Management of nonvariceal upper gastrointestinal bleeding

Nonvariceal upper gastrointestinal bleeding is unique from variceal bleeding in terms of patient characteristics, management, rebleeding rates, and prognosis, and should be managed differently. The majority of nonvariceal upper gastrointestinal bleeds will not rebleed once treated successfully. The incidence is 80 to 90% of all upper gastrointestinal bleeds and the mortality is between 5 to 10%. The causes include nonacid-related ulceration from tumors, infections, inflammatory disease, Mallory-Weiss tears, erosions, esophagitis, dieulafoy lesions, angiodysplasias, gastric antral vascular ectasia, and portal hypertensive gastropathy. Rarer causes include hemobilia, hemosuccus pancreaticus, and aortoenteric fistulas. Hematemesis and melena are the key features of bleeding from the upper gastrointestinal tract, but fresh per rectal bleeding may be present in a rapidly bleeding lesion. Resuscitation and stabilization before endoscopy leads to improved outcomes. Fluid resuscitation is essential to avoid hypotension. Though widely practiced, there is currently insufficient evidence to show that routine red cell transfusion is beneficial. Coagulopathy requires correction, but the optimal international normalized ratio has not been determined yet. Risk stratification scores such as the Rockall and Glasgow-Blatchford scores are useful to predict rebleeding, mortality, and to determine the urgency of endoscopy. Evidence suggests that high-dose proton pump inhibitors (PPI) should be given as an infusion before endoscopy. If patients are intolerant of PPIs, histamine-2 receptor antagonists can be given, although their acid suppression is inferior. Endoscopic therapy includes thermal methods such as coaptive coagulation, argon plasma coagulation, and hemostatic clips. Four quadrant epinephrine injections combined with either thermal therapy or clipping reduces mortality. In hypoxic patients, endoscopy masks allow high-flow oxygen during upper gastrointestinal endoscopy. The risk of rebleeding reduces after 72 hours. In rebleeding, repeat endoscopy is useful and persistent failure of endoscopic therapy mandates either embolization or surgery. In this review, we analyze the management of nonvariceal upper gastrointestinal bleeding with evidence from the currently published clinical trials.

Collagen remodelling by airway smooth muscle is resistant to steroids and β₂-agonists

Bi-directional interactions between airway smooth muscle (ASM) and the altered extracellular matrix (ECM) may influence airway wall remodelling and ASM function in asthma. We have investigated the capacity of cultured human ASM to reorganise the structure of three-dimensional collagen gels and the effects of endothelin (ET)-1 and agents used to treat asthma. Human ASM cells were cast in type I collagen gels. Reductions in gel area over 72 h were determined in the absence and presence of ET-1 and potential inhibitors, steroids and β₂-adrenoceptor agonists. Changes in gel wet weights and hydroxyproline content were measured and ASM gel morphology was examined by scanning electron microscopy. Cell density-dependent reductions in gel area were augmented by ET-1, mediated via ET(A) receptors. This process was not associated with ASM contraction or proliferation, but was consistent with ASM tractional remodelling and migration leading to collagen condensation rather than collagen degradation within gels. The collagen remodelling by ASM was unaffected by salbutamol and/or budesonide. This study demonstrates an additional potential role for ASM in ECM regulation and dysregulation in airways disease that is resistant to steroids and β₂-adrenoceptor agonists. Therapy-resistant collagen condensation within ASM bundles may facilitate ECM-ASM interactions and contribute to increased internal airways resistance.

Protein retention and localization in the endoplasmic reticulum and the golgi apparatus

Protein transport along the secretory pathway is supported by a noria of vesicles that bud and fuse, load and unload their cargo from one compartment into the other. However, despite this constant flow-through of proteins and lipids the various compartments of the secretory pathway are able to maintain their own specific composition. Here, we discuss recent insights into mechanisms of protein retention and localization that are necessary for the maintenance of endoplasmic reticulum (ER)- and Golgi-associated typical functions such as protein folding and glycosylation in plant cells.