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Biomedical subjects

H Rahmann

Publications and source records attributed to H Rahmann.

At least 145 records · Page 8Linked to original sources
PubMed1978

Gangliosides and thermal adaptation in vertebrates.

Gangliosides, which are highly enriched in synaptic membranes, show great differences in concentration and pattern constellation as well during early ontogenetical development as on interspecies level in vertebrates. As, up to now, there is no reasonable explanation for these findings, and as it is assumed the synapse to be the primary site of thermal adaptation, the attempt was made to investigate whether there are any correlations between brain gangliosides and the thermal adaptation phenomenon. 1. While in the brains of adult homeothermic vertebrates (with thermo-regulation: mammals, birds) the di-sialoganglioside GD1a predominates, in the brain of poikilotherms (without thermo-regulation: e.g. amphibia, teleost fishes) more polar polysialogangliosides are present. 2. In homeotherms during their early perinatal phase (heterothermic phase: thermor-regulation being not yet developed) a temporary poly-sialisation of brain-gangliosides occurs. 3. In poikilotherms, during the process of thermal adaptation to lowered environmental temperatures, a poly-sialisation of brain gangliosides can be observed, as well during the phase of acclimatization (adaptation to seasonal changes in temperature) as also to acclimation (experimentally induced changes in the environmental temperature). 4. The phenomenon of poly-sialisation of brain gangliosides during adaptation to lowered environmental temperatures can be correlated with changes in some behavioral (e.g. motorical activity) and electrophysiological parameters. 5. On the background of a general hypothesis on the involvement of gangliosides in the process of transmission [23, 24], a functional model on the participation of gangliosides in the process of thermal adaptation is discussed with special regard to the formation of Ca++-ganglioside-complexes, which are highly sensitive to temperature changes.

Acclimatization↗
PubMed1976

Changes in the protein metabolism of the CNS of a teleost following stimulation of the lateral-line organ.

Unilateral stimulation of the lateral-line organ (LLO) of the teleost Scardinius erythrophthalmus by current water caused an increase in the afferent fibre activity in the stimulated organ of about 3.5 times as compared with the non-stimulated LLO. There was an increase of [3H] histidine incorporation as compared to controls following stimulation applied either at the beginning (1 h) or at the end (1.5-6 h) of various incorporation times. Following a 1 h stimulation period, the different areas of the LLO-system (lateral nerve, medulla oblongata, cerebellum and valvulae cerebelli), as well as the optic tectum, subtectum and spinal cord showed a significant increase of protein labelling; whereas after 12 h post-incorporation times only the lateral nerve showed highly significant differences as compared to controls. In animals stimulated at the end of a 12 h pre-incorporation period (1.5-6 h) there was a significant increase of protein labelling in all investigated structures of the brain as compared to controls.

Action Potentials↗
PubMed1976

Possible functional role of gangliosides.

The brain ganglioside pattern of taxonomically close and distant related fish living at different temperatures were compared with the mammalian pattern. Furthermore the goldfish brain pattern was investigated after adaption (acclimitization, acclimation) to different temperatures. The results demonstrate correlations between body temperature and brain gangliosides: the lower the body temperature of animals, the higher the relative proportion of multi-sialo-gangliosides. The results are discussed with respect to the possible functional role of Ca++-ganglioside-complexes for the process of synaptic transmission.

Acclimatization↗
PubMed1975

[Histochemical investigations on sialic acid containing compounds in the CNS of teleosts (author's transl)].

By means of histochemical experiments the qualitative (microphotographs) and quantitative (cytophotometry) distribution of sialic acid containing compounds was investigated in the mesencephalon and cerebellum of Carassius carassius. 1. The perikarya of nerve cells are especially stained by means of Azur A. 2. Nerve fibres, on the other hand, showed positive reactions with colloidal ironhydroxyd (CIH). 3. In different structures of the CNS the intensity of CIH-staining is decreased up to about 55% following treatment with neuraminidase. 4. There are no differences in the reactions of 7 degrees C as compared to 20 degrees C adapted animals.

Animals↗