PET and MRI of the thalamus in never-medicated patients with schizophrenia.

OBJECTIVE: This study reports the first paired measurements of glucose metabolism and size of thalamic regions in never-medicated schizophrenic patients using coregistered magnetic resonance imaging (MRI) templates. METHOD: Positron emission tomography with [18F]fluorodeoxyglucose and matching MRI scans were obtained in 20 never-medicated patients with schizophrenia and 15 normal volunteers. Methods for thalamic edge finding, statistical testing of shape differences with chi-square maps, and MRI localization of major thalamic subregions were developed. RESULTS: Patients with schizophrenia showed a diminished metabolic rate in the right thalamus, with a loss of the normal pattern of right greater than left asymmetry. Division into anterior/posterior segments revealed that the left anterior and right posterior showed the decrease. Differences were greater for metabolism in the weighted thalamic area (ratexarea) than for rate per unit area, a finding consistent with reported greater decreases in total neuron number than of neuron density in the thalami of schizophrenic patients. The area of the thalamus was smaller in the patients than in the volunteers, and this difference was greatest in the left anterior region. CONCLUSIONS: The reduced thalamic activity observed in this study lends further support to the concept of deficits in sensory filtering in schizophrenia.

Striatal metabolic rate and clinical response to neuroleptics in schizophrenia.

A low metabolic rate in the caudate nucleus and putamen in schizophrenic patients while they were not receiving medication was found to predict a favorable clinical response to haloperidol. Twenty-five patients (21 men and four women) entered a double-blind crossover trial of haloperidol and placebo; to our knowledge, this is the first such trial with positron emission tomography to be reported. Patients received either placebo or medication for the first 5 weeks, and they received the other treatment for the second 5 weeks. Positron emission tomographic scans were obtained at weeks 5 and 10. Patients with low relative metabolic rates in the caudate nucleus and putamen while they were receiving placebo were more likely to show decreases in their Brief Psychiatric Rating Scale scores with haloperidol treatment than individuals with normal or high metabolic rates. Among responders, haloperidol treatment had a "normalizing" effect on metabolic activity in the striatum, with the metabolic rate while they were receiving haloperidol being higher than that while they were receiving placebo. Nonresponders were more likely to show a worsening of hypofrontality while they were receiving medication and an absence of change in the striatum.

[Determination of guanine and cytosine contents of Trichophyton rubrum nuclear DNA with the thermal denaturation technique].

We report here on the G + C mol% content of T. rubrum DNA (including T. rubrum types I-V and an isolate from a patient with tinea pedis) as determined by a thermal denaturation technique. The results are as follows: 45.5, 57.37, 44.22, 45.38, 45.54, and 49.41 mol% for T. rubrum types I-V and isolate respectively. The results are similar to those in the literature, except that the value of T. rubrum type II is slightly higher. Our observations indicate that the morphological heterogeneity of different types of T. rubrum do not seem to be reflected in their G + C mol% values. The authors suggest that the method used here for determining G + C mol% is easy and reproducible.