A comparison of the pharmacokinetics and tolerability of riluzole after repeat dose administration in healthy elderly and young volunteers.

The pharmacokinetics and tolerability of the novel antiexcitatory agent, riluzole, were compared in 18 healthy elderly and 18 healthy gender- and weight-matched young volunteers. All participants received riluzole 50 mg twice daily (the recommended dosage for patients with amyotrophic lateral sclerosis), administered orally for 5 days. The pharmacokinetics of riluzole, determined on the morning of the 5th day of dosing, were not significantly affected by age or gender. The mean terminal elimination half-life (t1/2), however, was statistically significant between elderly and young subjects. Riluzole was well tolerated upon repeat dose administration. Headache was the most frequent adverse event reported, and there was no overt difference in the type, frequency, or severity of adverse events between elderly and young volunteers or between genders. In conclusion, these results indicate that no dosage adjustments of riluzole are required in the elderly.

Joint memory.

Joint memory is defined as the property of a social group in actualizing its own past transformations. It may result from the coupling of individual memories or be inscribed in the external environment. The concept of joint memory becomes heuristic when it subsumes an ensemble of social processes that are sufficiently integrated to be treated as an entity belonging to the real world. In social insects, colonies can perform action-perception loops which give rise to collective outcomes based on past experience; selective pressures could favour individual behavioural algorithms the combination of which provides a historical record organizing activities both in space and time. In contrast, social groups do not appear sufficiently autonomous in most vertebrates for joint memory be more than a way of seeing collective performances. However, in human beings, the development of external representations has made possible the growth of a socially distributed cognition; the accumulation of epigenetic events through cultural processes produces a set of material and symbolic products that feed back upon the conditions of evolution of the species.

Seasonal variations of androgens and of several sexual parameters in male Meriones shawi in southern Morocco.

Seasonal changes of several parameters related to sexual activity were studied in the gerbil (Rodentia: Gerbillidae). The weight of the testes, seminal vesicles, and adrenals fluctuate throughout the year. Plasma androgen levels and histological aspect of the testes also vary throughout the year. Spermatogonial and steroid activities are synchronous and are maximal in winter and spring. The relationship between these activities and environmental climatic parameters is discussed: the beginning of sexual activity seems correlated with the first rains.