Social relationships and the management of stress.

Two different types of social relationships exist in mammalian social systems: dominance relationships and social bondings. This article shows that both are crucial for the management of stress. The following general conclusions are derived: (1) In stable social systems, established dominance relationships result in predictable behaviour. As a consequence, low positions in the hierarchy do not necessarily lead to enhanced endocrine stress responses. Under conditions of instability, however, distinct increases in the activities of the pituitary-adrenocortical- and the sympathetic-adrenomedullary systems are found; (2) The ability to establish and to respect dominance relationships is a prerequisite to build up stable social systems. Whether this ability is realized, however, depends on social experiences made during behavioural development. The time around puberty seems to be essential for the acquisition of those social skills needed to adapt to unfamiliar conspecifics in a non-stressful and non-aggressive way; (3) Stress responses can be ameliorated by the presence of members of the same species. This phenomenon is called social support. In general, social support cannot be provided by any conspecific, but the ability to give social support is restricted to bonding partners. In most mammalian species mothers are important bonding partners for their infants. In some species bondings also occur between adult individuals; and (4) On a physiological level the bonding partner reduces the activities of the pituitary-adrenocortical- and the sympathetic-adrenomedullary systems. On a psychological level he/she can be regarded as a 'security-giving and arousal-reducing structure'. This is true irrespective of whether the bonding partner is the mother, in the case of an infant, or a male or a female in the case of an adult individual.

Repeated blood collection in the laboratory mouse by tail incision--modification of an old technique.

Twenty years ago, tail incision for collecting serial blood samples from mice was introduced as a new technique. Despite a number of advantages over established methods, it has not become a frequently used technique. This report describes modifications of blood collection from mice by tail incision that allow obtaining rapid (1-1.5 min) serial blood samples (40-150 microliters) from unanaesthetized laboratory mice. Evaluation of corticosterone concentrations in the blood plasma from repeated samples indicated that subsequent samples were unaffected by the procedure. Furthermore, histopathological examination demonstrated that repeated bleeding did not cause any lasting harm to the animals. Blood collection by tail incision may, therefore, be of particular interest for studies that attempt to relate physiological measures to behavioral responses in laboratory mice, and may contribute to the refinement of animal experimentation according to the principles of the Three Rs.

Far-IR optical properties of freestanding and dielectrically backed metal meshes.

The optical properties of freestanding and dielectrically backed inductive metal meshes are investigated in the far IR spectral regime. The most pronounced effect of the substrate is to cause a shift in the diffraction edge to longer wavelengths by a factor equal to the substrate index of refraction. Various theoretical models are reviewed and tested with the main result being that only the microwave based waveguide-array model successfully predicts the freestanding and dielectrically back optical features in and around the diffraction edge. A simplified version of this model is presented and shown to be adequate for describing the majority of the spectral features. The backed meshes are then characterized in terms of mirror quality for use in optically pumped far IR lasers.