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Biomedical subjects

E Walum

Publications and source records attributed to E Walum.

At least 55 records · Page 3Linked to original sources
PubMed1981

Growth dependent induction of high affinity gamma-amino-butyric acid transport in cultures of a normal human brain cell line.

Dense, growth inhibited cultures of the human putative glial cell line U-787CG were found to take up gamma-aminobutyric acid (GABA) via a high-affinity transport mechanism (Km = 1.2 microM) not detectable in sparse, rapidly growing cultures. The uptake of GABA was essentially the same in young and old dense cultures indicating that the induction of the high-affinity GABA transport was dependent on cell density and/or growth rate rather than time in culture after trypsinization.

Astrocytes↗
PubMed1981

Uptake and release of choline in cultures of human glioma cells.

Human glioma cells (138MG) have a low-affinity uptake system for choline (Km = 20 microM; Vmax = 56 pmol/min/10(6) cells). The uptake is reduced by acetylcholine, hemicholinium-3, HgCl2, and phosphodiesterase inhibitors. Release of [3H]choline from preloaded cultures showed two pools with half-lives of 1.3 and 160 min. Choline release was stimulated by 8-bromo-cAMP or isobutylmethylxanthine. The results suggest that release of choline occurs by a facilitated diffusion transport system and is increased by elevations of intracellular cAMP.

Cell Line↗
PubMed1981

Acute toxicity of organic solvents, heavy metals and DDT tested in cultures of mouse neuroblastoma cells.

To test the toxicity of some substances, known to affect the nervous system i.e. organic solvents, heavy metals and DDT, their ability to cause cell detachment of cultured mouse neuroblastoma cells was investigated. A TD25 value was obtained by graphic estimation of the concentration needed to cause 25% of the total cell number to detach. These TD25 values were compared with LD50 values obtained from the literature and a correlation was found.

Animals↗
PubMed1979

Effects of dibutyryl cyclic AMP and cytochalasin B on cultured human glioma cells.

Cultured human glioma cells (138 MG) exposed to dibutyryl cyclic AMP (dbc-AMP; 0.1--5 mM) attained an arborized shape with thin processes extending from a rounded cell body. Cytochalasin B (CB; 1--1 muM) induced similar morphological changes. The processes in both dbc-AMP and CB treated cells were formed by retraction of the cell margin. Colchicine (1muM) completely and liver treated phalloidin (0.1 mg/ml) partially inhibited the morphological alterations induced by dbc-AMP and CB. Dbc-AMP was found to arrest cell movement, cell division and uptake of 2-deoxy-D-glucose. CB has the same effects but was more potent. The effects of dbc-AMP and CB could be due to interference with a common cellular structure, e.g. microfilaments.

Bucladesine↗
PubMedDate not supplied

Comparison of in vivo acute lethal potency and in vitro cytotoxicity of 48 chemicals.

The cytotoxicity of 48 compounds included in the MEIC (Multicenter Evaluation of In Vitro Cytotoxicity) list was determined in cultures of rat hepatocytes, McCoy, and MDBK cells. The average minimum concentration of each compound inducing cytotoxicity was measured in each cell type. The cytotoxicity values were then compared with published oral LD50 values for rats and mice. The logarithmic transformation of in vivo toxic doses and the corresponding in vitro cytotoxic concentrations showed a statistically significant correlation between the in vitro and in vivo values. The results show that an accurate in vivo LD50 dose could be predicted from in vitro data for at least 75% of the selected compounds. It is hoped that this finding will not only stimulate others to pursue in vitro technique but will eventually lead to elimination of the in vivo LD50 test.

Animal Testing Alternatives↗
PubMedDate not supplied

Differential effect of carbon tetrachloride on the cell membranes of neurons and astrocytes.

Primary cultures of neurons and astrocytes from chick embryos were used to study the effect of CCl4 on the plasma membranes. The cultures were exposed to 0, 1, 2, 3 or 4 mM CCl4 in a closed chamber system for 30 or 60 minutes. The effects of the exposure were examined by means of scanning electron microscopy and by measuring the degree of lipid peroxidation. In neuron cultures the presence of 1 mM CCl4 for 60 min caused holes in the plasma membranes and led to a swelling of the cell bodies. At 4 mM CCl4 the membranes were totally destroyed, leaving cytoskeletal elements visible. In astrocyte cultures, on the other hand, no effects up to 2 mM were observed. At 4 mM some cells had rounded up, but the membranes were still intact. These data correspond very well with the results that neurons, in contrast to astrocytes, show a concentration-dependent increase in lipid peroxidation. The results from this study may indicate that the mechanism of action of CCl4 is different in neurons and astrocytes.

Animals↗
PubMedDate not supplied

Photometric recording of cell viability using trypan blue in perfused cell cultures.

A perfusion system was developed to increase the reliability of cell viability estimations by continuous measurement of the uptake of trypan blue dye. Monolayer cell cultures were perfused with buffer containing toxic substances and trypan blue, and the staining of cells was continuously recorded at 591 nm in a spectrophotometer. Using mercuric chloride and methylmercuric chloride as test substances with C6 rat glioma cells, time- and dose-dependent increases in light absorbance were obtained over a 12h recording period. Methylmercuric chloride at 10(-6) M caused a half-maximal increase in relative absorbance in 4.5 h, whereas the corresponding time for mercuric chloride was 10.5 h.

Animals↗
PubMedDate not supplied

Effects of toxic chemicals on the respiratory activity of cultured mouse neuroblastoma cells.

Twenty common toxic chemicals were tested for their ability to inhibit respiratory activity in cultured mouse neuroblastoma C1300 cells, clone 41A3. Pentachlorophenol and hexachlorophene exhibited the properties of uncouplers of oxidative phosphorylation, whereas for KCN, pyridine, 2,5-hexandione, NaAsO2, K2Cr2O7, HgCl2, methylmercury and triethyltin more simple time-courses of inhibition were obtained. Ethanol, methanol, dimethyl sulphoxide, benzidine, nickel acetate, MnCl2, phenol, CoCl2, Na2SeO3 and CdCl2 did not cause any significant changes in respiratory activity. Among the effective compounds, those with well-known neurotoxic properties were the most potent in inhibiting respiration in 41A3 cells.

Animals↗