We numerically demonstrate a simple one-dimensional model of an acoustic diode formed by coupling a superlattice with a strongly nonlinear medium. The first numerical observation is presented of a significant rectifying effect on the acoustic energy flux within particular ranges of frequencies. By studying the underlying rectifying mechanism and the parameter dependence of the rectifying efficiency, the effectiveness of the acoustic diode is proved despite its simplicity. We also briefly discuss possible schemes of the experimental realization of this model as well as devising more efficient models.

Background: Acute pancreatitis is a common complication of endoscopic retrograde cholangiopancreatography and benefit of pharmacological treatment is unclear. Although prophylactic use of corticosteroid for reduction of pancreatic injury after ERCP has been evaluated, discrepancy about beneficial effect of corticosteroid on pancreatic injury still exists. The aim of current study is to evaluate effectiveness and safety of corticosteroid in prophylaxis of postendoscopic retrograde cholangiopancreatography pancreatitis (PEP).

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Background/AimsThis animal study aimed to define the underlying cellular mechanisms of intestinal barrier dysfunction.MethodsRats were fed 4% with dextran sodium sulfate (DSS) to induce experimental colitis. We analyzed the sugars in 24-hour urine output by high pressure liquid chromatography. The expression of claudins, mannan-binding lectin (MBL), and MBL-associated serine proteases 2 (MASP-2) were detected in the colonic mucosa by immunohistochemistry; and apoptotic cells in the colonic epithelium were detected by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling method assay.ResultsThe lactulose and sucralose excretion levels in the urine of rats with DSS-induced colitis were significantly higher than those in the control rats. Mannitol excretion was lower and lactulose/mannitol ratios and sucralose/mannitol ratios were significantly increased compared with those in the control group (p<0.05). Compared with the controls, the expression of sealing claudins (claudin 3, claudin 5, and claudin 8) was significantly decreased, but that of claudin 1 was increased. The expression of pore-forming claudin 2 was upregulated and claudin 7 was downregulated in DSS-induced colitis. The epithelial apoptotic ratio was 2.8%±1.2% in controls and was significantly increased to 7.2%±1.2% in DSS-induced colitis. The expression of MBL and MASP-2 in the intestinal mucosa showed intense staining in controls, whereas there was weak staining in the rats with colitis.ConclusionsThere was increased intestinal permeability in DSS-induced colitis. Changes in the expression and distribution of claudins, increased epithelial apoptosis, and the MASP-2-induced immune response impaired the intestinal epithelium and contributed to high intestinal permeability.

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Polariton-based band gap and generation of surface acoustic waves in acoustic superlattice lithium niobate

A large body of clinical and experimental evidence suggests that cytokines play a key role in the pathogenesis of local and systemic complications of acute pancreatitis. IL-18 is a pro-inflammatory cytokine that plays a key role in many human diseases, including acute pancreatitis. This review focuses on the present understanding in IL-18 and its potential role in acute pancreatitis. IL-18 levels reflect the severity of acute pancreatitis and display a significant negative correlation with the concentrations of antioxidative damage factors, serum selenium and glutathione peroxidases (GPx). The relationship between IL-18 and other pro-inflammatory cytokines shows that IL-18 is one of the key mediators of inflammation in the pathogenesis of acute pancreatitis. Elevation of serum IL-18 levels may mediate acute pancreatitis associated liver injury. The use of IL-18 antagonists as direct routes to block IL-18 activity and P2X7 receptor antagonists and interleukin-1beta-converting enzyme (ICE) inhibitors as indirect routes to block IL-18 activity suggest that specific therapeutic inhibition of IL-18 is a promising therapeutic approach for acute pancreatitis.

BackgroundCronkhite-Canada syndrome (CCS) is a rare multiple gastrointestinal polyposis. Up till now, many complications of CCS have been reported in the literature, but rib fracture is not included.Case PresentationWe report a case of a 58-year-old man who was admitted to our hospital with a 6-month history of frequent diarrhea, intermittent hematochezia and a weight loss of 13 kg. On admission, physical examination revealed alopecia of the scalp, hyperpigmentation of the hands and soles, and dystrophy of the fingernails. Laboratory data revealed hypocalcaemia and hypoproteinemia. Esophagogastroduodenoscopy, video capsule endoscopy and colonoscopy revealed various sizes of generalized gastrointestinal polyps. Histological examination of the biopsy specimens obtained from the stomach and the colon showed adenomatous polyp and inflammatory polyp respectively. Thus, a diagnosis of CCS was made. After treatment with corticosteroids for 24 days and nutritional support for two months, his clinical condition improved. Two months later, he was admitted to our hospital for the second time with frequent diarrhea and weight loss. The chest radiography revealed fractures of the left sixth and seventh ribs. Examinations, including emission computed tomography, bone densitometry test, and other serum parameters, were performed, but could not identify the definite etiology of the rib fractures. One month later, the patient suffered from aggravating multiple rib fractures due to the ineffective treatment, persistent hypocalcaemia and malnutrition.ConclusionsThis is the first case of a CCS patient with multiple rib fractures. Although the association between CCS and multiple rib fractures in this case remains uncertain, we presume that persistent hypocalcaemia and malnutrition contribute to this situation, or at least aggravate this rare complication. Besides, since prolonged corticosteroid therapy will result in an increased risk of osteoporotic fracture, CCS patients who accept corticosteroid therapy could be potential victims of rib fracture.