Biomedical subjects

T H Müller

Publications and source records attributed to T H Müller.

58 records · Page 4Linked to original sources

PubMed1983

Phenotypic plasticity of cultured bovine chromaffin cells. II. Fiber outgrowth induced by elevated potassium: morphology and ionic requirements.

Chromaffin cells isolated from the adult bovine adrenal medulla extend neurite-like processes in culture in response to a variety of agents. In the present study we investigated the effect of chronic depolarization by high potassium on fiber outgrowth and its ionic requirements. Elevated K+ in the culture medium induced process formation of isolated bovine chromaffin cells in a dose-dependent fashion, and so did veratridine. Short-term depolarization by acetylcholine or carbachol caused increased flattening out of the cells, but no outgrowth of neurite-like processes. Formation of processes was accompanied by a significant reduction of endogenous catecholamines in cultured cells after 18 h and 8 days and a relative shift towards storage of primary amines after 8 days. K+-induced fiber outgrowth was dependent on the presence of Ca2+ in the medium and Ca2+-influx into the cells: the effect was inhibited by EDTA, EGTA, CoCl2 and verapamil and mimicked by the Ca2+ ionophore A 23187. Tetrodotoxin, tetraethylammonium, amiloride and ouabain, which interfere with Na+- and K+-fluxes, did not inhibit K+-induced process formation nor did any of them by itself evoke fiber outgrowth. Fiber outgrowth required de novo protein synthesis as shown by the inhibitory effect of cycloheximide. K+-induced formation of processes was not affected by dexamethasone and dbcAMP, both of which inhibit NGF-induced neurite formation of early postnatal rat chromaffin cells in vitro. These results document that chronic depolarization may induce de novo formation of neurite-like processes of bovine chromaffin cells in vitro by a Ca2+- and protein synthesis-dependent mechanism.

Animals↗

PubMed1982

Ultrastructural, biochemical, and cell-culture studies of a presumed extraskeletal Ewing's sarcoma with special reference to differential diagnosis from neuroblastoma.

The history of a 6-year-old girl with a tumor originating from thoracic spine and finally becoming resistant to surgery, radio-, and chemotherapy is reported. Tumor-biopsy material was studied by light and electron microscopy, in cell culture, by acetylcholinesterase ultracytochemistry, and by quantitative catecholamine analysis and this led to the rejection of the initial diagnosis of a neuroblastoma. Light microscopy revealed a uniform population of undifferentiated cells incompletely lobulated by broad fibrovascular septa. Using the electron microscope, cells were characterized by large intracellular pools of glycogen, little cytoplasm with an abundance of free ribosomes and a paucity of organelles. A few cells displayed desmosome-like attachment sites. Staining for specific and unspecific acetylcholinesterase was negative with light and electron microscopy, as were the results of catecholamine histofluorescence using the glyoxylic acid method. The latter result was confirmed by the negative outcome of quantitative analyses of dopamine, noradrenaline, and adrenaline with high pressure liquid chromatography nd electrochemical detection in tissue samples. Tumor cells could easily be maintained in culture for up to 4 weeks. None of a variety of treatments that are known to favor expression of neuronal characteristics in neuroblastoma cells (serum withdrawal, nerve growth factor, dbcAMP, dexamethasone) induced morphological differentiation in cultured tumor cells. On the basis of the clinical history, morphology, and of our experiments with tumor cells, the diagnosis of a so-called extraskeletal Ewing's sarcoma is most likely. Our results strengthen the view that a cell biology approach may be valuable in neuroblastoma differential diagnosis.

Acetylcholinesterase↗

PubMed1981

High-performance liquid chromatography with electrochemical detection as a highly efficient tool for studying catecholaminergic systems. I. Quantification of noradrenaline, adrenaline and dopamine in cultured adrenal medullary cells.

A method for simultaneous determinations of noradrenaline (NA), adrenaline (A) and dopamine (DA) in tissue is described. After extraction from crude deproteinized homogenates by the batch mode aluminium oxide method individual catecholamines (CA) were separated in a high-performance liquid chromatography (HPLC) system by isocratic elution with pure aqueous buffers from an octadecyl column. These eluates were directly monitored with a new amperometric detector device (Metrohm VA E 641) in a wall-jet flow cell. Sensitivity, specificity, precision and performance of this relatively simple procedure are characterized. Different applications of this assay with relevance to neurobiological research are presented.

Adrenal Medulla↗

PubMed1981

Purification of bovine adrenal chromaffin cells by differential plating.

A method is described for obtaining highly purified cultures of bovine chromaffin cells from crude adrenomedullary cell suspensions. The method is based on the different adhesiveness of chromaffin and non-chromaffin cells to glass and plastic surfaces (differential plating). Crude suspensions isolated by a modified version of the method described by Livett et al. (1979) (cf. Fenwick et al., 1978) contain 74.4 +/- 7.7% (n = 7) chromaffin cells as determined by electron microscopy. Bringing the cells through 5 steps of differential plating results in cultures that are predominantly composed of chromaffin cells (97.5 +/- 0.85%, n = 8). More than 90% of these cells are viable as judged by trypan blue exclusion and by electron microscopy. Cultures obtained by differential plating contain a significantly lower proportion of non-chromaffin cells than primary cultures both after one week (45.5 +/- 1.2% vs 86.7 +/- 4.6%, n = 3) and after two weeks (85 vs 93%), when grown in Falcon flasks with medium 199 and 20% fetal calf serum, but without mitosis inhibitors. Cultures obtained by the method described in this paper may be profitably employed for studying the contribution of non-chromaffin cells to the functions of chromaffin cells.

Adrenal Medulla↗