Untersuchungen an Ionenaustauschmodellen zum Verständnis der Physiologie biogener Amine. Austauschversuche an einem schwefelsäuregruppentragenden Harz zum Verständnis von sogenannten Histaminliberationsvorgängen

Summary Mixtures of histamine and other basic substances as hydrochlorides were added in equivalent amounts to an acid ion exchange system containing SO₄-groups in the H⁺-form (Dowex 50 W × 2). After completion of the equilibrium, the amounts of both the free histamine and the competing substance were determined by potentiometric titration.Values are presented for the relative amounts of each substance which are retained by the resin.The results obtained show that histamine and a given competing substance are selectively distributed on the resin. The method may be useful as a test for the possible histamine-liberating capacity of biologically important substances.     

Bariumtitanat-Druckgeber für Dekompressionsversuche

Summary The properties and advantages of barium titanate transducers for pressure registrations have been described. If the rate of pressure change is less than 10^–3 s, a barium titanate transducer with a cathode ray oscilloscope as commonly used is sufficient. Pressure changes with a duration of up to 1 s can be recorded by means of a barium titanate transducer, cathode follower with open grid, and D.C. oscilloscope. This arrangement can be adapted to the registration of processes of even longer duration by a shunt capacity. The sensativity of the transducer used was in the order of 2 V per 1 atm.     

Local sleep and learning

Human sleep is a global state whose functions remain unclear. During much of sleep, cortical neurons undergo slow oscillations in membrane potential, which appear in electroencephalograms as slow wave activity (SWA) of <4 Hz. The amount of SWA is homeostatically regulated, increasing after wakefulness and returning to baseline during sleep. It has been suggested that SWA homeostasis may reflect synaptic changes underlying a cellular need for sleep. If this were so, inducing local synaptic changes should induce local SWA changes, and these should benefit neural function. Here we show that sleep homeostasis indeed has a local component, which can be triggered by a learning task involving specific brain regions. Furthermore, we show that the local increase in SWA after learning correlates with improved performance of the task after sleep. Thus, sleep homeostasis can be induced on a local level and can benefit performance.     

Cellular and molecular aspects of Lyme arthritis

Lyme disease is a multisystem illness initiated upon infection with the spirochete Borrelia burgdorferi. Whereas the majority of patients who develop Lyme arthritis may be successfully treated with antibiotic therapy, about 10% go on to develop arthritis which persists for months to years, despite antibiotic therapy. Development of what we have termed treatment-resistant Lyme arthritis has previously been associated with both the presence of particular major histocompatibility complex class II alleles and immunoreactivity to the spriochetal outer surface protein A (OspA). Recently, we showed that patients with treatment-resistant Lyme arthritis, but not patients with other forms of arthritis, generate synovial fluid T cell responses to an immunodominant epitope of OspA and a highly homologous region of the human-lymphocyte-function-associated antigen-1α _L chain. Identification of a bacterial antigen capable of propagating an autoimmune response against a self-antigen provides a model of molecular mimicry in the pathogenesis of treatment-resistant Lyme arthritis. Received 21 December 1999; received after revision 10 April 2000; accepted 11 April 2000