In Leicestershire (Lancet2001;357:1821–5) two postal questionnaire surveys, in 1990 and 1998, showed that the prevalence of wheezing in preschool children almost doubled between the two dates. The increase included both atopic (asthma) and nonatopic (early transient wheezing and viral wheezing) types of wheezing suggesting that there was an increase in bronchial responsiveness to environmental triggers, not necessarily involving atopy.

The urea cycle supplies arginine which is necessary for the synthesis of nitric oxide and nitric oxide is essential for the normal fall in pulmonary artery pressure to occur after birth. Researchers in Nashville, Tennessee (New England Journal of Medicine 2001;344:1832–8) have found low plasma concentrations of both arginine and nitric oxide metabolites in infants with pulmonary hypertension. They suggest that changes in the carbamoyl-phosphate synthetase gene might predispose to neonatal pulmonary hypertension though their genotype studies were inconclusive.

A large randomised trial in North America and Australia (New England Journal of Medicine2001;344;1966–72) involving 1200 extremely low birthweight infants has confirmed that intravenous indomethacin reduces the incidence of patent ductus arteriosus and severe periventricular and intraventricular haemorrhage but does not alter the risk of death, cerebral palsy, cognitive impairment, deafness, or blindness up to a corrected age of 18 months.

The prevalence of myopia appears …