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To study serotonergic involvement in the development of gastric lesions following activity wheel stress, three groups of rats (gastric lesions, no gastric lesions, and home--cage controls) were killed following exposure to the experimental procedures. The brains were dissected into eight specific areas and subjected to analyses for serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) using high performance liquid chromatography with EC detection. Lower levels of 5-HT were found in the midbrain, cortex, and hippocampus of rats with gastric lesions compared to either the no lesion group, subjected to shorter periods of activity--stress, or the home--cage control group. Levels of 5-HT and 5-HIAA were elevated in the pons/medulla oblongata of both the lesion and the no lesion groups compared to the home--cage controls. Corticosterone levels in blood were also significantly elevated in the lesion group. These data on serotonin changes in the CNS suggest a possible role for this neurotransmitter in stress-induced gastric pathology.

A group of 17 white male chronic schizophrenic subjects were divided on the basis of plexus visualization score (PVS). High and low PVS subjects were compared to each other and to low PVS controls on measures of platelet monamine oxidase (MAO), rbc catechol-o-methyl transferase (COMT), and plasma dopamine-beta-hydroxylase (D beta H). There were no differences between high and low PVS subjects on any biochemical variable. Schizophrenic subjects had lower platelet MAO activity than controls. Platelet MAO and rbc COMT were significantly correlated in schizophrenic subjects.

A molecular-dynamics simulation was used to examine the approach to equilibrium of a two-dimensional solid near the melting transition. The system examined consisted of 256 particles interacting through an r repulsive potential. It was found that near the transition the behavior is characterized by both increasing relaxation times and increasing thermodynamic fluctuations. No true metastable states were observed. This behavior appears to be the critical slowing down that accompanies continuous transitions, supporting the view that melting in two dimensions, at least under some circumstances, is continuous. Estimates of the effects of those fluctuations which are suppressed because of the finite size of the system further supports this view. The transition temperature was found to be consistent with the Kosterlitz-Thouless dislocation hypothesis for melting but the system was too small to make any reliable statements about the existence of the hexatic phase proposed by Nelson and Halperin.