The impact of performance uncertainty on the postimperative negative variation

In a delayed matching-to-sample task, the impact of clear or ambiguous go versus clear no-go signals on the post-imperative negative variation (PINV) was examined in 11 patients with a chronic schizophrenic disorder (DSM-III-R) and in a control group of 13 healthy subjects matched to the patient sample by age, sex, and education. Size and spatial position of a visual S2 had to be matched to one of two visual patterns in the S1 presented 4 s earlier. In 96 trials, the S2 was identical in size with one of the two patterns of S1 (clear matching). These trials varied pseudorandomly, with 60 trials in which the S2 was of intermediate size. On a randomly interspersed additional 48 trials, an S2 differing in color and shape signaled no-go. The electroencephalogram was recorded from Fz, Cz, Pz, F3, F4, C3, C4, P3, and P4. Although groups did not differ in contingent negative variation amplitude the PINV was generally more pronounced in patients than in controls. In both groups, ambiguity of the to-be-matched S2 produced larger PINV amplitudes; the no-go signal elicited only a small PINV. Differential effects of ambiguity and no-go on PINV amplitude and its scalp distribution suggest that “performance” and “action” uncertainty contribute to PINV generation and that thresholds for both effects are reduced in schizophrenics.     

THE USE OF CHLORAZEPATE FOR PREMEDICATION ON THE NIGHT BEFORE SURGERY

Chlorazepate, a long-acting benzodiazepine, allayed anxietybefore operation, being superior to placebo in a double-blindstudy in which the drug was given the night before surgery.Long-term relief of apprehension before surgery by the administrationof chlorazepate, combined with a narcotic analgesic when indicated,is advocated.     

AN ANAESTHETIC TECHNIQUE FOR ADENOTONSILLECTOMY IN CHILDREN

An anaesthetic technique for adenotonsillectomy, successfullyused in 650 children, is described. Premedication includes morphinein addition to trimeprazine and atropine. Following thiopentoneand suxamethonium-aided intubation, anaesthesia is maintainedby controlled hyperventilation with nitrous oxide and oxygenvia a modified Rees circuit, employing a combined T-piece andmodified Worcester connection, to simplify the use of the Doughtytongue-blade, and firm thermoplastic endotracheal tubes to resistblade compression. Continuity of relaxation is provided by intermittentinjections of suxamethonium. The authors' orotracheal assemblyis unobtrusive, secure and ensures a patent airway with minimaldeadspace. Airway resistance changes are readily appreciated.The technique makes for perfect airway control, relaxation forsurgical access, and rapid recovery. ^*A Short 16-mm film of this technique is avilable. Present address: Liverpool Royal Infirmary, Liverpool, Lancashire,England.     

A LOW DOSE REGIME OF 1α HYDROXYVITAMIN D3 IN THE MANAGEMENT OF SENILE OSTEOPOROSIS: A PILOT STUDY

A comparison has been made between the metabolic consequences of daily administration for 6 weeks of 1·0 μg and 0·5 μg la hydroxyvitamin D₃ (1α(OH)D3) in twenty patients with senile osteoporosis. There was no significant difference in the increase of calcium absorption which occurred in the two treatment groups between the beginning and end of the trial period. Serum and urinary calcium rose significantly in those receiving 1·0 μg 1α(OH)D₃ but not in the lower dosage group. Serum parathyroid hormone levels were suppressed in the higher dosage group only. There was a significantly greater rise of serum inorganic phosphate, and fall of serum magnesium, on the higher dosage, but no significant change in serum creatinine occurred in either group. It is, therefore, suggested that in long term therapy regimes for osteoporosis incorporating 1α(OH)D₃, 0·5 μg may be a more suitable daily dose than 1·0 μg 1α(OH)D₃.     

DISSOCIATION OF ADRENARCHE AND GONADARCHE IN DIABETES MELLITUS

Serum concentrations of testosterone and dehydroepiandrosterone sulphate (DHAS) have been measured in 10 stable insulin-dependent diabetic (IDD) males (chronological age (CA) range 13.0-17.5 years). Their results have been compared with those of a control population of 69 non-diabetic males who presented with mild constitutional growth delay and whose skeletal maturity and pubertal development were similar to the diabetic subjects. Within bone ages (BA) 11.0-14.5 years no significant difference was observed between the serum testosterone concentrations of the diabetic patients and controls: diabetic males, 8.2 (0.3-25) nmol/l (median and range); controls, 7.0 (less than 0.3-23) nmol/l. In contrast, within BA 11.0-14.5 years, the diabetic males had significantly lower serum DHAS concentrations: diabetic males, 1.1 (0.7-4.2) mumol/l; controls, 3.7 (0.7-5.6) mumol/l (P less than 0.001). The serum DHAS concentrations of the diabetic males were also significantly lower than the controls when matched separately for pubic hair and genital development, testicular volume and serum testosterone, (in each comparison P less than 0.02). Serum DHAS concentrations of the diabetic males did not correlate significantly with CA, BA, BA delay (CA-BA), age of onset of diabetes, duration of diabetes, or glycosylated haemoglobin (GHb), but significant correlation was observed between BA delay and duration of diabetes, r = 0.65, P less than 0.05. We conclude that gonadarche appears to proceed despite delayed adrenarche in IDD males. This study presents further evidence in favour of adrenarche and gonadarche being independent physiological events. The causes and clinical significance of low serum DHAS concentrations in adolescent diabetic males remain to be established.