T lymphocyte immunoregulatory subsets (T4+ and T8+ cells) have been analysed in eight cases of hepatosplenic schistosomiasis mansoni, and compared to parallel analyses of seven intestinal Schistosoma mansoni-infected patients and four uninfected control subjects. The mean T4+:T8+ ratio in hepatosplenic cases was markedly less than observed in other groups (0.94 vs 1.86 vs 2.22, respectively). Proliferative responses stimulated by a soluble adult worm extract correlated directly with the observed T4:T8 ratios. Normal levels of E rosette-positive and surface immunoglobulin-bearing lymphoid cells were observed in intestinal patients, while hepatosplenic patients demonstrated normal B lymphocyte proportions but highly erratic E rosette-positive percentages. Curiously, in hepatosplenic patients the percentage of E rosette-positive cells often did not correlate with the proportion of T3+ cells.

Backgroud: Psychosis frequently occurs in Alzheimer’s disease (AD), being associated with more severe cognitive decline, but the underlying mechanisms are unknown. Objective: To investigate the effect of centrally administered β-amyloid peptide, a model for AD, in the locomotor response to amphetamine, caffeine and MK-801, which are psychoactive drugs related to neurochemical changes occurring in psychosis. Methods: Mice were intracerebroventricularly injected with β-amyloid (25–35), and after 1 week they were tested in the passive avoidance, spontaneous alternation and locomotor tasks. Results: Besides impaired performance in inhibitory avoidance and spontaneous alternation tasks, β-amyloid-treated mice showed increased spontaneous locomotion, augmented response to amphetamine (1.5 mg/kg), blunted response to caffeine (30 mg/kg) and no difference in MK-801 (0.25 mg/kg)-induced locomotor activation when compared to its respective control. Conclusion: These results are compatible with the hypothesis that β-amyloid peptide may predispose to psychotic symptoms of AD by increasing sensitivity of the dopaminergic system, possibly related to a decreased adenosinergic inhibitory tone.

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Experimental drugs and/or plant extracts are often dissolved in solvents, including propylene glycol. Nevertheless, there is evidence for psychoactive properties of this alcohol. In this study we found that in the hole-board test 10% propylene glycol did not modify the headdipping behavior. However, 30% propylene glycol induced an increase in the number of head-dips (46.92 ± 2.37 compared to 33.83 ± 4.39, P<0.05, ANOVA/Student-Newman-Keuls), an effect comparable to that obtained with 0.5 mg/kg diazepam (from 33.83 ± 4.39 to 54 ± 3.8, P<0.01, ANOVA/Student-Newman-Keuls). These results demonstrate that 30% propylene glycol has significant anxiolytic effects in this model and therefore cannot be used as an innocuous solvent.