Gastrointestinal manifestations of cystic fibrosis: a review.
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Biliary Tract Diseases↗
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Results for “CYSTIC FIBROSIS OF PANCREAS”
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Possible regulation of CFTR-chloride channels by membrane-bound phosphatases in pancreatic duct cells.
We have studied CFTR-Cl- channels in non-CF CAPAN-1 and in CFTR-transfected CFPAC-PLJ-CFTR-6 epithelial cells from human pancreas. Theophylline and IBMX induced the opening of cell-attached CFTR-Cl- channels. Theophylline, IBMX and the alkaline phosphatase (AP) inhibitor levamisole enhanced the activity of excised channels and reduced by 70-75% the apical membrane-associated APs activity. Okadaic acid had no effect on APs and channel activities. A polyclonal anti-alkaline phosphatase antibody (which detected apical APs) reduced APs activity and activated quiescent excised chloride channels. These results suggest that CFTR channels may be regulated by membrane-bound phosphatases.
1-Methyl-3-isobutylxanthine↗
Vitamin B12 absorption in cystic fibrosis.
Vitamin B12 absorption was measured in 30 patients with cystic fibrosis by means of the urinary excretion method and found to be impaired, i.e. less than 10%, in 25. The mean urinary excretion amounted to 4.7 +/- 0.8%. In all patients vitamin B12 absorption improved by the addition of trypsin (18.9 +/- 2.1%). Addition of the vitamin B12 analogue cobinamide, which prevents vitamin B12-binding by R-binders, raised the vitamin B12 absorption to 15.0 +/- 2.2%. A further improvement was obtained by the simultaneous addition of cobinamide and trypsin, 18.2 +/- 2.6%, the same value as with trypsin alone. Assuming that cobinamide addition was effective in suppressing all R-binder activity, the additional effect of trypsin suggests a second, stimulatory function of trypsin on vitamin B12 absorption, separate from R-binder-inactivation. In 5 patients only marginal improvement of vitamin B12 absorption was gained by the addition of either trypsin or cobinamide. The deficient serum vitamin B12 (110 pmol/l) in one of them indicates that the normal pancreas-substitution therapy not always implies sufficient restoration of vitamin B12 absorption.
Adolescent↗
Cellular localization of calmodulin-dependent protein kinases I and II to A-cells and D-cells of the endocrine pancreas.
Ca2+/calmodulin-dependent protein kinases I and II, initially identified in brain on the basis of their ability to phosphorylate synapsin I, have been implicated in the regulation of Ca2+-dependent synaptic neurosecretion. Specific recombinant and synthetic peptide antibodies were used to examine the distribution of CaM kinases I and II in the rat pancreas and other tissues. The CaM kinase I antibodies detected a doublet of cytosolic proteins of approximately 38 and approximately 42 kD by immunoblot. CaM kinase I was observed in glucagon-containing A-cells at the periphery of the islet of Langerhans but had little or no overlap with pancreatic polypeptide or somatostatin cells. In contrast, CaM kinase II was localized to somatostatin-containing D-cells. CaM kinase I co-localized with glucagon secretory granules. CaM kinase II was not associated with the somatostatin granule but rather was enriched in areas of the cells that contained relatively little somatostatin. Because glucagon secretion is Ca2+-dependent, it is attractive to speculate that CaM kinase I may play a regulatory role in glucagon secretion. Glucagon and somatostatin cells both utilize intracellular Ca2+ for signaling. Therefore, specific CaM kinases may act as effectors of Ca2+ in these different cell types.
Animals↗
[A case report of cystic fibrosis and review of 16 cases of cystic fibrosis in Chinese patients].
OBJECTIVE: To report a case of cystic fibrosis (CF) in a Chinese and to review the clinical features, gene mutations, diagnosis and outcome of CF in Chinese patients. METHODS: A 14-year-old Chinese girl presenting with recurrent productive cough since birth with parasinusitis and otitis media was confirmed to have CF in Peking University First Hospital. Chest CT scan showed bronchiectasis, more severe in the right upper lobe. Sweat tests were taken three times, and the values of Na(+) and Cl(-) were (126.6 +/- 5.4) mmol/L and (108.9 +/- 3.3) mmol/L, respectively. The examination of the pancreas showed no remarkable cystic changes on CT scan and there was no pancreatic insufficiency. Sixteen patients with CF in Chinese reported from 1974 to 1999 were reviewed. RESULTS: Sixteen of the 17 patients (7 males and 9 females, aged from 6 months to 25 years) had clinical data available for analysis. Eleven of them had died, nine before the age of 13. They all suffered from frequent episodes of pneumonia, while 14 had malnutrition and 4 had jaundice. The diagnostic procedures included clinical features, sweat test and autopsy. Four of them had DNA screened and four kinds of novel mutations in the cystic fibrosis transmembrane conductance regulator gene were found. CONCLUSIONS: Chinese patients with CF show similar clinical manifestations to patients in the European and North American populations, but the CFTR mutation was different.
Adolescent↗
Effects of chronic furosemide treatment on rat exocrine glands.
It has been suggested that a defective chloride transport is the primary cellular basis for the disease cystic fibrosis (CF). Therefore, the effects of chronic furosemide treatment on the structure and function of rat exocrine glands were investigated. X-ray microanalysis of the submandibular gland showed an increase in the cellular Ca and Mg concentrations, and a decrease in the cellular Cl concentration. Transmission electron microscopy showed intracellular accumulation of mucus and the presence of mucus in acinar and ductal lumina. The volume of saliva secreted by the submandibular gland after pilocarpine stimulation was markedly reduced in furosemide-treated animals; the salivary concentrations of Na and Ca were higher, and that of K was lower, than in control animals. The protein concentration in submandibular saliva was not significantly affected. The response of the submandibular gland to isoproterenol stimulation was reduced in furosemide-treated animals. In the parotid gland, chronic furosemide treatment caused an accumulation of immature zymogen granules in the acinar cells and a decrease in the cellular Cl concentration. In the pancreas, the acinar lumen was dilated and completely filled with secretory material, and the acinar cells contained less Na and somewhat less Cl than in control animals. The chronically furosemide-treated rat shows a number of parallels with other animal models for CF, in particular the chronically reserpinized rat. There is also agreement with the human disease itself.
Animals↗
Identification of a splice site mutation (2789 +5 G > A) associated with small amounts of normal CFTR mRNA and mild cystic fibrosis.
A splicing mutation was identified at the +5 position of the splice donor site of exon 14b of CFTR in CF patients in a consanguineous family that is remarkable for unusually mild disease. Quantitative studies of nasal epithelial mRNA revealed that homozygotes for the spice site mutation produced approximately 4% of the normal amount of normally-spliced CFTR. We propose that this small amount of normally spliced mRNA is associated with synthesis of some normal CFTR protein, and accounts for the mild phenotype. Further characterization of epithelial function and clinical phenotype in patients bearing this form of mutation, termed a type V mutation, will be useful in determining the level of CFTR associated with amelioration of lung disease.
Adult↗
Mechanism of dysfunction of two nucleotide binding domain mutations in cystic fibrosis transmembrane conductance regulator that are associated with pancreatic sufficiency.
Variability in the severity of cystic fibrosis (CF) is in part due to specific mutations in the CF transmembrane conductance regulator (CFTR) gene. To understand better how mutations in CFTR disrupt Cl- channel function and to learn about the relationship between genotype and phenotype, we studied two CF mutants, A455E and P574H, that are associated with pancreatic sufficiency. A455E and P574H are located close to conserved ATP binding motifs in CFTR. Both mutants generated cAMP-stimulated apical membrane Cl- currents in heterologous epithelial cells, but current magnitudes were reduced compared with wild-type. Patch-clamp analysis revealed that both mutants had normal conductive properties and regulation by phosphorylation and nucleotides. These mutants had normal or increased Cl- channel activity: A455E had an open-state probability (Po) similar to wild-type, and P574H had an increased Po because bursts of activity were prolonged. However, both mutants produced less mature glycosylated protein, although levels were greater than observed with the delta F508 mutant. These changes in channel activity and processing provide a quantitative explanation for the reduced apical Cl- current. These data also dissociate structural requirements for channel function from features that determine processing. Finally, the results suggest that the residual function associated with these two mutants is sufficient to confer a milder clinical phenotype and infer approaches to developing treatments.
Adenosine Triphosphate↗
Report of the committe for a study for evaluation of testing for cystic fibrosis.
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Adult↗
Abnormal fatty-acid composition of plasma-lipids in cystic fibrosis. A primary or a secondary defect?
The percentage fatty-acid composition of the various plasma-lipid fractions from cystic-fibrosis patients with and without pancreatic insufficiency, obligate heterozygotes, and normal subjects was determined. Only the cystic-fibrosis patients with pancreatic insufficiency had significantly abnormal fatty-acid composition. This general observation did not correlate with vitamin-E deficiency, age, sex, or severity of the disease. Thus the altered fatty-acid composition of the different plasma-lipid fractions appears to be a secondary consequence of the pancreatic insufficiency commonly associated with cystic fibrosis and not a direct metabolic defect related to the cystic-fibrosis gene itself.
Adolescent↗
Genetically defined models of chronic pancreatitis.
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Animals↗
Towards an ovine model of cystic fibrosis.
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Animal Welfare↗
The deltaF508 mutation in the cystic fibrosis transmembrane conductance regulator alters control of essential fatty acid utilization in epithelial cells.
Essential fatty acid (EFA) incorporation into phospholipid is influenced by chloride channels, suggesting that the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) may regulate aspects of EFA metabolism. The objective of this study was to determine whether the DeltaF508 mutation in the CFTR lowers 18:2(n-6) levels in phospholipid. Control cells, CF cells and CF cells transfected with the "normal" CFTR gene or the DeltaF508 CFTR gene were cultured for 3-5 d and used to determine [1-(14)C]18:2(n-6) incorporation into cell lipids. CF cells exhibited low 18:2(n-6) levels in phospholipid, reduced [1-(14)C]18:2(n-6) incorporation into phospholipid (50% of control) and greater [1-(14)C]18:2(n-6) incorporation into the triacylglycerol fraction (400% of control; P: < 0.05). Kinetic modeling of time course data for [1-(14)C]18:2(n-6) incorporation revealed a loss of metabolic control over the intracellular partitioning of 18:2(n-6) between phospholipid and triacylglycerol pools in CF cells. Expression of the normal CFTR gene in transfected CF cells increased chloride efflux and the incorporation of [1-(14)C]18:2(n-6) into phospholipid and triacylglycerol fractions. The increased incorporation of [1-(14)C]18:2(n-6) into phospholipid was attributed to significantly increased incorporation of [1-(14)C]18:2(n-6) into phosphatidylcholine and phosphatidylinositol. In CF cells expressing the defective DeltaF508 CFTR gene, conversion of [1-(14)C]18:2(n-6) to 20:4(n-6) by desaturation-chain elongation was 1.8-fold greater (P: < 0.05) than observed for CF cells transfected with the normal gene. The observations suggest that CF results in a defect in the utilization of 18:2(n-6), which is attributed in part to the defective CFTR.
Cells, Cultured↗
Cystic fibrosis transmembrane conductance regulator and the etiology and pathogenesis of cystic fibrosis.
Cystic fibrosis (CF) is an inherited disorder causing pancreatic, pulmonary, and sinus disease in children and young adults. Abnormal viscosity of mucous secretions is a hallmark of the disease, and is believed to be the result of altered electrolyte transport across epithelial cell membranes. The monogenic etiology of this disease has been apparent for more than 40 years, but the defective gene has only recently been identified. This was made possible because of a revolution in genetic technology, called positional cloning, which can pinpoint disease genes without previous knowledge of the abnormal protein product. The protein encoded by the gene defective in CF has been termed the CF transmembrane conductance regulator (CFTR) because of its postulated role in electrolyte transport. Studies investigating the normal function of CFTR and how mutations affect that function, thereby causing CF, have required the combined skills of clinicians, geneticists, molecular biologists, and physiologists. From this collaborative effort a greater understanding of the pathogenesis of this disorder is now emerging. It may soon be possible to introduce novel therapies derived from this new knowledge that will be aimed directly at the basic defect. An ever-increasing number of genes of unknown function will be identified by continuing advances in molecular genetic technology and the advent of the genome sequencing project. The experience in cystic fibrosis research may prove to be a paradigm for investigation of the function of genes isolated by positional cloning methods.
Amino Acid Sequence↗
Indirect parameters of pancreatic function in cystic fibrosis (CF) during a controlled double-blind trial of pancreatic supplementation.
During two treatment periods (4 weeks each), serum immunoreactive trypsin (IRT), immunoreactive human lipase in stool (IRL), and chymotrypsin (CT) activity in stool were determined in 16 cystic fibrosis patients and compared with fecal fat excretion (72-h sampling). Fecal fat estimation revealed mild to severe steatorrhea in all 16 patients (X = 13.7 +/- 9.0 g/24 h) in at least one study period. Stool fat excretion was highest in underweight adolescents and adults. Comparison of IRT and IRL with stool fat values showed no significant statistical correlation. IRT values revealed an inverse exponential correlation with age, with a steep decline at the age of 5 years. CT levels were very high in 14 of our 16 patients during supplementation therapy, whereas 2 patients showed subnormal CT values. We conclude that since indirect parameters of pancreatic function do not correlate with stool fat excretion, stool fat remains the best indirect parameter for the assessment of pancreatic insufficiency in cystic fibrosis. Leaving pancreatic enzyme supplementation in cystic fibrosis patients on the basis of normal serum trypsin or fecal lipase values does not appear to be adequate.
Adolescent↗
Longitudinal follow-up of exocrine pancreatic function in pancreatic sufficient cystic fibrosis patients using the fecal elastase-1 test.
BACKGROUND: A progressive decline in pancreatic function is possible in cystic fibrosis (CF) patients with exocrine pancreatic sufficiency. The secretin-cholecystokinin test is invasive and not acceptable as a repeatable procedure for children. Steatorrhea, conversely, has low sensitivity. Therefore, the aim of the present study was to evaluate the usefulness of the noninvasive fecal elastase-1 (E1) test for the longitudinal assessment of exocrine pancreatic function (EPF) in pancreatic-sufficient (PS) CF patients. METHODS: One hundred eighty-four CF patients were included in the study. In all subjects, E1 concentrations and fecal fat excretion were measured. PS patients were followed for 5 years. RESULTS: At the beginning of the study, 35 (19.0%) CF patients were PS, and 32 (17.4%) had normal E1 concentrations. Longitudinal measurements of E1 concentrations in PS patients with CF demonstrated stable enzyme output in 27 and gradual decrease in 8. The decrease was rapid in five infant patients and gradual in three older patients. The decrease of E1 concentrations preceded the appearance of steatorrhea in all eight subjects. CONCLUSIONS: The decline of EPF in patients with CF appears more frequently during the first months and years of life. However, late PS to pancreatic-insufficient (PI) conversion is also possible. The appearance of maldigestion is preceded by the decrease of fecal E1 concentration. Thus, the fecal E1 test is a helpful screening tool for the longitudinal assessment of declining EPF in PS patients with CF to demonstrate pancreatic deterioration. In suspected patients, fecal fat excretion should be assessed.
Adolescent↗
Fecal elastase-1 is superior to fecal chymotrypsin in the assessment of pancreatic involvement in cystic fibrosis.
OBJECTIVE: Exocrine pancreatic function in patients with cystic fibrosis (CF) can be evaluated by direct and indirect tests. In pediatric patients, indirect tests are preferred because of their less invasive character, especially in CF patients with respiratory disease. Fecal tests are noninvasive and have been shown to have a high sensitivity and specificity. However, there is no comparative study in CF patients. Therefore, the aim of the present study was to compare the sensitivity and the specificity of the fecal elastase-1 (E1) test with the fecal chymotrypsin (ChT) test in a large cohort of CF patients and healthy subjects (HS). DESIGN: One hundred twenty-three CF patients and 105 HS were evaluated. In all subjects, E1 concentration and ChT activity were measured. In the CF group, fecal fat excretion was also determined. The sensitivity and specificity of the fecal E1 test and ChT test were compared. RESULTS: With a cutoff level of 3 U/g, ChT specificity in HS was similar to that of E1, but E1 sensitivity in CF patients was significantly higher (90.2% vs 81.3%). With a cutoff level of 6 U/g, ChT and E1 sensitivity in CF patients was identical, but E1 specificity in HS was again significantly higher (98.1% vs 90.5%). In all CF patients with severe steatorrhea (>15 g/d), E1 concentrations were abnormal and ChT activity was lower than 3 U/g. In contrast, in pancreatic-sufficient patients and patients with mild steatorrhea (< or =15 g/d), the E1 sensitivity was significantly higher compared with ChT (69.2% vs 41.0%). CONCLUSIONS: The fecal E1 test is superior to fecal ChT determination in the assessment of CF pancreatic involvement in pancreatic-sufficient patients and those patients with mild steatorrhea.
Adolescent↗
Nutritional imperatives in cystic fibrosis therapy.
Patients with CF who receive optimal nutrition have better growth, maintain better nutritional reserves, and have better pulmonary function than patients with CF who have poor nutrition. These factors influence quality of life as well as survival. The metabolic and immunologic response to infection, as well as the increased work of breathing, escalates calorie requirements in this patient population. No single strategy works for every patient. Therefore, close monitoring of growth, symptoms, and changes in respiratory status that could increase calorie requirements is necessary.
Child↗