Practical distributed source coding with impulse-noise degraded side information at the decoder

International audienceThis paper introduces a practical method for distributed lossy compression (Wyner-Ziv quantization) with side information available only at the decoder, where the side information is equal to the signal affected by background noise and additional impulse noise. At the core of the method is an LDPC-based lossless distributed (Slepian-Wolf) source code for q-ary alphabets, which is matched to the impulse probability and allows to remove the scalar-quantized impulse noise. Applications of this method to distributed compressed sensing of signals that differ in a sparse set of locations is also discussed, as well as some differences and similarities of variable- and fixed-length coding of sparse signals

Evolving Techniques in Pancreatic Surgery

Diseases of the pancreas and periampullary region form an important clinical group of malignant and also benign diseases which still carry relatively high morbidity and mortality rates. Pancreatic ductal adenocarcinoma, in particular, is associated with very poor outcome as the number of new cases per year is just slightly higher than the number of deaths from this disease. Therefore, treatment of these conditions should always be based on both the highest level of evidence and technical expertise

Author response to: Survival after active surveillance versus upfront surgery for incidental small pancreatic neuroendocrine tumours

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Pancreatic ductal adenocarcinoma can be detected by analysis of volatile organic compounds (VOCs) in alveolar air

Background: In the last decade many studies showed that the exhaled breath of subjects suffering from several pathological conditions has a peculiar volatile organic compound (VOC) profile. The objective of the present work was to analyse the VOCs in alveolar air to build a diagnostic tool able to identify the presence of pancreatic ductal adenocarcinoma in patients with histologically confirmed disease. Methods: The concentration of 92 compounds was measured in the end-tidal breath of 65 cases and 102 controls. VOCs were measured with an ion-molecule reaction mass spectrometry. To distinguish between subjects with pancreatic adenocarcinomas and controls, an iterated Least Absolute Shrinkage and Selection Operator multivariate Logistic Regression model was elaborated. Results: The final predictive model, based on 10 VOCs, significantly and independently associated with the outcome had a sensitivity and specificity of 100 and 84% respectively, and an area under the ROC curve of 0.99. For further validation, the model was run on 50 other subjects: 24 cases and 26 controls; 23 patients with histological diagnosis of pancreatic adenocarcinomas and 25 controls were correctly identified by the model. Conclusions: Pancreatic cancer is able to alter the concentration of some molecules in the blood and hence of VOCs in the alveolar air in equilibrium. The detection and statistical rendering of alveolar VOC composition can be useful for the clinical diagnostic approach of pancreatic neoplasms with excellent sensitivity and specificity

Elevated urinary levels of urokinase-type plasminogen activator receptor (uPAR) in pancreatic ductal adenocarcinoma identify a clinically high-risk group

BACKGROUND: The urokinase plasminogen activator receptor is highly expressed and its gene is amplified in about 50% of pancreatic ductal adenocarcinomas; this last feature is associated with worse prognosis. It is unknown whether the level of its soluble form (suPAR) in urine may be a diagnostic-prognostic marker in these patients. METHODS: The urinary level of suPAR was measured in 146 patients, 94 pancreatic ductal adenocarcinoma and 52 chronic pancreatitis. Urine from 104 healthy subjects with similar age and gender distribution served as controls. suPAR levels were normalized with creatinine levels (suPAR/creatinine, ng/mg) to remove urine dilution effect. RESULTS: Urinary suPAR/creatinine values of pancreatic ductal adenocarcinoma patients were significantly higher (median 9.8; 25(th)-75(th )percentiles 5.3-20.7) than those of either healthy donors (median 0; 0-0.5) or chronic pancreatitis patients (median 2.7; 0.9-4.7). The distribution of values among cancer patients was widespread and asymmetric, 53% subjects having values beyond the 95(th )percentile of healthy donors. The values of suPAR/creatinine did not correlate with tumour stage, Ca19-9 or CEA levels. Higher values correlated with poor prognosis among non-resected patients at univariate analysis; multivariate Cox regression identified high urinary suPAR/creatinine as an independent predictor of poor survival among all cancer patients (odds ratio 2.10, p = 0.0023), together with tumour stage (stage III odds ratio 2.65, p = 0.0017; stage IV odds ratio 4.61, p < 0.0001) and female gender (odds ratio 1.85, p = 0.01). CONCLUSIONS: A high urinary suPAR/creatinine ratio represents a useful marker for the identification of a subset of patients with poorer outcome

Routes of nutrition for pancreatic fistula after pancreatoduodenectomy: a prospective snapshot study identifies the need for therapy standardization

The aim of this study is to describe the current utilization of artificial nutrition [enteral (EN) or total parenteral (TPN)] for pancreatic fistula (POPF) after pancreatoduodenectomy (PD). Prospective data of 311 patients who consecutively underwent PD at a tertiary referral center for pancreatic surgery were collected. Data included the use of EN or TPN specifically for POPF treatment, including timing, outcomes, and adverse events related to their administration. POPF occurred in 66 (21%) patients and 52 (79%) of them were treated with artificial nutrition, for a median of 36 days. Forty (76%) patients were treated with a combination of TPN and EN. The median day of artificial nutrition start was postoperative day 7, with a median drain output of 180 cc/24 h. In 33 (63%) patients, artificial nutrition was started while only a biochemical leak was ongoing. Fungal infections and catheter-related bloodstream infection occurred in 13 (28%) and 15 (33%) TPN patients, respectively; among EN patients, 19 (41%) experienced diarrhea not responsive to pancreatic enzymes and 9 (20%) needed multiple endoscopic naso-jejunal tube positioning. The majority of the patients developing POPF after PD were treated with a combination of TPN and EN, with a clinically relevant rate of adverse events related to their administration. Standardization of nutrition routes in patients developing POPF is urgently needed

Early and Sustained Elevation in Serum Pancreatic Amylase Activity: A Novel Predictor of Morbidity After Pancreatic Surgery

Objective:To characterize early postoperative serum pancreatic amylase (spAMY) trends after pancreatic resections. Summary Background Data:A postoperative spAMY elevation is a common finding but uncertainties remain about its meaning and prognostic implications. Methods:Analysis of patients who consecutively underwent pancreatectomy from 2016 to 2019. spAMY activity was assessed from postoperative day (POD) 0 to 3. Different patterns of spAMY have been identified based on the spAMY standard range (10-52 U/l). Results:Three patterns were identified: (#1) spAMY values always &lt; the lower limit of normal/within the reference range /a single increase in spAMY &gt; upper limit of normal at any POD; (#2) Sustained increase in spAMY activity on POD 0 + 1; (#3) Sustained increase in spAMY activity including POD 1 + 2. Shifting through spAMY patterns was associated with increase morbidity (21% in #1 to 68% in #3 at POD 7; log rank &lt; 0.001). Almost all severe complications (at least Clavien-Dindo &gt;= 3) occurred in patients with pattern #3 (15% vs 3% vs 5% in #1 and #2 at POD 7, P = 0.006), without difference considering &gt;3-times or &gt;the spAMY normal limit (P = 0.85). POPF (9% in #1 vs 48% in #3, P &lt; 0.001) progressively increased across patterns. Pre-operative diabetes (OR 0.19), neoadjuvant therapy (OR 0.22), pancreatic texture (OR 8.8), duct size (OR 0.78), and final histology (OR 2.2) were independent predictors of pattern #3. Conclusions:A sustained increase in spAMY activity including POD 1 + 2 (#3) represents an early postoperative predictor of overall and severe early morbidity. An early and dynamic evaluation of spAMY could crucially impact the subsequent clinical course with relevant prognostic implications

Prospective randomised pilot study of management of the pancreatic stump following distal resection

Background Numerous surgical techniques have been described in the literature for pancreatic stump management following left resection, but there is only one prospective, randomised study. A prospective randomised pilot study was designed to assess five different pancreatic stump management techniques after distal resection in an attempt to identify which was the most effective in terms of complications and ease of execution. Methods Sixty-nine consecutive patients were randomly assigned to five different treatment groups: manual suturing, suturing plus fibrin glue, suturing plus polypropylene mesh, pancreaticojejunostomy and suturing with a stapler. All presented a soft residual pancreas. Results The overall incidence of pancreatic fistula was 19%, ranging from 7% to 33% in the different treatment groups. None of the techniques Significantly reduced the incidence of postoperative complications. Discussion On weighing the complications observed against ease and speed of execution, the construction of a pancreaticojejunostomy and closure of the stump with a mechanical stapler may be regarded as the procedures to be tested in future

Methylation Dynamics of RASSF1A and Its Impact on Cancer

5-methyl cytosine (5mC) is a key epigenetic mark entwined with gene expression and the specification of cellular phenotypes. Its distribution around gene promoters sets a barrier for transcriptional enhancers or inhibitor proteins binding to their target sequences. As a result, an additional level of regulation is added to the signals that organize the access to the chromatin and its structural components. The tumor suppressor gene RASSF1A is a microtubule-associated and multitasking scaffold protein communicating with the RAS pathway, estrogen receptor signaling, and Hippo pathway. RASSF1A action stimulates mitotic arrest, DNA repair and apoptosis, and controls the cell cycle and cell migration. De novo methylation of the RASSF1A promoter has received much attention due to its increased frequency in most cancer types. RASSF1A methylation is preceded by histones modifications and could represent an early molecular event in cell transformation. Accordingly, RASSF1A methylation is proposed as an epigenetic candidate marker in many cancer types, even though an inverse correlation of methylation and expression remains to be fully ascertained. Some findings indicate that the epigenetic abrogation of RASSF1A can promote the alternative expression of the putative oncogenic isoform RASSF1C. Understanding the complexity and significance of RASSF1A methylation is instrumental for a more accurate determination of its biological and clinical role. The review covers the molecular events implicated in RASSF1A methylation and gene silencing and provides a deeper view into the significance of the RASSF1A methylation patterns in a number of gastrointestinal cancer types