Changes in the cardiac glutathione status after ischemia and reperfusion

In the isolated and perfused rabbit heart ischemia induced a rapid decline of contractility, associated with a reduction of the content of tissue GSH with no significant changes in GSSG. Reperfusion induced a small recovery of contractility, a substantial release of total glutathione and a further decrease in the content of tissue GSH with a significant increase of tissue GSSG. Glutathione reductase and glutathione peroxidase activities were not affected by ischemia and reperfusion. This study suggests a possible role for glutathione in the determination of functional damage induced by myocardial ischemia and reperfusion.     

The dopamine autoreceptor agonist B-HT 920 markedly stimulates sexual behavior in male rats

Summary B-HT 920, a selective agonist at dopamine (DA) autoreceptors, strongly increased the incidence of penile erections (PE) in male rats, an effect which was dose-related and antagonized by haloperidol. B-HT 920 at 100 and 200 g/kg i.p. significantly altered the copulatory pattern of sexually active male rats, reducing the number of mounts and intromissions as well as the latency to the first ejaculation, a stimulant effect which was confirmed in sluggish males at a dose of 100 g/kg.     

Potential juvenile hormone analogues containing piperidine ring: Synthesis and biological assay on insects

Summary Some compounds containing piperidine rings have been synthesized, and submitted to biological tests on insects for their hormonal activity on pupae ofTenebrio molitor L. andBombyx mori L. Some of them display a hormoneanalogue or toxic activity.The editors do not hold themselves responsible for the opinions expressed in the authors' brief reports. — Les auteurs sont seuls responsables des opinions exprimées dans ces brèves communications. — Für die Kurzmitteilungen ist ausschliesslich der Autor verantwortlich. — Per le brevi comunicazioni è responsabile solo l'autore. — . — Solo los autores son responsables de las opiniones expresadas en estas comunicationes breves.This research has been supported by the Italian National Research Council (CNR) special ad hoc program Fitofarmaci e Fitoregolatori, Subproject. 7.Acknowledgments. We thank Prof. G. Jommi for helpful discussions related to this and previous articles on the same subject.     

The dynamics of measles in sub-Saharan Africa

Although vaccination has almost eliminated measles in parts of the world, the disease remains a major killer in some high birth rate countries of the Sahel. On the basis of measles dynamics for industrialized countries, high birth rate regions should experience regular annual epidemics. Here, however, we show that measles epidemics in Niger are highly episodic, particularly in the capital Niamey. Models demonstrate that this variability arises from powerful seasonality in transmission-generating high amplitude epidemics-within the chaotic domain of deterministic dynamics. In practice, this leads to frequent stochastic fadeouts, interspersed with irregular, large epidemics. A metapopulation model illustrates how increased vaccine coverage, but still below the local elimination threshold, could lead to increasingly variable major outbreaks in highly seasonally forced contexts. Such erratic dynamics emphasize the importance both of control strategies that address build-up of susceptible individuals and efforts to mitigate the impact of large outbreaks when they occur.     

Activation with (+/-)N-n-propyl-nor-apomorphine (NPA) of the male rat copulatory behavior

I.p. (+/-)N-n-propyl-nor-apomorphine HCl (NPA) influences copulatory behavior of vigorous adult male rats in the same ways as apomorphine, i.e., it reduces the latency to ejaculation as well as mount and intromission frequency. Furthermore, NPA administered to impotent male rats restores normal mating behavior in some of them.     

Di- and tripeptides containing homoleucine: synthesis and biological assays on insects

Summary Some di- and tripeptides containing homoleucine (2-amino-4-methylhexanoic acid) have been synthetized. These compounds have been submitted to biological tests on insects for their hormonal activity in comparison with the known tripeptide pivaloyl-alanyl-p-aminobenzoic acid ethyl ester. Only 2 of them (3 and 4) caused morphological changes on larvae ofPyrrhocoris apterus.This work has received financial support from the Consiglio Nazionale delle Ricerche.The biological assays were done in the Research Center of Montedison S.p.A. (Linate, Milano); the collaboration of Dr G. Michièli is gratefully acknowledged.     

Superior avoidance learning in the offspring of rats treated with an anabolic steroid during pregnancy

Summary Treatment of pregnant rats with stanozolol, an anabolic steroid, increases the avoidance learning of the offspring at maturity.     

An intense stratospheric jet on Jupiter

The Earth's equatorial stratosphere shows oscillations in which the east-west winds reverse direction and the temperatures change cyclically with a period of about two years. This phenomenon, called the quasi-biennial oscillation, also affects the dynamics of the mid- and high-latitude stratosphere and weather in the lower atmosphere. Ground-based observations have suggested that similar temperature oscillations (with a 4-5-yr cycle) occur on Jupiter, but these data suffer from poor vertical resolution and Jupiter's stratospheric wind velocities have not yet been determined. Here we report maps of temperatures and winds with high spatial resolution, obtained from spacecraft measurements of infrared spectra of Jupiter's stratosphere. We find an intense, high-altitude equatorial jet with a speed of approximately 140 m s(-1), whose spatial structure resembles that of a quasi-quadrennial oscillation. Wave activity in the stratosphere also appears analogous to that occurring on Earth. A strong interaction between Jupiter and its plasma environment produces hot spots in its upper atmosphere and stratosphere near its poles, and the temperature maps define the penetration of the hot spots into the stratosphere.     

Transformation of spin information into large electrical signals using carbon nanotubes

Spin electronics (spintronics) exploits the magnetic nature of electrons, and this principle is commercially applied in, for example, the spin valves of disk-drive read heads. There is currently widespread interest in developing new types of spintronic devices based on industrially relevant semiconductors, in which a spin-polarized current flows through a lateral channel between a spin-polarized source and drain. However, the transformation of spin information into large electrical signals is limited by spin relaxation, so that the magnetoresistive signals are below 1% (ref. 2). Here we report large magnetoresistance effects (61% at 5 K), which correspond to large output signals (65 mV), in devices where the non-magnetic channel is a multiwall carbon nanotube that spans a 1.5 microm gap between epitaxial electrodes of the highly spin polarized manganite La(0.7)Sr(0.3)MnO3. This spintronic system combines a number of favourable properties that enable this performance; the long spin lifetime in nanotubes due to the small spin-orbit coupling of carbon; the high Fermi velocity in nanotubes that limits the carrier dwell time; the high spin polarization in the manganite electrodes, which remains high right up to the manganite-nanotube interface; and the resistance of the interfacial barrier for spin injection. We support these conclusions regarding the interface using density functional theory calculations. The success of our experiments with such chemically and geometrically different materials should inspire new avenues in materials selection for future spintronics applications.