheric pressure varies with the bed porosity, so a porosity was selected where the rate of change was at a minimum. The study suggests that, at reduced pressures, the gas flow rate is a linear function of the mean pressure.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ceat.270100111
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  • 5
    Electronic Resource
    Electronic Resource
    Modern Methods of On-Line Size Analysis for Particulate Process StreamsDedicated to Professor Kurt Leschonski on the occasion of his 60th birthdayThis paper was presented at The Engineering Foundation Conference “Control of Particulate Processes”, Matinkyla, Espoo, Finland, August 13-18, 1989. (1991)
    Weinheim : Wiley-Blackwell
    Particle and Particle Systems Characterization 8 (1991), S. 29-34 
    Details
    ISSN: 0934-0866
    Keywords: Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Two techniques for on-line particle size measurement are evaluated on the reproducibility of their volume distribution determinations. A forward scattering laser light devise is interfaced with a dilutor to examine the potential of this technique for high concentration streams. The forward scattering instruments are capable of outputting extremely reproducible distributions and here we show that when the dilutor is well designed, the on-line instrument can have similar performance. We compare this with a scanning back scatter instrument which is directly inserted in highly concentrated slurries. We present the methods used to improve the robustness of the conversion of the output of the back scatter instrument to volume distributions. The output of the back scatter instrument is inherently less stable but with the proper methods one can obtain reproducibilities of the order of 2 to 6 percent.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ppsc.19910080107
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  • 6
    Electronic Resource
    Electronic Resource
    Preparation of isolated nuclei from K 562 haemopoietic cell line for high resolution scanning electron microscopy (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 29 (1994), S. 54-61 
    Details
    ISSN: 1059-910X
    Keywords: Nuclear envelope ; Nuclear pore complex ; Percoll purification ; Field emission scanning electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The aim of the work is to visualise nuclear pore complexes (NPCs) in mammalian cells by high resolution scanning electron microscopy. A detergent-free isolation protocol was employed to obtain clean nuclei from the haemopoietic cell line K 562. Nuclear isolation was performed by mechanical homogenisation under hypotonic conditions followed by purification of the nuclear fraction. The isolated nuclei were attached to silicon chips, fixed, critical point dried, and sputter coated with a thin film (3-4 nm) of tantalum. Analysis of the nuclear surface by scanning electron microscopy (SEM) revealed a strong sensitivity of the outer nuclear membrane (ONM) to disruption during the isolation procedure. A significant reduction of the characteristic pattern of damage to the ONM was achieved by means of an isopicnic centrifugation on an isoosmolar balanced Percoll gradient. Analysis of the population of isolated nuclei by flow cytometry showed no signs of cell cycle specific losses of nuclei during isolation. The SEM investigations of the morphology of the nuclear envelope (NE) and of substructural details of NPCs and polyribosomes were performed using an in-lens field emission scanning electron microscope. © 1994 Wiley-Liss, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1070290108
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  • 7
    Electronic Resource
    Electronic Resource
    Ultrastructural morphometric study of efferent nerve terminals on murine bone marrow stromal cells, and the recognition of a novel anatomical unit: The “neuro-reticular complex” (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    American Journal of Anatomy 187 (1990), S. 261-276 
    Details
    ISSN: 0002-9106
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: In order to extend our understanding of the role of nerve fibers in the structure and function of bone marrow stroma, we have examined nerve terminals, arterioles, and capillaries in femoral bone marrow tissues of 50 C57BL strain mice, using electron microscopy and mor-phometric methods.Within the adventitia of arterioles, a particular type of cell, termed periarterial adventitial (PAA) cell, is characterized by a thin veil-like cytoplasm which concentrically surrounds both nerves and arterioles. Nerve fibers containing both unmyelinated and myelinated axons are distributed mainly between the layers of PAA cells, but are found rarely on the sinus walls or within the hematopoietic parenchyma. Quantitatively, the efferent nerve terminals with many synaptic vesicles are distributed mainly beside arterial smooth muscle cells (Type I: 58.8%) or between the layers of PAA cells (Type III: 33.2%), and rarely in hematopoietic parenchyma (Type II: 5.3%) or on sinus walls (Type IV: 2.7%).In the case of Type II-IV nerve terminals, efferent (autonomic) nerves and bone marrow stromal cells which are connected by gap junctions (sinus adventitial reticular cells, intersinusoidal reticular cells, and PAA cells) appear to constitute a potential functional unit for signal conduction. We would like to propose a new term for this anatomical unit in marrow, the “neuro-reticular complex.”
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aja.1001870306
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