Ethical reasoning concerning the feeding of severely demented patients: an international perspective.

Structured interviews were held with 149 registered nurses in seven countries in America, Asia, Australia and Europe concerning the feeding of severely demented patients who do not accept food. The most common reasons for nurses being willing to change their decision to feed or not to feed were an order from the medical head, a request from the patient's husband and/or the staff meeting. There was a connection between the willingness to feed and the ranking of ethical principles. Nurses who were most prone to feed the patient most often gave a high rank to the ethical principle of sanctity of life, while those who primarily chose not to feed the patient gave a high rank to the ethical principle of autonomy. All nurses stressed the ethical principle of beneficence.

Prolonged exposure to an odor or deodorized air alters the size of mitral cells in the olfactory bulb.

The size and distribution of mitral cells in the olfactory bulbs of rats were determined using a computer-assisted morphometric technique. Rats were reared from 2 weeks of age for 10 weeks in an animal colony, or in cages through which a stream of deodorized air or cyclohexanone vapor passed. Statistical analyses indicated that each treatment produced a different distribution of cell sizes in the coronal but not along the rostrocaudal plane of the bulb. The mean size of mitral cells in rats reared in deodorized air was substantially smaller than that of normal rats, and the mean length of their mitral cell layer in the coronal plane was less than in the other groups. Overall, these findings indicate that mitral cells which were of normal size in rats exposed to cyclohexanone had been stimulated by this odor. Cells which had not been stimulated by an odor in either of the experimental groups were smaller than normal and were degenerating or underdeveloped. The results also suggest that there are bands of mitral cells aligned along the rostrocaudal axis of the olfactory bulb which are responsive to specific odors and other evidence is presented which supports this view. The functional significance of exposure effects and their implications for the spatial coding of odor quality are discussed.

The distribution of the size and number of mitral cells in the olfactory bulb of the rat.

A computer assisted method was used to measure the distribution of the size and number of cells in the mitral cell layer of ten olfactory bulbs from six Sprague-Dawley rats. The size of mitral cells was found to vary around the coronal but not along the rostrocaudal extent of the bulb. Cells were smaller in the ventral and dorsal aspects of the bulb, and larger in the medial and lateral aspects; possible causes of these differences are discussed. The pattern of cell size variation in the coronal plane was consistent both within and between animals, although the average size of mitral cells varied from rat to rat. These changes in mean cell size in the coronal plane were due to overall shifts in the size of cells and not to altered proportions of large and small cells. There was no consistent pattern however for cell density as measured by inter-cell distances of mitral cells, either in the coronal or the rostrocaudal planes. Estimates of the number of cells per bulb and the size of cells were observer dependent, whereas the pattern of cell size variation was observer independent. This characteristic pattern of size variation of mitral cells in rats reared in a normal rat colony environment may be due to a functional differentiation of mitral cells, as size has been shown to be associated with the amount of information processed by a cell. That mitral cells possess such a distinct pattern of size variation should therefore be considered if representative data are to be obtained from anatomical, electrophysiological and other studies of the olfactory bulb.

Quality and intensity of binary odor mixtures.

The perceived intensity and quality of binary mixtures consisting of the common but dissimilar odorants, benzaldehyde (almond), eugenol (cloves), propionic acid (vinegar) and (-)-carvone (spearmint), were determined over a wide range of environmentally relevant concentrations. Consistent data were obtained from each of the odor pairs. This showed that the intensity of odorants not their quality determined the contribution of each to the quality of a mixture. Except for the pair carvone-propionic acid, both odorants were perceived only when the difference between their intensities was small. The results confirmed an earlier finding that the total intensity of a mixture is less than the sum of the intensities of the two components, and also showed that it is never less than the intensity of the weaker component. Seven major characteristics of binary odor mixtures are defined.