Hypokalaemia is a common finding in acutely ill patients and may be related in part to increased sympathoadrenal activity. In an investigation to determine whether pretreatment with thiazide diuretics causes the serum potassium to fall to an even lower level during increased sympathoadrenal activity, adrenaline was infused into healthy subjects after pretreatment for 7 days with either bendrofluazide (5 mg) or placebo. Thiazide diuretic pretreatment had no effect on the adrenaline-induced changes in blood pressure and heart rate. However, not only was the baseline serum potassium lower after bendrofluazide (3 . 40 mmol/l vs 3 . 83 mmol/l) but the serum potassium also fell to a significantly lower level during adrenaline infusion after bendrofluazide (2 . 73 mmol/l vs 3 . 08 mmol/l). Transient profound hypokalaemia may increase the risk of ventricular arrhythmias in patients on diuretics, and routine monitoring of the resting serum potassium may underestimate this risk.

Dexamethasone was compared with placebo in a double-blind, crossover, randomised study of infants with severe bronchopulmonary dysplasia who had required mechanical ventilation for at least four weeks, despite treatment with diuretics, methylxanthines, bronchodilators, fluid restriction, nutritional supplementation, and ligation of the patent ductus arteriosus when indicated. Gestational age ranged from 27 to 33 weeks and birth weight from 800 to 1730 g. Patients received dexamethasone (0 . 5 mg/kg/day) or normal saline for the first 3 days, then treatment was crossed over for the next 3 days. The study was terminated when sequential analysis showed that all six patients had improved during dexamethasone therapy. Significant improvements were seen in ventilator-determined respiratory rate, peak inspiratory pressure, fractional inspired oxygen concentration, and alveolar arterial oxygen gradients (p less than 0 . 05). Although dexamethasone hastened weaning from mechanical ventilation, infection occurred in a substantial proportion of patients.

This study was designed to determine whether oestrogens in oral contraceptives and other drugs have a protective effect against development of rheumatoid arthritis. The medical records of 229 women with rheumatoid arthritis and 458 individually matched controls identified through the comprehensive records system for the population of Rochester, Minnesota, were examined for current and prior use of oestrogens. No association was found between rheumatoid arthritis and the use of oral contraceptives, or the use of oestrogens for menopause-related or postmenopausal symptoms.

A randomised study of 189 deliveries was conducted to compare performance in the conventional dorsal position with that in a birth chair. There was no significant difference in the length of the second stage of labour, the time spent bearing down, or the need for operative delivery. Overall blood-loss was greater among patients delivered in the chair but more of this group had either an intact perineum or only superficial damage. The condition of the neonates in the two delivery groups was similar.

Objective evidence of food hypersensitivity was sought by the use of exclusion diets and provocation tests in 23 patients who attributed a wide variety of symptoms to food allergy. Hypersensitivity to ingested substances was confirmed in 4, each of whom presented with typical atopic symptoms. None of these had psychological symptoms, but a high incidence of psychiatric disorder was found in patients whose belief that they had a food allergy could not be confirmed.

Oral bromocriptine (1.25 mg) was given to 8 healthy volunteers in a double-blind placebo controlled cross-over study. 3 and 4 h after taking the tablet there was a significant reduction in intraocular pressure but no change in pupil diameter. There were no changes in heart rate, blood pressure, and systolic time intervals in 6 other healthy volunteers within 3 h of being given 1.25 mg bromocriptine. These results suggest that dopamine receptors may be involved in the control of intraocular pressure.

Urinary prostacyclin (PGI2) was measured in 12 chronic smokers and 12 non-smokers after inhalation of smoke from nicotine-containing and nicotine-free cigarettes. In a separate study a pressor dose of noradrenaline, which increases PGI2, was given to smokers and non-smokers. PGI2 was measured as the stable metabolite, 6-keto-PGF1 alpha in 4 h urine samples by radioimmunoassay after chromatography on LH-20 'Sephadex'. Smoking of nicotine-free cigarettes had no effect on PGI2 release in either smokers or non-smokers. In non-smokers inhalation of nicotine-containing tobacco smoke increased heart-rate, blood-pressure, and urine osmolality, but did not affect urinary 6-keto-PGF1 alpha. In contrast, when chronic smokers used nicotine-containing cigarettes there was a highly significant reduction in excretion of 6-keto-PGF1 alpha (192 +/- 20 to 138 +/- 17 ng/g creatinine). Noradrenaline increased PGI2 in non-smokers (181 +/- 16 to 348 +/- 56) but not in smokers. Smoking of nicotine-containing tobacco abolished the PGI2 response to noradrenaline. These observations suggest that inhalation of nicotine-containing tobacco smoke reduces vascular PGI2 production; this may be a factor in the development of accelerated cardiovascular disease.

78 patients with bacterial meningitis were evaluated in a prospective, randomised study comparing twice-daily ceftriaxone as single-drug therapy with ampicillin and chloramphenicol given every 6 h. The groups were comparable in age, sex, days of illness before admission, and bacterial colony counts in cerebrospinal fluid (CSF). The pathogens were Haemophilus influenzae type b (54 cases), streptococci (9 cases), meningococci (9 cases), and unknown (6 cases). In 40 CSF specimens obtained 4-12 h after initiation of therapy, cultures were negative in 57% of the ceftriaxone patients and in 42% of the others. The mean falls in the CSF bacterial colony counts were 4.7 and 5.0 log10 colony-forming units/ml, respectively. Mean bactericidal activity in CSF was significantly greater in the ceftriaxone than in the conventional treatment group at the beginning and end of therapy. There were no significant differences in clinical responses or in frequency of complications, except for mild diarrhoea, which occurred in 16 ceftriaxone patients and in 8 in the other group (p less than 0.05).

Cervical injury is one of the most frequent complications of suction curettage abortion, yet little is known about its risk factors or prevention. In 15 438 suction curettage abortions carried out at less than or equal to 12 weeks' gestation in hospitals in the USA from 1975 to 1978 the incidence of cervical injury requiring suturing was 1.03 per 100 abortions. Among factors potentially within the physician's control, use of laminaria rather than rigid dilators for dilatation had a strong protective effect (relative risk 0.19), whereas performance of the abortion by a resident rather than an attending physician (relative risk 2.0) and use of general rather than local anaesthesia (relative risk 2.6) had detrimental effects on rates of cervical injury. Among other factors, a previous abortion had a protective effect (relative risk 0.46), whereas patient age less than or equal to 17 years had a detrimental effect (relative risk 1.9). Use of laminaria, performance of the abortion by an attending physician, and local anaesthesia together yield a 27-fold protective effect.

28 patients who had a sustained diastolic blood pressure of 95 to 104 mm Hg and who had no treatment for it for at least 13 months before the trial, but who were otherwise unselected, took part in a randomised controlled trial in which the effect of a restricted sodium diet was compared with that of a general health package. The general health package did not include any specific hypotensive procedures. Changes in blood pressure were measured at predetermined intervals over the course of a year. Within each group both systolic and diastolic blood pressure fell to a highly significant extent after a year, but there was no significant difference between the groups. It would thus seem that the antihypertensive effect of a restricted sodium diet may be related to the increased consultation and monitoring activity of such intervention rather than to the dietary manipulation itself.

To determine whether advertising by infant formula companies shortens the duration of breast-feeding, we randomly assigned 448 breast-feeding new mothers to either receive or not receive a formula sample packet upon discharge from a maternity ward. These mother, unaware of the study, were then telephoned 3 months post partum by a research assistant blind to the randomisation status. "Sample" mothers were less likely to still be breast-feeding at 1 month (78% vs 84%, p = 0.07) and more likely to have introduced solid foods by 2 months (18% vs 10%, p = 0.01). These trends became more significant in three vulnerable subgroups: less educated mothers, primiparas, and mothers who had been ill post partum. Our results suggest that infant formula samples may shorten the duration of breast-feeding and hasten the age at which solids are introduced.

254 patients with serious gram-negative bacillary infections were enrolled into a multicentre, randomised, blind clinical trial and treated with tobramycin-ticarcillin or netilmicin-ticarcillin. The two treatment groups were similar as to sex, age, and weight. The mean daily dose of netilmicin (237 mg) was higher than that of tobramycin (211 mg), p less than 0.01, but the mean duration of therapy was longer with tobramycin (9.4 days versus 8.7 days), p less than 0.01. The netilmicin cohort also had more serious underlying diseases, p less than 0.028. Clinical (tobramycin, 93% and netilmicin, 91%) and bacteriological responses (tobramycin, 87% and netilmicin, 89%) were similar. 84 tobramycin and 73 netilmicin patients had serial audiograms. Eighth nerve deficits developed in 10 (12%) tobramycin and two (3%) netilmicin patients, p = 0.037. Drug-related renal dysfunction developed in 5 (4%) of 114 tobramycin patients whose renal function was monitored and in 1 (1%) of 116 netilmicin patients, p = 0.12.