Cell and tissue research
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Cell and tissue research · Nov 2002
Crucial role of fibroblasts in regulating epidermal morphogenesis.
Epidermis reconstructed on de-epidermized dermis (DED) was used to investigate whether fibroblasts can substitute growth factors needed for generation of a fully differentiated epidermis. For this purpose, a centrifugal seeding method was developed to reproducibly incorporate different fibroblast numbers into DED. Using (immuno)histochemical techniques, we could demonstrate that in the absence of fibroblasts the formed epidermis consisted only of two to three viable cell layers with a very thin stratum corneum layer. ⋯ Irrespective of the number of fibroblasts incorporated into DED, the expression of alpha(3), alpha(6), beta(1), and beta(4) integrin subunits was upregulated. In fibroblast-free DED matrices normalization of epidermal differentiation was only achieved when the culture medium was supplemented by keratinocyte growth factor. The results of this study indicate that normalization of epidermal differentiation can be achieved using a non-contractile dermal matrix populated with fibroblasts.
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Cell and tissue research · Oct 2002
Comparative StudyPhenotype of Per1- and Per2-expressing neurons in the suprachiasmatic nucleus of a diurnal rodent (Arvicanthis ansorgei): comparison with a nocturnal species, the rat.
In mammals, the suprachiasmatic nuclei (SCN) are the site of the master circadian pacemaker whose molecular core mechanism is based on interlocking transcriptional/translational feedback loops involving clock genes. Among clock genes, Per1 and Per2 are important for both the maintenance of circadian rhythmicity and entrainment to light cues. Several circadian rhythms (e.g., locomotor activity) present opposite patterns in diurnal and nocturnal species. ⋯ This differential expression of Per1 and Per2 in AVP and VIP neurons is more distinct in A. ansorgei than in the rat. Thus, our data suggest a major role for the dorsomedial part of the SCN in the maintenance of circadian rhythmicity. Furthermore, the similar diurnal pattern of Per1 and Per2 expression in diurnal and nocturnal rodents suggests that the circadian organization of locomotor activity rhythms probably relies on differential cellular integration mechanisms downstream of the clock.
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SCO-spondin is a large-molecular mass glycoprotein, secreted by the subcommissural organ (SCO), which has been implicated in neuronal development during ontogeny of the central nervous system. The expression of SCO-spondin is not restricted to the SCO but it also occurs in the floor plate, a key structure participating in neuronal differentiation and patterning of the neural tube. ⋯ The study of floor plate explants and their conditioned media allowed us to demonstrate that: (1) organ-cultured floor plate cells are actively secretory for up to 25 days; (2) SCO-spondin gene is actively transcribed and translated by the cultured floor plate cells; (3) SCO-spondin is released into the culture medium via the apical cell pole; and (4) upon release, SCO-spondin does not aggregate in the conditioned medium but remains soluble. Furthermore, in the cultured floor plate cells, SCO-spondin may be secreted through a route bypassing the Golgi apparatus.
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Cell and tissue research · Jun 2001
Comparative StudyEffects of SCO-spondin thrombospondin type 1 repeats (TSR) in comparison to Reissner's fiber material on the differentiation of the B104 neuroblastoma cell line.
SCO-spondin is a newly identified protein that is strongly expressed in the subcommissural organ (SCO), an ependymal differentiation of the brain. When released into the cerebrospinal fluid at the entrance to the Sylvian aqueduct, the glycoproteins condense and form a thread-like structure, Reissner's fiber (RF). To analyze the role of SCO-spondin on neuronal development, we studied the effects induced by an oligopeptide derived from a thrombospondin type 1 repeat (TSR) of SCO-spondin on neuroblastoma B104 cells and compared them with the effects of soluble RF material containing complete SCO-spondin proteins. ⋯ In high-density cell culture, both TSR peptide and RF material induced prominent neurite outgrowth and subsequent rapid cell aggregation. Whereas soluble RF material inhibited cell proliferation, no respective effect was observed in the presence of the TSR peptide. A direct interaction of TSR peptide and soluble RF material with a B104 cell binding site was revealed by increased B104 cell metabolic activity by flow cytometry.
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Cell and tissue research · May 2001
Comparative StudyDifferential storage of hydroxyethyl starch (HES) in the skin: an immunoelectron-microscopical long-term study.
Hydroxyethyl starch (HES) is widely used as a plasma substitute. Serious side effects occur only rarely, whereas a high incidence of severe pruritus has been reported. Moreover, tissue storage of HES has been demonstrated in various organs. ⋯ In nerves, HES deposits persisted no longer than 17 months paralleling the cessation of pruritus. Biopsies taken after 94 months exhibited no HES deposits in the skin. The condensation and final dissolution of the vacuoles may either indicate the release and subsequent redistribution of HES into the circulation or lysosomal degradation.