Structural and functional basis of mammalian microRNA biogenesis by Dicer

MicroRNA (miRNA) and RNA interference (RNAi) pathways rely on small RNAs produced by Dicer endonucleases. Mammalian Dicer primarily supports the essential gene-regulating miRNA pathway, but how it is specifically adapted to miRNA biogenesis is unknown. We show that the adaptation entails a unique structural role of Dicer’s DExD/H helicase domain. Although mice tolerate loss of its putative ATPase function, the complete absence of the domain is lethal because it assures high-fidelity miRNA biogenesis. Structures of murine Dicer⋅miRNA precursor complexes revealed that the DExD/H domain has a helicase-unrelated structural function. It locks Dicer in a closed state, which facilitates miRNA precursor selection. Transition to a cleavage-competent open state is stimulated by Dicer-binding protein TARBP2. Absence of the DExD/H domain or its mutations unlocks the closed state, reduces substrate selectivity, and activates RNAi. Thus, the DExD/H domain structurally contributes to mammalian miRNA biogenesis and underlies mechanistical partitioning of miRNA and RNAi pathways

Management of Low Anterior Resection Syndrome (LARS) Following Resection for Rectal Cancer

Introduction: A total of 60–80% of patients undergoing rectal resection (mostly as a treatment for rectal cancer) suffer from a variety of partly severe functional problems despite preservation of the anal sphincter. These patients are summarized under the term low anterior resection syndrome (LARS). Preoperative radiotherapy, vascular dissection and surgical excision of the low rectum and mesorectum lead, alone or all together, to a significant impairment of colonic and (neo-) rectal motility. This results in a variety of symptoms (multiple defecation episodes, recurrent episodes of urge, clustering, incontinence, etc.) which are associated with severe impairment of quality of life (QOL). Methods: This narrative review summarizes the present state of knowledge regarding the pathophysiology of LARS as well as the evidence for the available treatment options to control the symptoms resulting from this condition. Results: A review of the literature (Medline, Pubmed) reveals a variety of treatment options available to control symptoms of LARS. Medical therapy, with or without dietary modification, shows only a modest effect. Pelvic floor rehabilitation consisting of muscle exercise techniques as well as biofeedback training has been associated with improvement in LARS scores and incontinence, albeit with limited scientific evidence. Transanal irrigation (TAI) has gained interest as a treatment modality for patients with LARS due to an increasing number of promising data from recently published studies. Despite this promising observation, open questions about still-unclear issues of TAI remain under debate. Neuromodulation has been applied in LARS only in a few studies with small numbers of patients and partly conflicting results. Conclusion: LARS is a frequent problem after sphincter-preserving rectal surgery and leads to a marked impairment of QOL. Due to the large number of patients suffering from this condition, mandatory identification, as well as treatment of affected patients, must be considered during surgical as well as oncological follow-up. The use of a standardized treatment algorithm will lead to sufficient control of symptoms and a high probability of a marked improvement in QOL

Diagnostic and Therapeutic Indications for Endoscopic Ultrasound (EUS) in Patients with Pancreatic and Biliary Disease—Novel Interventional Procedures

There is growing evidence supporting the substantial, essential and indispensable role of endoscopic ultrasound (EUS) as a key diagnostic armamentarium for upper GI oncologic surgery. Well described in countless publications, EUS holds that position in gastroenterological expert centers all over Europe. Despite its undisputable contributions to oncologic upper GI surgery, the availability of this technique at the expert level shows up in an irregular spread pattern. Endoscopic ultrasound’s primary use during the first few years after its creation was the detection of pancreatic cancer. From then on, EUS developed in different directions, becoming a diagnostic tool that increasingly better defines its status as a method of minimally invasive therapeutic applications and a useful addition to surgical options. As a result, several surgical interventions could even be replaced by ultrasound-targeted interventions. This process took place in just a few years and was made possible by technical development that sensibly combined high-resolution ultrasound with therapeutic endoscopy. The present article will serve to cover the most prevalent uses with supporting data considering the growing list of suggested indications for EUS while also examining cutting-edge initiatives that might soon become the standard of clinical practice. Endoscopic centers with high expertise are needed to train future experts in the growing field of EUS interventions

Unveiling New Horizons: Progress in the Management of Gastrointestinal and Hepatobiliary Cancer

The field of gastrointestinal cancer research continues to make significant strides in understanding the complexities of these challenging diseases [...

Diagnosis of infection with human herpes viruses in routine laboratory practice

Background: The potential for faster detection of human herpes viruses using PCR compared to other methods is undisputed. However, because of fear of contamination, the clinical implication of nucleic amplification methods in routine laboratories is not widespread. Herpes viruses cause a wide spectrum of diseases and can cause morbidity and mortality in immune-compromised patients. Using real-time PCR, most of the problems associated with PCR (contamination, cumbersome detection, and rather expensive tests) are solved, and a rapid, economical, and – most importantly – closed system is at hand. Methods: We evaluated work procedures in our laboratory that enable the routine diagnosis of viral infections with high accuracy and rapid turn-around time. In parallel, inherent problems usually associated with PCR testing, especially cross-contamination could be suppressed to a minimum. The start of the work flow process begins with an automated nucleic acid extraction procedure that yields high quality DNA. A common – internally and externally controlled – PCR program for all six viruses allows rapid sample turn around. Results: In all, 7500 analyses for human herpes virus infection were performed in the last 5 years. Results for various different specimens were produced within 24 h. Contamination occurred rarely and could be ameliorated easily. The use of internal controls identified rare PCR-inhibited samples. The detection limits for our assays are markedly below the clinically relevant range. Conclusions: Our workflow allowed rapid, cost-efficient, and labor saving routine diagnostic detection of viral infections. Clin Chem Lab Med 2009;47:1141–5.Peer Reviewe

Somalia versus Captain ‘Hook’: assessing the EU's security actorness in countering piracy off the Horn of Africa

An internal security problem of Somalia — state failure from internal conflict resulting in increased piracy — has increasingly become an external security problem for the European Union (EU). This article contributes to analysing the role of the EU as a security actor in countering piracy off the Horn of Africa, by examining three different dimensions of the EU response to this problem: (a) the immediate EU response (the EU military mission EUNAVFOR Atalanta); (b) the medium-term EU response (the Critical Maritime Routes (CMR) programme launched by the European Commission); and (c) the long-term EU response (development and security assistance). This article concludes that the EU has been very active in addressing piracy through its naval task-force to protect maritime transport in the western Indian Ocean and the Gulf of Aden, as well as its efforts to enhance regional counter-piracy capacities and thematic and geographical financial instruments. The EU thus has taken up the fight against ‘Captain Hook’