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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 96 (1977), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Recent evidence suggested that cyclic adenosine 3′,5′-monophosphate (cAMP) may be involved in the regulation of cell proliferation and differentiation. The effects of theophylline and dibutyryl cAMP on cell division and keratinization of human epidermal cultures were examined. Nine to 12-dayold cultures were treated with these agents, separately and in combination, for various intervals. Both agents, either singly or in combination, depressed mitoses. The maximum mitotic inhibition was obtained in cultures treated with theophylline or theophylline plus dibutyryl cAMP. Tritiated thymidine studies showed that the test agents had no effect on labelling index (LI) at 4 h, but a 74% inhibition of LI was observed at 24 h. The maximum inhibition of LI (93%) occurred at 96 hours. In contrast to the control cultures, which rarely contain keratohyaline granules (KG), a marked increase in the production of these granules occurred in cultures treated with dibutyryl cAMP plus theophylline. The KG were present over the whole outgrowth. Theophylline alone also stimulated the production of KG, whereas dibutyryl cAMP had no effect. These data show that these agents inhibit cell division and this inhibition may be accompanied by an increased production of KG.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 90 (1974), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Crude human skin extracts having tissue-specific mitotic inhibitory activity (chalone), were studied by ethanol precipitation and disc gel electrophoresis. Precipitates obtained at various ethanol concentrations were dialyzed, lyophilized and tested for their mitotic inhibitory activity. It was found that the greatest inhibitory activity was concentrated in the precipitate formed in 81% ethanol, the active principle being concentrated about 200 times. Proteins in crude extracts were separated by disc gel electrophoresis, and at least eight bands were identified. Groups of bands were extracted from the electrophoretic gels and tested for their mitotic inhibitory activity. Fraction II, containing two bands, had the highest activity. Disc gel electrophoretic analysis of the 81% ethane precipitate revealed only two major bands, one of which could also be found in fraction II of the crude extract. This protein band, which is present in both of the mitotic inhibitory samples, may represent the human epidermal chalone.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 265 (1977), S. 339-341 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Table 1 Inhibition of testosterone (1.810-5 M)-induced hyperplasia (m.i.±s.d.)* by different concentrations of -retinoic acid (RA) Cultures were simultaneously treated with testosterone (1.810-5 M) and different concentrations of RA from the beginning of the experiment Days after ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Methods in cell science 5 (1979), S. 1165-1168 
    ISSN: 1573-0603
    Keywords: colon ; proliferative ; differentiated ; epithelial cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Methods in cell science 4 (1978), S. 893-896 
    ISSN: 1573-0603
    Keywords: organ culture ; prostate ; carcinogens ; retinoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 229 (1991), S. 61-72 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Limited studies have described the ultrastructure of trachea of late fetal and neonatal hamsters but the effects of parturition and the onset of breathing on structure have not been discussed. This study describes morphological features of ante- and post-partum tracheal mucosa and submucosa and contrasts these features in fetal and neonatal hamster siblings. Significant differences between these siblings are noted in tracheal cells interfacing the lumen. Such cells of the fetal animals usually possessed cytoplasm of medium electron density with cisternal rough endoplasmic reticulum (RER). Surface membranes of these cells possessed numerous microvilli. In contrast, corresponding cells of post-natal animals often had lucent cytoplasm with mostly tubular or vesicular RER. Surface membranes of these cells possessed microplicae (microridges).This study also considers characteristics of fetal and neonatal tracheal development including: lomasome-like structures in secretory cells; dichotomous forms of oligocilia in mucosal and submucosal cells; intramembranous particles of hemidesmosomes; particles and mitochondria associated with desmosomes; and affiliations of ciliary basal bodies with the cytoskeleton, cell membrane, and with endoplasmic reticulum.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 155 (1993), S. 223-233 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The secretions of the salivary gland system are essential for the maintenance of oral health. The nature of cell-specific secretions of the various glands and their regulation is not completely understood. The objective of this study was to establish epithelial cell cultures from the human parotid gland that exhibit the tissue-specific function of α-amylase secretion. A specimen of normal human parotid gland was obtained at surgery and used to obtain primary cultures by the explant/outgrowth procedure. The cultures were maintained in keratinocyte basal medium, supplemented with insulin (5 μg/ml), EGF (10 ng/ml), hydrocortisone (0.5 μg/ml), bovine pituitary extract (25 μg/ml), and antibiotics. The cultures were passaged using 0.125% trypsin to dissociate the cells. Phase contrast and ultrastructural observations showed that the cells were polygonal and exhibited desmosomes. Their cytoplasm contained tonofilament bundles and abundant rough endoplasmic reticulum and Golgi complexes. Immunofluorescence studies showed that all cells were positive for cytokeratins. Immunoblot analysis revealed keratins with molecular weights of 58, 56, 52, 50, 48, 46, and 40 KD, which are characteristic of secretory epithelia. The cells have been passaged 35 times so far, undergoing a cumulative 120-140 population doublings. The serially passaged epithelial cell cultures produced and secreted α-amylase, a major component of parotid gland acinar cell secretion. The β-adrenergic agonist, isoproterenol (ISP), stimulated α-amylase secretion, which was accompanied by increased intracellular concentrations of cAMP. ISP-induced stimulation of amylase and cAMP was blocked by the β-adrenergic antagonist, propranolol. Further, dibutryl cAMP also enhanced the secretion of amylase. Thus we have established a long-term epithelial cell culture model of human parotid gland epithelial cells that exhibits differentiated function and retains the intact β-adrenergic receptor system. © 1993 Wiley-Liss, Inc.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
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