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Biomedical subjects

E Habermann

Publications and source records attributed to E Habermann.

At least 91 records · Page 5Linked to original sources
PubMed1981

Tetanus toxin and botulinum A toxin inhibit acetylcholine release from but not calcium uptake into brain tissue.

Slices or particles from rat forebrain cortex were preloaded with [3H]choline, and the release of [3H]acetylcholine was evoked with potassium ions in a superfusion system. Release depended on the presence of calcium. 1. Incubation of the preloaded tissue preparation for 2 h with tetanus or botulinum A toxin did not change the [3H]acetylcholine content or the ratio [3H]acetylcholine/[3H]choline. Tetanus toxin diminished, dependent on dose and time, the release of [3H]acetylcholine evoked by 25 mM K+. It was about ten times more potent than botulinum A toxin. The effect of botulinum toxin was due to its neurotoxin content. Raising the potassium concentration partially overcame the inhibition by the toxins. Hemicholinium-3, applied to preloaded slices, left the subsequent [3H]acetylcholine release unchanged. Pretreatment of particles with neuraminidase diminished the content of long-chain gangliosides to the detection limit. Such particles remained fully sensitive to tetanus toxin, and at least partially sensitive to botulinum A toxin. 2. The potassium or sea anemone toxin II stimulated uptake of 45Ca2+ into cortex synaptosomes or particles was not inhibited by either toxin. Both toxins appear to impede the Ca2+-dependent mobilization of an easily releasable acetylcholine pool, without inhibiting the transmembranal calcium fluxes.

Acetylcholine↗
PubMed1981

Tetanus toxin and botulinum A neurotoxin inhibit and at higher concentrations enhance noradrenaline outflow from particulate brain cortex in batch.

Tetanus toxin and, to a lesser degree, botulinum A toxin partially depress the basal and the potassium evoked outflow of [3H]noradrenaline from preloaded particulate rat forebrain cortex. The effect is due to the toxins and not to any contaminant, as shown by dialysis, heating and antitoxin treatment, and also by replacement of crystalline botulinum A toxin with purified neurotoxin. Tetanus toxin also depresses the outflow due to sea anemone toxin II, 4-aminopyridine and d-amphetamine. The effect of the toxins proceeds with time and strongly depends on temperature. Once manifest the tetanus toxin effect is not reversed by antitoxin. Pretreatment with V. cholerae neuraminidase degrades the long-chain gangliosides quantitatively to GM1. Tetanus toxin, applied subsequently remains fully active. High concentrations of tetanus toxin and botulinum A neurotoxin promote the outflow of small amounts of tritium within short incubation times. It is concluded: a) Tetanus toxin is a broad range neurotoxin which acts on processes subsequent to the depolarization step. b) Long-chain gangliosides are only binding sites, but not receptors of tetanus toxin. c) Botulinum A toxin is less potent but resembles tetanus toxin in both promoting and depressing the outflow of noradrenaline.

Animals↗
PubMed1979

Normal and pseudorabies virus infected primary nerve cell cultures in scanning electron microscopy.

Primary cell cultures from the central nervous system of the embryonic rat were inoculated with pseudorabies virus. Their morphological changes were studied by phase contrast microscopy and by scanning as well as by transmission electron microscopy. Uninfected cultures display two distinct cell layers in scanning electron microscopy: a flat continuous monolayer supports a heterogeneous population of individual, presumably neural cells, which emit processes of different number and size. The latter cells form contacts by a dense network of fibres. Infectious virus is propagated in these nerve cell cultures with similar effectivity as in other cultures. The infectoin leads to fusion and death of the cells. By the time the cytopathic effect is visible, nearly all cells, including those of neuronal and those of nonneuronal appearance, are studded with ample amounts of virus-sized particles. The particles represent viruses as demonstrated by transmission electron microscopy or by treatment with a hyperimmune serum directed against pseudorabies virus structural components. Hyperimmune serum leads to clustering of the particles at the cell surface. The amount of virus particles per surface unit was about 10 times higher on neural cells as compared to primary rabbit kidney cells. The concentration of infectious particles in the supernatant, however was approximately the same. The system described appears to be useful for the study of acute virus effects on neural tissue under strictly controlled conditions.

Animals↗
PubMed1979

Investigations on the mechanism of cyclic guanosine monophosphate increase due to depolarizing agents as studied with sea anemone toxin II in mouse cerebellar slices.

Sea anemone toxin II (ATX II) and MCD-peptide, like other depolarizing agents, raise the content of cGMP and to a lesser extent of cAMP in mouse cerebellar slices. Na+ influx and Ca2+ movement are involved in their mode of action, as indicated by the following observations: 1. The rise of cGMP due to ATX II, MCD-peptide and high potassium was diminished when Na+ had been replaced by Li+. 2. The effects of both toxins and veratridine, but not of high potassium stimulation were prevented by tetrodotoxin (TTX). 3. The cGMP accumulation due to both toxins was abolished in the absence of extracellular Ca2+. 4. The so-called Ca2+-antagonist (-)-D-600 blocked the increase of cGMP due to ATX II, MCD-peptide, veratridine and high potassium. 5. ATX II stimulated the 45Ca2+ uptake in mouse cerebellar slices which was prevented by TTX and (-)-D-600.

Adenosine Deaminase↗
PubMed1979

Iodine labelling of sea anemone toxin II, and binding to normal and denervated diaphragm.

1. Sea anemone toxin II (ATX II) which keeps the activated sodium channels open, can be labelled at its histidine residues with 125I up to a specific radioactivity of 500 Ci/mmole. Upon intraventricular injection in mice, ATX II causes acute, short-lasting hyperexcitation and convulsions. Its LD50 in mice is between 25 and 50 ng of the native peptide, and between 50 and 100 ng of the radioactive material per animal. 2. The labelled peptide is bound to mouse diaphragm from where it can be displaced by ATX II and, even better, by scorpion neurotoxin but not by other basic peptides, e.g., histone or aprotinin. Binding is not significantly influenced by 50 mM potassium, by replacing sodium with choline, by veratridine or tetrodotoxin. In contrast to binding of alpha-bungarotoxin, binding of ATX II is not changed by denervation of the diaphragm. ATX II binds not only to the muscular but also to the tendinous moiety of the mouse diaphragm. 3. ATX II lowers the surface tension of water. Further experiments are needed to establish the usefulness of 125I-ATX for labelling sodium channels in excitable membranes.

Animals↗
PubMed1978

Suppression of 3H-acetylcholine release from primary nerve cell cultures by tetanus and botulinum-A toxin.

Primary nerve cell cultures derived from embryonic rat central nervous system form [3H]ACh from exogenous [3H]Ch, and release it upon potassium depolarization. Pretreatment of the cultures with botulinum-A toxin or tetanus toxin diminishes the cellular accumulation of [3H]ACh. Poisoning the cultures during the period of [3H]Ch uptake fails to lower [H]ACh formation. Dependent on dosage, both toxins suppress the release of [3H]ACh upon potassium depolarization. Heat-denaturated toxins as well as tetanus toxin preincubated with tetanus antitoxin were without effect.

Acetylcholine↗