Pancreatic enzymes digest obstructive meconium from cystic fibrosis pig intestines

Introduction

Meconium ileus (MI) is a life-threatening obstruction of the intestines affecting ∼15% of newborns with cystic fibrosis (CF). Current medical treatments for MI often fail, requiring surgical intervention. MI typically occurs in newborns with pancreatic insufficiency from CF. Meconium contains mucin glycoprotein, a potential substrate for pancreatic enzymes or mucolytics. Our study aim was to determine whether pancreatic enzymes in combination with mucolytic treatments dissolve obstructive meconium using the CF pig model.

Methods

We collected meconium from CF pigs at birth and submerged it in solutions with and without pancreatic enzymes, including normal saline, 7% hypertonic saline, and the reducing agents N-acetylcysteine (NAC) and dithiothreitol (DTT). We digested meconium at 37 °C with agitation, and measured meconium pigment release by spectrophotometry and residual meconium solids by filtration.

Results and discussion

In CF pigs, meconium appeared as a solid pigmented mass obstructing the ileum. Meconium microscopically contained mucus glycoprotein, cellular debris, and bile pigments. Meconium fragments released pigments with maximal absorption at 405 nm after submersion in saline over approximately 8 h. Pancreatic enzymes significantly increased pigment release and decreased residual meconium solids. DTT did not improve meconium digestion and the acidic reducing agent NAC worsened digestion. Pancreatic enzymes digested CF meconium best at neutral pH in isotonic saline. We conclude that pancreatic enzymes digest obstructive meconium from CF pigs, while hydrating or reducing agents alone were less effective. This work suggests a potential role for pancreatic enzymes in relieving obstruction due to MI in newborns with CF.

Prevalence of tracheobronchomalacia is higher than previously reported in children with cystic fibrosis

BACKGROUND

Tracheobronchomalacia (TBM) is estimated to be present in 1 in 2100 children. Previous reports suggest the prevalence is higher in children with cystic fibrosis (CF). This has clinical implications with potential to influence airway clearance and lung health.

AIM

To determine the prevalence and clinical associations of TBM in Western Australian children with CF.

METHODS

Children with CF born between 2001 and 2016 were included. Operation reports from bronchoscopies performed until the age of 4 were retrospectively reviewed. Data were collected on the presence, persistence defined as a repeat diagnosis, and severity of TBM. Data on genotype, pancreatic status, and symptoms at CF diagnosis were extracted from the medical record. Associations between categorical variables were compared using χ2 and Fisher's exact test.

RESULTS

Of 167 children (79 male), 68 (41%) were diagnosed with TBM at least once, with TBM persistent in 37 (22%) and severe in 31 (19%). TBM was significantly associated with pancreatic insufficiency (χ2  = 7.874, p < 0.05, odds ratio [OR] 3.4), delta F508 gene mutation (χ2  = 6.489, p < 0.05, OR 2.3), and a presentation of meconium ileus (χ2  = 8.615, p < 0.05, OR 5.0). Severe malacia was less likley in females (χ2 = 4.523, p < 0.05, OR 0.42) . No significant relationship was found with respiratory symptoms at the time of CF diagnosis (χ2  = 0.742, p = 0.39).

CONCLUSIONS

TBM was common in this group of children under the age of 4 with CF. A high index of suspicion for airway malacia should be considered in children with CF, particularly those who present with meconium ileus and have gastrointestinal symptoms at diagnosis.

A Case of Jejunal Atresia Associated With Heterotrophic Pancreas and Meckel's Diverticulum

Apart from meconium ileus, amniotic fluid plug syndrome, malrotation of the gut, Hirschprung's disorder, trauma, and other rare causes, bowel atresia is one of the most common causes of bowel obstruction in newborns. Jejunal atresia can affect multiple lengths of the bowel. The higher the level of atresia, the greater the severity. The outcome of bowel atresia related to surgical repair is favorable. In general, both mortality and morbidity are affected by affiliated medical conditions such as preterm birth, cystic fibrosis, and other congenital anomalies; the sophistication of the lesion; and surgical complications. We present the case of a one-day-old baby who had two episodes of bilious vomiting with abdominal distension within 10 minutes of birth. The baby was advised to undergo ultrasonography of the abdomen and pelvis for further evaluation, and the findings were reported.

Pleiotropic modifiers of age-related diabetes and neonatal intestinal obstruction in cystic fibrosis

Individuals with cystic fibrosis (CF) develop complications of the gastrointestinal tract influenced by genetic variants outside of CFTR. Cystic fibrosis-related diabetes (CFRD) is a distinct form of diabetes with a variable age of onset that occurs frequently in individuals with CF, while meconium ileus (MI) is a severe neonatal intestinal obstruction affecting ∼20% of newborns with CF. CFRD and MI are slightly correlated traits with previous evidence of overlap in their genetic architectures. To better understand the genetic commonality between CFRD and MI, we used whole-genome-sequencing data from the CF Genome Project to perform genome-wide association. These analyses revealed variants at 11 loci (6 not previously identified) that associated with MI and at 12 loci (5 not previously identified) that associated with CFRD. Of these, variants at SLC26A9, CEBPB, and PRSS1 associated with both traits; variants at SLC26A9 and CEBPB increased risk for both traits, while variants at PRSS1, the higher-risk alleles for CFRD, conferred lower risk for MI. Furthermore, common and rare variants within the SLC26A9 locus associated with MI only or CFRD only. As expected, different loci modify risk of CFRD and MI; however, a subset exhibit pleiotropic effects indicating etiologic and mechanistic overlap between these two otherwise distinct complications of CF.

It All Depends What You Count-The Importance of Definitions in Evaluation of CF Screening Performance

Screening metrics are essential to both quality assessment and improvement, but are highly dependent on the way positive tests and cases are counted. In cystic fibrosis (CF) screening, key factors include how mild cases of late-presenting CF and CF screen positive, inconclusive diagnosis (CFSPID) are counted, whether those at prior increased risk of CF are excluded from the screened population, and which aspects of the screening pathway are considered. This paper draws on the New Zealand experience of almost forty years of newborn screening for CF. We demonstrate how different definitions impact the calculation of screening sensitivity. We suggest that, to enable meaningful comparison, CF screening reports should clarify what steps in the screening pathway are included in the assessment, as well as the algorithm used and screening target.

Mutational landscape of receptor guanylyl cyclase C: Functional analysis and disease-related mutations

Guanylyl cyclase C (GC-C) is the receptor for the heat-stable enterotoxin, which causes diarrhea, and the endogenous ligands, guanylin and uroguanylin. GC-C is predominantly expressed in the intestinal epithelium and regulates fluid and ion secretion in the gut. The receptor has a complex domain organization, and in the absence of structural information, mutational analysis provides clues to mechanisms of regulation of this protein. Here, we review the mutational landscape of this receptor that reveals regulatory features critical for its activity. We also summarize the available information on mutations in GC-C that have been reported in humans and contribute to severe gastrointestinal abnormalities. Since GC-C is also expressed in extra-intestinal tissues, it is likely that mutations thus far reported in humans may also affect other organ systems, warranting a close observation of these patients in future.

Applying whole-genome sequencing in relation to phenotype and outcomes in siblings with cystic fibrosis

Variations in disease onset and/or severity have often been observed in siblings with cystic fibrosis (CF), despite the same CFTR genotype and environment. We postulated that genomic variation (modifier and/or pharmacogenomic variants) might explain these clinical discordances. From a cohort of patients included in the Wisconsin randomized clinical trial (RCT) of newborn screening (NBS) for CF, we identified two brothers who showed discordant lung disease courses as children, with one milder and the other more severe than average, and a third, eldest brother, who also has severe lung disease. Leukocytes were harvested as the source of DNA, and whole-genome sequencing (WGS) was performed. Variants were identified and analyzed using in-house-developed informatics tools. Lung disease onset and severity were quantitatively different between brothers during childhood. The youngest, less severely affected brother is homozygous for HFE p.H63D. He also has a very rare PLG p.D238N variant that may influence host-pathogen interaction during chronic lung infection. Other variants of interest were found differentially between the siblings. Pharmacogenomics findings were consistent with the middle, most severely affected brother having poor outcomes to common CF treatments. We conclude that genomic variation between siblings with CF is expected. Variable lung disease severity may be associated with differences acting as genetic modifiers and/or pharmacogenomic factors, but large cohort studies are needed to assess this hypothesis.

Differences in clinical outcomes of paediatric cystic fibrosis patients with and without meconium ileus

BACKGROUND

Meconium ileus (MI) affects up to 20% of newborns with cystic fibrosis (CF). We compared clinical outcomes between Australian paediatric CF patients with and without meconium ileus (non-MI).

METHODS

This was a retrospective case-control study of MI and non-MI patients in New South Wales, Australia, from 1988 to 2010. MI patients were matched 1:1 with pancreatic insufficient non-MI patients for age, sex and CF clinic. Clinical measurements, nutrition and gastrointestinal outcomes over this period were compared between groups using linear mixed models for continuous variables to account for age.

RESULTS

There were 162 matched pairs (N=324, 52% female) with mean (SD) age of 15.3 (8.2) and 14.9 (7.9) years for MI and non-MI patients respectively (P=0.6). MI patients aged 5-23 had poorer FEV1% compared to non-MI patients (estimate -0.070 SE [0.02], P=0.003). There were no significant differences in P. aeruginosa isolation rates; however S. aureus isolation rates were lower in MI patients (72%) compared to non-MI (82%) (OR 0.6 [0.3-1.0], P=0.03). Chronic colonisation rates for P. aeruginosa and S. aureus were not significantly different between groups. MI patients aged 2-20 had significantly lower BMI Z-scores over time (estimate -0.25 SE [0.1], P=0.02). MI patients were more likely to receive oral feed supplements (OR 2.8 [1.4-6.1], P=0.003) and gastrostomy formation (OR 4.4 [1.1-24.6], P=0.02).

CONCLUSIONS

CF patients with MI may have worse lung function, growth and nutrition than non-MI patients over time. Meconium ileus may be an early poor prognostic factor for CF.

N-acetylcysteine for Management of Distal Intestinal Obstruction Syndrome

With the improving life expectancy of cystic fibrosis patients, new manifestations of the disease are emerging. Distal intestinal obstruction syndrome is one of the increasingly noted complications. Traditionally this syndrome was treated surgically. N-acetylcysteine is sometimes used as a non-surgical treatment option despite lack of definitive evidence for its efficacy and safety and not being mentioned in current treatment guidelines. The existing case reports suggest that N-acetylcysteine may have a place in therapy for older patients with incomplete distal intestinal obstruction syndrome to relieve the initial obstruction or following disimpaction to ensure clearance of remaining ileus and to prevent obstruction recurrence. In younger patients (e.g., <3 years of age), efficacy of N-acetylcysteine has been controversial and its use has been associated with drug-induced liver injury and hypernatremia. In the cases included in this review, 4% N-acetylcysteine was the formulation most commonly used. Since higher concentrations have been associated with increased adverse effects and mucosal injury, lower concentrations and dosages should be used when using N-acetylcysteine until further evidence becomes available. Proper administration technique and monitoring parameters are not well defined in current literature. Prospective, well-designed clinical trials are lacking and would be helpful to better define the role of N-acetylcysteine in distal intestinal obstruction syndrome.

Management Strategy of Meconium Ileus-Outcome Analysis

Background:

Meconium ileus (MI) is defined as an intestinal obstruction caused by the impaction of inspissated meconium in the terminal ileum. In this study, we have evaluated the nonoperative management of patients of simple MI without fluoroscopic support –an important requisite of the Noblett's criteria. Besides this, surgical management in cases of failed conservative management and complicated MI was also assessed.

Materials and Methods:

This was a retrospective observational study. Various clinical and radiological parameters were evaluated. Conservative management included the use of water-soluble contrast diatrizoate meglumine and diatrizoate sodium. In case of nonpassage of meconium in 24 h from first intervention, exploratory laparotomy with ileostomy was performed. All complicated MI underwent exploratory laparotomy with creation of stoma as and when needed.

Results:

The duration of this study was 6½ years. Twenty-five neonates of MI were admitted. Of these, 22 had simple MI and remaining three had complicated MI. Eighteen neonates responded to the conservative management. In four neonates, who did not respond, exploratory laparotomy was performed. All three neonates having complicated MI underwent exploratory laparotomy. One patient expired in follow-up.

Conclusion:

MI is an important neonatal emergency, which needed immediate attention of a pediatric surgeon. Proper evaluation of the patient, careful application of principals of conservative management, and timely surgical intervention may fetch satisfactory results.

Meconium Ileus

Cystic fibrosis is one of the most common inheritable traits in Caucasians. Meconium ileus and its potential complications are the most likely reasons that these patients will need surgical care. Surgical intervention is usually needed in the neonatal period but may also be required later in life. This article discusses the various ways cystic fibrosis can affect the gastrointestinal tract. Both the operative and nonoperative management of complicated and uncomplicated meconium ileus are discussed in the neonatal period as well as long-term issues, such as distal intestinal obstructive syndrome, fibrosing colonopathy, and rectal prolapse, all of which may be seen in older children and adults.

Comparative Effectiveness of Imaging Modalities for the Diagnosis of Intestinal Obstruction in Neonates and Infants:: A Critically Appraised Topic

RATIONALE AND OBJECTIVES

The purpose of this study was to critically appraise and compare the diagnostic performance of imaging modalities that are used for the diagnosis of upper and lower gastrointestinal (GI) tract obstruction in neonates and infants.

METHODS

A focused clinical question was constructed and the literature was searched using the patient, intervention, comparison, outcome method comparing radiography, upper GI contrast study, and ultrasound in the detection of upper GI tract obstruction such as duodenal atresia and stenosis, jejunal and ileal atresia, and malrotation and volvulus. The same methods were used to compare radiography and contrast enema in the detection of lower GI tract obstruction such as meconium plug syndrome, meconium ileus, Hirschsprung disease, and imperforate anus. Retrieved articles were appraised and assigned a level of evidence based on the Oxford University Centre for Evidence-Based Medicine hierarchy of validity for diagnostic studies.

RESULTS

There were no sensitivities/specificities available for the imaging diagnosis of duodenal atresia or stenosis, jejunal or ileal atresias, meconium plug, and meconium ileus or for the use of cross-table lateral radiography for the diagnosis of rectal pouch distance from skin in imperforate anus. The retrieved sensitivity for the detection of malrotation on upper GI contrast study is 96%, and the sensitivity for the diagnosis of midgut volvulus on upper GI contrast study is 79%. The retrieved sensitivity and specificity for the detection of malrotation with volvulus on ultrasound were 89% and 92%, respectively. The retrieved sensitivity and specificity for the detection of Hirschsprung disease on contrast enema were 70% and 83%, respectively. The retrieved sensitivity of invertogram for the diagnosis of rectal pouch distance from skin in imperforate anus is 27%. The retrieved sensitivities of perineal ultrasound and colostography for the diagnosis of rectal pouch distance from skin in imperforate anus were 86% and 100%, respectively.

CONCLUSIONS

There is limited evidence for the imaging diagnosis of duodenal atresia and stenosis, jejunal and ileal atresias, meconium plug, meconium ileus, and imperforate anus, with recommended practice based mainly on low-quality evidence or expert opinion. The available evidence supports the use of upper GI contrast study for the diagnosis of malrotation and volvulus, with ultrasound as an adjunct to diagnosis. Contrast enema is useful in the investigation of suspected Hirschsprung disease, but a negative study does not outrule the condition. Colostography is the investigation of choice for the work-up of infants with complex anorectal malformations before definitive surgical repair.

Tracheomalacia is associated with lower FEV1 and Pseudomonas acquisition in children with CF

BACKGROUND

Tracheomalacia (TM) occurs in approximately 1 in 2,100 children. Because the trachea develops abnormally in animal models of cystic fibrosis (CF), we hypothesized this may also occur in children with CF, increasing their risk of TM.

PURPOSE

To examine the prevalence and clinical consequences of TM in children with CF.

METHODS

We studied children with CF born between 1995 and 2012. TM was defined as dynamic collapse of the trachea, and the severity was recorded as described in the chart. The effect of TM on patient outcomes, including FEV1 , CT changes, and acquisition of CF pathogens, was assessed using a longitudinal patient dataset.

RESULTS

Eighty-nine percent of children with CF had at least one bronchoscopy (n = 97/109). Fifteen percent of these children had TM described in any bronchoscopy report (n = 15/97). Of the patients with TM, eight had meconium ileus (P = 0.003) and all were pancreatic insufficient. Pseudomonas aeruginosa infection occurred 1.3 years earlier among children with TM (P = 0.01). Starting FEV1 values by age 8 were diminished by over 18% of predicted for patients with TM. Life-threatening episodes of airway obstruction occurred in 3 of 15 patients with CF and TM, including one leading to death. Gender, prematurity, and hepatic disease were not associated with TM. No difference was observed in the frequency of bronchiectasis.

CONCLUSIONS

TM is significantly more common in infants and children with CF than in the general population and is associated with airway obstruction and earlier Pseudomonas acquisition.

Comparison of different IRT-PAP protocols to screen newborns for cystic fibrosis in three central European populations

BACKGROUND

In recent years different IRT/PAP protocols have been evaluated, but the individual performance remains unclear. To optimize the IRT/PAP strategy we compared protocols from three regional CF newborn screening centers (Heidelberg, Dresden, and Prague).

METHODS

We evaluated the effect of elevating the IRT-cut-off from 50 to 65 μg/l (~97.5th to ~99.0th percentile), the need of a failsafe protocol (FS, IRT ≥ 99.9th percentile) and the relative performance using either two IRT-dependent PAP-cut-offs or one PAP-cut-off.

FINDINGS

Elevation of the IRT cut-off to 65 μg/l (~99.0th percentile) increased the PPV significantly (Dresden: 0.065 vs. 0.080, p < 0.0001, Prague: 0.052 vs. 0.074, p < 0.0001) without reducing sensitivity. All three IRT/PAP protocols showed a trend towards a higher sensitivity with FS than without and when using one PAP-cut-off instead of two IRT-dependent PAP-cut-offs.

CONCLUSIONS

For best performance we suggest an IRT/PAP protocol with an IRT-cut-off close to the 99.0th percentile, FS, and a single PAP-cut-off.

Issues in the management of simple and complex meconium ileus

INTRODUCTION

Various surgical methods are used to treat meconium ileus (MI), including resection with enterostomy (RES), primary anastomosis (RPA), and purse-string enterotomy with intra-operative lavage (PSI). The aim of this study is to discuss the surgical treatment of MI, based on our experience.

PATIENTS AND METHODS

Of the 41 MI patients treated at our institution between 1984 and 2007, 18 had simple MI and 23 had complex MI. These groups were analyzed according to treatment modality, concentrating on length of hospital stay, complications [peritonitis, septicemia, adhesive small bowel obstruction (ASBO), and malabsorption/diarrhea], need for additional surgical procedures, mortality.

RESULTS

Of the 18 patients with simple MI, 7 (39%) were successfully treated with diluted Gastrografin® enema. The remaining 11 patients were treated surgically: two underwent RPA, of whom one died; five had RES, of whom one developed ASBO; four underwent PSI, of whom two developed peritonitis. In the complex MI group, 14 patients underwent RPA, with peritonitis occurring in three (one died); nine underwent RES, of whom two developed ASBO.

CONCLUSION

In patients with simple MI, conservative treatment with diluted Gastrografin® enema is an effective initial treatment in our hands. In case of failure, RES is advisable. Patients with complex MI are candidates for RES. RPA and PSI seem to have higher complication rates.

Reduced NHE3-mediated Na+ absorption increases survival and decreases the incidence of intestinal obstructions in cystic fibrosis mice

In cystic fibrosis, impaired secretion resulting from loss of activity of the cystic fibrosis transmembrane conductance regulator (CFTR) causes dehydration of intestinal contents and life-threatening obstructions. Conversely, impaired absorption resulting from loss of the NHE3 Na+/H+ exchanger causes increased fluidity of the intestinal contents and diarrhea. To test the hypothesis that reduced NHE3-mediated absorption could increase survival and prevent some of the intestinal pathologies of cystic fibrosis, Cftr/Nhe3 double heterozygous mice were mated and their offspring analyzed. Cftr-null mice lacking one or both copies of the NHE3 gene exhibited increased fluidity of their intestinal contents, which prevented the formation of obstructions and increased survival. Goblet cell hyperplasia was eliminated, but not the accumulation of Paneth cell granules or increased cell proliferation in the crypts. Microarray analysis of small intestine RNA from Cftr-null, NHE3-null, and double-null mice all revealed downregulation of genes involved in xenobiotic metabolism, including a cohort of genes involved in glutathione metabolism. Expression of energy metabolism genes was altered, but there were no changes in genes involved in inflammation. Total intracellular glutathione was increased in the jejunum of all of the mutants and the ratio of reduced to oxidized glutathione was reduced in Cftr-null mutants, indicating that CFTR deficiency affects intestinal glutathione metabolism. The data establish a major role for NHE3 in regulating the fluidity of the intestinal contents and show that reduced NHE3-mediated absorption reverses some of the intestinal pathologies of cystic fibrosis, thus suggesting that it may serve as a potential therapeutic target.

Identification of a novel mutation of CFTR gene in a Korean patient with cystic fibrosis

Cystic fibrosis (CF) is the most common lethal autosomal recessive disease in Caucasians, but rare in Asians. The mutations of cystic fibrosis transmembrane conductance regulator (CFTR) gene are responsible for CF. To date, less than 5 cases of CF have been reported and a few of them diagnosed based on the genotype of the CFTR gene in Korea. We encountered a 4-month-old Korean infant with CF and the diagnosis was confirmed by CFTR gene mutation analysis. The patient underwent surgical operation, due to meconium ileus at birth. He suffered by recurrent respiratory infections, failure to thrive, fatty liver with hepatomegaly, and cholestasis. The mutations of the CFTR gene were identified in the patient and his parents. The patient was a compound heterozygote with a nonsense mutation of c.263T>G, resulting in an amino acid change of p.Leu88X in exon 3. It was previously described in a Korean patient with CF. The other is a novel mutation; c.2089-2090insA mutation (p.Arg697LysfsX33) in exon 13. The mutation c.263T>G was inherited from his father, and the c.2089-2090insA mutation from his mother. Respiratory infection was recovered by supportive care, and cholestasis was improved slowly with sufficient feeding and supplementation of pancreatic exocrine enzymes. He is 19- month old now and shows catch-up growth. We report a novel CFTR mutation in a Korean infant with CF.