To test or not to test, that is the question.

This paper describes a system that is used in Maastricht, the Netherlands, to provide general practitioners with feedback about the adequateness of their test requesting behaviour. The system has proven to be effective. Since the screening of test requests and additional patient data is work-intensive a project was started in the framework of the AIM programme OPENLABS to design a computer-based feedback system. In this system the general practitioner sends test requests to the laboratory decision support system by means of electronic data interchange (EDI). The authors were involved in the development of the EDI messages, which are now accepted standards in the Netherlands. The requests are stored in a database that is part of the laboratory decision support system. The other part of the decision support system, an expert system, obtains the request data (including patient data) from the database, screens the requests for adequateness and provides feedback when necessary.

The influence of sodium bromide in man: a study in human volunteers with special emphasis on the endocrine and the central nervous system.

Sodium bromide was administered orally in capsules to healthy volunteers in doses of 0, 4 or 9 mg Br-/kg/day using a double-blind design. Each treatment was given to seven males for 12 weeks and to seven non-pregnant females (not using oral contraceptives) over three full cycles. Special attention was paid to possible effects on the endocrine and central nervous systems. At the start and end of the study, a full medical history, the results of a physical examination, haematological studies and standard clinical chemistry and urine analyses were recorded for each subject. These showed no changes for individuals following treatment, except for some incidence of nausea associated with bromide-capsule ingestion. Mean plasma-bromide concentrations at the end of treatment were 0.08, 2.14 and 4.30 mmol/litre for males and 0.07, 3.05 and 4.93 mmol/litre for females of the 0-, 4- and 9-mg Br-/kg/day groups, respectively. Plasma half-life was about 10 days. In the females taking 9 mg Br-/kg/day (but in no other group) there was a significant (P less than 0.01) increase in serum thyroxine and triiodothyronine between the start and end of the study but all concentrations remained within normal limits. No changes were observed in serum concentrations of free thyroxine, thyroxine-binding globulin, cortisol, oestradiol, progesterone or testosterone, or of thyrotropin, prolactin, luteinizing hormone (LH) and follicle-stimulating hormone before or after the administration of thyrotropin-releasing hormone and LH-releasing hormone. Analysis of neurophysiological data (EEG and visual evoked response) showed a decrease in delta 1- and delta 2-activities and increases in beta-activities and in mean frequency (Mobility parameter) in the groups on 9 mg Br-/kg/day, but all the findings were within normal limits.

The no-effect level of sodium bromide in healthy volunteers.

1. A total of 0, 4 and 9 mg kg-1 body weight sodium bromide was administered orally to 45 healthy female volunteers. 2. The experiment lasted for six menstrual cycles: only during the first three cycles was bromide administered; 3. At the start, at the end of the administration period and at the end of the experiment a physical examination and haematological and routine clinical chemistry tests were performed. Except for nausea in relation to the intake of bromide, no adverse effects were observed. 4. The bromide concentration in plasma rose to 3.22 +/- 0.93 mmol kg-1 in the 4 mg kg-1 group and to 7.99 +/- 1.89 in the 9 mg kg-1 group by the end of the administration period. 5. Before and at the end of the experiment the thyroid hormones (T4, FT4, TBG, T3 and TSH) were analysed. No significant differences were observed between the groups. 6. Before, after three menstrual cycles and at the end of the experiment an EEG with a Visual Evoked Response was recorded. At the 4 and 9 mg kg-1 dose level in the alpha 1-band and the beta-bands significant changes were found (P < 0.1 and P < 0.05, respectively). The Visual Evoked Response showed no significant differences between the three groups. 7. From this experiment and previous experiments a no-effect level in humans for sodium bromide of 4 mg kg-1 body weight is proposed.

The visual evoked potential in the first six years of life.

With routine techniques the flash-evoked VEPs in 11 consecutive age groups between 0--6 years, each consisting of 8 children, were measured under clinical circumstances. The children were carefully screened to fit within predetermined normal limits. The main results are: (1) The primary part, consisting of 3 components, is well discernible at birth and its latency declines exponentially with age and reaches adult values between 3--4 years. (2) The secondary part is barely discernible at birth and its latency increases until the age of 2--4 months, after which a sharp decline occurs. At the age of 6 years the latencies remain longer than adult values. (3) The integrated amplitude is small until the age of 2--4 months, after which a sharp increase is seen. Thereafter it remains rather constant but shows a sudden increase after the age groups 5--6 years. (4) Generally, values which were compared with those in the literature agreed well. (5) It is suggested that the development of the secondary part of the VEP reflects the increase in complexity of the connections within the visual cortex as well as between the cortex and subcortical centres.

Visual evoked response in senile and presenile dementia.

The visual cortical evoked response was studied in 19 patients suffering from a condition diagnosed as senile or presenile (type Alzheimer) dementia. When compared with a group of normal subjects used as reference group, the latencies of waves II through VI were increased or markedly increased in these patients, and the amplitudes of waves III and VI (and, less consistently, those of waves II and IV) were increased. This corroborates the sparse data on other types of dementia available in the literature.