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Biomedical subjects

W Hartschuh

Publications and source records attributed to W Hartschuh.

At least 91 records · Page 5Linked to original sources
PubMed1986

Variability of expression and arrangement of cytokeratin and neurofilaments in cutaneous neuroendocrine carcinomas (Merkel cell tumors): immunocytochemical and biochemical analysis of twelve cases.

Twelve specimens of cutaneous neuroendocrine carcinomas (Merkel cell tumors) available as fresh tissue were analyzed for intermediate filament (IF) expression by immunocytochemical and biochemical methods. In immunofluorescence microscopy, most cases were positive for both simple-epithelium-type cytokeratins and the neurofilament L- and M-polypeptides. Several different IF staining patterns ranging from presence of plaque-like structures (fibrous bodies) only to nearly exclusive expression of delicate cytokeratin fibrils could be distinguished. In immunoelectron microscopy the labeling for both cytokeratin and neurofilament polypeptides seemed evenly distributed among the IFs of the fibrous bodies. In primary culture, tumor cells maintained the coexpression of both IF types. Desmoplakin-positive true desmosomes were found in 5 specimens. Biochemically, cytokeratins nos. 8, 18 and, variably, 19, as well as IT protein and, in many specimens, the neurofilament L-protein and a putative neurofilament M-protein were detected. Only traces of the neurofilament H-polypeptide were found. Our results show that a coexpression of cytokeratin IFs and neurofilaments in variable patterns is a characteristic feature of cutaneous neoendocrine carcinomas; occasionally, however, neurofilaments may be very scarce. The biological, histogenetic and diagnostic implications are discussed.

Adult↗
PubMed1985

Prodynorphin opioid peptides in small somatosensory primary afferents of guinea pig.

By the use of light microscopic immunohistochemistry it was shown that a significant population of small primary sensory afferents of guinea pig contains immunoreactivities to antisera directed against prodynorphin-opioid peptides, whereas immunoreactivities to antisera directed against opioid peptides exclusively contained in proenkephalin were absent. Immunoreactivities to antisera against different prodynorphin-opioid peptides were seen in small ganglionic cells and in small diameter fibers of spinal and trigeminal ganglia, of dorsal roots, of somatic peripheral nerve trunks and in cutaneous sensory nerves. There was evidence for colocalization of different prodynorphin-opioid peptides. High-performance liquid chromatography and the mouse vas deferens assay revealed opioid-active material (22.7 pmol Met-enkephalin equivalents per gram wet weight) in extracts of somatic peripheral nerves. The results indicate for the first time that opioid peptides derived from prodynorphin are peripheral and central neurotransmitter candidates of small primary somatosensory afferents.

Animals↗
PubMed1983

Denervation reduces extractable Met-enkephalin-like immunoreactivity in guinea-pig lips.

Skin extracts of the upper lip of 18 guinea pigs were made and subjected to a Met-enkephalin radioimmunoassay 3-4 weeks, 8 weeks, and 12 weeks after transection of one infraorbital nerve. There was a significant reduction in the concentration of extractable Met-enkephalin-like immunoreactivity in the denervated half of the lip as compared to the innervated side. The reduction increased with time. These results show that the enkephalin content of the guinea pig upper lip depends on an intact innervation by the infraorbital nerve.

Animals↗
PubMed1983

Characterization of opioid peptides in guinea-pig heart and skin.

Using reverse phase HPLC separations, and assay of eluate fractions in the mouse vas deferens, extracts of heart and skin from guinea-pigs were shown to contain several species of opioid-active material in low amounts (3-20 pmol/g as [Met5]enkephalin). Immunohistochemical studies revealed in the heart a small number of enkephalin-immunoreactive nerve fibres, particularly in cardiac ganglia and some small cells (paraganglionic cells, APUD cells). In the skin, enkephalin-immunoreactivity was confined to Merkel cells. Cardiac and cutaneous opioid peptides may modulate peripheral cardiovascular and sensory functions.

Animals↗
PubMed1983

Immunohistochemical localization of vasoactive intestinal polypeptide (VIP) in Merkel cells of various mammals: evidence for a neuromodulator function of the Merkel cell.

Since met-enkephalin-like substance has been demonstrated only in Merkel cells of some rodents but not of cat, dog, pig, and humans, Merkel cells of these species were analyzed by immunohistochemistry using a variety of different antisera for the occurrence of neuropeptides different from met-enkephalin. In various locations of all species investigated Merkel cells were found to be immunoreactive exclusively to vasoactive intestinal polypeptide (VIP) but not to any of the other antisera used. Thus, in mammalian Merkel cells, neuropeptides occur that are different from met-enkephalin. It is suggested that the Merkel cell-axon complex represents a complex regulatory system involving a presumptive receptor or modulator function whereby the Merkel cell may influence the threshold of the sensory nerve ending via release of a neuropeptide (VIP- or met-enkephalin-like material).

Animals↗
PubMed1980

Met-enkephalin-like immuno- and bioreactivity in extracts from skin containing Merkel cells.

Skin from the upper lip, bearing the sinus hair follicles rich in Merkel cells was investigated in guinea pig, rat, cat and rabbit by radioimmunoassay and radioreceptor assay. In all species Met-enkephalin-like immunoreactive material was extracted. In guinea pig this material had the same molecular size as Met-enkephalin. In a radioreceptor assay made with rat brain membranes extracts of guinea pig skin caused displacement of [3H]Met-enkephalin. The endogenous opioid of the size of Met-enkephalin contained in these skin extracts possibly derives from the Merkel cells.

Animals↗
PubMed1980

Fine structural analysis of the synaptic junction of Merkel cell-axon-complexes.

The ultrastructure of synaptic contact areas in Merkel cell-axon-complexes from sinus hair follicles and touch domes of various mammals (nude mice, rats, cats, rabbits, opossums and monkeys) was investigated by electron microscopy of ultrathin sections from perfusion fixed tissue. Synapses between Merkel cells and axons were a common feature in all analyzed species. Special staining with digallic acid and goniometric tilting facilitated the resolution of the membranous and paramembranous synaptic elements. The synaptic contact revealed the typical characteristics of a chemical synapse, except for presynaptic clear vesicles: a postsynaptic membrane thickening and dense projections at the presynaptic membrane (i.e., the Merkel cell membrane). The cleft material was resolved as a fuzzy coating of the outer leaflets of the synaptic membranes with occasional bridges across the synaptic cleft. The presence of a synapse in the Merkel cell-axon-complexes emphasizes the receptor function of the Merkel cell besides other possible functions of this cell.

Animals↗
PubMed1979

The Merkel cell--a member of the APUD cell system. Fluorescence and electron microscopic contribution to the neurotransmitter function of the Merkel cell granules.

Merkel cells of sinus hair follicles of nude mice were investigated by fluorescence and electron microscopy following pretreatment with amine precursors (L-Dopa, L-5-Hydroxytryptophan) and monoaminoxidase-inhibitors (Marsilid, Harmaline). Neither in control animals nor in pretreated animals any evidence for an involvement of Merkel cells in monoamine metabolism could be found. Therefore, the hypothesis that Merkel cells might share the most constant cytochemical characteristics of the cells of the APUD series, i.e., to take up amine precursors, should definitely be left. Following Harmaline treatment, however, Merkel cells were found fluorescent; cytophotometric analysis of the fluorescence emission spectra of formaldehyde-treated tissue ascertained that this fluorescence was due merely to a specific Harmaline fluorescence. The significance of Harmaline uptake in Merkel cells, most probably in the Merkel cell granules, is discussed.

5-Hydroxytryptophan↗
PubMed1979

Met enkephalin-like immunoreactivity in Merkel cells.

The Merkel cells from sinus hair follicles of rats were investigated by immunohistochemistry using different antisera against neuropeptides and gastroenteropancreatic (GEP)-hormones. For the first time it has been demonstrated that Merkel cells exhibit an immunoreactivity towards metenkephalin (methionine-enkephalin). The met-enkephalin immunoreactivity was restricted to Merkel cells and was not found in associated nerve axons or terminals. Denervation of Merkel cells did not affect the met-enkephalin immunoreactivity. Antisera leu-enkephalin (leucine-enkephalin) and other polypeptides did not produce an immunoreaction. The demonstration of met-enkephalin-like immunoreactivity supports the concept that the Merkel cell is a member of the paraneuronal system and a potential neuroreceptor cell.

Animals↗
PubMed1977

The use of ionic lanthanum as a diffusion tracer and as a marker of calcium binding sites.

The distribution of ionic lanthanum (La3+) was studied after perfusion of the isolated rat heart with a buffered salt solution containing lanthanum chloride. We have demonstrated that the localization of lanthanum differed from that shown in previous studies in which hearts were exposed to ionic or colloidal lanthanum during or after fixation. La3+ passed rapidly through the intercellular cleft between endothelial cells. There was relatively little transport by micropinocytosis and no evidence of transendothelial passage through the cytoplasm. Perfusion with a solution containing 1 to 15 mM LaCl3 resulted in localization of La3+ on the entire cytoplasmic membrane system of muscle cells, i.e.: the non-specialized parts of the muscle cell membranes were stained by La3+ as well as the membranes of micropinocytotic vesicles, of the T-system and of the intercalated disc. The cytoplasmic leaflets of gap junctions were especially stained. However, the cell membranes of non-muscle cells were free of lanthanum precipitates. Freeze-fracturing of muscle cells showed concomitant alteration in the distribution of membrane-associated particles. The gap junction membranes also showed changes in particle aggregation. Intracellular binding of La3+ are restricted to muscle cells. Lanthanum was found in the cell nucleus associated with heterochromatin, in the nucleolus, and along the nuclear membrane. The myofibrils were stained mainly over the I-band.

Animals↗