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S-nitrosoglutathione increases cystic fibrosis transmembrane regulator maturation.

Endogenous S-nitrosoglutathione (GSNO) is known to increase the expression of certain proteins at concentrations present in the normal human airway. We hypothesized that GSNO would increase expression and maturation of the cystic fibrosis transmembrane conductance regulator (CFTR). Cells expressing DeltaF508 and wild type CFTR were exposed to GSNO and analyzed for expression and maturation by Western blot analysis. Physiologically relevant concentrations of GSNO resulted in dose- and time-dependent increases in expression. The GSNO-induced increases were eliminated by cycloheximide, suggesting a posttranscriptional effect. Unlike proteasome inhibitors, GSNO resulted in an increase CFTR maturation. The GSNO effect could be reversed by dithiothreitol and inhibited by acivicin, a gamma glutamyl transpeptidase inhibitor. These observations suggest that GSNO leads to maturation of mutated DeltaF508 CFTR, a process associated with restoration of CFTR function. Because endogenous levels of GSNO are low in the cystic fibrosis (CF) airway, these results raise the possibility that GSNO replacement therapy could be an effective treatment for CF.

Animals↗

Cystic fibrosis--a challenging masquerader.

CF, a generalized dysfunction of the exocrine glands, is an inherited disorder with variable clinical manifestations and prognosis. Because of the multisystem involvement, CF can masquerade as other disorders, including allergy. A high index of suspicion and a knowledge of the variable manifestations of this complex multisystem syndrome are essential for early diagnosis of this challenging masquerader. Quantitative analysis of sweat electrolyte levels after pilocarpine iontophoresis is the cornerstone of the diagnosis of CF. Because respiratory involvement causes most of the morbidity and mortality, aggressive treatment of pulmonary infection and efforts to reduce obstruction of the airways are essential in the treatment of CF. Until the basic defect that causes CF is identified, control or stabilization of the disease and management of its complications, rather than a cure, are the realistic goals of treatment. A comprehensive approach to management includes education of the patient about the disease and its treatment, supportive counseling, dietary supplementation, and aggressive therapy for pulmonary disease.

Adolescent↗

Gastro-oesophageal reflux in infants under 6 months with cystic fibrosis.

AIM: To establish the incidence of pathological gastro-oesophageal reflux (GOR) in newly diagnosed infants with cystic fibrosis and to identify clinical predictors of increased reflux. METHODS: 26 infants with cystic fibrosis less than 6 months of age (14 male, 12 female; mean (SEM) age 2.1 (0.21) months, range 0.8 to 5.6 months) underwent prolonged oesophageal pH monitoring (mean duration 27.1 (0.49) hours; range 21.3 to 30.2 hours). Reflux symptoms, anthropometric variables, pancreatic status, meconium ileus, genotype, and chest x ray findings were correlated with pH monitoring data. RESULTS: Five infants (19.2%) had an abnormal fractional reflux time of greater than 10%, seven (26.9%) of 5-10%, and 14 (53.8%) of below 5%. Infants who presented with frequent vomiting had a significantly higher fractional reflux time than infants who had infrequent or no vomiting. There was no significant association between abnormal chest x rays and pathological GOR. Sex, genotype, nutritional status, meconium ileus, and pancreatic enzyme supplementation were not significantly associated with pathological GOR. CONCLUSIONS: About one in five newly diagnosed infants with cystic fibrosis had pathological GOR. Pathologically increased reflux was present before radiological lung disease was established. Apart from frequent vomiting, no useful clinical predictors of pathological reflux were found.

Cystic Fibrosis↗

A proinflammatory, antiapoptotic phenotype underlies the susceptibility to acute pancreatitis in cystic fibrosis transmembrane regulator (-/-) mice.

BACKGROUND & AIMS: Cystic fibrosis transmembrane regulator (CFTR) gene mutations are associated with pancreatic insufficiency and pancreatitis. Chronic pancreatitis, including cystic fibrosis-related disease, may exist as a continuum between acute and chronic disease and may manifest as recurrent pain. We hypothesized that cftr(m1UNC) (-/-) mice, which have no evidence of chronic pancreatitis, are susceptible to developing acute pancreatitis. METHODS: We used a cerulein hyperstimulation model of acute pancreatitis and measured histological changes, tissue edema, neutrophil infiltration, inflammatory mediators' mRNA expression, apoptosis markers, and pancreatic trypsin and serum lipase activities. Additionally, we quantitated in vivo pancreatic secretion and pancreatic digestive enzymes. RESULTS: Multiple proinflammatory cytokine genes were constitutively overexpressed in cftr (-/-) pancreas compared with wild-type mice. During acute pancreatitis, cftr (-/-) mice developed more severe acute pancreatitis than wild-type, as indicated by greater pancreatic edema, neutrophil infiltration, mRNA expression of multiple inflammatory mediators, and less apoptotic cell death. In contrast to wild-type mice, cftr (-/-) mice had blunted increases in pancreatic trypsin and serum lipase activities, but similar percentages of pancreatic trypsinogen activation. Finally, cftr (-/-) mice had less in vivo pancreatic secretion in response to cholecystokinin octapeptide and reduced pancreatic digestive enzyme protein and mRNA levels, thus suggesting mild pancreatic insufficiency. CONCLUSIONS: A baseline proinflammatory state and an antiapoptotic phenotype may sensitize cftr (-/-) mice to developing more severe acute pancreatitis with an exuberant pancreatic inflammatory response. Cftr (-/-) mice have mild pancreatic insufficiency, which partially explains the blunted increase of pancreatic and serum digestive enzymes during acute pancreatitis. These findings may explain the susceptibility to acute pancreatitis in persons with classic and nonclassic cystic fibrosis.

Acute Disease↗

Serum lipase after secretin stimulation detects mild pancreatic involvement in cystic fibrosis.

BACKGROUND: The assessment of severe pancreatic insufficiency in cystic fibrosis (CF) is not a diagnostic problem. However, identification of mild cases remains a challenge. The aim of this study was to assess the ability of serum lipase after secretin stimulation to identify mild pancreatic insufficiency in patients with CF. MATERIAL AND METHODS: Thirty patients with CF and pancreatic insufficiency (CF-PI) and 30 patients with CF and pancreatic sufficiency (CF-PS) were studied. Thirty healthy subjects with no known gastrointestinal disease served as controls. In all subjects, fecal fat excretion, fecal elastase-1 (E1) concentration and basal and secretin-stimulated serum lipase concentration were measured. RESULTS: All patients with CF-PI and 3 with CF-PS had abnormally low fecal E1 concentrations. The remaining 27 CF-PS patients and all controls had normal values. Basal and post-stimulation lipase levels were extremely low in patients with CF-PI. Mean basal and poststimulation serum lipase concentrations were significantly higher in CF-PS who had normal fecal E1 concentrations but were still below those of controls (P < 0.001). Among the 27 CF-PS patients with normal fecal elastase, high basal and poststimulation lipase values were found in 6 and 17 patients respectively. CONCLUSION: In patients with CF-PS who have normal fecal elastase-1 concentration, the measurement of basal or secretin-stimulated lipase levels might be helpful in identifying the progression of the destructive process in the pancreas.

Adolescent↗

A clinical perspective of cystic fibrosis and new genetic findings: relationship of CFTR mutations to genotype-phenotype manifestations.

The present report describes several aspects of the relationship of mutations in the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) gene to phenotype expression of the disease including several clinical vignettes from the authors' experience. The genotype-phenotype relationships in CF are complex, and are affected by many factors, including pollution, smoking, bacterial infection, malnutrition, and certain therapeutic agents. The number of CFTR mutations is growing continuously and rapidly, and more than 1,000 mutations have been discovered so far. From a genetic point of view, the deltaF508 mutation is not only the most frequently encountered but also the most severe genetic lesion for homozygotes. The great clinical variability observed in patients with CF, particularly the severity of lung disease, involvement of the pancreas, and male infertility, are beginning to be better understood through the knowledge, although incomplete, of CFTR mutations and their phenotype expressions. This knowledge has had very significant research and clinical applications in all dimensions of the CF problem. It has not only contributed to the enhancement of better diagnosis and clinical management, but it also has opened new and unanticipated lines of investigation and research.

Cystic Fibrosis↗

Search for mutations in pancreatic sufficient cystic fibrosis Italian patients: detection of 90% of molecular defects and identification of three novel mutations.

A cohort of 31 cystic fibrosis patients showing pancreatic sufficiency and bearing an unidentified mutation on at least one chromosome was analyzed through denaturing gradient gel electrophoresis of the whole coding region of the cystic fibrosis transmembrane conductance regulator gene, including intron-exon boundaries. Three new and 19 previously described mutations were detected. The combination of these with known mutations detected by other methods, allowed the characterization of mutations on 56/62 (90.3%) chromosomes. Among those identified, 17 can be considered responsible for pancreatic sufficiency, since they were found in patients carrying a severe mutation on the other chromosome. Among these presumed mild mutations, eight were detected more than once, R352Q being the most frequent in this sample (4.83%). Intragenic microsatellite analysis revealed that the six chromosomes still bearing unidentified mutations are associated with five different haplotypes. This may indicate that these chromosomes bear different mutations, rarely occurring among cystic fibrosis patients, further underlying the molecular heterogeneity of the genetic defects present in patients having pancreatic sufficiency.

Adolescent↗

Localization of cystic fibrosis transmembrane conductance regulator mRNA in the human gastrointestinal tract by in situ hybridization.

We have used in situ hybridization to localize expression of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in the human gastrointestinal tract and associated organs. The stomach exhibits a low level of CFTR expression throughout gastric mucosa. In the small intestine, expression is relatively high in the mucosal epithelium, with a decreasing gradient of expression along the crypt to tip axis. The cells of the Brunner's glands express high levels of CFTR mRNA. In addition, there is a small subpopulation of highly positive cells scattered along the epithelium in the duodenum and jejunum, but not in the ileum. These cells do not represent endocrine cells, as determined by lack of colocalization with an endocrine-specific marker. The distribution of CFTR mRNA in the colon is similar to the small intestine, with highest level of expression in the epithelial cells at the base of the crypts. In the pancreas, CFTR is expressed at high levels in the small, intercalated ducts and at lower levels in the interlobular ducts. CFTR transcripts are expressed at uniformly high levels in the epithelium of the gallbladder. Throughout the gastrointestinal tract, CFTR expression is increased in mucosal epithelial cells that are near lymph nodules.

Antisense Elements (Genetics)↗

A termination mutation (2143delT) in the CFTR gene of German cystic fibrosis patients.

German patients with cystic fibrosis (CF) were screened for molecular lesions in exon 13 of the cystic fibrosis transmembrane conductance regulator (CFTR) gene by single strand conformation polymorphism (SSCP) and chemical cleavage of mismatch analyses. Direct sequencing of four samples that displayed the same SSCP pattern and that were susceptible to cleavage of hetero-duplexes by osmium tetroxide revealed, in all cases, a deletion of a single T residue at nucleotide position 2143 within codon 671 of the CFTR gene. As a result, leucine codon 671 is changed into a termination codon. In total, the 2143delT mutation was confirmed in 6 out of 271 German non-delta F508 CF chromosomes by artificial restriction fragment length polymorphism analysis, indicating that this frameshift mutation accounts for about 2% of German non-delta F508 mutations. The 6 pancreas insufficient patients who are compound heterozygous for 2143-delT suffer from the typical features of pulmonary and gastrointestinal CF disease. The 2143delT mutation completes the panel of the more frequent CFTR mutations that reside on the "delta F508 haplotype" and that contribute to its overpresentation among German non-delta F508 alleles that are associated with severe forms of disease.

Adolescent↗

Pancreatic function testing in meconium disease in CF: two case reports.

We report two infants with cystic fibrosis (CF), presenting with meconium ileus and meconium plug, who had no clinical or biochemical evidence of pancreatic insufficiency during infancy. They underwent pancreatic secretory function testing at 11 and 9 months of age, respectively. Both patients had sufficient lipase and colipase secretion to maintain normal digestion of fat, confirming that meconium disease in CF does not necessarily imply pancreatic insufficiency and the need for enzyme supplementation in infancy. Nonetheless, we documented markedly reduced enzyme secretion in both patients, implying a potential role for the pancreas in the pathogenesis of meconium disease, even when clinical pancreatic insufficiency is absent. In addition, our patient with meconium ileus had a severely limited fluid secretory capacity (10.3% of mean normal values). In contrast, the patient with the milder presentation of meconium plug had a far greater ability to secrete fluid (75% of mean normal), but had poorer pancreatic proteolytic activity. We suggest that impaired fluid secretion may be a very significant factor in the pathogenesis of meconium ileus, and we speculate that an inability to maintain sufficient intraluminal fluid relative to the degree of pancreatic proteolytic deficiency may more adequately explain the risk of occurrence and the severity of intestinal obstruction in CF than either factor alone.

Age Factors↗

Angiotensin II receptor type I-regulated anion secretion in cystic fibrosis pancreatic duct cells.

The beta-adrenergic (cAMP-dependent) regulation of Cl- conductance is defective in cystic fibrosis (CF). The present study explored alternative regulation of anion secretion in CF pancreatic ductal cells (CFPAC-1) by angiotensin II (AII) using the short-circuit current (ISC) technique. An increase in ISC could be induced in CFPAC-1 cells by basolateral or apical application of AII in a concentration-dependent manner (EC50 at 3 microm and 100 nm, respectively). Angiotensin receptor subtypes were identified using specific antagonists, losartan and PD123177, for AT1 and AT2 receptors, respectively. It was found that losartan (1 microm) could completely inhibit the AII-induced ISC, whereas, PD123177 exerted insignificant effect on the ISC, indicating predominant involvement of AT1 receptors. The presence of AT1 receptors in CFPAC-1 cells was also demonstrated by immunohistochemical studies using specific antibodies against AT1 receptors. Confocal microscopic study demonstrated a rise in intracellular Ca2+ upon stimulation by AII indicating a role of intracellular Ca2+ in mediating the AII response. Depletion of intracellular but not extracellular pool of Ca2+ diminished the AII-induced ISC. Treatment of the monolayers with a Cl- channel blocker, DIDS, markedly reduced the ISC, indicating that a large portion of the AII-activated ISC was Cl--dependent. AII-induced ISC was also observed in monolayers whose basolateral membranes had been permeabilized by nystatin, suggesting that the ISC was mediated by apical Cl- channels. Our study indicates an AT1-mediated Ca2+-dependent regulatory mechanism for anion secretion in CF pancreatic duct cells which may be important for the physiology and pathophysiology of the pancreas.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗

[Are pancreatic cystadenocarcinomas degenerated mucinous cystadenomas? French Association of Surgery].

OBJECTIVES OF THE STUDY: To define arguments in agreement or disagreement with the generally accepted theory of transformation from benign mucinous cystadenoma (MC) to malignant cystadenocarcinoma (CC) of the pancreas. METHODS: A review of the literature since 1978 was conducted together with a comparative analysis of a multicentre retrospective study of the different mucinous cystic tumours of the pancreas: 150 MC, 79 CC and 55 intraductal papillary mucinous tumours of the pancrease (TIPMP). Multiple epidemiological and clinicopathological data were compared between MC and CC: mean age at diagnosis, sex distribution, association with diabetes or concurrent cancer, tumour location and size, type of pancreatic main duct communication, pancreatic fibrosis and serum CA 19-9 levels. The analysis concerned also histopathological features of resected cystadenocarcinomas (n = 58). RESULTS: Two features suggested malignant transformation of mucinous cystadenomas: older mean age at diagnosis of CC and histological characteristics revealing areas of benign-appearing epithelium associated with areas of invasive carcinoma in 55% of cases. Conversely, two statistically significant discordant features were observed: a higher proportion of men (40% for CC vs 13% for MC) and a more frequent location in the head of the pancreas (49% vs 27%). The other differences were not in contradiction with the malignant transformation of MC: associated diabetes mellitus, increasing serum CA 19-9 levels and chromosomal aberrations were more frequent in CC. TIPMP were predominant in men (67%), and more common in the head of the pancreas (67%). CONCLUSION: The risk of malignant transformation of MC should not be questioned despite sex distribution and location differences between MC and CC. These differences may be due to inaccurate designation of intraductal mucinous carcinomas as communicating CC or of CC as pancreatic mucinous adenocarcinomas.

Aged↗

Calcium and magnesium in exocrine secretion--an X-ray microanalytical study.

Calcium and magnesium distribution in mammalian exocrine glands under resting, stimulated and pathological conditions was investigated by X-ray microanalysis of thick and ultrathin cryosections. Ultrathin sections were cut from tissue frozen in the presence of a polymer cryoprotectant, dextran. The effect of this treatment on isolated rabbit pancreas. Dextran caused a disturbance in water and ion transport, partly due to an osmotic effect and the impermeability of the pancreatic epithelium to dextran; this does, however, not necessarily invalidate intracellular measurements on frozen-dried sections. Cholinergic stimulation of the rat pancreas caused a change of Ca distribution from the basal to the apical part of the cell; this may be a component of the secretory Ca flux. Kinetic considerations make a significant Ca movement via the ER-Golgi endomembrane space less likely. The mitochondrial Ca concentration is low, and not significantly changed by cholinergic stimulation. X-ray microanalysis was carried out on submandibular glands of rats after chronic treatment with reserpin and/or isoproterenol (an animal model for cystic fibrosis, CF). The acinar cells had elevated Mg and Ca and lowered K concentrations. Analysis of ultrathin cryosections showed high levels of Ca and Mg in secretory granules, mucus globules and the ER. Ca and Mg in the ER may be transported intracellularly with secretory proteins to secretion granules or mucus globules. The decrease in cell K may be due to efflux of K caused by elevated cytoplasmic Ca levels. A similar decrease in cell K was caused by incubation of rat salivary glands with diluted serum from CF patients, a treatment which has been reported to mimic the effect of a rise in cytoplasmic Ca.

Animals↗

Organ-specific over-sulfation of glycosaminoglycans and altered extracellular matrix in a mouse model of cystic fibrosis.

Cystic fibrosis (CF) is a fatal inherited disease caused by the loss of function of a plasma membrane chloride channel-the cystic fibrosis transmembrane conductance regulator (CFTR). It is characterized by viscous mucous secretions which have abnormal glycosylation and sulfation. The development of a CFTR knockout mouse has allowed in vivo experiments aimed at investigating the over-sulfation phenomenon reported for CF glycoconjugates. Four CF and five control mice injected with [35S]sulfate were examined for differences in the sulfation of glycosaminoglycans (GAGs) synthesized by 12 tissues after 48 h. The liver and pancreas of CF mice incorporated significantly higher amounts of [35S]sulfate into GAGs (dpm/microg) than the controls, while the ileum, jejunum, colon, cecum, spleen, trachea, and gall bladder of CF mice exhibited higher incorporation levels that were not significant. The lung and nasal septum were not different, and the nasal mucosa of CF mice was significantly lower (P < 0.05). Structural analysis of the chondroitin/dermatan sulfate component by strong anion-exchange HPLC revealed that the liver and ileum of CF mice incorporated significantly more total sulfate than controls. However, for other organs, the explanation for higher isotope incorporation was a 40-50% higher specific activity of [35S]sulfate within GAGs. This finding implied different uptake kinetics of sulfate from the circulation or that CF mice have altered sulfate pools. CF mice also had altered proportions of chondroitin/dermatan sulfate to heparan sulfate in the ileum and gall bladder (P < 0.05). We conclude that extracellular matrix architecture in some CF organs may be abnormal and that sulfation of glycoconjugates by some organs and sulfate utilization in others have been affected by the loss of CFTR. This study provides the first in vivo evidence for an influence of CFTR on glycoconjugate sulfation and suggests other secondary manifestations of CFTR dysfunction associated with abnormalities of the extracellular matrix.

Animals↗

A molecular mechanism for aberrant CFTR-dependent HCO(3)(-) transport in cystic fibrosis.

Aberrant HCO(3)(-) transport is a hallmark of cystic fibrosis (CF) and is associated with aberrant Cl(-)-dependent HCO(3)(-) transport by the cystic fibrosis transmembrane conductance regulator (CFTR). We show here that HCO(3)(-) current by CFTR cannot account for CFTR-activated HCO(3)(-) transport and that CFTR does not activate AE1-AE4. In contrast, CFTR markedly activates Cl(-) and OH(-)/HCO(3)(-) transport by members of the SLC26 family DRA, SLC26A6 and pendrin. Most notably, the SLC26s are electrogenic transporters with isoform-specific stoichiometries. DRA activity occurred at a Cl(-)/HCO(3)(-) ratio > or =2. SLC26A6 activity is voltage regulated and occurred at HCO(3)(-)/Cl(-) > or =2. The physiological significance of these findings is demonstrated by interaction of CFTR and DRA in the mouse pancreas and an altered activation of DRA by the R117H and G551D mutants of CFTR. These findings provide a molecular mechanism for epithelial HCO(3)(-) transport (one SLC26 transporter-electrogenic transport; two SLC26 transporters with opposite stoichiometry in the same membrane domain-electroneutral transport), the CF-associated aberrant HCO(3)(-) transport, and reveal a new function of CFTR with clinical implications for CF and congenital chloride diarrhea.

Amino Acid Sequence↗