Size and base composition of RNA in supercoiled plasmid DNA

The average size and base composition of the covalently integrated RNA segment in supercoiled ColE(1) DNA synthesized in Escherichia coli in the presence of chloramphenicol (CM-ColE(1) DNA) have been determined by two independent methods. The two approaches yielded similar results, indicating that the RNA segment in CM-ColE(1) DNA contains GMP at the 5' end and comprises on the average 25 to 26 ribonucleotides with a base composition of 10-11 G, 3 A, 5-6 C, and 6-7 U.

A stable haemagglutinating antigen for detecting toxoplasma antibodies

The production of a toxoplasma-sensitized cell preparation stable for at least one year at 5 degrees C and its performance in the diagnosis of toxoplasmosis is described.

Prevalence, natural history, and relationship of wheezy bronchitis and asthma in children. An epidemiological study

Three randomly selected groups of 7-year-old schoolchildren in Melbourne with mild wheezy bronchitis, with moderate wheezy bronchitis, and with asthma were compared with a control group, and the patients followed up until 10 years of age. Comparison showed that if there was any significant difference between the study groups and the controls it was usually present in all these study groups. It was considered that children with wheezy bronchitis and asthma were from the same population with the same underlying basic disorder, and that there was a wide spectrum in various aspects of the natural history of the disorder.About 11% of all children aged 10 years had had some asthmatic episodes. Seventy per cent. of these children ceased having asthma before 10 years of age, while about 30% (3.7% of the whole community) continued to have episodes. There was a highly significant correlation between early age of onset, the frequency of episodes in the first year of symptoms, and the persistence of asthmatic episodes up to 10 years of age.Ten per cent. of all children with asthmatic episodes continued to have symptoms as severely at 10 years as at an earlier period. In this group the onset of symptoms was almost always before 3 years of age, there was a high frequency of episodes in the first year of symptoms, and boys and girls were affected in the ratio of 7:3.