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  • 1
    ISSN: 1600-0625
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Cell envelopes (CEs) are insoluble, chemically and mechanically tough structures formed during terminal differentiation of keratinocytes, providing skin with a protective barrier against the environment. They are 15 to 20 nm thick structures beneath the plasma membrane and continuous with desmosomal attachment plaques. Sequential deposition of several proteins including involucrin and loricrin leads to a gradual increase in envelope thickness and rigidity. Cross-linking of demosomal components to other CE-proteins has been demonstrated and desmosomes in the cornified cells have been demonstrated and desmosomes in the cornified cells have been regarded as a part of CEs. Our previous immunoelectron microscopy studies showed that desmosomal areas of granular cells were loricrin-positive, but those in cornified cells were negative. We asked whether this is due to epitope masking and applied trypsin digestion of the electron microscopy sections to retrieve the possibly masked epitopes. Since this treatment made desmosomal structures obscure, one side of the sections was stained with anti-desmoglein antibody as an indicator of desmosomes. Trypsin was applied on the other side followed by immunolabeling with anti-loricrin antibody. Trypsin digestion indeed unmasked the loricrin epitopes in the desmoglein-positive desmosomal areas of CEs. It seems therefore that loricrin is first accumulated at the desmosomes before the CE-assembly and cross-linking of loricrin occurs at the desmosomal areas of CEs as well as at the non-desmosomal areas.
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 135 (1996), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Psoriatic hyperproliferative epidermis is characterized by a regular elongation of rete ridges, accompanied by altered keratinization. Another notable finding is close positioning of the vasculature to the suprapapillary epidermis. These architectural/morphological changes are naturally described by a concept of epidermal remodelling based on decreased epidermal turnover time. The recently described positioning of stem cells to the tips of dermal papillae fits nicely with this concept.
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  • 3
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We used PUVA therapy in a patient with crisis-type adult T-cell leukaemia/lymphoma and generalized cutaneous leukaemic cell infiltration. PUVA proved very effective in reducing leukaemic cells and in clearing the eruption. To understand the way in which PUVA produced a reduction in the number of leukaemic cells, we examined peripheral blood cells by light and electron microscopy. Light microscopy was of little help, but electron microscopy revealed that PUVA induced apoptosis-like changes in circulating leukaemic cells. This suggests that apoptosis-like changes in leukaemic cells might be the reason for the success of this treatment.
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  • 4
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Psoriatic hyperproliferative epidermis is characterized by a decreased β2-adrenergic adenylate cyclase response as well us by altered differentiation markers that include decreased loricrin and increased involucrin, Using a quantitative reverse transcription-polymerase chain reaction, we analysed the expression of β2-adrenergic receptor-mRNA. loricrin-mRNA, and involucrin-mRNA in the epidermis of five patients with psoriasis vulgaris. The mRNAs of the β2-adrenergic receptor and loricrin in the involved epidermis were significantly decreased, by 0.35-fold (P 〈 0.01) and 0.55-fold (P 〈 0.05) respectively, compared with uninvolved epidermis. In contrast, the involucrin mRNA expression of the involved epidermis was significantly increased, by 3.77-fold (P 〈 0.01). No significant difference in β-actin mRNA transcripts was detected between the involved and the uninvolved epidermis. These results indicate that the altered expression of the β2-adrenergic receptor, loricrin. and involucrin. in the psoriatic involved epidermis, is associated with different amounts of each mRNA transcripts.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 288 (1995), S. 24-30 
    ISSN: 1432-069X
    Keywords: Key words G-protein ; Adenylate cyclase ; Phorbol ; esters ; Densensitization ; Keratinocytes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Although the protein kinase C (PKC) activator, phorbol 12-myristate 13-acetate (PMA) has been known to induce heterologous desensitization of the epidermal adenylate cyclase, the precise mechanism of PMA action remains unknown. Effects of PMA on the receptor-G-protein-adenylate cyclase system of fetal rat skin keratinocytes (FRSK) were investigated. Choleratoxin catalysed the ADP ribosylation of 45 kDa and 52 kDa membrane proteins and islet activating protein (IAP) catalysed the ADP ribosylation of a 40 kDa membrane protein. Incubation of FRSK with PMA decreased the cholera toxin-catalysed ADP ribosylation of the membrane protein, but not the IAP-catalysed ADP ribosylation. The effect of PMA on the cholera toxin-catalysed ADP ribosylation was inhibited by the PKC inhibitor, H-7 (1-(5-isoquinolinesulfonyl)-2-methyl piperazine dihydrochloride). 1-Oleoyl-2-acetylglycerol (OAG), a membrane-permeable diacylglycerol analogue, also decreased the cholera toxin-catalysed ADP ribosylation, but 4- O -methyl PMA, a very weak PKC activator, had no effect. Keratinocytes are known to express the guanine nucleotide binding proteins, Gsα, Gi2α and Gi3α. Immunoblot analysis of the PMA-treated FRSK showed no detectable difference in the amount of Gsα, Gi2α, Gi3α or the β subunit of the G-protein. PMA significantly decreased the β-adrenergic adenylate cyclase response and cholera toxin-induced cyclic AMP accumulation, while it markedly increased forskolin-induced cyclic AMP accumulation. These results indicate that phorbol esters affect the stimulatory guanine nucleotide binding protein (Gs) of FRSK via a PKC-dependent pathway.
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  • 6
    ISSN: 1432-069X
    Keywords: Bullous congenital ichthyosiform erythroderma ; Involucrin ; SPRR1 ; Loricrin ; Trichohyalin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Epidermolytic hyperkeratosis (EH) is a genetic disorder of keratins associated with epidermal differentiation. Affected individuals carry gene mutations for conserved sequences of keratins K1 or K10. The structural alterations of tonofilaments in EH seem to be a direct consequence of the keratin gene mutations. EH epidermis, however, shows many other unexplained abnormalities including acanthosis, hypergranulosis, and hyperkeratosis. To further elucidate the pathogenetic mechanism of EH, we studied distribution patterns of other keratinization-associated molecules including involucrin, small proline-rich protein (SPRR) 1, loricrin and trichohyalin in the skin of four patients by light and electron microscopic immunohistochemistry in conjunction with conventional transmission electron microscopy. The middle to upper epidermal cells showed moderate to strong immunoreactivities to involucrin, SPRR1 and loricrin antibodies. Both intracellular staining and cell peripheral staining was seen for involucrin and SPRR1 antibodies. Loricrin labelling was prematurely associated with the plasma membrane of granular cells, possibly relating to abnormal keratin filament aggregation and cellular vacuolization. Some loricrin labelling was localized on the keratin aggregates, suggesting intermolecular associations between keratin and loricrin. Trichohyalin, hardly detectable in normal epidermis, was present in some granular and cornified cells in EH in association with keratin filaments, suggesting that it may function as an intermediate filament-associated protein. While cornified cell envelopes were intensely labelled only with loricrin antibodies in normal skin, they were immunoreactive to involucrin, SPRR1 and loricrin antibodies in EH. Sequential change in electron density of the cornified cell envelopes, a constant feature in normal skin, was often absent in EH. These results suggest an altered assembly process of cornified cell envelopes in EH.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 287 (1995), S. 740-746 
    ISSN: 1432-069X
    Keywords: Involucrin ; TEF-1 ; Limiting transcriptional intermediary factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Involucrin is one of the precursor proteins of keratinocyte cornified envelope that is formed beneath the inner surface of the cell membrane during terminal differentiation. Although involucrin is specifically expressed in the upper squamous cells of the epidermis, the precise regulatory mechanism of involucrin gene expression remains unknown. Transcriptional enhancer factor 1 (TEF-1), which binds to SV40 enhancer, is a nuclear protein expressed in various types of cells including keratinocytes. Immunohistochemical study has revealed that TEF-1 protein is highly expressed on the basal cell layer of the epidermis. To examine the possible regulatory mechanism of involucrin gene expression by TEF-1 protein, we analysed involucrin promoter activity of the INV-CAT vector, which was constructed by connecting the 5′ upstream region of the involucrin gene (−801 bp upstream from the transcription start site and downstream including the untranslated first exon) to the chloramphenicol acetyltransferase (CAT) reporter gene. The INV-CAT vector was transfected to SV40-transformed human keratinocytes (SVHK). Cotransfection of the TEF-1 expression vector significantly repressed INV-CAT promoter activity in a dose-dependent manner. The repression was also observed by transfection of the GAL4-TEF-1 vector, which was constructed by replacement of the TEF-1 DNA binding domain by the GAL4 activator domain. This suggests that TEF-1-induced repression is due to interference/squelching of a limiting transcriptional intermediary factor that is essential for involucrin expression. Analysis of the deleted INV-CAT vector suggested that the region from −599 to −495 of the involucrin gene, which contains two possible TEF-1 binding sites, was critical for the repression of the involucrin gene by TEF-1. By gel retardation analysis, the specific DNA binding of SVHK cell nuclear extracts and the recombinant TEF-1 protein was confirmed. TEF-1-dependent repression of involucrin gene expression might explain the suprabasal involucrin expression in the epidermis.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-8798
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We sequenced the entire genome of an Italian isolate of hepatitis C virus: the first full-length sequence for the genotype 2c. We report hereby its characteristics and differential detection of 2c isolates using PCR.
    Type of Medium: Electronic Resource
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