In a double-blind, interindividual comparative study 30 healthy volunteers were randomly allocated to oral treatment with 5 or 10 mg of dihydroergotamine (DHE) or placebo once daily for 16 days. Regional basic venous blood volume (BBV), pressure dependent venous capacitance (CV) of the calf, resting heart rate and blood pressure were determined on Days 1 and 15 of treatment. Plasma concentrations of DHE were monitored on Days 2 and 16. Due to spontaneous vasodilation BBV varied considerably, showing that it is an inappropriate parameter for investigating the venoconstrictor activity of DHE. CV remained unchanged after the first dose of DHE but it had declined significantly on both dosage regimens at the end of the treatment phase. In contrast, the blood concentration profiles of DHE were comparable at the beginning and the end of the trial. The discrepancy can best be explained by the existence of an effect compartment, e.g. smooth vascular musculature, which slowly becomes filled with DHE and/or its active metabolites. The venoconstrictor activity of DHE exhibited a significant dose-response relationship.

3 Methoden zur Bestimmung des Gesamtthyroxins im Serum werden hinsichtlich Richtigkeit und Präzision miteinander verglichen. Die praktische Bewährung der drei Tests wurde anhand von 179 Seren überprüft. Die Errechnung des Gesamt-T^ aus dem PJB 127 I (T^PBJ) ergab sowohl "in Serie" als auch "von Tag zu Tag" mit Variationskoeffizienten von 3,5 bzw. 3,1% die beste Präzision. Auch bei der Prüfung der Richtigkeit zeigte sich für das T 4 -PBI die beste Korrelation zwischen Beobachtung und Erwartung (r = 0,9972). Der Nachteil der Methode liegt in der fehlenden Spezifität für Thyroxin. Bei der direkten Bestimmung des Gesamtthyroxins nach der Isotopenverdünmmgsmethode von MURPHY und PATTEE (T^-M) lag der Variationskoeffizient als Maß der Präzision doppelt so hoch wie beim T 4 -PBI. Die Richtigkeit erfüllte mit einem r = 0,989 die üblichen Anforderungen an ein klinisch-chemisches Verfahren. Vorteil des Isotopenverdünnungsprinzips ist seine absolute Spezifität für Thyroxin. Die Bestimmungskapazität entspricht mit 100 Seren/5 Stdn. etwa der Leistungsfähigkeit der automatischen PBI-Bestimmung. Eine kommerzielle Modifikation der MuRPHY-PATTEE-Methode (Tetrasorb-Abbott-Test', T C T) erwies sich sowohl hinsichtlich der Präzision (VK = 15,8 bzw. 11,6%) als auch der Richtigkeit (r = 0,963) als den beiden anderen Verfahren unterlegen. Besonders im Meßbereich über 12 /Mg/100 m/ Thyroxin waren Präzision und Genauigkeit unbefriedigend.

Stabilizing the balance of the boat is a main task of the rowing motion. This leads to movements which are asymmetrical relative to the boat's plane of symmetry. The three-dimensional motion of the boat should be measured when investigating the elements of keeping the balance. This spatial motion must be described by the three components of the translational velocity and the three components of the angular velocity. The latter values can be measured using gyros. A system was developed which employs these sensors. The system is small and light enough to be used aboard a single scull. Measurements which were obtained using this system conclude the article. They illustrate some factors of importance for the stability of the boat and demonstrate the suitability of the system presented.

No abstract

The role of the vestibular system during physical exercise has only been rarely analyzed by scientific investigations. An investigation was carried out with the purpose of obtaining information on vestibular regulation in rowers. The process of maintaining balance in the boat and the limiting factors were examined. Twenty beginners and 20 well-trained rowers participated in standardized vestibular tests in the laboratory as well as in the boat (single) on the water. The results suggest that several mechanisms in the physiologic field (torque of the body) are affected by training. The well-trained oarsmen showed a significant minor nystagmus frequency, and this criterion for general vestibular regulation also showed a relationship with the specific ability for maintaining balance in the boat.