The effect of small doses of mecamylamine on shuttlebox behavior in the guinea-pig

Zusammenfassung Bei trainierten Meerschweinchen wurde der Prozentsatz von Vermeidungsreaktionen, deren Latenzzeiten, und die Spontanreaktionen zwischen den Reizen in einer «two-way shuttlebox» unter dem Einfluss von Mecamylamin gemessen. Unter Verwendung eines flexiblen Dosierungsplanes wurde für 1 mg/kg Mecamylamin eine signifikante Depression des «Shuttlebox»-Verhaltens beobachtet. Für die Verminderung der Vermeidungsleistung innerhalb einer Sitzung, die für diese Spezies charakteristisch ist, war die gemessene Reaktionslatenz der empfindlichste Indikator.

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This study was supported by a grant from the Swiss Association of Cigarette Manufacturers.     

Enhancement of p-aminohippurate accumulation in renal cortical slices after repeated administrations of various organic anionic drugs to rats of different ages

Summary After repeated administrations of various organic anionic drugs to rats of different ages, an enhancement of p-aminohippurate accumulation was observed in renal cortical slices from adult but not from newborn and infant rats. The effect can be interpreted as specific substrate-induced stimulation of the organic anion transport.Acknowledgment: The authors thank Miss Karin Müller for technical assistance.     

Augenrückbildung und Lichtstinn beiAnoptichthys jordani Hubbs und Innes

Summary After hatching, young individuals of the Mexican blind characinAnoptichthys jordani Hubbs and Innes possess small, movable eyes. In the course of growth, the eyes are overlapped by skinfolds and tend to sink into the depth of the orbital cavity. Lens and pupilar opening may disappear and degeneration is to be found in the retina.Even very young blind characins seem to have no vision of movements, while they are able to perceive light. The lower limit is about 0.12 Lux of light intensity. Experiments concerning the localisation of this perception of light are in progress.     

Subzelluläre Verteilung der Brenzcatechinamine in Herz und Nebennieren von Meerschweinchen nach Vorbehandlung mitl-α-Methyl-Dopa

Summary -Methyl-noradrenalin synthesized after pretreatment of the guinea-pig with -methyl-dopa was found to be localized, like noradrenalin, mainly in the granular fraction 100 000g of the heart and in the fraction of the chromaffin granules of the suprarenal medulla (15000 g). -Methyl-adrenalin could not bo found.

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Ausgeführt mit Unterstützung der Deutschen Forschungsgemeinschaft.     

The effect of ethanol infusion on the calcium-phosphorus balance in man

Zusammenfassung äthanol wurde 9 Versuchspersonen i.v. verabreicht (50 ml 94% äthanol in 500 ml physiologischer Kochsalzlösung). Unter der Infusion stieg der Kalzium- und Phosphorgehalt des Blutserums an. Eine gleichzeitige Calciurie und starke Phosphaturie wurde beobachtet. Der Mechanismus dieser Phänomene ist noch ungeklärt.     

Detection and imaging of atmospheric radio flashes from cosmic ray air showers

The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >10(20) eV remains a mystery. They are likely to be of extragalactic origin, but should be absorbed within approximately 50 Mpc through interactions with the cosmic microwave background. As there are no sufficiently powerful accelerators within this distance from the Galaxy, explanations for UHECRs range from unusual astrophysical sources to exotic string physics. Also unclear is whether UHECRs consist of protons, heavy nuclei, neutrinos or gamma-rays. To resolve these questions, larger detectors with higher duty cycles and which combine multiple detection techniques are needed. Radio emission from UHECRs, on the other hand, is unaffected by attenuation, has a high duty cycle, gives calorimetric measurements and provides high directional accuracy. Here we report the detection of radio flashes from cosmic-ray air showers using low-cost digital radio receivers. We show that the radiation can be understood in terms of the geosynchrotron effect. Our results show that it should be possible to determine the nature and composition of UHECRs with combined radio and particle detectors, and to detect the ultrahigh-energy neutrinos expected from flavour mixing.     

Lack of long-term cortical reorganization after macaque retinal lesions

Several aspects of cortical organization are thought to remain plastic into adulthood, allowing cortical sensorimotor maps to be modified continuously by experience. This dynamic nature of cortical circuitry is important for learning, as well as for repair after injury to the nervous system. Electrophysiology studies suggest that adult macaque primary visual cortex (V1) undergoes large-scale reorganization within a few months after retinal lesioning, but this issue has not been conclusively settled. Here we applied the technique of functional magnetic resonance imaging (fMRI) to detect changes in the cortical topography of macaque area V1 after binocular retinal lesions. fMRI allows non-invasive, in vivo, long-term monitoring of cortical activity with a wide field of view, sampling signals from multiple neurons per unit cortical area. We show that, in contrast with previous studies, adult macaque V1 does not approach normal responsivity during 7.5 months of follow-up after retinal lesions, and its topography does not change. Electrophysiology experiments corroborated the fMRI results. This indicates that adult macaque V1 has limited potential for reorganization in the months following retinal injury.     

A late Eemian aridity pulse in central Europe during the last glacial inception

Investigating the processes that led to the end of the last interglacial period is relevant for understanding how our ongoing interglacial will end, which has been a matter of much debate (see, for example, refs 1, 2). A recent ice core from Greenland demonstrates climate cooling from 122,000 years ago driven by orbitally controlled insolation, with glacial inception at 118,000 years ago. Here we present an annually resolved, layer-counted record of varve thickness, quartz grain size and pollen assemblages from a maar lake in the Eifel (Germany), which documents a late Eemian aridity pulse lasting 468 years with dust storms, aridity, bushfire and a decline of thermophilous trees at the time of glacial inception. We interpret the decrease in both precipitation and temperature as an indication of a close link of this extreme climate event to a sudden southward shift of the position of the North Atlantic drift, the ocean current that brings warm surface waters to the northern European region. The late Eemian aridity pulse occurred at a 65 degrees N July insolation of 416 W m(-2), close to today's value of 428 W m(-2) (ref. 9), and may therefore be relevant for the interpretation of present-day climate variability.