Circadian rhythm-dependent development of melatonin effects and tolerance to PHNO in rats.

Male Sprague-Dawley rats were given 12 days of continuous infusions of (+)-4-propyl-9-hyroxynapthoxazine (PHNO, 5microg/h), a highly selective dopamine D(2) receptor agonist, via subcutaneous ALZET((R)) osmotic pumps. Motor stimulant effects (locomotion and rearing) were monitored throughout the treatment period, including after the animals were injected with 2-iodo-melatonin (0.5 mg/kg) on days 8-10 and 13 after initiation of PHNO infusions. The rats (maintained on 12 L:12 D cycle) developed tolerance to the motor stimulant effects of PHNO during the day, and behavioral sensitization to PHNO during the night. Arousing rats with a vehicle injection transiently blocked the daytime tolerance. A more sustained environmental noise without handling of animals, which had a stronger effect on increasing motor activity of control rats, reversed tolerance to sensitization. Therefore, graded levels of arousal produce graded increases in motor activity in rats otherwise tolerant to the effects of PHNO. Daytime tolerance to PHNO was reversed to sensitization by 2-iodo-melatonin. This effect was more than an additive effect of drug + injection procedure stress. The differential development of nocturnal sensitization and diurnal tolerance to PHNO effects on motor activity may depend upon circadian rhythms in melatonin release, as well as on state of arousal.

Epidemiology and the extent of mental retardation.

Drawing firm conclusions from various findings of epidemiologic research in the mental retardation field is fraught with seemingly endless frustration and confusion. There have been so many studies in different countries on various sized populations with dissimilar methodologies, and concepts and conditions often have been defined differently. Results from various surveys too often lack congruity, and sometimes findings are not reported until several years after the data are collected. However, these criticisms of epidemiologic studies are not meant to suggest that they are worthless or that investigators have been incompetent. Each was attempting to examine different features of particular populations under diverse circumstances, with varying resources and measurement tools, and with distinct goals in mind. It is safe to say that attempting to compare or generalize information collected in one geographic location with another can be very difficult and often unwise. If one intends to plan rationally the services for a particular geographic area, then one must use data that are derived from the population in that area. Finally, results from epidemiologic surveys have been useful in educating professionals and the general public about the extent of problems presented and experienced by persons with mental retardation. As well, this information has proved essential for properly planning and prioritizing the need for services of a diagnostic, treatment, prevention, and research nature. To improve epidemiologic research in the future, it is hoped that coordinated, multipurpose, nationwide, and international data reporting systems for the collection of uniform mental health-mental retardation data can be developed.

Effect of front-line staff turnover on the behavior of institutionalized mentally retarded adults.

The effect of front-line (direct-care) staff turnover on the behavior of institutionalized mentally retarded adults was investigated using two procedures. One measured the effect of turnover on residents' behavior across whole wards. Another measured the impact of turnover on the behavior of a group of residents who acted as their own controls. Contrary to our hypothesis, results suggested that staff turnover had little effect on residents' behavior. These results were discussed, along with suggestions for future research.

Preventing front-line collapse in institutional settings.

Front-line staff in institutions for the mentally ill and mentally retarded are in the best position to help the patients develop to their full potential. However, they are usually poorly paid, and their work seldom receives the respect it deserves. They work under conditions of extreme stress, and burnout often results. The author describes what happens when burnout affects the entire staff on a ward, leading to what he terms front-line collapse. He examines the contributing factors and lists some possible preventive approaches.