Research in cystic fibrosis (second of three parts).

Tissue-culture studies involving metachromasia, glycosaminoglycans, RNA methylation, cell membranes, and ciliatoxic activity 
in medium are described. Although not fulfilling the hopes of a 
quick route to discovery of the basic defect in this disease 
that were raised by the first findings, the study of fibroblasts 
in cystic fibrosis has given important information. The evidence at present 
indicates that lysosomes and probably other intracellular organelles are normal in 
morphology and function in cystic fibrosis. Several humoral abnormalities have been 
found in cystic fibrosis: those that influence ciliary activity in experimental 
models; those that affect membrane transport; and the abnormality in polyamine 
distribution. A number of abnormal humoral factors have been found in 
cystic fibrosis. The limitations in their interpretation are serious: the assays 
used to delineate these abnormalities are often not universally reproducible, some 
because of their inherent variability and others because they are technically 
forbidding. Therefore, unified definition of the so-called "cystic fibrosis factors" is 
not possible at present. 