CNP in cor pulmonale and heart failure than as a circulating hormone involved in cardiovascular homeostasis. Thus, measurement of plasma CNP levels and studies involving systemic infusions of CNP may have only a limited role in clarifying its physiological significance. Background-Normal subjects have a negative nasal transmucosal potential difference (TPD) at rest which becomes more negative with exercise. Patients with cystic fibrosis have a more negative resting nasal TPD than controls. The present study was designed to determine the effects of exercise on the TPD of patients with cystic fibrosis. Methods -Seven subjects with cystic fibrosis and seven control subjects had their usual TPD measured at rest, and during and after a 12 minute period on an exercise bicycle designed to produce a pulse rate of 80% of their maximum predicted value. Results -The normal subjects developed a more negative nasal TPD during exercise which returned towards normal at the completion ofthe rest period. The patients with cystic fibrosis had higher resting values which became less negative during exercise. At the end of the exercise period there was no difference between the two groups. At the end of the recovery period

Aims-To evaluate the sensitivity and specificity of two selective media for the isolation of Burkholderia cepacia from sputum specimens in patients with cystic fibrosis (CF). Methods-In total, 149 expectorated sputum specimens from 113 patients with CF (32 cepacia colonised patients and 81 noncepacia colonised patients) attending three CF centres were examined for the presence of B cepacia on two selective media: (1) MAST selective agar, a commercially available selective medium widely used in the UK and (2) BCSA (B cepacia selective agar), a new medium recently described, which is used predominantly in North America. Results-Burkholderia cepacia was isolated from 53 of 149 (35.6%) specimens examined, representing 32 of 113 (28.3%) patients, using both the MAST and BCSA media. Growth was most rapid on BCSA with all (53 of 53) isolates detectable after 48 hours, compared with 50 of the 53 isolates on MAST agar, with the remaining three isolates detectable at five days. Twenty eight contaminants were identified on MAST agar and 13 on BCSA agar; mainly Alcaligenes xylosoxidans and yeast on MAST agar and Flavobacterium indologenes on BCSA medium. BCSA was equivalent to MAST agar in its ability to isolate B cepacia from patients with CF with a history of B cepacia infection. Conclusions-The increased selectivity and reduced time to detection of BCSA makes it an attractive alternative to MAST. However, its present limited commercial availability in the UK may delay its use in routine diagnostic laboratories because of complications with media preparation and quality control. (J Clin Pathol 2001;54:803-805)

Acquisition of B. cepacia may be a cause of, rather than a marker for, a decrease in pulmonary function.

A previously well 10 year old boy presented with scoliosis, a mass in the chest wail, and a pleural effusion. Chest eighth ribs (figure). A computed tomogram of the thorax showed a lesion spreading from the left lower lobe of the lung to the pleura, invading the ribs, and then passing through the chest wall. Radiographs of the mandible, abdominal ultrasound scan, liver function tests, and immunological screen were normal. Blood cultures grew no pathogens and a Mantoux test was negative.When the abscess pointed, it was incised.

This study compared the relative effectiveness of a standard pancreatic enzyme supplement (' Creon ', Duphar) and a new preparation ('Pancrease HL', Cilag) containing about 3 times the lipase and more than 5 times the protease activity. Capsule dosage was adjusted to a ratio of approximately 3 : 1. Fat balances showed that absorption of fat did not change significantly on conversion to the new high-lipase product, and the coefficient of absorption of total energy was similarly maintained. The coefficient of protein absorption was significantly enhanced with the high enzyme preparation ( P < 0.01), which may explain the reported subjective improvement in stool odour. No adverse effects were recorded. Patient acceptability of the new compound was high; the great reduction in the number of capsules required at each meal was cited by all patients as the reason for their preference.