A decreased noradrenaline turnover in the hypothalami of rats was observed at the peak of the immune response to sheep red blood cells. The decrease in noradrenergic neuronal activity was mimicked by injection of soluble r mediators released by immunological cells activated in vitro. Noradrenaline also tended to decrease in the brainstem but not in the residual brain. It is suggested that products released from activated immunological cells during the immune response may induce the previously described autonomic and endocrine mechanisms that contribute to immunoregulation.

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Ascorbic acid, cysteine, glutathione and uric acid were determined by reverse-phase high-pressure liquid chromatography (HPLC) in 46 breast tissue samples [neoplastic (C) and non-neoplastic (N) from the same patient]. Cholesterol, alpha-tocopherol and gamma-tocopherol were quantified in 64 similar samples by extraction into heptane followed by direct-phase HPLC. DNA was measured in all samples and the percentages of epithelium, fat and connective tissue were estimated in sections adjacent to the sample. Results confirm previous findings that ascorbic acid and glutathione, expressed as mumol/g DNA, were greatly increased in the epithelium of neoplastic tissue. Similar increases in cysteine could be accounted for by the presence of inflammatory cells. Although values of alpha- and gamma-tocopherol correlated with the percentage of fat in both types of tissue, these compounds were also present in the epithelium. Because of the varying amounts of fat in the samples, no significant difference could be found between N and C values. Cholesterol correlated with fat in N and epithelium in C. Consideration of 10 cases with equal amounts of fat in C and N tissue suggests that cholesterol is reduced in C in the epithelial cells.

Summary: Extracellular concentrations of ascorbic acid, glutathione, cysteine, uric acid, tyrosine, and tryptophan were monitored using intracerebral microdialysis in the left frontoparietal cortex of spontaneous hypertensive rats before, and for 3 h after, either focal ischemia [left middle cerebral artery occlusion (MCAO)] or sham oper ation. The size of the ischemic area and the position of the microdialysis probe were checked using the enzyme his totopochemical acid phosphatase reaction. The probe was always located in the cortex inside the stained area. Ascorbic acid levels rose immediately after MCAO and remained at about 12-fold for 3 h. There was a transient Microdialysis (Tossman and V ngerstedt, 1986; Benveniste and Huttemeier, 1990) provides a mini mally invasive method for continuously monitoring changes in concentrations of low-molecular-weight substances in the extracellular (EC) fluid of various organs. It has been used to study cerebral ischemia in the rat, measurements being made mainly in the striatum, one of the areas most susceptible to isch emic damage. Changes have been found in this re gion at the onset of cerebral ischemia in the EC concentrations of various parameters, e. g. , ascor bic acid (Hillered et aI. , 1988), lactate (Hillered et aI., 1989), purine metabolites (Hagberg et aI. , 1987),

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