In postmortem studies of patients with schizophrenia, D2 dopamine receptors in the basal ganglia have been observed to be more numerous than in patients with no history of neurological or psychiatric disease. Because most patients with schizophrenia are treated with neuroleptic drugs that block D2 dopamine receptors in the caudate nucleus, it has been suggested that this increase in the number of receptors is a result of adaptation to these drugs rather than a biochemical abnormality intrinsic to schizophrenia. With positron emission tomography (PET), the D2 dopamine receptor density in the caudate nucleus of living human beings was measured in normal volunteers and in two groups of patients with schizophrenia--one group that had never been treated with neuroleptics and another group that had been treated with these drugs. D2 dopamine receptor densities in the caudate nucleus were higher in both groups of patients than in the normal volunteers. Thus, schizophrenia itself is associated with an increase in brain D2 dopamine receptor density.

The open-field activity of 140 children three to nine years of age was observed in a room divided into four parts, each of which contained a chair and a table with the same five toys on the tables in all of the quadrants. The children participated in two 15-minute sessions, one with free-play instructions, the other with instructions to stay in one part of the room and play with a single toy. Parents of the children filled out a questionnaire version of the Werry-Weiss-Peters Activity Scale. Open-field activity decreased with age in almost perfectly monotonic fashion. Parents' activity ratings were also lower for older children. There were no significant sex differences on either the open-field measures or the parental ratings. Restrictive instructions decreased activity and toy-changing behavior in the open-field situation, but this effect was somewhat attenuated when restrictive instructions were the first ones given. A factor analysis of the ratings provided evidence for a number of independent components of activity in children.

Saliva and plasma levels of phenytoin (DPH) and phenobarbital (PB) in a series of epileptic patients were compared by means of a radioimmunoassat (RIA) that required only 10 mul of saliva or plasma. There was an excellent linear relation (r = 0.98) between the logarithms of the concentrations of DPH in the two fluids. The ratio saliva/plasma was remarkably constant at 0.10 and was unaffected by varying levels of PB. The ratio was close to the fraction of DPH reported unbound in plasma at 37 degrees. PB plasma and saliva levels were also closely related (r = 0.98 for logarithm of plasma and saliva levels). This relation was nonlinear [plasma ocncentration = 4.43 X (salivary concentration)0.86], but could be approximated by the ratio plasma/saliva = 3.4. The simplicity of sample collection and the sensitivity of the RIA procedure suggest that clinical monitoring of these anticonvulsant levels may be carried out by RIA on saliva samples.

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