| 1. |
- Andersson, Anders, et al.
(författare)
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The epidermal indeterminate cell- a special cell type?
- 1981
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Ingår i: Acta dermato-venereologica. Supplementum. - 0365-8341. ; 99, s. 41-48
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Tidskriftsartikel (refereegranskat)abstract
- Electron microscopy of normal human epidermiscomprising very large series of sections in combination withtilting of the sections has revealed that all "indeterminatecells" carry the specific markers of either melanocytes orLangerhans cells. The term "indeterminate cells" can thusbe abandoned. In addition, it is suggested that an epidermaldendritic cell lacking specific markers in the section underobservation can be characterized by the amount and distributionpattern of its microfilaments, an additional criterionbeing that the melanocytes carry a ciliunu
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| 2. |
- Axelsson, S, et al.
(författare)
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In vitro-uptake of L-Dopa and catecholamines into the epidermal Langerhans cell
- 1978
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Ingår i: Acta dermato-venereologica. Supplementum. - 0365-8341. ; 79, s. 31-35
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Tidskriftsartikel (refereegranskat)abstract
- The Langerhans cells are capable of taking up L-dopa and the catecholamines dopamine and noradrenaline when exposed to these substances in vitro. Within the cell L-dopa is found in the cytoplasm as well as in the nucleus, whereas the catecholamines are confined to cytoplasmic granules. The L-dopa uptake is most probably carrier-mediated and the hypothesis is brought forward that L-dopa enters the cell by exchange diffusion. At present little is known about the nature of the amine uptake mechanism.
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| 3. |
- Elofsson, Rolf, et al.
(författare)
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Catcholaminergic salivary glands in Gammarus pulex (Crustacea, Amphipoda): An electron microscopic and microspectrofluorometric study
- 1978
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Ingår i: Journal of Ultrastructure Research. - 0022-5320. ; 64, s. 14-22
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Tidskriftsartikel (refereegranskat)abstract
- The type of gland (salivary gland) described here for the amphipod Gammarus pulex belongs to the tegumental glands, which have different structural characteristics. The present type, called rosette gland, is common in some crustaceans and is located in the ventral half of the head. The functional unit is a lobule of gland cells with a central-draining duct. Ducts from groups of lobules conjoin and terminate on the body surface at different points around and in the mouth and mouth parts. With the fluorescence histochemical method of Falck and Hillarp, specific green fluorescence was discerned centrally in the lobules and was confined to the gland cells. The spectral characteristics of the fluorescence, as revealed by microspectrofluorometric analysis, indicated either a mixture of dopamine and a presumed new catechol compound or the presence of two tautomeric forms either of dopamine or of a new catechol compound. Evidence of new catechol compounds with similar spectral characteristics has previously been found in the sensory cells of some invertebrates. The fluorescence distribution within the lobule coincides with the presence, ultrastructurally, of large dense vesicles in the gland cells. These dense vesicles occur in the predominant cell type, also characterized by a smooth endoplasmic reticulum. The other cell type in the lobules differs ultrastructurally by possessing a rough endoplasmic reticulum and a different vesicle type. No innervation of the salivary gland was perceived.
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| 4. |
- Elofsson, Rolf, et al.
(författare)
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Evidence for endocytotic mechanisms in the epidermal Langerhans cells.
- 1981
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Ingår i: Acta dermato-venereologica. Supplementum. - 0365-8341. ; 99, s. 29-39
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Tidskriftsartikel (refereegranskat)abstract
- When the Langerhans cells (LC) are prepared forelectron microscopy with an osmotically balanced prefixative,they display their classical criteria, but in additionthey are provided with numerous microvilli and containpinocytotic vesicles. In cross-sections the specific discshapedgranules are visualized as rod-like profiles limited bya trilaminar membrane similar to the cell membrane. Inface-on projection the electron density of a single granule istoo low to permit its observation. It ts suggested that theracquet-shaped profile bounded by a non-trilaminar membrane,regarded as classical, is a fixation artifact. The viewis advanced that the Birbeck granules are formed by a processimplying a superimposition of membrane folds. Theoccurrence of phagocytosed melanosomes seems to be anormal phenomenon.The LC are highly activated in contact allergic dermatitis,as expressed by an increase in number, a polarizationof dendrites towards the surface and the appearance ofmembrane active zones characterized by intense membranefolding, combined with a formation of pinocytotic vesiclesand specific granules. Challenging sensitized skin withnickel leads to the occurrence of dark vesicles which probablylack a limiting membrane. It is concluded that the LCshow endocytotic activity and that they constitute animportant defense system in the epidermis, i.e., capable ofcapturing extracellular (endogenous or exogenous) materialvia different routes.
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| 5. |
- Elofsson, Rolf, et al.
(författare)
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Evidence for new catecholamines or related amino acids in some invertebrate neurons
- 1977
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Ingår i: Cell and Tissue Research. - 1432-0878. ; 182, s. 525-536
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Tidskriftsartikel (refereegranskat)abstract
- In certain sensory neurons of many different invertebrate species, including the sea anemones. Metridium senile and Tealia felina and the crustacean Anemia salina, fluorophores are formed during the course of the fluorescent histochemical technique of Falck-Hillarp. The presumed catecholamine nature of the neuronal fluorogenic compound was investigated by microspectrofluorometry, and the spectral characteristics of the fluorescence in the taxonomically different species was found to be very similar (excitation maximum at 375 nm with a smaller peak or shoulder at 330 nm and sometimes a shoulder in the spectrum at 410 nm; emission maximum at 475 nm). The emission maximum coincides with that of the catecholamines and DOPA (475 nm). The excitation maximum (375 nm) directly after formaldehyde treatment, however, differs from that of the catecholamines and DOPA (410 nm), but is similar to the excitation maximum displayed by these catechol derivatives at acid pH. The spectral characteristics of the fluorophore in the sensory cells might therefore theoretically be explained by an acid pH in the cells. This seems improbable, however, and it is suggested that the phenomenon is due to the presence of unknown catechol derivatives. Analyses of the pH-dependent spectral changes indicate that the presumed catechol derivative in Tealia felina is β-hydroxylated, whereas that in Anemia salina is not.
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| 6. |
- Elofsson, Rolf, et al.
(författare)
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The ciliated human keratinocyte
- 1983
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Ingår i: Journal of Ultrastructure Research. - 0022-5320. ; 87, s. 212-220
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Tidskriftsartikel (refereegranskat)abstract
- Human keratinocytes were investigated for the presence of single cilia. Almost all basal keratinocytes were found to carry a single cilium in normal, occluded, and psoriatic skin. The ciliary structure was progressively reduced in keratinocytes approaching the surface. No remnants of the ciliary apparatus were found in the granular layer. In one case of nickel-allergic dermatitis (patch test), the keratinocytes had lost their cilia; the significance of this surprising finding remains to be elucidated.
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| 7. |
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| 8. |
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| 9. |
- Falck, Bengt, et al.
(författare)
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New mechanism for amino acid influx into human epidermal Langerhans cells: L-dopa/proton counter-transport system.
- 2003
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Ingår i: Experimental Dermatology. - : Wiley. - 0906-6705. ; 12:5, s. 602-609
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Tidskriftsartikel (refereegranskat)abstract
- We have characterized a stereospecific transport mechanism for L-dopa into human epidermal Langerhans cells (LCs). It is different from any other amino acid transport system. It is highly concentrative, largely pH-independent, and independent of exogenous Na+, glucose and oxygen, and fuelled by a renewable intracellular energy source inhibited by iodoacetate but not by arsenate. We propose that the mechanism is a unidirectional L-dopa/proton counter-transport system. We have recently demonstrated anaerobic glycolysis in human epidermis, which substantiates the need of proton pumps for resident LCs. The findings prompt a re-evaluation of the profound changes LCs undergo when exposed to oxygen in aerobic culture. L-dopa is not metabolized by LCs but can rapidly be dislocated to the intercellular space by certain extracellular amino acids, i.e. LCs can profit by L-dopa in a dualistic way, altogether a remarkable biological phenomenon.
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| 10. |
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