Hypothesis: posture is one of the determinants of the circadian rhythm of urine flow and electrolyte excretion in elderly female patients.

In view of recent investigations suggesting that the circadian rhythm of urine output is reversed in the elderly, the present study was designed to see if increased urine flow at night may be related to change in posture. Urine flow, urea and electrolyte excretion were measured 4-hourly for 6 consecutive days and nights in four catheterized female patients, mean age 83 years. Two were nursed in chairs for 8 h daily for 3 days, followed by total bed-rest for 3 days, and the other two in reverse order. None of the patients showed the morning rise of water and electrolyte excretion which has been described in young people. On full bed-rest, there was no significant day-night difference in water, sodium, potassium, urea or creatinine excretion. Chair nursing produced a negative mean day-night difference in water excretion (-321 ml: P less than 0.001) and in sodium (-11.7 mmol: P less than 0.002), urea (-26.6 mmol: P = 0.005) and creatinine excretion (-0.6 mmol: P = 0.008), but had no significant effect on potassium excretion. These results suggest that sitting upright may have important effects on water and electrolyte balance in elderly patients and may contribute to nocturia and nocturnal incontinence.

Development of a single reagent polarisation fluoroimmunoassay for the detection of opiates in urine.

The design, development, and optimisation of a simple polarisation fluoroimmunoassay to detect the opiate group of drugs, in urine, is described. Urine (10 microL) is added to 1.5 mL of a single reagent, prepared by mixing ovine anti-opiate serum with fluorescein-labelled morphine. After incubation for 30 min at 30 degrees C, or 60 min at room temperature, fluorescence polarisation is measured. The assay can be used as a "stat" test or automated for large batch screening and detects the commonly abused opiates, heroin (through its metabolite morphine), codeine, and dihydrocodeine.

Single-reagent polarization fluoroimmunoassay for amphetamine in urine.

This simple polarization fluoroimmunoassay for detection of amphetamine in urine involves the use of a single reagent: suitably diluted antiserum plus fluorescein-labeled amphetamine as tracer. To this, one adds 10 microL of urine, incubates for a few minutes at room temperature, and measures the fluorescence polarization. By using an antiserum obtained against an immunogen conjugated via the para position of the drug's phenyl ring, we have attained greater specificity than that of most existing immunoassays. As little as 1 mg of amphetamine per liter was easily detected. Results for 266 patients' urines agreed completely with those by gas-liquid chromatography. When a nonseparation enzymoimmunoassay (EMIT-d.a.u., Syva) was applied to 62 specimens chosen without conscious bias, three results were falsely negative, three falsely positive.

The adrenergic response to surgery involving cardiopulmonary bypass, as measured by plasma and urinary catecholamine concentrations.

Plasma and urinary catecholamine concentrations have been measured in 13 patients undergoing cardiac surgery involving cardiopulmonary bypass. The large and progressive increase in plasma catecholamines during bypass reported in previous studies has not been confirmed, and this may be a result of improvements in surgical, anaesthetic and perfusion techniques. The interpretation of urinary findings was complicated by the finding of a positive correlation between catecholamine excretion and urine flow-rate. The findings suggest the need to modify current concepts of the adrenergic response to cardiac surgery and bypass, and question the validity of measuring the urinary catecholamine concentration as an index of stress in these circumstances.

The development and evaluation of a semi-automated assay for catecholamines suitable for plasma and urine.

A simple semi-automated procedure for assay of catecholamines in plasma and urine is described. Each step is examined and the end product is the culmination of these investigations. Use is made of batch alumina adsorption and elution, after comparison with column methods had shown no real advantage. Urine estimations included a preliminary ion-exchange column step. The estimation is such that 40 to 50 specimens of plasma or 60 to 70 specimens of urine can be assayed in a day by a trained laboratory technician. The method is both specific and reproducible, and the sensitivity is increased over previously reported methods. Interference by other catecholamines and compounds is examined and discussed, as are alternative stabilising agents and reactions for the rearrangement and stabilisation of the fluorescent compounds in strong alkali.

The adrenergic response to cardiopulmonary bypass.

12 out of 13 patients who underwent cardiac surgery requiring extracorporeal circulation survived the operation. Arterial and venous catecholamines were measured throughout the operation. Larges rises in catecholamine levels were not seen although significant changes did occur in arteriovenous differences and also between samples at certain points in the operation. These facts do not agree with Lillehei's findings (3) and may reflect improvements in surgical technique, anaesthesia and the reduced time on bypass. However the lack of an overall measurable adrenergic response in terms of plasma catecholamine levels does agree with similar findings after open heart surgery (4) and during other surgical procedures (5).