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  • 1990-1994  (2)
  • 1955-1959
  • 1940-1944
  • 1930-1934
  • 61.16.Fk  (1)
  • Acyl-neuramic acids  (1)
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  • 1990-1994  (2)
  • 1955-1959
  • 1940-1944
  • 1930-1934
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  • 1
    ISSN: 1432-1440
    Keywords: Acyl-neuramic acids ; Plasma ; T-lymphocyte ; Mammary carcinoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Increased sialic acid levels reflecting tumor burden are found on the surface of T-lymphocytes and in the plasma of patients with carcinoma of the mammary gland. The data of the determinations of sialic acid content and distribution on T-cells, using microanalytical methods such as HPLC and a colorimetric test, show that the total sialic acid content is increased by about 60% and that nearly 80–90% of the sialic acids consist of Nacetyl-9-O-acetyl-neuraminic acid, in comparison to the healthy controls (not containing O-acetylated neuraminic acid). Investigations on lymphocytes of malignant melanoma patients show similar changes of sialic acid content and distribution on the cell surface. Increased sialic acid levels are also found in the plasma of patients with cancer but no O-acetylated derivative can be found. Furthermore the examinations show that the separation of the T-lymphocytes from the total lymphocyte fraction is not required. Determination of sialic acids in the total lymphocyte fraction can be a simplification in carrying out further diagnostic investigations. A high level of sialic acids as “antirecognition factor” seems to be not only a marker of tumor cells but also an attribute of T-lymphocytes, involved in the defence against the malignoma (malignant melanoma, breast cancer). Considering the possible contribution of sialic acid to the immunoregulatory protective mechanism during the first stage of pregnancy, sialic acid content and distribution on T-cells of pregnant women are investigated. Both an increase and a change in the distribution of sialic acids can be excluded.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 53 (1991), S. 369-376 
    ISSN: 1432-0630
    Keywords: 68.55.−a ; 68,35.Fx ; 61.16.Fk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract The growth of Pt(111) by Pt vapour deposition is studied by He diffraction as a function of substrate temperature and deposition rate. At a deposition rate of about 2.5×10−2 monolayers/second several growth modes are observed: layer-by-layer (2D-) growth at 450 K≲T s≲800 K, multilayer (3D-) growth at 340 K≲T s≲450 K and reentrant layer-by-layer (2D-) growth at T s≲340 K. The observed growth modes and in particular the reentrant 2D-growth are shown to be characteristic of growing Pt(111) under clean conditions, i.e. not influenced by contaminants. The influence of the intra- and interlayer mass transport on the growth mode is discussed in the light of experimental and simulation results. The 3D-growth mode is attributed to the existence of an activation barrier which suppresses the descent of adatoms from the top of the growing adatom islands onto the lower terraces. The barrier can be overcome by thermal adatoms at T s≳450 K enabling interlayer mass transport which leads to 2D-growth. The reentrant 2D-growth occurs due to a break down of this barrier for small, irregularly shaped islands.
    Type of Medium: Electronic Resource
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