Characterization of neuronal nicotinic acetylcholine receptors in the membrane of unmyelinated human C-fiber axons by in vitro studies.

Application of acetylcholine to peripheral nerve terminals in the skin is a widely used test in studies of human small-fiber functions. However, a detailed pharmacological profile and the subunit composition of nicotinic acetylcholine receptors in human C-fiber axons are not known. In the present study, we recorded acetylcholine-induced changes of the excitability and of the intracellular Ca2+ concentration in C-fiber axons of isolated human nerve segments. In addition, using immunohistochemistry, an antibody of a subtype of nicotinic acetylcholine receptor was tested. Acetylcholine and agonists reduced the current necessary for the generation of action potentials in C fibers by > 5-Iodo-A-85380 > 1,1-dimethyl-4-phenylpiperazinium iodide > nicotine > cytisine > acetylcholine; choline had no effect. The epibatidine-induced increase in axonal excitability was blocked by mecamylamine and, less efficiently, by methyllycacontine and dihydro-beta-erythroidine. Many C-fiber axons were labeled by an antibody that recognizes the alpha5 subunit of nicotinic acetylcholine receptors. In summary, electrophysiological and immunohistochemical data indicate the functional expression of nicotinic acetylcholine receptors composed of alpha3, alpha5, and beta4 but not of alpha4/beta2 or of alpha7 subunits in the axonal membrane of unmyelinated human C fibers. In addition, the observations suggest that the axonal membrane of C fibers in isolated segments of human sural nerve can be used as a model for presumed cholinergic chemosensitivity of axonal terminals.

[Efficacy of child and adolescent health protection in a district--approaches for studying the effectiveness]. / Wirksamkeit des Kinder- und Jugendgesundheitsschutzes im Territorium--Untersuchungsansätze zur Effektivität.

The evaluation of the effectiveness of medical in particular preventive measures is an essential prerequisite for the determination of the priorities in the further improvement of medical care conceptions taking into account practical demands. Endeavours to define the terms of quality and effectiveness prove the difficulty of the problem. The description of approaches allows to deduce investigation approaches to judgements on the individual and collective state of health, and to coordinative and cooperative correlations in the medical care for children and adolescents for the purpose of optimizing a health care model on district level.

Serum levels of eleven steroid hormones following motion sickness.

In order to grade motion sickness objectively, the following 11 adrenal hormones were investigated in subjects with different motion sickness susceptibility: Aldosterone, corticosterone, 11-deoxycorticosterone, progesterone, 17-OH-progesterone, 11-deoxycortisol, cortisol, cortisone, testosterone, androstendione, dehydroepiandrosterone sulfate. Motion sickness was induced by the coriolis effect on a rotary chair. Both severe kinetosis after short rotation time and mild motion sickness after 30 min of rotation occurred together with small hormonal changes. Androstendione and 11-deoxycortisol appear to be sensitive indicators of motion sickness if the rotation time is taken into consideration. A significant increase of all hormones except progesterone, cortisone, testosterone, and dehydroepiandrosterone sulfate was observed when pronounced malaise had come after a long rotation stress (24.6 min). The changes in plasma aldosterone concentration appeared to correlate with time only. The present study demonstrates that hormonal analysis can be helpful in estimating the degree of motion sickness.