Biomedical subjects
Publications and source records attributed to P S Baxter.
We report 3 cases where the diagnosis of cystic fibrosis (CF) was either confirmed or refuted by studies of chloride secretion in intestinal mucosal biopsies. In one case a heterozygous state was indicated and later confirmed by gene probe studies. The technique clearly distinguishes between CF and control patients and can provide a rapid diagnosis even in the neonatal period.
Ion transport was measured in jejunal biopsies using short-circuit current (SCC) as an index of net electrogenic ion transport. Increases in SCC associated with stimulation of Cl- secretion were observed in control tissues, but CF tissues did not exhibit such a response, indicating a failure of intestinal Cl- secretion. The rise in SCC associated with Na(+)-linked glucose absorption was greater in CF tissues than in controls, reflecting an enhanced active absorption of glucose.
Transmucosal potential difference (PD) and intraluminal pressure were recorded from the same jejunal site in 15 healthy adult controls and 4 adults with cystic fibrosis. In the controls, runs of contractions were associated with wave-like changes in PD with, during phase III-like activity, a mean peak amplitude of -9.7 mV. Although there were no obvious differences in motor patterns, wave-like changes in PD were absent in patients with cystic fibrosis. Intraluminal boluses of 4 mg pilocarpine, or 0.1 mg prostaglandin E2, caused changes of -4.6 mV and -4.5 mV, respectively, in controls; these responses were not seen in patients with cystic fibrosis. There were no significant differences in basal PD and PD changes caused by altered concentrations of infused saline or glucose between patients and controls.
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Three children with cystic fibrosis developed steatorrhoea unresponsive to changes in pancreatic supplements. The final diagnoses were chronic giardiasis, stagnant loop syndrome, and Crohn's disease. Refractory intestinal symptoms in cystic fibrosis merit further investigation.
The secretory activity of jejunal biopsies from children with cystic fibrosis (CF) has been investigated using a modified Ussing chamber technique. Samples from six children with CF failed to respond when challenged with the intestinal secretagogues acetylcholine (10(-3) M), prostaglandin E2 (1.4 X 10(-6) M) and dibutyryl cyclic AMP (10(-3) M), while control tissues exhibited rises in short circuit current of 28.1 (7.4) (6) microA/cm2, 23.4 (4.6) (6) microA/cm2 and 10.0 (2.0) (4) microA/cm2 respectively in response to these agents. The calcium ionophore, A23187 (3.8 X 10(-6) M), increased the short circuit current in all the control tissues (mean change = 10.1 (2.7) (5) microA/cm2) and induced a small response in some of the CF tissues. Both groups of tissues generated a rise in short circuit current associated with sodium linked glucose (10 mM/l) absorption (control = 32.6 (9.3) (6) microA/cm2, CF = 36.2 (13.9) (6) microA/cm2, p greater than 0.05). These results show that the defect in chloride transport observed in other epithelia in CF also exists in the jejunum and could contribute to the intestinal effects of the disease. The technique used should permit further studies of the basic defect and may be of diagnostic value.
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