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With promising applications in medical diagnosis and therapy, the behavior of shell-encapsula-ted ultrasound contrast agents (UCAs) has attracted considerable attention. Currently, second-generation contrast agents stabilized by a phospholipid membrane are widely used and studies have focused on the dynamics of single phospholipid shell-encapsulated microbubbles. To improve the safety and the efficiency of the methods using the propagation or targeted ultrasound, a better understanding of the propagation of ultrasound in liquids containing multiple encapsulated microbubbles is required. By incorporating the Marmottant–Gompertz model into the multiple scale analysis of two-phase model, this study derived a Korteweg–de Vries–Burgers equation as a weakly nonlinear wave equation for one-dimensional ultrasound in bubbly liquids. It was found that the wave propagation characteristics changed with the initial surface tension, highlighting two notable features of the phospholipid shell: buckling and rupture. These results may provide insights into the suitable state of microbubbles, and better control of ultrasound for medical applications, particularly those that require high precision.

Background and Aim A previous UK study showed that 6.1% of patients with diarrhea-predominant irritable bowel syndrome (IBS-D) had evidence of severe pancreatic exocrine insufficiency (PEI), but these findings need replication. We aimed to identify the prevalence of PEI based on fecal elastase stool testing in consecutive outpatients presenting with chronic unexplained abdominal pain and/or diarrhea and/or IBS-D. Methods Patients aged over 40 years presenting to hospital outpatient clinics from six sites within Australia with unexplained abdominal pain and/or diarrhea for at least 3 months and/or IBS-D were studied. Patients completed validated questionnaires and donated a stool sample in which elastase concentration was measured by ELISA. A concentration of

TPS4172 Background: Eighty per cent of patients with non-metastatic pancreatic cancer have high-risk, borderline resectable (BRPC) or locally advanced pancreas cancer (LAPC), conferring a 5-year overall survival of only 12%. MASTERPLAN evaluates the safety and activity of stereotactic body radiotherapy (SBRT) added to neoadjuvant chemotherapy in these patient cohorts. Methods: MASTERPLAN is an investigator-initiated prospective multi-centre randomized phase II trial. Inclusion criteria include histologically confirmed high-risk, BRPC or LAPC. High risk is defined as tumour > 4cm, extrapancreatic extension or node positive. Randomisation is 2:1 to chemotherapy + SBRT (investigational arm) or chemotherapy (control arm) by minimisation with stratification by operability (potentially operable - high risk; BRPC versus inoperable – LAPC; medically inoperable), planned chemotherapy and institution. Both treatment arms receive 6 x 2 weekly cycles of modified FOLFIRINOX (mFOLFIRINOX). Gemcitabine and nab-paclitaxel is permitted if mFOLFIRINOX is unsuitable. The investigational arm receives SBRT (40Gy in 5 fractions) with real time quality assurance. Resectability will be evaluated following initial chemotherapy +/- SBRT. Adjuvant chemotherapy is 6 cycles (12 weeks) of mFOLFIRINOX, or the same duration of gemcitabine and capecitabine (GEMCAP) if neoadjuvant gemcitabine/ nab-paclitaxel given. SBRT adverse events (AEs) will be recorded until study cessation. The primary endpoint is 12-month locoregional control. Secondary endpoints: safety, surgical morbidity and mortality, radiological response rate, progression free survival, pathological response rate, surgical resection rate, R0 resection rate, quality of life, deterioration free survival and overall survival. Biospecimens are collected for translational research for potential prognostic/predictive biomarkers of clinical endpoints and include serial tumour tissue collection from patients undergoing fiducial marker insertion and/or surgery, biopsy at disease progression, serial blood collection and serial buccal and faecal sample collection. An interim analysis will review locoregional failure, distant metastasis and rate of death on the first 40 patients after completion of 12 months follow up. The sample size is 120 patients (80 intervention:40 control), balanced for BRPC/LAPC (60 in each cohort). The minimum follow up is 12 months. The first site opened in October 2019 and 10 patients have been recruited from five sites at 17 Feb 2021. Overall 15 sites in Australia and New Zealand are planned to open to recruitment. Australian Clinical Trials Registry Number: ACTRN12619000409178. Clinical trial information: ACTRN12619000409178.

A previous UK study showed that 6.1% of patients with diarrhea-predominant irritable bowel syndrome (IBS-D) had evidence of severe pancreatic exocrine insufficiency (PEI), but these findings need replication. We aimed to identify the prevalence of PEI based on fecal elastase stool testing in consecutive outpatients presenting with chronic unexplained abdominal pain and/or diarrhea and/or IBS-D.Patients aged over 40 years presenting to hospital outpatient clinics from six sites within Australia with unexplained abdominal pain and/or diarrhea for at least 3 months and/or IBS-D were studied. Patients completed validated questionnaires and donated a stool sample in which elastase concentration was measured by ELISA. A concentration of 100 mcg/g stool represented severe and 200 mcg/g mild to moderate PEI. Patients whose fecal elastase was 200 mcg/g underwent testing for pancreatic pathology with an endoscopic ultrasound or abdominal CT.Two hundred eighteen patients (mean age of 60 years, 29.4% male) were studied. PEI was found in 4.6% (95% CI 2.2-8.3%) (n = 10), with five patients (2.3% (95% CI 0.8-5.3%) having severe PEI. Only male sex and heavy alcohol use were significantly associated with abnormal versus normal pancreatic functioning. Of seven patients who underwent endoscopic ultrasound or CT, two had features indicative of chronic pancreatitis.One in 50 patients with IBS-D or otherwise unexplained abdominal pain or diarrhea have an abnormal fecal elastase, but unexpected pancreatic insufficiency was detected in only a minority of these. This study failed to confirm the high prevalence of PEI among patients with unexplained GI symptoms previously reported.