Body fat distribution measured with CT: correlations in healthy subjects, patients with anorexia nervosa, and patients with Cushing syndrome

Computed tomography (CT) was used to study fat distribution in three groups of women of comparable age: 39 healthy volunteers, 15 patients with anorexia nervosa, and seven with Cushing syndrome. Patients with anorexia nervosa had a fivefold decrease in subcutaneous fat and only a twofold decrease in intraabdominal fat compared with the values for the volunteers. Patients with Cushing syndrome had less than a twofold increase in subcutaneous fat and greater than a fivefold increase in intraabdominal fat compared with values for the healthy subjects. These findings suggest that fat in different body compartments responds differently to disease processes and that CT can be used to measure these changes.     

Suppression of behavioral activity by norfenfluramine and related drugs in rats is not mediated by serotonin release

Fenfluramine, a phenalkylamine with serotonin (5-HT) releasing properties, decreases motor activity in rats. The following studies assessed the contribution of 5-HT release to the behavioral effects of fenfluramine and norfenfluramine using a behavioral pattern monitor that simultaneously assesses locomotor and investigatory behavior. First, both fenfluramine and its active metabolited-norfenfluramine dose-dependently reduced locomotor and investigatory activity. The norfenfluramine-induced reduction in activity was not antagonized by pretreatment with the 5-HT uptake inhibitor fluoxetine or the 5-HT synthesis inhibitorp-chlorophenylalanine, drugs that reduce drug-induced 5-HT release. Second, thed- andl-enantiomers of norfenfluramine were nearly equipotent at reducing behavioral activity, althoughd-norfenfluramine is more potent as a 5-HT releasing agent. Third,p-chloroamphetamine, a drug that shares the 5-HT releasing properties of fenfluramine produced locomotor hyperactivity in the same paradigm. Previous studies indicate that other 5-HT releasing phenalkylamines have behavioral effects resembling those ofp-chloroamphetamine rather than those of fenfluramine. Finally, a structurally related drug, 4-methoxy-5-methyl-aminoindan (MMAI), produced dose-dependent reductions in behavioral activity that are similar to the effects of fenfluramine. The behavioral effects of MMAI were not antagonized by fluoxetine or by the 5-HT receptor antagonist methiothepin. These data suggest that the decrease in activity induced by fenfluramine, norfenfluramine and the related drug MMAI is not related to 5-HT release.     

Neuronal firing in the nucleus accumbens is associated with the level of cortical arousal.

Because of evidence that the nucleus accumbens mediates the activating effects of many drugs, this study examined the hypothesis that the firing rates of individual nucleus accumbens neurons are positively correlated with spontaneous changes in behavioral arousal that occur during the sleep-wake cycle. The present report examined the firing patterns of 80 neurons in the nucleus accumbens of unanesthetized, unrestrained rats during various electrographically determined levels of arousal. Synaptic responses to stimulation of hippocampal and pallidal nucleus accumbens afferents indicated that the present sample of neurons was similar to a large population of nucleus accumbens neurons previously recorded in anesthetized rats. Confirming the participation of the nucleus accumbens in behavioral arousal, the firing rates of nucleus accumbens neurons were greatest during wakefulness and rapid eye movement sleep and lowest during non-rapid eye movement sleep. Furthermore, the induction of halothane anesthesia decreased behavioral and electrocorticographic arousal concurrent with a suppression of the spontaneous nucleus accumbens unit discharge. These data support the hypothesis that the firing of nucleus accumbens neurons is closely related to arousal.     

The effects of stimulant drugs on information processing in elderly adults

The effects of stimulant drug on information processing in elderly adults was studied. In Experiment 1, the effect of methylphenidate (MP) was examined in 8 young and 8 elderly women using a task (SERS) in which stimulus and response complexities were varied. MP speeded processing in the young but not in the elderly women. A second experiment was then conducted to isolate the age-stimulant effects. In Experiment 2, the effects of MP and 10 mg of d-amphetamine (DAMP) were studied in 12 young and 12 elderly men on different types of information processing. Stimulants changed performance on a continuous performance task in both groups. Both stimulants speeded processing on SERS in young, but not in elderly men. MP, however, speeded processing in both groups on a response processing task. The findings suggest that stimulants act on response processing and there appear to be several such processes. Some of these stages decline with age whereas others do not.     

The clinical validity of the Mattis Dementia Rating Scale in staging Alzheimer's dementia

Considerable heterogeneity exists in the criteria used for the establishment of stages of impairment for patients with dementia. The valid distinction of stages is important both for clinical interpretation and the study of dementia. This study reports on the use of the Mattis Dementia Rating Scale (DRS) in staging dementia. Using a sample of 42 patients diagnosed with Alzheimer-type dementia, DRS performance and a rating of Instrumental Activities of Daily Living (IADL) were compared with clinical ratings of dementia severity. Total DRS score provides a clinically valid measure of stage of impairment and appeared to provide a better distinction among stages than IADL score. However, use of the IADL score in conjunction with total DRS may improve correspondence with clinical staging over use of the total DRS score alone. Normative data for the DRS are also provided.