Visualization of the leakage of pancreatic juice using a chymotrypsin-activated fluorescent probe

Molecular docking studies of isolated marine natural products against α-chymotrypsin

The α-chymotrypsin is widely present in the digestive system of prokaryotes and eukaryotes that helps in the digestion by the hydrolysis of the peptide bond. It is serine protease enzyme (E.C. 3.4.21.1) and involves in many biological processes as well as in pancreatic disorders. In the previous study, marine red alga namely Jolyna laminariodes was used for the isolation of succinylanthranilic acid ester (2). Further, analogues were synthesised from anthranilic acid by using succinic anhydride, maleic anhydride and glutaric anhydride into corresponding dicarboxylic acids and further into acid ester including succinylanthranilic acid (1), succinylanthranilic acid ester (2), maleinylanthranilic acid (3), maleinylanthranilic acid ester (4), glutarnylanthranilic acid (5) and glutarnylanthranilic acid ester (6). For all natural products analogues percent inhibition against α-chymotrypsin have been calculated. In this study, molecular docking is used to estimate the binding energy of natural product analogues against α-chymotrypsin enzyme. The docking energies are in good agreement with experimental findings.

Advancement of fluorescent aminopeptidase probes for rapid cancer detection-current uses and neurosurgical applications

Surgical resection is considered for most brain tumors to obtain tissue diagnosis and to eradicate or debulk the tumor. Glioma, the most common primary malignant brain tumor, generally has a poor prognosis despite the multidisciplinary treatments with radical resection and chemoradiotherapy. Surgical resection of glioma is often complicated by the obscure border between the tumor and the adjacent brain tissues and by the tumor's infiltration into the eloquent brain. 5-aminolevulinic acid is frequently used for tumor visualization, as it exhibits high fluorescence in high-grade glioma. Here, we provide an overview of the fluorescent probes currently used for brain tumors, as well as those under development for other cancers, including HMRG-based probes, 2MeSiR-based probes, and other aminopeptidase probes. We describe our recently developed HMRG-based probes in brain tumors, such as PR-HMRG, combined with the existing diagnosis approach. These probes are remarkably effective for cancer cell recognition. Thus, they can be potentially integrated into surgical treatment for intraoperative detection of cancers.

Advances and Perspectives of Responsive Probes for Measuring γ-Glutamyl Transpeptidase

Gamma-glutamyltransferase (GGT) is a plasma-membrane-bound enzyme that is involved in the γ-glutamyl cycle, like metabolism of glutathione (GSH). This enzyme plays an important role in protecting cells from oxidative stress, thus being tested as a key biomarker for several medical conditions, such as liver injury, carcinogenesis, and tumor progression. For measuring GGT activity, a number of bioanalytical methods have emerged, such as chromatography, colorimetric, electrochemical, and luminescence analyses. Among these approaches, probes that can specifically respond to GGT are contributing significantly to measuring its activity in vitro and in vivo. This review thus aims to highlight the recent advances in the development of responsive probes for GGT measurement and their practical applications. Responsive probes for fluorescence analysis, including "off-on", near-infrared (NIR), two-photon, and ratiometric fluorescence response probes, are initially summarized, followed by discussing the advances in the development of other probes, such as bioluminescence, chemiluminescence, photoacoustic, Raman, magnetic resonance imaging (MRI), and positron emission tomography (PET). The practical applications of the responsive probes in cancer diagnosis and treatment monitoring and GGT inhibitor screening are then highlighted. Based on this information, the advantages, challenges, and prospects of responsive probe technology for GGT measurement are analyzed.

Evaluation of pancreatic chymotrypsin activity for on-site prediction of clinically relevant postoperative pancreatic fistula

OBJECTIVES

Although the risk of complications due to postoperative pancreatic fistula (POPF) have been evaluated based on the amylase level in drained ascitic fluid, this method has much room for improvement regarding diagnostic accuracy and facility of the measurement. This study aimed to investigate the clinical value of measuring pancreatic chymotrypsin activity for rapid and accurate prediction of POPF after pancreaticoduodenectomy.

METHODS

In 52 consecutive patients undergoing pancreaticoduodenectomy, the chymotrypsin activity in pancreatic juice was measured by calculating the increase in fluorescence intensity during the first 5 min after activation with an enzyme-activatable fluorophore. The predictive value for clinically relevant POPF (CR-POPF) was compared between this technique and the conventional method based on the amylase level.

RESULTS

According to receiver operating characteristic analyses, pancreatic chymotrypsin activity on postoperative day (POD) 3 measured with a multiplate reader had the highest predictive value for CR-POPF (area under the curve [AUC], 0.752; P < 0.001), yielding 77.8 % sensitivity and 68.8 % specificity. The AUC and sensitivity/specificity of the amylase level in ascitic fluid on POD 3 were 0.695 (P = 0.053) and 77.8 %/41.2 %, respectively. Multivariable analysis identified high pancreatic chymotrypsin activity on POD 3 as an independent risk factor for CR-POPF. Measurement of pancreatic chymotrypsin activity with a prototype portable fluorescence photometer could significantly predict CR-POPF (AUC, 0.731; P = 0.010).

CONCLUSION

Measurement of pancreatic chymotrypsin activity enabled accurate and rapid prediction of CR-POPF after pancreaticoduodenectomy. This can help surgeons to implement appropriate drain management at the patient's bedside without delay.

A protease activity-based machine-learning approach as a complementary tool for conventional diagnosis of diarrhea-predominant irritable bowel syndrome

Irritable bowel syndrome (IBS) has no clinically accepted biomarkers even though it affects a large number of individuals worldwide. To address this lack of understanding, we evaluated peptidase activity in fecal samples from 35 patients with diarrheal IBS without symptom exacerbation (IBS-n) and 35 healthy subjects using a library of 384 fluorescent enzymatic substrate probes. IBS-n patients had high trypsin-like peptidase activity for cleavage of C-terminal lysine and arginine residues and low elastase-like activity for cleavage of C-terminal serine and glycine residues. These fluorescent probe library data, together with diagnostic machine-learning techniques, were able to accurately predict IBS-n. This approach can be used to diagnose diseases where no clinically accepted biomarkers exist, in which fecal enzyme activity is altered and also suggests that the development of new therapies targeting enzyme activities is possible.

Rational Design of Esterase-Insensitive Fluorogenic Probes for In Vivo Imaging

Small-molecule fluorogenic probes are indispensable tools for performing research in biomedical fields and chemical biology. Although numerous cleavable fluorogenic probes have been developed to investigate various bioanalytes, few of them meet the baseline requirements for in vivo biosensing for disease diagnosis due to their insufficient specificity resulted from the remarkable esterase interferences. To address this critical issue, we developed a general approach called fragment-based fluorogenic probe discovery (FBFPD) to design esterase-insensitive probes for in vitro and in vivo applications. With the designed esterase-insensitive fluorogenic probe, we successfully achieved light-up in vivo imaging and quantitative analysis of cysteine. This strategy was further extended to design highly specific fluorogenic probes for other representative targets, sulfites, and chymotrypsin. The present study expands the bioanalytical toolboxes available and offers a promising platform to develop esterase-insensitive cleavable fluorogenic probes for in vivo biosensing and bioimaging for the early diagnosis of diseases.

De Novo Design of a Highly Selective Nonpeptide Fluorogenic Probe for Chymotrypsin Activity Sensing in a Living System

Chymotrypsin, an extensively known proteolytic enzyme, plays a substantial role in maintaining physiological functions, including protein digestion, immune response, and tissue repair. To date, intense attention has been focused on the invention of efficient and sensitive chemical tools for chymotrypsin activity measurement. Among them, the "nonpeptide"-based chymotrypsin probe design strategy utilizing the esterase activity of chymotrypsin has been well-developed due to its low cost and high atom-economy feature. However, the ester-bond-based nature of these probes make them possibly vulnerable to esterases and active chemicals. These defects strictly restricted the application of the previously reported probes, especially for imaging in living systems. Therefore, to acquire fluorogenic probes with sufficient stability and specificity for chymotrypsin sensing in a complicated biological environment, a more stable skeleton for nonpeptide-based chymotrypsin probe construction is urgently needed. Herein, a novel nonpeptide-based fluorogenic probe for specific chymotrypsin activity sensing was designed and synthesized by the substitution of an ester-based linker with a heptafluorobutylamide moiety. The acquired probe, named TMBIHF, showed high selectivity toward various enzymes and reactive chemicals, while it retained high sensitivity and catalytic efficiency toward chymotrypsin. Moreover, TMBIHF was successfully applied for monitoring chymotrypsin activity and pancreas development in live zebrafish, specific sensing of exogenous and endogenous chymotrypsin in nude mice, and visualizing chymotrypsin-like activity-dependent cellular apoptosis, thus providing an alternative and reliable way for chymotrypsin-targeted biosensor or prodrug construction.

Intraoperative visualisation of pancreatic leakage (ViP): study protocol for an IDEAL Stage I Post Market Clinical Study

INTRODUCTION

Pancreatic resections are an important field of surgery worldwide to treat a variety of benign and malignant diseases. Postoperative pancreatic fistula (POPF) remains a frequent and critical complication after partial pancreatectomy and affects up to 50% of patients. POPF increases mortality, prolongs the postoperative hospital stay and is associated with a significant economic burden. Despite various scientific approaches and clinical strategies, it has not yet been possible to develop an effective preventive tool. The SmartPAN indicator is the first surgery-ready medical device for direct visualisation of pancreatic leakage already during the operation. Applied to the surface of pancreatic tissue, it detects sites of biochemical leak via colour reaction, thereby guiding effective closure and potentially mitigating POPF development.

METHODS AND ANALYSIS

The ViP trial is a prospective single-arm, single-centre first in human study to collect data on usability and confirm safety of SmartPAN. A total of 35 patients with planned partial pancreatectomy will be included in the trial with a follow-up of 30 days after the index surgery. Usability endpoints such as adherence to protocol and evaluation by the operating surgeon as well as safety parameters including major intraoperative and postoperative complications, especially POPF development, will be analysed.

ETHICS AND DISSEMINATION

Following the IDEAL-D (Idea, Development, Exploration, Assessment, and Long term study of Device development and surgical innovation) framework of medical device development preclinical in vitro, porcine in vivo, and human ex vivo studies have proven feasibility, efficacy and safety of SmartPAN. After market approval, the ViP trial is the IDEAL Stage I trial to investigate SmartPAN in a clinical setting. The study has been approved by the local ethics committee as the device is used exclusively within its intended purpose. Results will be published in a peer-reviewed journal. The study will provide a basis for a future randomised controlled interventional trial to confirm clinical efficacy of SmartPAN.

TRIAL REGISTRATION NUMBER

German Clinical Trial Register DRKS00027559, registered on 4 March 2022.

Closure and anastomosis of the pancreas using a four-needle three-loop suture device

Pancreatic juice can leak not only from the main pancreatic duct but also from unclosed ductal branches appearing on the pancreatic stump. We have developed a suture device consisting of three loops of suture attached to four small-curvature needles with the aim to maximize the area of pancreatic parenchyma to be ligated and reduce the number of punctures made on the pancreas during pancreatic closure or anastomosis. In pancreatojejunostomy, the dorsal wall of the jejunum and then the pancreatic parenchyma are sutured using the four needles. Following duct-to-mucosa anastomosis, the ventral jejunal wall is sutured, and the three threads are finally tied sequentially to complete the reconstruction following the Blumgart method. In distal pancreatectomy, the pancreatic stump is sutured from the dorsal aspect sequentially using the four needles, before or after the pancreatic transection. The three threads are then respectively tied on the ventral surface of the pancreas. This device was used in six pancreatoduodenectomies (including two minimally invasive procedures) and five distal pancreatectomies. A postoperative pancreatic fistula requiring additional drainage or repositioning of abdominal drains developed in two patients. No adverse events associated with this device were encountered. The four-needle three-loop suture device can be an alternative to conventional staplers or sutures for closure and anastomosis of the pancreatic stump.

Development of Small-Molecule Fluorescent Probes Targeting Enzymes

As biological catalysts, enzymes are vital in controlling numerous metabolic reactions. The regulation of enzymes in living cells and the amount present are indicators of the metabolic status of cell, whether in normal condition or disease. The small-molecule fluorescent probes are of interest because of their high sensitivity and selectivity, as well as their potential for automated detection. Fluorescent probes have been useful in targeting particular enzymes of interest such as proteases and caspases. However, it is difficult to develop an ideal fluorescent probe for versatile purposes. In the future, the design and synthesis of enzyme-targeting fluorescent probes will focus more on improving the selectivity, sensitivity, penetration ability and to couple the fluorescent probes with other available imaging molecules/technologies.

SmartPAN: in vitro and in vivo proof-of-safety assessments for an intra-operative predictive indicator of postoperative pancreatic fistula

Pancreatic surgery is complicated by untreated fluid leakage, but no tenable techniques exist to detect and close leakage sites during surgery. A novel hydrogel called SmartPAN has been developed to meet this need and is here assessed for safety before trials on human patients. Firstly, resazurin assays were used to test the cytotoxic effects of SmartPAN's active bromothymol blue (BTB) indicator and its solution of phosphate-buffered saline (PBS) on normal (HPDE: Human Pancreatic Duct Epithelial) or carcinomic (FAMPAC) human pancreatic cells. Cells incubated with BTB showed no significant reduction in cell viability below threshold safety levels. However, PBS had a mild cytotoxic effect on FAMPAC cells. Secondly, SmartPAN's pathological effects were evaluated in vivo by applying 4 mL SmartPAN to a porcine (Sus scrofa domesticus) model of pancreatic resection. There were no significant differences in macroscopic and microscopic pathologies between pigs treated with SmartPAN or saline. Thirdly, measurements using HPLC-MS/MS demonstrate that BTB does not cross into the bloodstream and was eliminated from the body within two days of surgery. Overall, SmartPAN appears safe in the short-term and ready for first-in-human trials because its components are either biocompatible or quickly neutralized by dilution and drainage.

Activatable endoplasmic reticulum-targeted NIR fluorescent probe with a large Stokes shift for detecting and imaging chymotrypsin

In this work, the first endoplasmic reticulum-targeted near-infrared fluorescent probe, ISO-Chy, with a large Stokes shift is reported by introducing a recognition group of 4-bromobutyl for chymotrypsin detection.

A non-peptide probe for detecting chymotrypsin activity based on protection-deprotection strategy in living systems

Chymotrypsin (CHT) plays a vital role in the metabolism of organisms and affects cell proliferation and apoptosis. Abnormal levels of CHT will lead to a variety of diseases, such as inflammatory arthritis, diabetes, pharyngitis, indigestion, and pancreatic cancer. Therefore, it is significant to design an effective method for the detection of CHT in living systems. Here, we synthesized a specific deep-red non-peptide probe DT by effectively combining isophorone and p-hydroxybenzaldehyde for the detection of CHT using 3-phenylpropionate chloride as the recognition group based on a protection-deprotection strategy. The DT probe exhibited an emission range of 525-700 nm and showed excellent photostability, high sensitivity (LOD = 0.071 U mL^-1), and selectivity for CHT detection. The cellular experiments demonstrated that DT could sensitively recognize CHT activity in three cell lines and the content of CHT was much higher in P815 cells than in MCF-7 and 3T3 cells. Also, DT was successfully used to visualize the endogenous CHT in zebrafish. Notably, the DT probe provided an intuitive way to visualize endogenous CHT in mouse pancreas for the first time, demonstrating the potential for application in the future clinical diagnosis of pancreatic diseases. Therefore, the small-molecule probe DT is expected to be a useful molecular tool for CHT-related disease diagnosis and drug discovery.

Applying an intraoperative predictive indicator for postoperative pancreatic fistula: randomized preclinical trial

Leaking pancreatic fluid can contribute to postoperative pancreatic fistula (POPF), which can complicate pancreatic surgery. Surgeons lack reliable tools to identify pancreatic leaks, so a novel hydrogel indicator called SmartPAN was developed for intraoperative application. In this preclinical efficacy assessment study, SmartPAN was capable of detecting sites associated with biochemical leak and POPF-related symptoms, thereby guiding effective closure. Thus, SmartPAN may help to reduce POPF development in upcoming clinical trials.

Review on the recent progress in the development of fluorescent probes targeting enzymes

Enzymes are very important for biological processes in a living being, performing similar or multiple tasks in and out of cells, tissues and other organisms at a particular location. The abnormal activity of particular enzyme usually caused serious diseases such as Alzheimer's disease, Parkinson's disease, cancers, diabetes, cardiovascular diseases, arthritis etc. Hence, nondestructive and real-time visualization for certain enzyme is very important for understanding the biological issues, as well as the drug administration and drug metabolism. Fluorescent cellular probe-based enzyme detectionin vitroandin vivohas become broad interest for human disease diagnostics and therapeutics. This review highlights the recent findings and designs of highly sensitive and selective fluorescent cellular probes targeting enzymes for quantitative analysis and bioimaging.

The Effect of a Peptide Substrate Containing an Unnatural Branched Amino Acid on Chymotrypsin Activity

7-Amino-4-methylcoumarin (AMC) is a low molecular weight fluorescent probe that can be attached to a peptide to enable the detection of specific proteases, such as chymotrypsin, expressed in certain diseases. Because this detection depends on the specificity of the protease toward the peptidyl AMC, the development of specific substrates is required. To investigate the specificity of chymotrypsin, peptidyl AMC compounds incorporating four different amino acid residues were prepared by liquid-phase synthesis. Two unnatural amino acids, 2-amino-4-ethylhexanoic acid (AEH) and cyclohexylalanine (Cha), were used to investigate the substrate specificity as these amino acids have structures different from natural amino acids. AEH was synthesized using diethyl acetamidemalonate as a starting material. The substrate containing Cha had high hydrophobicity and showed a high reaction velocity with chymotrypsin. Although the AEH substrate with a branched side chain had high hydrophobicity, it showed a low reaction velocity. The substrate containing the aromatic amino acid phenylalanine was less hydrophobic than the Cha and AEH substrates, but chymotrypsin showed the highest specificity for this compound. These results demonstrated that the substrate specificity of chymotrypsin is not only affected by the hydrophobicity and aromaticity, but also by the structural expanse of amino acid residues in the substrate.

A novel reaction force-fluorescence measurement system for evaluating pancreatic juice leakage from an excised swine pancreas during distal pancreatectomy

BACKGROUND

Resection using a stapler is a popular approach to distal pancreatectomy. However, the resulting leakage of pancreatic juice represents a serious problem. We have developed a force-fluorescence measurement as a first step towards the quantitative evaluation of pancreatic leakage due to tissue tearing under compression.

METHODS

The system comprises a testing machine with an indenter, similar in size to a stapler, which controls compression speed and measures reaction force, and a fluorescence measurement system to measure pancreatic juice leakage. Pancreatic juice leakage is measured as the maximum value of the increasing rate of fluorescence intensity (max value). Ten excised swine pancreases were compressed at a speed of 500, 100, and 10 mm/min until their thicknesses became 2 mm.

RESULTS

A strong positive correlation (0.804) was observed between the increase in max value before and after compression and the amount of reaction force drop due to tissue destruction. No pancreatic juice leakage was observed when compressed slowly (10 mm/min).

CONCLUSIONS

We have successfully developed a novel force-fluorescence measurement system that can detect and quantify pancreatic juice leakage caused by tissue tearing. This system can determine the optimal compression conditions for preventing pancreatic juice leakage.

On-Site Monitoring of Postoperative Bile Leakage Using Bilirubin-Inducible Fluorescent Protein

Background

Bile leakage is the most common postoperative complication associated with hepatobiliary and pancreatic surgery. Until now, however, a rapid, accurate diagnostic method for monitoring intraoperative and postoperative bile leakage had not been established.

Method

Bilirubin levels in drained abdominal fluids collected from 23 patients who had undergone hepatectomy (n = 22) or liver transplantation (n = 1) were measured using a microplate reader with excitation/emission wavelengths of 497/527 nm after applying 5 µM of UnaG to the samples. UnaG was also sprayed directly on hepatic raw surfaces in swine hepatectomy models to identify bile leaks by fluorescence imaging.

Results

The bilirubin levels measured by UnaG fluorescence imaging showed favorable correlations with the results of the conventional light-absorptiometric methods (indirect bilirubin: rs = 0.939, p < 0.001; direct bilirubin: rs = 0.929, p < 0.001). Approximate time required for bilirubin measurements with UnaG was 15 min, whereas it took about 40 min with the conventional method at a hospital laboratory. Following administration of UnaG on hepatic surfaces, the fluorescence imaging identified bile leaks not only on the resected specimens but also in the abdominal cavity of the swine hepatectomy models.

Conclusion

Fluorescence imaging techniques using UnaG may enable real-time identification of bile leaks during hepatectomy and on-site rapid diagnosis of bile leaks after surgery.

Electronic supplementary material

The online version of this article (10.1007/s00268-020-05774-x) contains supplementary material, which is available to authorized users.

Förster resonance energy transfer (FRET)-Labeled nanoprobe enables real-time diagnosis of pancreatic juice activation due to postoperative pancreatic fistula

OBJECTIVES

Postoperative pancreatic fistula (POPF) subsequent to pancreatectomy often causes activation of pancreatic juice, resulting in serious complications. In POPF, the types of pancreatic juices found are active and inactive, and the identification of these two types of pancreatic juice greatly contributes to the development of postoperative management after pancreatectomy. This study reports favorable results of the clinical application of the Förster resonance energy transfer (FRET) nanoprobe that was independently developed to distinguish between the active and inactive types of pancreatic juice.

METHODS

The FRET nanoprobe developed was a nanoprotein capsule. It exuded a red color when the capsule structure was maintained. When activated protease in the pancreatic juice acts on it, the capsules are reduced quantitatively and FRET is abolished, resulting in a change in color from red to green. Pancreatic juice activation can be measured by the FRET signal. A total of 117 drainage fluid samples from 16 postpancreatoduodenectomy cases were obtained and evaluated.

RESULTS

The diagnosis of pancreatic juice activation was possible using the FRET signal with a cut-off value of 1.6. Pancreatic juice activation was not associated with drainage fluid amylase (AMY) levels. The results demonstrated that pancreatic juice was activated when drainage fluid was infected.

CONCLUSION

The use of a FRET nanoprobe enabled real-time detection of the presence or absence of pancreatic juice activation in pancreatic fistula after pancreatic surgery. There was an adequate correlation between infection and pancreatic juice activation regardless of drain AMY levels.

SmartPAN: A novel polysaccharide-microsphere-based surgical indicator of pancreatic leakage

Postoperative pancreatic fistula is a major surgical complication that can follow pancreatic resection. Postoperative pancreatic fistula can develop as a consequence of leaking pancreatic fluid, which calls for an intraoperative indicator of leakage. But suitable indicators of pancreatic leakage have yet to be found. This study details the evidence-based development and early efficacy assessments of a novel pancreatic leakage indicator (SmartPAN), following the IDEAL framework of product development. We developed 41 SmartPAN prototypes by combining indicators of pancreatic fluid with a polysaccharide-microsphere matrix. The prototypes were assessed in vitro using porcine ( Sus scrofa domesticus) pancreatic tissue and ex vivo with human pancreatic fluid. From these initial tests, we chose a hydrogel-based compound that uses the pH indicator bromothymol blue to detect alkali pancreatic fluid. This prototype was then assessed in vivo for usability, effectiveness and reliability using a porcine model. Treatment groups were defined by SmartPAN-reaction at initial pancreatic resection: indicator-positive or negative. Indicator-positive individuals randomly received either targeted closure of leakage sites or no further closure. We assessed SmartPAN’s reliability and effectiveness by monitoring abdominal drainage for amylase and with relaparotomy after 48 h. SmartPAN responses were consistent between both surgical procedures and conformed to amylase measurements. In conclusion, we have developed the first surgery-ready indicator for predicting the occurrence of pancreatic leakage during pancreatic resection. SmartPAN can enable targeted prophylactic closure in a simple and reliable way, and thus may reduce the impact of postoperative pancreatic fistula by guiding peri- and post-operative management.

Has the pancreatic fistula already occurred in the operation? An intraoperative predictive factor of clinical relevant-postoperative pancreatic fistula after the distal pancreatectomy

Purpose

The aim of this study was to assess the predictive effect of intraoperative amylase value from pancreatic remnant on the development of clinical relevant-postoperative pancreatic fistula after distal pancreatectomy.

Methods

Patients undergoing distal pancreatectomy between June 2017 and October 2018 were studied retrospectively. The intraoperative amylase value was measured followed by drain fluid for amylase on postoperative day 3. The analysis of clinical relevant-postoperative pancreatic fistula predictors was carried out using the logistic regression. The receiver operating characteristic analysis was performed to evaluate the discriminative capacity of intraoperative amylase value as a predictive risk factor.

Results

The study population consisted of 40 patients. The clinical relevant-postoperative pancreatic fistula occurred in 13 patients, no grade C pancreatic fistula (PF). The intraoperative amylase value correlated significantly with clinical relevant-postoperative pancreatic fistula. An intraoperative amylase value > 3089 U/L was proposed as the cut-off level to predict clinical relevant-postoperative pancreatic fistula by the receiver operating characteristic curve. The sensitivity, specificity and accuracy of this level were respectively 84.6%, 88.9% and 88.5%. The multivariate logistic regression analysis revealed that intraoperative amylase value and suture closure for the pancreatic stump were the significant predictive risk factors for the clinical relevant-postoperative pancreatic fistula.

Conclusion

The intraoperative amylase value can be early and easily measured as a predictive risk factor, which seems useful for postoperative management of clinical relevant-postoperative pancreatic fistula after distal pancreatectomy. While, the stapler closure might be a feasible way for the pancreatic transection during the operation.

A non-peptide NIR fluorescent probe for detection of chymotrypsin and its imaging application

A novel non-peptide NIR fluorescent probe for the detection of chymotrypsin and its imaging application.

Pancreatic Compression during Lymph Node Dissection in Laparoscopic Gastrectomy: Possible Cause of Pancreatic Leakage

Purpose

Postoperative pancreatic fistula is a serious and fatal complication of gastrectomy for gastric cancer. Blunt trauma to the parenchyma of the pancreas can result from an assistant's forceps compressing and retracting the pancreas, which in turn may result in pancreatic juice leakage. However, no published studies have focused on blunt trauma to the pancreas during laparoscopic surgery. Our aim was to investigate the relationship between compression of the pancreas and pancreatic juice leakage in a swine model.

Materials and Methods

Three female pigs were used in this study. The pancreas was gently compressed dorsally for 15 minutes laparoscopically with gauze grasped with forceps. Pancreatic juice leakage was visualized by fluorescence imaging after topical administration of chymotrypsin-activatable fluorophore in real time. Amylase concentrations in ascites collected at specified times was measured. In addition, pancreatic tissue was fixed with formalin, and the histology of the compressed sites was evaluated.

Results

Fluorescence imaging enabled visualization of pancreatic juice leaking into ascites around the pancreas. Median concentrations of pancreatic amylase in ascites increased from 46 U/L preoperatively to 12,509 U/L 4 hours after compression. Histological examination of tissues obtained 4 hours after compression revealed necrotic pancreatic acinar cells extending from the surface to deep within the pancreas and infiltration of inflammatory cells.

Conclusions

Pancreatic compression by the assistant's forceps can contribute to pancreatic juice leakage. These findings will help to improve the procedure for lymph node dissection around the pancreas during laparoscopic gastrectomy.

Intra-Operative Amylase Concentration in Peri-Pancreatic Fluid Predicts Pancreatic Fistula After Distal Pancreatectomy

Post-operative pancreatic fistula (POPF) is a potentially severe complication following distal pancreatectomy. The aim of this study was to assess the predictive value of intra-operative amylase concentration (IOAC) in peri-pancreatic fluid after distal pancreatectomy for the diagnosis of POPF. Consecutive patients who underwent a distal pancreatectomy between November 2014 and September 2016 were included in the analysis. IOAC was measured, followed by drain fluid analysis for amylase on post-operative days (PODs) 1, 3, and 5. Receiver operator characteristic (ROC) analysis was performed to evaluate the discriminative capacity of IOAC as a predictor of POPF. IOAC was measured after distal pancreatectomy in 26 patients. The IOAC correlated significantly with (i) PODs 1, 3, and 5 drain amylase (p < 0.01); (ii) the development of POPF (p < 0.01); and (iii) the Clavien-Dindo grade of surgical complications (p = 0.02). Eighty-three percent of patients with an IOAC > 1000 experienced a post-operative complication (OR 18.3, 95% CI 2.51-103, p < 0.01). ROC curve analysis confirmed the predictive relationship of IOAC and POPF as an excellent test with an area under the curve of 0.92 (95% CI 0.81-0.99, p < 0.01). Measurement of IOAC allows early and accurate categorization of patients at risk for POPF in distal pancreatectomy.

Advantages and Disadvantages of Prophylactic Abdominal Drainage in Distal Pancreatectomy

BACKGROUND

A method to completely prevent postoperative pancreatic fistula (PF) in distal pancreatectomy (DP) is lacking. Hence, prophylactic abdominal drains could be used to prevent PF from developing into life-threatening complications.

METHODS

In 152 consecutive patients undergoing DP, three drains were placed routinely toward the pancreatic stump, supra-pancreatic space, and left subphrenic space. Abdominal drains were removed after surgery gradually based on amylase levels and positivity for bacterial infection in abdominal fluids.

RESULTS

Postoperative symptomatic PF occurred in 57 of 152 patients (37.5 %). Prevalence of severe postoperative complications (Clavien-Dindo grade ≥ IIIa) was 16 %, with surgery-associated mortality observed in one patient (0.7 %). Prevalence of infection in drained abdominal fluids increased gradually and was >10 % on postoperative day (POD)-7. Severe postoperative complications led to longer postoperative hospital stays and higher treatment costs. Multivariate analyses revealed that a body mass index ≥ 25 kg/m(2), serum albumin level ≤ 3.8 g/dL, and white blood cell count at POD-3 ≥ 15,000/μL were independent predictors for development of severe postoperative complications.

CONCLUSION

Use of prophylactic abdominal drains in DP seems to be effective for preventing PF from developing into fatal complications. However, definitive criteria should be established for enhancing safety and cost efficiency of DP through selective use and early removal of prophylactic drains.

Novel Bio-imaging Tools Based on the Precise Design of Functional Fluorescence Probes

Fluorescence imaging is one of the most powerful techniques currently available for continuous observation of intracellular processes in living cells and tissues, and so it would be useful to have a large toolset of fluorescence probes suitable for visualizing bioactive molecules or biological phenomena. However, design strategies for small molecule-based fluorescence probes have been limited. Therefore, we are interested in establishing novel rational design strategies for developing functional fluorescence probes. For this purpose, we have focused on the intramolecular spirocyclization reaction of rhodamine derivatives bearing intramolecular nucleophiles as a fluorescence switching mechanism; these derivatives exist in thermal equilibrium between a fluorescent open form and a non-fluorescent spirocyclic form. By utilizing this reaction, we have successfully developed various kinds of fluorescence probes. This review first describes the design of our recently developed fluorescence probes, and then introduces their applications for visualizing the activities of reporter enzymes, for in vivo cancer imaging, and for super-resolution imaging. We believe these probes can serve as key tools to provide unprecedented insights into a wide range of biological phenomena.

Risk factors and preventive strategies for post-operative pancreatic fistula after pancreatic surgery: a comprehensive review

BACKGROUND

Pancreas surgery has developed into a fairly safe procedure in terms of mortality, but is still hampered by considerable morbidity. Among the most frequent and dreaded complications are the development of a post-operative pancreatic fistula (POPF). The prediction and prevention of POPF remains an area of debate with several questions yet to be firmly addressed with solid answers.

METHODS

A systematic review of systematic reviews/meta-analyses and randomized trials in the English literature (PubMed/MEDLINE, Cochrane library, EMBASE) covering January 2005 to December 2015 on risk factors and preventive strategies for POPF.

RESULTS

A total of 49 systematic reviews and meta-analyses over the past decade discussed patient, surgeon, pancreatic disease and intraoperative related factors of POPF. Non-modifiable factors (age, BMI, comorbidity) and pathology (histotype, gland texture, duct size) that indicates surgery are associated with POPF risk. Consideration of anastomotic technique and use of somatostatin-analogs may slightly modify the risk of fistula. Sealant products appear to have no effect. Perioperative bleeding and transfusion enhance risk, but is modifiable by focus on technique and training. Drains may not prevent fistulae, but may help in early detection. Early drain-amylase may aid in detection. Predictive scores lack uniform validation, but may have a role in patient information if reliable pre-operative risk factors can be obtained.

CONCLUSIONS

Development of POPF occurs through several demonstrated risk factors. Anastomotic technique and use of somatostatin-analogs may slightly decrease risk. Drains may aid in early detection of leaks, but do not prevent POPF.

Förster Resonance Energy Transfer-Based Self-Assembled Nanoprobe for Rapid and Sensitive Detection of Postoperative Pancreatic Fistula

Postoperative pancreatic fistula (POPF) is the most serious and challenging complication following gastroenterological surgery. Activated pancreatic juice leaking from the organ remnant contains proteases that attack the surrounding tissue, potentially leading to severe inflammation, tissue necrosis, and fistula formation. However, it is difficult to observe pancreatic leakage during surgery and to evaluate the protease activity of leaked fluid at the patient's bedside. This report describes a protein nanocage-based protease ratiometric sensor comprising a pancreatic protease-sensitive small heat-shock protein (HSP) 16.5, which is a naturally occurring protein in Methanococcus jannaschii that forms a spherical structure by self-assembly of 24 subunits, and a chemically conjugated donor-acceptor dye pair for Förster resonance energy transfer (FRET). The HSP-FRET probe was constructed by subunit exchange of each dye-labeled engineered HSP, resulting in a spherical nanocage of approximately 10 nm in diameter, which exhibited very high stability against degradation in blood plasma and no remarkable toxicity in mice. The efficiency of FRET was found to depend on both the dye orientation and the acceptor/donor ratio. Pancreatic proteases, including trypsin, α-chymotrypsin, and elastase, were quantitatively analyzed by fluorescence recovery with high specificity using the HSP-FRET nanoprobe. Furthermore, the HSP-FRET nanoprobe was sufficiently sensitive to detect POPF in the pancreatic juice of patients using only the naked eye within 10 min. Thus, this novel nanoprobe is proposed as an effective and convenient tool for the detection of POPF and the visualization of activated pancreatic juice during gastroenterological surgery.

Acoustic radiation force impulse imaging of the pancreas for estimation of pathologic fibrosis and risk of postoperative pancreatic fistula

BACKGROUND

We sought to evaluate whether pancreatic elasticity, measured using acoustic radiation force impulse (ARFI) imaging, can determine the degree of pancreatic fibrosis and risk of pancreatic fistula (PF) in patients undergoing pancreatic resection. Although soft pancreatic texture is a reliable predictor of postoperative PF, noninvasive, quantitative methods of assessing pancreatic hardness have not been established.

STUDY DESIGN

Shear wave velocity (SWV) of the pancreas was preoperatively measured by ARFI imaging in 62 patients undergoing pancreatic resection. Correlations of SWV with pathologic degree of fibrosis in the resected pancreas, exocrine function of the remnant pancreas, and the incidence of postoperative PF were determined.

RESULTS

The SWV was positively correlated with the degree of pancreatic fibrosis (Spearman's rank correlation coefficient [ρ] = 0.660, p < 0.001) and inversely correlated with postoperative amylase concentrations and daily output of pancreatic juice. The incidence of postoperative PF was significantly higher in the 32 patients with soft (SWV < 1.54 m/s) than in the 30 with hard (SWV ≥ 1.54 m/s) pancreata (63% vs 17%, p < 0.001). Multivariate analysis showed that a soft pancreas (SWV < 1.54 m/s) was an independent predictor of postoperative PF (odds ratio 38.3; 95% CI 5.82 to 445; p = 0.001).

CONCLUSIONS

Pancreatic elasticity on preoperative ARFI imaging accurately reflected the pathologic degree of fibrosis and exocrine function of the pancreas, enabling surgeons to adopt appropriate surgical procedures according to the risk of postoperative PF in each patient undergoing pancreatic resection.

Internal compared with external drainage of pancreatic duct during pancreaticoduodenectomy: a retrospective study

OBJECTIVE

To compare internal with external drainage of the pancreatic duct during pancreaticoduodenectomy with regard to the incidence of postoperative pancreatic fistula (POPF) and other complications.

METHODS

We retrospectively analyzed 316 patients who underwent pancreaticoduodenectomy with a placed drainage tube (external, n=128; internal, n=188) in the pancreatic duct from 1 January 1999 to 31 December 2011 in Tianjin Third Central Hospital of China. The incidence of POPF and some other complications were compared.

RESULTS

There was no difference in the incidence rates of POPF between those given an internal or external drainage tube (P=0.788), but POPF was more severe in the former (P=0.014). Intraperitoneal bleeding rate was also higher in the patients with internal drainage (P=0.040), but operative time and postoperative hospitalization were longer in those with external drainage (P=0.002 and P=0.007, respectively). There was no difference between the groups with regard to the incidence rates of gastrointestinal bleeding, delayed gastric emptying, pulmonary infection, or incision infection and in-hospital mortality.

CONCLUSIONS

External drainage of the pancreatic duct during pancreaticoduodenectomy can decrease the severity of POPF, but operative time and postoperative hospitalization will be extended.

Spacer-enhanced chymotrypsin-activated peptide-functionalized gold nanoparticle probes: a rapid assay for the diagnosis of pancreatitis

A spacer-enhanced FITC-labeled peptide self-assembled onto AuNPs was fabricated as a chymotrypsin activated fluorescent AuNP probe and was used for the diagnosis of pancreatitis with fecal specimens.