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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 278 (1986), S. 283-292 
    ISSN: 1432-069X
    Keywords: Keratinocyte differentiation ; Desmosome ; Immunogold labelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The keratinocyte membrane antigen KM 48 was defined by a new monoclonal antibody obtained after mouse immunization with normal human epidermal cell suspension. Specific reactivity of the antibody with desmosomal regions of keratinocyte cell membrane was demonstrated by immunoelectronmicroscopy. Langerhans cells, melanocytes, and indeterminate cells did not express the KM 48 antigen. Immunogold labelling permitted ultrastructural quantitation of KM 48 antibody binding on keratinocytes from various epidermal layers. A gradual increase in desmosome-related KM 48 antigen expression accompanied differentiation of keratinocytes durign their transit from basal to granular layer. Distribution of the antigen on individual cells was uneven. The upper pole of a keratinocyte facing overlying more differentiated cells was always found to be laden with an immunogold marker about twice that of the opposite, lower surface of the cell. The results support the previous reports on gradual development of desmosomes during epidermal cell maturation and open up new possibilities for keratinocyte differentiation studies. They also underline the virtues of the immunogold-labelling method used for cell-surface antigen tracing and quantitation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-069X
    Keywords: HLA class I antigens ; Human epidermis ; Immunogold labelling ; Langerhans cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Using an immunogold labelling procedure, we quantified the density of major histocompatibility (MHC) class I antigens on the surface of Langerhans cells (LCs) and keratinocytes of the normal human epidermis. According to ultrastructural features, keratinocytes were divided into three subpopulations: stratum basalis (SBK), stratum spinosum (SSK), and stratum granulosum keratinocytes (SGK), and analyzed separately. For this purpose, three monoclonal antibodies (MCAs) were employed: an anti-HLA A,B,C, an anti-B2-microglobulin (B2-m), and a polymorphic anti-HLA A2 Aw69 MCA. Under electron microscopy, quantitative analysis demonstrated: (a) the presence of a high amount of HLA monomorphic determinants on SBK and SSK and moderate but significant labelling of SGK; (b) the very weak density of MHC class I antigens on the surface of epidermal LCs; (c) the expression, at an identical level, of the HLA heavy chain common determinant (HLA A,B,C), B2-m, and the alloantigen HLA A2 by all epidermal cells (ECs) apart from SGKs and LCs that presented far fewer HLA A2 sites than monomorphic determinants (B2-m and HLA A,B,C); (d) the absence of HLA class I on corneocytes and a moderate labelling of melanocytes. A knowledge of the precise quantitative distribution of HLA class I antigens among various cell subpopulations of the normal human epidermis would be very useful for the study and followup of cutaneous malignancies that are known to lose these molecules as well as for the understanding of immune responses, especially allospecific, that involve the skin.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2022-06-14
    Description: Thirty years after oxygen isotope records frommicrofossils deposited in ocean sediments confirmed the hypothesis that variations in the Earth’s orbital geometry control the ice ages1, fundamental questions remain over the response of the Antarctic ice sheets to orbital cycles2. Furthermore, an understanding of the behaviour of the marine-based West Antarctic ice sheet (WAIS) during the ‘warmer-than- present’ early-Pliocene epoch (̃5–3Myr ago) is needed to better constrain the possible range of ice-sheet behaviour in the context of future global warming3. Here we present a marine glacial record from the upper 600 m of theAND-1B sediment core recovered from beneath the northwest part of the Ross ice shelf by the ANDRILL programme and demonstrate well-dated, ̃40-kyr cyclic variations in ice-sheet extent linked to cycles in insolation influenced by changes in the Earth’s axial tilt (obliquity) during the Pliocene. Our data provide direct evidence for orbitally induced oscillations in the WAIS, which periodically collapsed, resulting in a switch from grounded ice, or ice shelves, to open waters in the Ross embayment when planetary temperatures were up to ̃3 C warmer than today4 and atmospheric CO2 concentration was as high as ̃400 p.p.m.v. (refs 5, 6). The evidence is consistent with a new ice-sheet/ice-shelf model7 that simulates fluctuations in Antarctic ice volume of up to + 7 m in equivalent sea level associated with the loss of the WAIS and up to +3 m in equivalent sea level from the EastAntarctic ice sheet, in response to ocean-induced melting paced by obliquity.During interglacial times, diatomaceous sediments indicate high surface-water productivity, minimal summer sea ice and air temperatures above freezing, suggesting an additional influence of surface melt8 under conditions of elevated CO2.
    Description: Published
    Description: 322 - 328
    Description: 2.2. Laboratorio di paleomagnetismo
    Description: 3.8. Geofisica per l'ambiente
    Description: 2.3. TTC - Laboratori di chimica e fisica delle rocce
    Description: JCR Journal
    Description: reserved
    Keywords: Antarctica ; paleoclimate ; Pliocene ; stratigraphy ; 02. Cryosphere::02.02. Glaciers::02.02.99. General or miscellaneous ; 03. Hydrosphere::03.01. General::03.01.06. Paleoceanography and paleoclimatology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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