Julie C. Shea

Analysis of Cystic Fibrosis Gener Product (CFTR) Function in Patients with Pancreas Divisum and Recurrent Acute Pancreatitis

BACKGROUND:The mechanism by which pancreas divisum may lead to recurrent episodes of acute pancreatitis in a subset of individuals is unknown. Abnormalities of the cystic fibrosis gene product (CFTR) have been implicated in the genesis of idiopathic chronic pancreatitis. The aim of this study was to determine if CFTR function is abnormal in patients with pancreas divisum and recurrent acute pancreatitis (PD/RAP).METHODS:A total of 69 healthy control subjects, 12 patients with PD/RAP, 16 obligate heterozygotes with a single CFTR mutation, and 95 patients with cystic fibrosis were enrolled. CFTR function was analyzed by nasal transepithelial potential difference testing in vivo. The outcomes of the PD/RAP patients following endoscopic and surgical treatments were concomitantly analyzed.FINDINGS:Direct measurement of CFTR function in nasal epithelium in response to isoproterenol demonstrated that the values for PD/RAP were intermediate between those observed for healthy controls and cystic fibrosis patients. The median value was 13 mV for PD/RAP subjects, which was statistically different from healthy controls (22 mV, p= 0.001) and cystic fibrosis pancreatic sufficient (−1 mV, p < 0.0001) and pancreatic insufficient (−3 mV, p < 0.0001) patients.INTERPRETATIONS:These results suggest a link between CFTR dysfunction and recurrent acute pancreatitis in patients with pancreas divisum and may explain why a subset of patients with pancreas divisum develops recurrent acute pancreatitis.

The cystic fibrosis transmembrane conductance regulator gene and ion channel function in patients with idiopathic pancreatitis

Cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations are associated with cystic fibrosis (CF)-related monosymptomatic conditions, including idiopathic pancreatitis. We evaluated prospectively enrolled patients who had idiopathic recurrent acute pancreatitis or idiopathic chronic pancreatitis, healthy controls, CF heterozygotes, and CF patients (pancreatic insufficient or sufficient) for evidence of CFTR gene mutations and abnormalities of ion transport by sweat chloride and nasal potential difference testing. DNA samples from anonymous blood donors were controls for genotyping. At least one CFTR mutation or variant was carried in 18 of 40 patients (45%) with idiopathic chronic pancreatitis and in 6 of 16 patients (38%) with idiopathic recurrent acute pancreatitis but in only 11 of the 50 controls (22%, P=0.005). Most identified mutations were rare and would not be identified in routine genetic screening. CFTR mutations were identified on both alleles in six patient (11%). Ion transport measurements in patients with pancreatitis showed a wide range of results, from the values in patients with classically diagnosed CF to those in the obligate heterozygotes and healthy controls. In general, ion channel measurements correlated with the number and severity of CFTR mutations. Twelve of 56 patients with pancreatitis (21%) fulfilled current clinical criteria for the diagnosis of CF, but CFTR genotyping alone confirmed the diagnosis in only two of these patients. We concluded that extensive genotyping and ion channel testing are useful to confirm or exclude the diagnosis of CF in the majority of patients with idiopathic pancreatitis.

Interleukin 8 secretion from monocytes of subjects heterozygous for the deltaF508 cystic fibrosis transmembrane conductance regulator gene mutation is altered

ABSTRACT Patients with cystic fibrosis (CF) exhibit an excessive host inflammatory response. The aim of this study was to determine (i) whether interleukin 8 (IL-8) secretion is increased from monocytes from subjects heterozygous as well as homozygous for cystic fibrosis transmembrane conductance regulator (CFTR) mutations and (ii) whether this is due to increased cell surface lipopolysaccharide (LPS) receptors or, alternatively, increased activation of mitogen-activated protein kinases (MAPK). The basal level of IL-8 secretion was higher from monocytes from CF patients than from monocytes from healthy controls (P = 0.02) and obligate heterozygotes (parents of the CF patients). The 50% effective concentrations for LPS-induced IL-8 production for monocytes from both CF patients and obligate heterozygotes were 100-fold lower than those for monocytes from healthy controls (P < 0.05). No differences in the levels of IL-1β production were seen between these groups. Expression of the LPS surface receptors CD14 and Toll-like receptor 4 were not different between CF patients and healthy controls. In contrast, phosphorylation of the MAPKs p38 and ERK occurred at lower doses of LPS in monocytes from patients heterozygous and homozygous for CFTR mutations. These results indicate that a single allelic CFTR mutation is sufficient to augment IL-8 secretion in response to LPS. This is not a result of increased LPS receptor expression but, rather, is associated with alterations in MAPK signaling.

MECHANISMS TO EXPLAIN PANCREATIC DYSFUNCTION IN CYSTIC FIBROSIS

This article focuses on three potential mechanisms by which pancreatic dysfunction occurs in cystic fibrosis. These include (1) obstruction of pancreatic ducts by inspissated plugs, (2) inhibition of endocytosis in acinar cells, and (3) imbalance in membrane lipids in cystic fibrosis regulated cells. Any of these abnormalities alone or in combination may explain the development of pancreatic exocrine insufficiency.

Fatty acids in cystic fibrosis.

Cystic fibrosis (CF) is associated with deficiencies in certain essential fatty acids. These deficiencies have been studied in plasma, red blood cells, and mucus and were previously thought to be a result of malnutrition or malabsorption. More recent studies have indicated that these deficiencies are independent of nutritional status. However, these studies examined fatty acids in plasma but not in CF–regulated tissues. In the pancreas, lungs, and ileum of CF knock-out mice, membrane-bound arachidonic acid levels have been shown to be increased while docosahexaenoic acid levels are decreased. This lipid abnormality is reversed following oral administration of docosahexaenoic acid (DHA). In addition, DHA therapy reverses the increased neutrophil infiltration in the lungs of CF knock-out mice. Further studies are required to determine the mechanism by which CF gene mutations lead to this lipid abnormality.

An Enteral Therapy Containing Medium-Chain Triglycerides and Hydrolyzed Peptides Reduces Postprandial Pain Associated with Chronic Pancreatitis

Background/Aim: Pain in patients with chronic pancreatitis is difficult to manage. We examined if an enteral formulation containing medium-chain triglycerides (MCT) and hydrolyzed peptides would (1) minimally stimulate the exocrine pancreas by blunting cholecystokinin release and (2) decrease pain in patients with chronic pancreatitis. Methods: In the first part of the study, on separate days, 6 healthy controls consumed a standard enteral formulation, an enteral formulation containing MCT and hydrolyzed peptides, and a high-fat meal. Baseline and postprandial plasma cholecystokinin (CCK) concentrations were analyzed. Subsequently, 8 patients with chronic pancreatitis were enrolled and instructed to complete a visual analog pain assessment for a baseline period of 2 weeks followed by three cans per day of the enteral formulation containing MCT and hydrolyzed peptides for 10 weeks. Results: Mean CCK levels for our control subjects were 0.46 ± 0.29 pM at baseline, 10.75 ± 0.45 pM in response to the high-fat meal, and 7.9 ± 1.25 pM in response to the standard enteral formulation. Of note, CCK levels were 1.43 ± 0.72 pM in response to the enteral supplement containing MCT and hydrolyzed peptides. In patients with chronic pancreatitis, the average improvement in pain scores from baseline to the conclusion of the study was 61.8% (p = 0.01). This corresponded to a clinical improvement in 6 of the 8 patients. Conclusions: A complete enteral supplement containing MCT and hydrolyzed peptides minimally increases plasma CCK levels. This therapy may be effective in reducing postprandial pain associated with chronic pancreatitis.

Familial Occurrence of Neurocardiogenic Syncope

To the Editor: We report two cases of neurocardiogenic syncope in a family. A 19-year-old college student was evaluated for abrupt loss of consciousness which had occurred approximately twice each ...

Sudden cardiac arrest prevention pathways and tools

Evidence-based consensus treatment guidelines are available to assist physicians with management of patients at risk for sudden cardiac arrest (SCA), including patients with heart failure and those after myocardial infarction with left ventricular dysfunction. Although it has been generally presumed that health care providers incorporate cardiovascular treatment guidelines into clinical practice, the actual assimilation of evidence-based strategies and guidelines has been demonstrated to be less than ideal. Studies of heart failure and postmyocardial infarction care show that treatment guidelines are slowly adopted and inconsistently applied, and thus often fail to lead to improvements in patient care and outcomes. These treatment gaps may result in part because evidence-based tools to identify appropriate patients and provide practitioners with useful reminders based on the guidelines have not been widely available. The SCA prevention pathways and tools program is a comprehensive set of pathways and tools to help facilitate optimal patient care for those at increased risk for SCA, including patients with a prior myocardial infarction with left ventricular dysfunction and those with heart failure. Intended for inpatient, outpatient, and transitional care settings, the SCA prevention pathways and tools program supports the recognition and implementation of evidence-based, guideline-recommended care in eligible patients without contraindications. By facilitating best-care practices, the program aims to assist physicians and other health care providers in a meaningful way to improve cardiovascular care and optimize clinical outcomes.