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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 131 (1994), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have previously developed methods for the isolation and maintenance of human sebaceous glands and hair follicles. However, in long-term culture the maintenance of both is suboptimal. This may be due to a lack of stem cells, which are thought to be located in the bulge area of the hair follicle, and this region is not present in either model. Isolation of the entire pilosebaceous unit would retain this region, and may lead to improved maintenance of both structures. We describe a method for the isolation of viable, individual, pilosebaceous units by microdissection from human scalp face-lift skin. The viability of isolated pilosebaceous units has been determined by light microscopy, patterns of DNA synthesis by [methyl-3H] thymidine autoradiography, and lipogenesis by [U-14C] acetate uptake into lipids.When maintained for 7 days in supplemented Williams E medium, isolated pilosebaceous units showed a significant increase in length. This was due to the production of a keratinized hair fibre which grew at the in vivo rate of 0.3 mm/day.Light microscopy and [methyl-3H] thymidine autoradiography confirmed that after 7 days maintenance the hair follicle retained apparently normal morphology and patterns of DNA synthesis. However, the morphology of the sebaceous gland on maintenance was more variable, generally showing luminal keratinization. Moreover [methyl-3H] thymidine autoradiography of sebaceous glands showed a marked reduction on maintenance.The rates and patterns of lipogenesis by the whole pilosebaceous unit were, respectively, lower and different from those seen with isolated human sebaceous glands: this indicates that the bulk of pilosebaceous lipogenesis is derived from the hair follicle. Rates of recovery of [14C] from 2 mM-[U-14C] sodium acetate into thin-layer chromatography plates after 7 days maintenance decreased, although this was not statistically significant, indicating that rates of lipogenesis may fall on maintenance. Pilosebaceous units were maintained for 7 days on Gelfoam (an absorbable gelatin sponge) at the media-air interface. Initial results show a marked improvement in sebaceous gland morphology. It is possible, therefore, to obtain viable human pilosebaceous units by microdissection, and to maintain them in vitro for up to 7 days, with apparently full retention of hair follicle function, but only partial retention of sebaceous gland function.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 137 (1997), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The hair follicle is a heterogeneous tissue involving differentiation of both hair forming (trichocyte) and non-hair forming (root sheath) cells; while there are many antibody markers available which can determine the distribution of ‘soft’ epithelial keratins, fewer have been described which are truly monospecific for hair specific ‘hard’ keratins. We employed the proven strategy of raising monoclonal antibodies to a short synthetic peptide from the carboxy-terminal sequence of mouse Ha1 and report here the successful production of a monospecific monoclonal antibody which we have called LHTric-1. We have characterized the antibody using immunostaining on rat and human tissues and by immunoblotting against an extract of human follicles. The antibody cross-reacted between rat and human tissue but did not stain formalin-fixed tissue. LHTric-1 localized very specifically to the pre-cortical region of the hair follicle in early anagen and to pre-cortical cells in the upper bulb in anagen. Telogen follicles did not react. LHTric-1 immunoreacted within tongue and nail, staining being restricted to the mid-line above the connective tissue core in tongue and to the suprabasal layers of the nail matrix. The antibody did not react with the fully keratinized hair or nail plate. Finally, in immunoblotting. LHTric-1 reacted with a single band of 44kDa, suggesting that a single protein was recognized. We conclude that this antibody, by virtue of its known antigen sequence specificity, will be useful in research into the formation of hair and nail in normal and diseased states.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The immune system may be involved in the regulation of normal hair follicle growth as well as in the pathogenesis of some hair diseases. Immunomodulatory cytokines not only act as mediators of immunity and inflammation but also regulate cell proliferation and differentiation and. as such, may play an important part in regulating hair growth. We have investigated the effects of a number of interleukins (IL). colony stimulating factors and tumour necrosis factors (TNF) on hair follicle growth in vitro. Dose-response studies showed that IL-1α. IL-1ß and TNF-o were potent inhibitors of hair follicle growth. The histology of hair follicles maintained with inhibitory doses of IL-1α. IL-1ß and TNF-α showed similar changes in hair follicle morphology, resulting in the formation of dystrophic anagen hair follicles. These changes in histology were characterized by the condensation and distortion of the dermal papilla, marked vacuolation of the hair follicle matrix, abnormal keratinization of the follicle bulb and inner root sheath, disruption of follicular melanocytes and the presence of melanin granules witbin the dermal papilla. Moreover, these changes in hair follicle morphology are similar to those reported in alopecia areata and suggest that IL-1α, IL-1ß and TNF-α may play an important part in the pathophysiology of inflammatory hair disease.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 129 (1993), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: We have previously reported the in vitro growth of human hair follicles for up to 4 days in a partially defined medium containing serum. We now report the prolonged in vitro growth of isolated human hair follicles for at least 9 days. This was achieved after analysis of the contribution of certain components of the original medium and, by a process of elimination, deriving a completely defined medium supplemented only with antibiotics. l-glutamine, insulin and hydrocortisone. We have shown, by [methyl-3H] thymidine autoradiography, that the hair follicles grown in this medium maintain an in vivo pattern of DNA synthesis, and that the gross morphology and histology of these maintained hair follicles remains similar to that of freshly isolated hair follicles. We have also shown that the patterns of keratin synthesis, as determined by [35S] methionine labelling, do not alter with maintenance.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    British journal of dermatology 127 (1992), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Pelage hair follicles were isolated by gentle microdissection from 8–12-day-old rats, and maintained in supplemented Williams E medium. Length measurements made on freshly isolated hair follicles, and at 24-h intervals, showed a significant increase in hair follicle length over 48 h, after which time no further significant increase in length was observed. Photomicrographs of maintained follicles showed that this increase in hair follicle length could be attributed to the production of a keratinized hair shaft. Histology and [methyl-3H] thymidine autoradiography of freshly isolated hair follicles showed the dermal papilla to be elongated, with thymidine uptake located predominantly in the matrix cells of the hair follicle bulb adjacent to the dermal papilla. This pattern remained unaltered for the first 48 h of maintenance, but after 72 h the dermal papilla had rounded into a tight ball of cells, with very little thymidine uptake occurring in the adjacent matrix cells.On maintenance, fetal calf serum (FCS), epidermal growth factor (EGF) and 12-o-tetradecanoyl phorbol 13-acetate (TPA) all significantly stimulated [methyl-3H] thymidine and [U-14C] leucine uptake, but inhibited hair follicle elongation. Insulin-like growth factor-1 (IGF-1) had no significant effect on rates of hair follicle elongation and [methyl-3H] thymidine uptake, but significantly stimulated rates of [U-14C] leucine uptake. Transforming growth factor-β1 (TGF-β1) significantly inhibited both the rate of [methyl-3H] thymidine uptake and hair follicle elongation.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 148 (2003), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  Adrenomedullin (AM) is a regulatory peptide that is synthesized and secreted by a wide number of cells and tissues. AM is a potent vasodilator, but also exerts other functions, such as regulating cell growth and antimicrobial defence. Two receptors, L1 and calcitonin receptor-like receptor (CRLR), which are able to bind AM, have been cloned and characterized.Objectives  To investigate expression of AM protein and its receptors in human skin and during different stages of the human hair cycle and, moreover, because of the suggested antimicrobial function of AM in skin, to investigate AM immunoreactivity (IR) in inflammatory acne lesions compared with healthy pilosebaceous follicles.Methods  We used immunohistochemistry to determine the distribution of AM and its receptors in human skin and during different stages of the human hair cycle. AM IR in inflammatory acne lesions was investigated to evaluate the antimicrobial function of the protein, and hair follicle cultures were performed to examine the role of AM in differentiation and proliferation of hair follicle keratinocytes.Results  Strong IR for AM and its receptors was present in the suprabasal epidermis, in the melanocytes of the epidermis, and in sweat and sebaceous glands. In the hair follicle, AM protein was strongly expressed in the basal and suprabasal layers of the hair bulb and the proximal outer root sheath (ORS). In the distal ORS, AM expression was increasingly suprabasal, especially in proximity to the bulge region where the basal cell layer was free of IR. IR for the CRLR revealed a similar expression pattern to that seen for AM. In contrast, L1 IR showed a suprabasal pattern of IR throughout the ORS. Similar expression of AM and its receptors was observed in catagen and early anagen follicles. AM expression was not markedly upregulated in acne lesions, suggesting a minor role for this antimicrobial peptide in acne. Despite its well-documented mitogenic effects, particularly in oral and skin keratinocytes, AM had no significant effect on hair follicle growth in vitro.Conclusions  AM and its receptors are expressed in human hair follicles, and both AM and its receptors are colocalized in the same compartments and cell types of the skin. This finding is consistent with the proposed autocrine/paracrine mechanism in the physiology of AM.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background  The hair follicle continually undergoes dynamic remodelling in a cyclical manner involving tightly coordinated patterns of cell proliferation, differentiation and apoptosis. The oncoprotein c-Myc is a key regulator of these events in epidermal keratinocytes, but its importance in the hair growth cycle has not previously been determined.Objectives  To determine the role of c-Myc in the hair growth cycle.Methods  We characterized the hair follicle phenotype of transgenic mice that permit expression of a switchable form of c-Myc (c-Myc-ER™) in the suprabasal epithelial layers of the epidermis and hair follicle.Results  c-Myc activation increased epithelial cell proliferation in the outer root sheath and distal hair follicle, without any substantial alteration in levels of apoptosis. Moreover, chronic c-Myc activation resulted in marked desynchronization of the murine hair growth cycle, uncoupling of hair cycle-related skin thickness and enlargement of the sebaceous gland.Conclusions  These data implicate c-Myc in the control of hair growth cycling and hair cycle-related epidermal and sebaceous gland homeostasis. We suggest that c-Myc may be activating follicular stem cells either directly or indirectly and that this has important implications for control of the ‘hair cycle clock’, hair growth and epidermal maintenance.
    Type of Medium: Electronic Resource
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