Rie Maurer

Identification and regulation of the cystic fibrosis transmembrane conductance regulator-generated chloride channel.

Cystic fibrosis transmembrane conductance regulator (CFTR) generates cAMP-regulated Cl- channels; mutations in CFTR cause defective Cl- channel function in cystic fibrosis epithelia. We used the patch-clamp technique to determine the single channel properties of Cl- channels in cell expressing recombinant CFTR. In cell-attached patches, an increase in cellular cAMP reversibly activated low conductance Cl- channels. cAMP-dependent regulation is due to phosphorylation, because the catalytic subunit of cAMP-dependent protein kinase plus ATP reversibly activated the channel in excised, cell-free patches of membrane. In symmetrical Cl- solutions, the channel had a channel conductance of 10.4 +/- 0.2 (n = 7) pS and a linear current-voltage relation. The channel was more permeable to Cl- than to I- and showed no appreciable time-dependent voltage effects. These biophysical properties are consistent with macroscopic studies of Cl- channels in single cells expressing CFTR and in the apical membrane of secretory epithelia. Identification of the single channel characteristics of CFTR-generated channels allows further studies of their regulation and the mechanism of ion permeation.

A prospective evaluation of the bedside index for severity in acute pancreatitis score in assessing mortality and intermediate markers of severity in acute pancreatitis.

OBJECTIVES:Our aim was to prospectively evaluate the ability of the bedside index for severity in acute pancreatitis (BISAP) score to predict mortality as well as intermediate markers of severity in a tertiary center.METHODS:The BISAP score was evaluated among 397 consecutive cases of acute pancreatitis admitted to our institution between June 2005 and December 2007. BISAP scores were calculated on all cases using data within 24 h of presentation. The ability of the BISAP score to predict mortality was evaluated using trend and discrimination analysis. The optimal cutoff score for mortality from the receiver operating curve was used to evaluate the development of organ failure, persistent organ failure, and pancreatic necrosis.RESULTS:Among 397 cases, there were 14 (3.5%) deaths. There was a statistically significant trend for increasing mortality (P < 0.0001) with increasing BISAP score. The area under the receiver operating curve for mortality by BISAP score in the prospective cohort was 0.82 (95% confidence interval: 0.70, 0.95), which was similar to that of the previously published validation cohort. A BISAP score ≥3 was associated with an increased risk of developing organ failure (odds ratio=7.4, 95% confidence interval: 2.8, 19.5), persistent organ failure (odds ratio=12.7, 95% confidence interval: 4.7, 33.9), and pancreatic necrosis (odds ratio=3.8, 95% confidence interval: 1.8, 8.5).CONCLUSIONS:The BISAP score represents a simple way to identify patients at risk of increased mortality and the development of intermediate markers of severity within 24 h of presentation. This risk stratification capability can be utilized to improve clinical care and facilitate enrollment in clinical trials.

A comparative evaluation of radiologic and clinical scoring systems in the early prediction of severity in acute pancreatitis.

OBJECTIVES:The early identification of clinically severe acute pancreatitis (AP) is critical for the triage and treatment of patients. The aim of this study was to compare the accuracy of computed tomography (CT) and clinical scoring systems for predicting the severity of AP on admission.METHODS:Demographic, clinical, and laboratory data of all consecutive patients with a primary diagnosis of AP during a two-and-half-year period was prospectively collected for this study. A retrospective analysis of the abdominal CT data was performed. Seven CT scoring systems (CT severity index (CTSI), modified CT severity index (MCTSI), pancreatic size index (PSI), extrapancreatic score (EP), ‘‘extrapancreatic inflammation on CT’’ score (EPIC), ‘‘mesenteric oedema and peritoneal fluid’’ score (MOP), and Balthazar grade) as well as two clinical scoring systems: Acute Physiology, Age, and Chronic Health Evaluation (APACHE)-II and Bedside Index for Severity in AP (BISAP) were comparatively evaluated with regard to their ability to predict the severity of AP on admission (first 24 h of hospitalization). Clinically severe AP was defined as one or more of the following: mortality, persistent organ failure and/or the presence of local pancreatic complications that require intervention. All CT scans were reviewed in consensus by two radiologists, each blinded to patient outcome. The accuracy of each imaging and clinical scoring system for predicting the severity of AP was assessed using receiver operating curve analysis.RESULTS:Of 346 consecutive episodes of AP, there were 159 (46%) episodes in 150 patients (84 men, 66 women; mean age, 54 years; age range, 21–91 years) who were evaluated with a contrast-enhanced CT scan (n=131 episodes) or an unenhanced CT scan (n=28 episodes) on the first day of admission. Clinically severe AP was diagnosed in 29/159 (18%) episodes; 9 (6%) patients died. Overall, the Balthazar grading system (any CT technique) and CTSI (contrast-enhanced CT only) demonstrated the highest accuracy among the CT scoring systems for predicting severity, but this was not statistically significant. There were no statistically significant differences between the predictive accuracies of CT and clinical scoring systems.CONCLUSIONS:The predictive accuracy of CT scoring systems for severity of AP is similar to clinical scoring systems. Hence, a CT on admission solely for severity assessment in AP is not recommended.

Early systemic inflammatory response syndrome is associated with severe acute pancreatitis.

BACKGROUND & AIMS There have been few clinical studies of systemic inflammatory response syndrome (SIRS) in patients with acute pancreatitis. The aim of this study was to evaluate the role of SIRS in assessing severity of acute pancreatitis. METHODS We prospectively enrolled 252 consecutive patients with acute pancreatitis who were admitted directly to our institution between 2005-2007. The incidence and duration of SIRS (transient <or=48 hours vs persistent >48 hours) during the first 7 days of hospitalization, and the number of SIRS criteria (0-4) on the first day of hospitalization (day 1) were evaluated with individual markers of severity, including persistent organ failure, pancreatic necrosis, need for intensive care unit, and mortality. RESULTS SIRS occurred in 155/252 patients (62%) on day 1. SIRS on day 1 predicted severe disease with high sensitivity (85%-100%). The absence of SIRS on day 1 was associated with a high negative predictive value (98%-100%). Patients with a higher number of systemic inflammatory response (SIR) criteria on day 1 and persistent SIRS had an increased risk for severe disease (P < .01). CONCLUSIONS The majority of patients hospitalized with acute pancreatitis have SIRS on day 1. The severity of acute pancreatitis is greater among patients with SIRS on day 1 and, in particular, among those with 3 or 4 SIRS criteria, compared with those without SIRS on day 1.

Incidence, Prevalence, and Clinical Significance of Abnormal Hematologic Indices in Compensated Cirrhosis

BACKGROUND & AIMS Patients with cirrhosis develop abnormal hematologic indices (HI) from multiple factors, including hypersplenism. We aimed to analyze the sequence of events and determine whether abnormal HI has prognostic significance. METHODS We analyzed a database of 213 subjects with compensated cirrhosis without esophageal varices. Subjects were followed for approximately 9 years until the development of varices or variceal bleeding or completion of the study; 84 subjects developed varices. Abnormal HI was defined as anemia at baseline (hemoglobin, < or =13.5 g/dL for men and 11.5 g/dL for women), leukopenia (white blood cell counts, < or =4000/mm3), or thrombocytopenia (platelet counts, < or =150,000/mm3). The primary end points were death or transplant surgery. RESULTS Most subjects had thrombocytopenia at baseline. Kaplan-Meier analysis showed that leukopenia occurred by 30 months (95% confidence interval, 18.5-53.6), and anemia occurred by 39.6 months (95% confidence interval, 24.1-49.9). Baseline thrombocytopenia (P = .0191) and leukopenia (P = .0383) were predictors of death or transplant, after adjusting for baseline hepatic venous pressure gradient (HVPG), and Child-Pugh scores. After a median of 5 years, a significant difference in death or transplant, mortality, and clinical decompensation was observed in patients who had leukopenia combined with thrombocytopenia at baseline compared with patients with normal HI (P < .0001). HVPG correlated with hemoglobin and white blood cell count (hemoglobin, r = -0.35, P < .0001; white blood cell count, r = -0.31, P < .0001). CONCLUSIONS Thrombocytopenia is the most common and first abnormal HI to occur in patients with cirrhosis, followed by leukopenia and anemia. A combination of leukopenia and thrombocytopenia at baseline predicted increased morbidity and mortality.

5‐Aminosalicylate therapy is associated with higher 6‐thioguanine levels in adults and children with inflammatory bowel disease in remission on 6‐mercaptopurine or azathioprine

Background: Small uncontrolled trials have suggested that 5‐aminosalicylate (5‐ASA) medications increase 6‐thioguanine nucleotide (6‐TGn) levels in adults with Crohns disease (CD) on azathioprine (AZA) or 6‐mercaptopurine (6‐MP), presumably through the inhibition of thiopurine methyltransferase (TPMT). We tested the theory that coadministration of 5‐ASA agents with AZA/6‐MP results in higher 6‐TGn levels in a large cohort of children and adults with CD or ulcerative colitis (UC). Methods: A retrospective cohort study identified all children and adults treated for IBD with AZA/6‐MP at 2 tertiary medical centers. Patients were included if their TPMT genotype was known and 6‐TGn and 6‐methymercaptopurine (6‐MMP) levels had been obtained after 3 months of clinical remission at a stable dose of AZA/6‐MP. 6‐TGn and 6‐MMP levels were compared between patients taking and those not taking 5‐ASA medications through the use of linear regression models to identify and adjust for potentially confounding variables. Results: Of the 126 patients included, 88 were taking 5‐ASA medications. Patients on 5‐ASA agents had higher mean 6‐TGn levels after adjustment for confounding variables (&Dgr;6‐TGn, 47.6 ± 21.8 pmol/8 × 108 red blood cells; P = 0.03). CD and TPMT heterozygosity was independently associated with higher 6‐TGn levels (P = 0.01 and P = 0.03, respectively). 5‐ASA exposure was not associated with a change in 6‐MMP levels. Conclusions: We found that 5‐ASA therapy is associated with higher 6‐TGn levels in children and adults with IBD on 6‐MP/AZA. TPMT inhibition may not explain this effect because 5‐ASA exposure did not affect 6‐MMP levels. The observed association of CD with higher 6‐TGn levels is novel and needs to be verified in prospective studies.

Platelet count is not a predictor of the presence or development of gastroesophageal varices in cirrhosis.

Current guidelines recommend esophagogastroduodenoscopy (EGD) in patients with cirrhosis to screen for gastroesophageal varices (GEV). Thrombocytopenia has been proposed as a noninvasive test to predict the presence of GEV. There is no agreement regarding a specific platelet count (PLT) that can reliably predict GEV. The present longitudinal study aims to (1) further investigate the relationship between varices and PLT at the time of endoscopy, (2) investigate whether changes in PLT from the baseline over time can predict the development of GEV, and (3) investigate whether changes in PLT correlate with the hepatic venous pressure gradient (HVPG). A secondary analysis was conducted for 213 subjects with compensated cirrhosis with portal hypertension but without GEV enrolled in a randomized, placebo‐controlled, double‐blind trial of a nonselective beta‐blocker used to prevent GEV. PLTs were obtained every 3 months, and HVPG measurements and EGD were done annually. The PLTs were compared between subjects who did and did not develop GEV. In a median follow‐up of 54.9 months, 84 patients developed GEV. PLT was greater than 150,000 in 15% of patients at the development of GEV. A receiver operating curve did not show any PLT with high sensitivity or specificity for the presence of GEV. Subjects with clinically insignificant portal hypertension (HVPG < 10 mm Hg) whose PLT remained greater than 100,000 had a 2‐fold reduction in the occurrence of GEV (P = 0.0374). A significant correlation was found between HVPG and PLT at the baseline, year 1, and year 5 (P < 0.0001). Conclusion: Cross‐sectional or longitudinal evaluations of PLTs are inadequate noninvasive markers for GEV. Patients with mild portal hypertension whose PLT remains greater than 100,000 have significantly less risk of GEV. Although HVPG correlates somewhat with PLT, changes in PLT cannot be used as a surrogate for HVPG changes. (HEPATOLOGY 2008;47:153–159.)

An Assessment of the Severity of Interstitial Pancreatitis

BACKGROUND & AIMS There is limited information on the incidence of and factors associated with severe disease among patients with interstitial pancreatitis (IP). We evaluated a large cohort of patients with IP and compared data with those from patients with extrapancreatic necrosis (EXPN). METHODS We evaluated 149 consecutive patients with IP admitted over a 2.5-year period. Transferred patients were excluded. We collected data on age, Charlson comorbidity score (CCI), measures of severity on admission or within 24 hours (Acute Physiology and Chronic Health Evaluation II, bedside index for severity of acute pancreatitis scores), persistent (>48 h) systemic inflammatory response syndrome, persistent organ failure, need for intensive care unit, length of hospital stay (in days), and mortality. We also analyzed levels of severity among those with IP and EXPN. Statistical analysis was performed using SAS version 9.1 (Cary, NC). RESULTS Among the patients with IP, the median CCI score was 1, the median Acute Physiology and Chronic Health Evaluation II score was 7, and the median bedside index for severity of acute pancreatitis score was 1. In addition, the median length of hospital stay was only 4 days; only 1% had persistent organ failure and only 1% to 2% required intervention. The mortality rate of IP was 3%; it was associated significantly with comorbidity (the median CCI scores of nonsurvivors and survivors was 4 and 1, respectively, P = .003). Patients with EXPN had greater levels of disease severity, compared with patients with IP. CONCLUSIONS IP is severe in only 1% to 3% of patients; mortality of IP is associated strongly with comorbidity. EXPN is more frequently severe than IP; EXPN must be distinguished from IP in clinical studies.

Cystic Fibrosis Sputum DNA Has NETosis Characteristics and Neutrophil Extracellular Trap Release Is Regulated by Macrophage Migration-Inhibitory Factor

Neutrophils are the main proinflammatory cell type in chronically infected lungs of cystic fibrosis (CF) patients; however, they fail to effectively clear the colonizing pathogens. Here, we investigated the molecular composition of non-mucoid and mucoid Pseudomonas aeruginosa-induced neutrophil extracellular traps (NETs) in vitro and compared them to the DNA-protein complexes present in the CF sputum. The protein composition of P. aeruginosa-induced NET fragments revealed that irrespective of the inducing stimuli, NET fragments were decorated with a conserved set of proteins. The DNA-protein complexes derived from CF sputum were consistent with NETosis and shared a similar protein signature, suggesting that the majority of the extracellular DNA was NET derived. The ability of polymorphonuclear leukocytes to produce NETs in response to P. aeruginosa was driven by macrophage migration-inhibitory factor (MIF) by promoting mitogen-activated protein kinase. Analysis of 132 CF patient samples revealed that elevated MIF protein levels correlated with poorer lung function. We suggest that targeting MIF by small molecular inhibitors might reduce the presence of extracellular DNA and serve as an adjunct to the use of antimicrobial drugs that could ultimately reduce bacterial fitness in the lungs during the later stages of CF disease.

Comparative Evaluation of the Modified CT Severity Index and CT Severity Index in Assessing Severity of Acute Pancreatitis

OBJECTIVE The purpose of this study was to compare the modified CT severity index (MCTSI) with the CT severity index (CTSI) regarding assessment of severity parameters in acute pancreatitis (AP). Both CT indexes were also compared with the Acute Physiology, Age, and Chronic Health Evaluation (APACHE II) index. MATERIALS AND METHODS Of 397 consecutive cases of AP, 196 (49%) patients underwent contrast-enhanced CT (n = 175) or MRI (n = 21) within 1 week of onset of symptoms. Two radiologists independently scored both CT indexes. Severity parameters included mortality, organ failure, pancreatic infection, admission to and length of ICU stay, length of hospital stay, need for intervention, and clinical severity of pancreatitis. Discrimination analysis and kappa statistics were performed. RESULTS Although for both CT indexes a significant relationship was observed between the score and each severity parameter (p < 0.0001), no significant differences were seen between the CT indexes. Compared with the APACHE II index, both CT indexes more accurately correlated with the need for intervention (CTSI, p = 0.006; MCTSI, p = 0.01) and pancreatic infection (CTSI, p = 0.04; MCTSI, p = 0.06) and more accurately diagnosed clinically severe disease (area under the curve, 0.87; 95% CI, 0.82-0.92). Interobserver agreement was excellent for both indexes: for CTSI, 0.85 (95% CI, 0.80-0.90) and for MCTSI, 0.90 (95% CI, 0.85-0.95). CONCLUSION No significant differences were noted between the CTSI and the MCTSI in evaluating the severity of AP. Compared with APACHE II, both CT indexes more accurately diagnose clinically severe disease and better correlate with the need for intervention and pancreatic infection.