Systematic review and meta-analysis: Diagnostic performance of DNA alterations in pancreatic juice for the detection of pancreatic cancer.

BACKGROUND AND AIMS: Pancreatic cancer has a dismal prognosis. So far, imaging has been proven incapable of establishing an early enough diagnosis. Thus, biomarkers are urgently needed for early detection and improved survival. Our aim was to evaluate the pooled diagnostic performance of DNA alterations in pancreatic juice. METHODS: A systematic literature search was performed in EMBASE, MEDLINE Ovid, Cochrane CENTRAL and Web of Science for studies concerning the diagnostic performance of DNA alterations in pancreatic juice to differentiate patients with high-grade dysplasia or pancreatic cancer from controls. Study quality was assessed using QUADAS-2. The pooled prevalence, sensitivity, specificity and diagnostic odds ratio were calculated. RESULTS: Studies mostly concerned cell-free DNA mutations (32 studies: 939 cases, 1678 controls) and methylation patterns (14 studies: 579 cases, 467 controls). KRAS, TP53, CDKN2A, GNAS and SMAD4 mutations were evaluated most. Of these, TP53 had the highest diagnostic performance with a pooled sensitivity of 42% (95% CI: 31-54%), specificity of 98% (95%-CI: 92%-100%) and diagnostic odds ratio of 36 (95% CI: 9-133). Of DNA methylation patterns, hypermethylation of CDKN2A, NPTX2 and ppENK were studied most. Hypermethylation of NPTX2 performed best with a sensitivity of 39-70% and specificity of 94-100% for distinguishing pancreatic cancer from controls. CONCLUSIONS: This meta-analysis shows that, in pancreatic juice, the presence of distinct DNA mutations (TP53, SMAD4 or CDKN2A) and NPTX2 hypermethylation have a high specificity (close to 100%) for the presence of high-grade dysplasia or pancreatic cancer. However, the sensitivity of these DNA alterations is poor to moderate, yet may increase if they are combined in a panel.

Longitudinal changes of serum protein N-Glycan levels for earlier detection of pancreatic cancer in high-risk individuals.

BACKGROUND: Surveillance of individuals at risk of developing pancreatic ductal adenocarcinoma (PDAC) has the potential to improve survival, yet early detection based on solely imaging modalities is challenging. We aimed to identify changes in serum glycosylation levels over time to earlier detect PDAC in high-risk individuals. METHODS: Individuals with a hereditary predisposition to develop PDAC were followed in two surveillance programs. Those, of which at least two consecutive serum samples were available, were included. Mass spectrometry analysis was performed to determine the total N-glycome for each consecutive sample. Potentially discriminating N-glycans were selected based on our previous cross-sectional analysis and relative abundances were calculated for each glycosylation feature. RESULTS: 165 individuals ("FPC-cohort" N = 119; Leiden cohort N = 46) were included. In total, 97 (59%) individuals had a genetic predisposition (77 CDKN2A, 15 BRCA1/2, 5 STK11) and 68 (41%) a family history of PDAC without a known genetic predisposition (>10-fold increased risk of developing PDAC). From each individual, a median number of 3 serum samples (IQR 3) was collected. Ten individuals (6%) developed PDAC during 35 months of follow-up; nine (90%) of these patients carried a CDKN2A germline mutation. In PDAC cases, compared to all controls, glycosylation characteristics were increased (fucosylation, tri- and tetra-antennary structures, specific sialic linkage types), others decreased (complex-type diantennary and bisected glycans). The largest change over time was observed for tri-antennary fucosylated glycans, which were able to differentiate cases from controls with a specificity of 92%, sensitivity of 49% and accuracy of 90%. CONCLUSION: Serum N-glycan monitoring may support early detection in a pancreas surveillance program.

Gastrointestinal actions of glucagon-like peptide-1-based therapies: glycaemic control beyond the pancreas.

The gastrointestinal hormone glucagon-like peptide-1 (GLP-1) lowers postprandial glucose concentrations by regulating pancreatic islet-cell function, with stimulation of glucose-dependent insulin and suppression of glucagon secretion. In addition to endocrine pancreatic effects, mounting evidence suggests that several gastrointestinal actions of GLP-1 are at least as important for glucose-lowering. GLP-1 reduces gastric emptying rate and small bowel motility, thereby delaying glucose absorption and decreasing postprandial glucose excursions. Furthermore, it has been suggested that GLP-1 directly stimulates hepatic glucose uptake, and suppresses hepatic glucose production, thereby adding to reduction of fasting and postprandial glucose levels. GLP-1 receptor agonists, which mimic the effects of GLP-1, have been developed for the treatment of type 2 diabetes. Based on their pharmacokinetic profile, GLP-1 receptor agonists can be broadly categorized as short- or long-acting, with each having unique islet-cell and gastrointestinal effects that lower glucose levels. Short-acting agonists predominantly lower postprandial glucose excursions, by inhibiting gastric emptying and intestinal glucose uptake, with little effect on insulin secretion. By contrast, long-acting agonists mainly reduce fasting glucose levels, predominantly by increased insulin and reduced glucagon secretion, with potential additional direct inhibitory effects on hepatic glucose production. Understanding these pharmacokinetic and pharmacodynamic differences may allow personalized antihyperglycaemic therapy in type 2 diabetes. In addition, it may provide the rationale to explore treatment in patients with no or little residual ß-cell function.

Glucagon-like peptide-1 receptor agonist exenatide has no acute effect on MRI-measured exocrine pancreatic function in patients with type 2 diabetes: a randomized trial.

AIMS: To investigate the effect of infusion of the glucagon-like peptide-1 (GLP-1) receptor agonist exenatide on exocrine pancreatic function. METHODS: This was a randomized, placebo-controlled, double-blind, crossover study in 12 male patients with type 2 diabetes, treated with oral glucose-lowering agents. On two separate occasions, exenatide or placebo (saline 0.9%) were administered intravenously, in randomized order. Exocrine pancreatic function was measured using secretin-enhanced magnetic resonance cholangiopancreatography. The primary outcome measure was defined as secretin-stimulated pancreatic excretion volume. Secondary outcome measures were maximum secretion speed and the time to reach this maximum. In addition, changes in pancreatic duct (PD) diameter were measured. RESULTS: Exenatide did not change secretin-stimulated pancreatic excretion volume, as compared with placebo (mean ± standard error of the mean 142.2 ± 15.6 ml vs 142.6 ± 8.5 ml, respectively; p = 0.590). Also, exenatide did not change the maximum secretion speed (33.1 ± 1.4 vs 36.9 ± 2.2; p = 0.221), nor the time to reach this maximum (both 4 min 30 s). No differences in PD diameter were observed between the two groups. CONCLUSIONS: Infusion of exenatide did not directly influence MRI-measured exocrine pancreatic excretion in patients with type 2 diabetes. Although long-term studies are warranted, these findings suggest that potential adverse pancreatic effects of GLP-1 receptor agonists are not mediated by changes in exocrine pancreatic secretion.

Prospective assessment of the influence of pancreatic cancer resection on exocrine pancreatic function.

BACKGROUND: Exocrine insufficiency frequently develops in patients with pancreatic cancer owing to tumour ingrowth and pancreatic duct obstruction. Surgery might restore this function by removing the primary disease and restoring duct patency, but it may also have the opposite effect, as a result of resection of functional parenchyma and anatomical changes. This study evaluated the course of pancreatic function, before and after pancreatic resection. METHODS: This prospective cohort study included patients with tumours in the pancreatic region requiring pancreatic resection in a tertiary referral centre between March 2010 and August 2012. Starting before surgery, exocrine function was determined monthly by measuring faecal elastase 1 levels (normal value over 0.200 µg per g faeces). Endocrine function, steatorrhoea-related symptoms and bodyweight were also evaluated before and after surgery. Subjects were followed from diagnosis until 6 months after surgery, or until death. RESULTS: Twenty-nine patients were included, 12 with pancreatic cancer, 14 with ampullary carcinoma and three with bile duct carcinoma (median tumour size 2.6 cm). Twenty-six patients underwent pancreaticoduodenectomy and three distal pancreatectomy. Thirteen patients had exocrine insufficiency at preoperative diagnosis. After a median follow-up of 6 months, this had increased to 24 patients. Diabetes was present in seven patients at diagnosis, and developed in one additional patient within 1 month after surgery. CONCLUSION: Most patients with tumours in the pancreatic region requiring pancreatic resection either had exocrine insufficiency at diagnosis or became exocrine-insufficient soon after surgical resection.

Surgical and endoscopic treatment of pain in chronic pancreatitis: a multidisciplinary update.

Chronic pancreatitis is an inflammatory disease of the pancreas with abdominal pain as the most prominent symptom. Adequate treatment of patients with chronic pancreatitis remains a major challenge, mainly because of the lack of evidence-based treatment protocols. The primary goal of treatment is to achieve long-term pain relief, control of the complications associated with the disease, and to restore the quality of life. Currently, a conservative step-up approach is often used for the treatment of pain; progression to severe and intractable pain is considered necessary before invasive treatment is considered. Recent studies, however, suggest that surgical intervention should not be considered only as last-resort treatment, since it can mitigate disease progression, achieve excellent pain control, and preserve pancreatic function. In this review, we present a state-of-the art overview of endoscopic and surgical treatment options for patients with painful chronic pancreatitis, and elaborate on the timing of surgery.

Benchmarking patient experiences in colonoscopy using the Global Rating Scale.

INTRODUCTION: The Global Rating Scale (GRS) is a quality assurance program that was developed in England to assess patient-centered care in endoscopy. The aim of the current study was to evaluate patient experiences of colonoscopy using the GRS in order to compare different departments and to provide benchmarks. The study also evaluated factors associated with patient satisfaction. METHODS: A GRS questionnaire was used both before and after the procedure in outpatients undergoing colonoscopy. The questionnaire assessed the processes associated with the colonoscopy, from making the appointment up until discharge. Mean values and ranges of 12 endoscopy departments were calculated together with P values in order to assess heterogeneity. RESULTS: In total, 1904 pre-procedure and 1532 (80 %) post-procedure questionnaires were returned from 12 endoscopy departments. The mean time patients had to wait for their procedure was 4.3 weeks (range 3.1 - 5.8 weeks), and 54 % (range 35 - 64 %; P < 0.001) reported being given a choice of appointment dates/times. Discomfort during colonoscopy was reported by 20 % (range 8 - 40 %; P < 0.001). Recovery room privacy was satisfactory for 76 % of patients (range 66 - 90 %; P < 0.05). The majority of patients reported being sufficiently informed about what to do in case of problems after discharge (79 %, range 43 - 98 %; P < 0.001), and 85 % of individuals stated that they would be willing to repeat the colonoscopy procedure (range 72 - 92 %; P < 0.001). Factors associated with a decreased willingness to return were the burdensome bowel preparation (odds ratio [OR] = 0.25; P < 0.001), "rushing staff" attitude (OR = 0.57; P < 0.05), low acceptance of the procedure (OR = 0.42; P < 0.01), and more discomfort than expected (OR = 0.54; P < 0.05). CONCLUSION: Overall patient experiences with colonoscopy were satisfactory, but they also showed considerable variation. This study shows that use of a GRS patient questionnaire is feasible in the Dutch endoscopy setting for the assessment of patient experience. The significant variability between endoscopy units can be used to benchmark services and enable shortcomings to be identified.

[Pancreatic cystic neoplasms: a clinical dilemma]. / Neoplastische cysten van het pancreas.

Pancreatic cystic neoplasms are increasingly detected in the general population. Although most of these lesions are benign, some are (pre)malignant and require follow-up or even surgical intervention. Three cases are presented and used to discuss the clinical implications of the renewed European Guideline on pancreatic cystic neoplasms in which relative and absolute indications for resection are proposed. In the first case, a pancreatic cystic lesion was found on abdominal ultrasound in a 77-year old female patient. After endoscopic ultrasound was performed, a serous cystic neoplasm was diagnosed without need for surveillance. In a 57-year old male, an abdominal MRI was performed to further assess an incidentally found pancreatic cystic lesion. Based on the MRI, a side-branch intraductal papillary mucinous neoplasm (SB-IPMN) was diagnosed and yearly surveillance was initiated. A 61-year old male underwent a laparoscopic distal pancreatectomy because of a mixed-type IPMN (MT-IPMN). The pathological results showed an IPMN with high-grade dysplasia.

The pursuit of stability in halide perovskites: the monovalent cation and the key for surface and bulk self-healing.

We find significant differences between degradation and healing at the surface or in the bulk for each of the different APbBr3 single crystals (A = CH3NH3+, methylammonium (MA); HC(NH2)2+, formamidinium (FA); and cesium, Cs+). Using 1- and 2-photon microscopy and photobleaching we conclude that kinetics dominate the surface and thermodynamics the bulk stability. Fluorescence-lifetime imaging microscopy, as well as results from several other methods, relate the (damaged) state of the halide perovskite (HaP) after photobleaching to its modified optical and electronic properties. The A cation type strongly influences both the kinetics and the thermodynamics of recovery and degradation: FA heals best the bulk material with faster self-healing; Cs+ protects the surface best, being the least volatile of the A cations and possibly through O-passivation; MA passivates defects via methylamine from photo-dissociation, which binds to Pb2+. DFT simulations provide insight into the passivating role of MA, and also indicate the importance of the Br3- defect as well as predicts its stability. The occurrence and rate of self-healing are suggested to explain the low effective defect density in the HaPs and through this, their excellent performance. These results rationalize the use of mixed A-cation materials for optimizing both solar cell stability and overall performance of HaP-based devices, and provide a basis for designing new HaP variants.

Molecular control over Au/GaAs diodes

The use of molecules to control electron transport is an interesting possibility, not least because of the anticipated role of molecules in future electronic devices. But physical implementations using discrete molecules are neither conceptually simple nor technically straightforward (difficulties arise in connecting the molecules to the macroscopic environment). But the use of molecules in electronic devices is not limited to single molecules, molecular wires or bulk material. Here we demonstrate that molecules can control the electrical characteristics of conventional metal-semiconductor junctions, apparently without the need for electrons to be transferred onto and through the molecules. We modify diodes by adsorbing small molecules onto single crystals of n-type GaAs semiconductor. Gold contacts were deposited onto the modified surface, using a 'soft' method to avoid damaging the molecules. By using a series of multifunctional molecules whose dipole is varied systematically, we produce diodes with an effective barrier height that is tuned by the molecule's dipole moment. These barrier heights correlate well with the change in work function of the GaAs surface after molecular modification. This behaviour is consistent with that of unmodified metal-semiconductor diodes, in which the barrier height can depend on the metal's work function.

The dependence of electron transfer efficiency on the conformational order in organic monolayers.

The electron transfer through an organized organic monolayer of alkyl chains adsorbed on a silicon wafer has been studied. The silicon was used as an electrode in a three-electrode electrochemical cell, and the current versus voltage response was measured. The results show that when the chains in the monolayer are in the "all trans" configuration, the charge transfer efficiency is higher than when the chains have a "gauche" configuration. A mechanism rationalizing all the observations is suggested.

Room-Temperature, Electric Field-Induced Creation of Stable Devices in CulnSe2 Crystals.

Multiple-junction structures were formed, on a microscopic scale, at room temperature, by the application of a strong electric field across originally homogeneous crystals of the ternary chalcopyrite semiconductor CulnSe(2). After removal of the electric field, the structures were examined with electron beam-induced current microscopy and their current-voltage characteristics were measured. Bipolar transistor action was observed, indicating that sharp bulk junctions can form in this way at low ambient temperatures. The devices are stable under normal (low-voltage) operating conditions. Possible causes for this effect, including electromigration and electric field-assisted defect reactions, are suggested.

Removable fully covered self-expandable metal stents in the treatment of common bile duct strictures due to chronic pancreatitis: a case series.

The aim of this study was to test the removability of fully covered self-expandable metal stents (FCSEMS) in patients with a benign common bile duct (CBD) stricture. A FCSEMS was inserted in six patients with a CBD stricture due to chronic pancreatitis who were considered to be unfit for surgery, and stent removal was attempted after predefined intervals of 4 and 6 months. FCSEMS were successfully placed in all patients (100 % placement success) and stent extraction was accomplished in four patients (66 % removal rate), all of whom achieved stricture resolution (66 % resolution rate). In one patient a recurrent stenosis developed after 6 months (recurrence rate 25 %). Proximal stent migration occurred in two patients. In conclusion, FCSEMS removal was possible in the majority of patients and results regarding stricture dilation were promising. Nevertheless, before FCSEMS can become an acceptable treatment option for benign CBD strictures, innovative stent design modifications are necessary and removability must be ascertained.

Management of Intraductal Papillary Mucinous Neoplasms: Controversies in Guidelines and Future Perspectives.

PURPOSE OF REVIEW: Management of intraductal papillary mucinous neoplasm (IPMN) is currently based on consensus, in the absence of evidence-based guidelines. In recent years, several consensus guidelines have been published, with distinct management strategies. In this review, we will discuss these discrepancies, in order to guide treating physicians in clinical management. RECENT FINDINGS: The detection rate of pancreatic cysts has increased substantially with the expanded use of high-quality imaging techniques to up to 45%. Of these cysts, 24-82% are IPMNs, which harbour a malignant potential. Timely detection of high-risk lesions is therefore of great importance. Surgical management is based on the presence of clinical and morphological high-risk features, yet the majority of resected specimens appear to be low risk. International collaboration and incentive large-scale prospective registries of individuals undergoing cyst surveillance are needed to accumulate unbiased data and develop evidence-based guidelines. Additionally, development of non-invasive, accurate diagnostic tools (e.g. biomarkers) is needed to differentiate between neoplastic and non-neoplastic pancreatic cysts and detect malignant transformation at an early stage (i.e. high-grade dysplasia).

[Surgical drainage of the pancreatic duct in patients with chronic pancreatitis is more effective than endoscopic drainage: randomized trial]. / Chirurgische drainage van de ductus pancreaticus bij patiënten met chronische pancreatitis effectiever dan endoscopische drainage: gerandomiseerde trial.

OBJECTIVE: To compare endoscopic and surgical drainage of the pancreatic duct for ductal decompression in patients with severe pain due to chronic pancreatitis and a dilated pancreatic duct. DESIGN: Randomized clinical trial. METHOD: All symptomatic patients with chronic pancreatitis and a distal obstruction of the pancreatic duct, but without an inflammatory mass, were eligible for this study. Patients were randomized to endoscopic transampullary pancreatic duct drainage or to operative pancreaticojejunostomy. The primary end point was the average Izbicki pain score, measured during 2 years of follow-up. The secondary endpoints were pain relief at the end of follow-up, physical and mental health, morbidity, mortality, hospital stay and number of procedures performed. RESULTS: Of 118 patients who were evaluated between January 2000-October 2004 39 patients were randomized; 19 were treated endoscopically (16 of whom underwent lithotripsy) and 20 by operative pancreaticojejunostomy. During 24 months of follow-up, compared with endoscopic drainage, surgery was associated with lower Izbicki pain scores (51 versus 25; p < 0.001) and better SF-36 physical health summary scores (p = 0.003). Furthermore, at the end of follow-up, pain relief was achieved in 32% of patients randomized to endoscopic drainage and 75% of patients randomized to surgical drainage (p = 0.007). Complication rates and hospital stay were similar, but endoscopic treatment required more procedures (median 8 versus 3; p < 0.001).

Photoacoustic detection of photosynthetic activities in isolated broken chloroplasts.

Methodology and demonstration how to utilize the photoacoustic technique in photosynthesis research are presented. Photoacoustic signals were obtained from suspensions of isolated broken chloroplasts. In the presence of strong, continuous (non-modulated) background light the signals were normally larger than without the background light. The effect of the background light was saturable and was absent when non-active (e.g. heat-treated) samples were used, showing that the normal smaller signal in the absence of background light is a genuine reflection of the loss of heat due to the competing photochemistry. The effect of the background light is to close the reaction-centers and hence to inhibit the photochemical process. The percent difference of the photoacoustic signal (+/- background light) is taken as a measure of the photochemical activity ('photochemical loss'). Initial results demonstrate the wavelength dependence of the 'photochemical loss'. As expected there was a 'red-drop' decrease of the 'photochemical loss' for lambda greater than 690 nm, when the cofactor methyl viologen was present. Surprisingly, however, there was a 'red-rise' increase for lambda greater than 690 nm when no cofactor was present. These findings indicate that under the last conditions there is an unsuspected photoactivity of PS I which was not detected hitherto by the conventional techniques. The dependence on the background light intensity confirms this result. This photoactivity can be explained tentatively as a cyclic electron flow around PS I, present without any added cofactor. Initial results on the modulation frequency dependence in the presence of electron acceptors are also demonstrated.

Simulations of frequency-dependent photoacoustic magnitude signals and their implications for bacteriorhodopsin photocycle energetics.

The modulation frequency dependence of photoacoustic signals obtained from photoactive samples can provide information on the time-dependent enthalpy changes occurring during the light-induced process. The experimental requirements for this type of calorimetry, and the interpretation ot the results, are critically examined with reference to the light-driven proton pump bacteriorhodopsin. For a three-step unbranched model of the bacteriorhodopsin photocycle we derive an expression for the photoacoustic magnitude signal as a function of frequency. Simulations are performed for various values of the rate constants and energetic changes. It is shown that the net heat uptake during a low, final step postulated by some workers should be reflected in the photoacoustic magnitude frequency spectrum, giving rise to a characteristic maximum. However, this effect, which has been observed experimentally, may also be produced by a fast, strongly endothermic step occurring earlier. The precise chronology of an endothermic transition cannot be resolved unambiguously by magnitude measurements alone, although they are free from assumptions regarding difficult-to-measure phase relationships. Hence, the published photoacoustic observations showing the effect are consistent with a cyclic sequence of events in which the bacteriorhodopsin system first undergoes an increase of entropy, followed by a decrease on returning to the initial state, as well as the reverse. It is argued that the molecular disorder-order sequence is more probable.

Photoacoustics in life sciences.

Photoacoustic (PA) measurements provide, by the very nature of the PA effect, the possibility to obtain information on the optical and thermal properties of samples. In addition they can yield information on the enthalpy changes and characteristic times involved in photo-induced processes as the acoustic signal is proportional to the hear produced following the absorption of the modulated excitation. In the study of optical properties the relative insensitivity to scattered light of the PA signal makes such measurement an attractive way to measure biological samples in vivo, or, at least, without the need to isolate the absorbing compounds. The dependence of the PA signal on the thermal properties of the sample is particularly useful when heterogeneous samples are studied. As a photocalorimetric method the technique shows considerable promise in the study of photo-bioenergetics, especially photosynthesis. Only in special cases can analytical applications of the PA method compete with fluorescence measurements for detection, and with increasingly sophisticated optical transmission and reflectance techniques (for identification).. However, the PA method may find important uses in fundamental research and in applied areas such as biomedicine and agricultural biochemistry.

Simple setup for single and differential photoacoustic spectroscopy.

Simple cells are described for normal and differential measurements in photoacoustic spectroscopy. The differential cell allows for easy background signal correction and for comparison of related samples. The arrangement allows great flexibility in cell design for adaptation to special sample forms. The normal cell can be used for very small volumes, liquids as well as solids, and is constructed in such a way as to allow the possibility of Helmholtz resonance to occur over a range of frequencies. The two cells are compared in terms of background and maximal signal strength and examples of spectra obtained with each of them are given. The general spectrometer setup is outlined as well.