Loss of a pyridoxal-phosphate phosphatase rescues Arabidopsis lacking an endoplasmic reticulum ATP carrier.

The endoplasmic reticulum (ER)-located ATP/ADP-antiporter (ER-ANT1) occurs specifically in vascular plants. Structurally different transporters mediate energy provision to the ER, but the cellular function of ER-ANT1 is still unknown. Arabidopsis (Arabidopsis thaliana) mutants lacking ER-ANT1 (er-ant1 plants) exhibit a photorespiratory phenotype accompanied by high glycine levels and stunted growth, pointing to an inhibition of glycine decarboxylase (GDC). To reveal whether it is possible to suppress this marked phenotype, we exploited the power of a forward genetic screen. Absence of a so far uncharacterized member of the HaloAcid Dehalogenase (HAD)-like hydrolase family strongly suppressed the dwarf phenotype of er-ant1 plants. Localization studies suggested that the corresponding protein locates to chloroplasts, and activity assays showed that the enzyme dephosphorylates, with high substrate affinity, the B6 vitamer pyridoxal 5'-phosphate (PLP). Additional physiological experiments identified imbalances in vitamin B6 homeostasis in er-ant1 mutants. Our data suggest that impaired chloroplast metabolism, but not decreased GDC activity, causes the er-ant1 mutant dwarf phenotype. We present a hypothesis, setting transport of PLP by ER-ANT1 and chloroplastic PLP dephosphorylation in the cellular context. With the identification of this HAD-type PLP phosphatase, we also provide insight into B6 vitamer homeostasis.

Multi-omics data integration reveals link between epigenetic modifications and gene expression in sugar beet (Beta vulgaris subsp. vulgaris) in response to cold.

BACKGROUND: DNA methylation is thought to influence the expression of genes, especially in response to changing environmental conditions and developmental changes. Sugar beet (Beta vulgaris ssp. vulgaris), and other biennial or perennial plants are inevitably exposed to fluctuating temperatures throughout their lifecycle and might even require such stimulus to acquire floral competence. Therefore, plants such as beets, need to fine-tune their epigenetic makeup to ensure phenotypic plasticity towards changing environmental conditions while at the same time steering essential developmental processes. Different crop species may show opposing reactions towards the same abiotic stress, or, vice versa, identical species may respond differently depending on the specific kind of stress. RESULTS: In this study, we investigated common effects of cold treatment on genome-wide DNA methylation and gene expression of two Beta vulgaris accessions via multi-omics data analysis. Cold exposure resulted in a pronounced reduction of DNA methylation levels, which particularly affected methylation in CHH context (and to a lesser extent CHG) and was accompanied by transcriptional downregulation of the chromomethyltransferase CMT2 and strong upregulation of several genes mediating active DNA demethylation. CONCLUSION: Integration of methylomic and transcriptomic data revealed that, rather than methylation having directly influenced expression, epigenetic modifications correlated with changes in expression of known players involved in DNA (de)methylation. In particular, cold triggered upregulation of genes putatively contributing to DNA demethylation via the ROS1 pathway. Our observations suggest that these transcriptional responses precede the cold-induced global DNA-hypomethylation in non-CpG, preparing beets for additional transcriptional alterations necessary for adapting to upcoming environmental changes.

Acclimation in plants - the Green Hub consortium.

Acclimation is the capacity to adapt to environmental changes within the lifetime of an individual. This ability allows plants to cope with the continuous variation in ambient conditions to which they are exposed as sessile organisms. Because environmental changes and extremes are becoming even more pronounced due to the current period of climate change, enhancing the efficacy of plant acclimation is a promising strategy for mitigating the consequences of global warming on crop yields. At the cellular level, the chloroplast plays a central role in many acclimation responses, acting both as a sensor of environmental change and as a target of cellular acclimation responses. In this Perspective article, we outline the activities of the Green Hub consortium funded by the German Science Foundation. The main aim of this research collaboration is to understand and strategically modify the cellular networks that mediate plant acclimation to adverse environments, employing Arabidopsis, tobacco (Nicotiana tabacum) and Chlamydomonas as model organisms. These efforts will contribute to 'smart breeding' methods designed to create crop plants with improved acclimation properties. To this end, the model oilseed crop Camelina sativa is being used to test modulators of acclimation for their potential to enhance crop yield under adverse environmental conditions. Here we highlight the current state of research on the role of gene expression, metabolism and signalling in acclimation, with a focus on chloroplast-related processes. In addition, further approaches to uncovering acclimation mechanisms derived from systems and computational biology, as well as adaptive laboratory evolution with photosynthetic microbes, are highlighted.

Vacuolar sucrose homeostasis is critical for plant development, seed properties, and night-time survival in Arabidopsis.

Most cellular sucrose is present in the cytosol and vacuoles of plant cells; however, little is known about the effect of this sucrose compartmentation on plant properties. Here, we examined the effects of altered intracellular sucrose compartmentation in Arabidopsis thaliana leaves by heterologously expressing the sugar beet (Beta vulgaris) vacuolar sucrose loader BvTST2.1 and by generating lines with reduced vacuolar invertase activity (amiR vi1-2). Heterologous expression of BvTST2.1 led to increased monosaccharide levels in leaves, whereas sucrose levels remained constant, indicating that vacuolar invertase activity in mesophyll vacuoles exceeds sucrose uptake. This notion was supported by analysis of tobacco (Nicotiana benthamiana) leaves transiently expressing BvTST2.1 and the invertase inhibitor NbVIF. However, sucrose levels were strongly elevated in leaf extracts from amiR vi1-2 lines, and experiments confirmed that sucrose accumulated in the corresponding vacuoles. The amiR vi1-2 lines exhibited impaired early development and reduced seed weight. When germinated in the dark, amiR vi1-2 seedlings were less able to convert sucrose into monosaccharides than the wild type. Cold temperatures strongly down-regulated both VI genes, but the amiR vi1-2 lines showed normal frost tolerance. These observations indicate that increased vacuolar sucrose levels fully compensate for the effects of low monosaccharide concentrations on frost tolerance.

The Tapetal Major Facilitator NPF2.8 Is Required for Accumulation of Flavonol Glycosides on the Pollen Surface in Arabidopsis thaliana.

The exine of angiosperm pollen grains is usually covered by a complex mix of metabolites including pollen-specific hydroxycinnamic acid amides (HCAAs) and flavonoid glycosides. Although the biosynthetic pathways resulting in the formation of HCAAs and flavonol glycosides have been characterized, it is unclear how these compounds are transported to the pollen surface. In this report we provide several lines of evidence that a member of the nitrate/peptide transporter family is required for the accumulation and transport of pollen-specific flavonol 3-o-sophorosides, characterized by a glycosidic ß-1,2-linkage, to the pollen surface of Arabidopsis (Arabidopsis thaliana). Ectopic, transient expression in Nicotiana benthamiana epidermal leaf cells demonstrated localization of this flavonol sophoroside transporter (FST1) at the plasmalemma when fused to green fluorescent protein (GFP). We also confirmed the tapetum-specific expression of FST1 by GFP reporter lines driven by the FST1 promoter. In vitro characterization of FST1 activity was achieved by microbial uptake assays based on 14C-labeled flavonol glycosides. Finally, rescue of an fst1 insertion mutant by complementation with an FST1 genomic fragment restored the accumulation of flavonol glycosides in pollen grains to wild-type levels, corroborating the requirement of FST1 for transport of flavonol-3-o-sophorosides from the tapetum to the pollen surface.

AXER is an ATP/ADP exchanger in the membrane of the endoplasmic reticulum.

To fulfill its role in protein biogenesis, the endoplasmic reticulum (ER) depends on the Hsp70-type molecular chaperone BiP, which requires a constant ATP supply. However, the carrier that catalyzes ATP uptake into the ER was unknown. Here, we report that our screen of gene expression datasets for member(s) of the family of solute carriers that are co-expressed with BiP and are ER membrane proteins identifies SLC35B1 as a potential candidate. Heterologous expression of SLC35B1 in E. coli reveals that SLC35B1 is highly specific for ATP and ADP and acts in antiport mode. Moreover, depletion of SLC35B1 from HeLa cells reduces ER ATP levels and, as a consequence, BiP activity. Thus, human SLC35B1 may provide ATP to the ER and was named AXER (ATP/ADP exchanger in the ER membrane). Furthermore, we propose an ER to cytosol low energy response regulatory axis (termed lowER) that appears as central for maintaining ER ATP supply.

High V-PPase activity is beneficial under high salt loads, but detrimental without salinity.

The membrane-bound proton-pumping pyrophosphatase (V-PPase), together with the V-type H+ -ATPase, generates the proton motive force that drives vacuolar membrane solute transport. Transgenic plants constitutively overexpressing V-PPases were shown to have improved salinity tolerance, but the relative impact of increasing PPi hydrolysis and proton-pumping functions has yet to be dissected. For a better understanding of the molecular processes underlying V-PPase-dependent salt tolerance, we transiently overexpressed the pyrophosphate-driven proton pump (NbVHP) in Nicotiana benthamiana leaves and studied its functional properties in relation to salt treatment by primarily using patch-clamp, impalement electrodes and pH imaging. NbVHP overexpression led to higher vacuolar proton currents and vacuolar acidification. After 3 d in salt-untreated conditions, V-PPase-overexpressing leaves showed a drop in photosynthetic capacity, plasma membrane depolarization and eventual leaf necrosis. Salt, however, rescued NbVHP-hyperactive cells from cell death. Furthermore, a salt-induced rise in V-PPase but not of V-ATPase pump currents was detected in nontransformed plants. The results indicate that under normal growth conditions, plants need to regulate the V-PPase pump activity to avoid hyperactivity and its negative feedback on cell viability. Nonetheless, V-PPase proton pump function becomes increasingly important under salt stress for generating the pH gradient necessary for vacuolar proton-coupled Na+ sequestration.

Purification and functional characterization of the vacuolar malate transporter tDT from Arabidopsis.

The exact transport characteristics of the vacuolar dicarboxylate transporter tDT from Arabidopsis are elusive. To overcome this limitation, we combined a range of experimental approaches comprising generation/analysis of tDT overexpressors, 13CO2 feeding and quantification of 13C enrichment, functional characterization of tDT in proteoliposomes, and electrophysiological studies on vacuoles. tdt knockout plants showed decreased malate and increased citrate concentrations in leaves during the diurnal light-dark rhythm and after onset of drought, when compared with wildtypes. Interestingly, under the latter two conditions, tDT overexpressors exhibited malate and citrate levels opposite to tdt knockout plants. Highly purified tDT protein transports malate and citrate in a 1:1 antiport mode. The apparent affinity for malate decreased with decreasing pH, whereas citrate affinity increased. This observation indicates that tDT exhibits a preference for dianion substrates, which is supported by electrophysiological analysis on intact vacuoles. tDT also accepts fumarate and succinate as substrates, but not α-ketoglutarate, gluconate, sulfate, or phosphate. Taking tDT as an example, we demonstrated that it is possible to reconstitute a vacuolar metabolite transporter functionally in proteoliposomes. The displayed, so far unknown counterexchange properties of tDT now explain the frequently observed reciprocal concentration changes of malate and citrate in leaves from various plant species. tDT from Arabidopsis is the first member of the well-known and widely present SLC13 group of carrier proteins, exhibiting an antiport mode of transport.

First Case Report of a Late Onset Knee Periprosthetic Joint Infection Caused by Lactococcus garvieae.

Lactococcus garvieae is known as a Gram-positive, catalase-negative, and facultatively anaerobic fish pathogen. The association between Lactococcus spp. and human infectious diseases is described as being mainly associated with lumbar osteomyelitis, hepatic abscess, and infective endocarditis. In the literature of orthopedic post-prosthetic infections, L. garvieae was associated with a case of hip prosthetic infection in a fishmonger woman. We present the case of a 79-year-old male patient with multiple comorbidities, who is admitted to our center with a 5-day history of pain, swelling, and motility disorder of the right knee by the presence of a bicondylar knee replacement surgery, which was performed due to gonarthrosis 17 years ago. The radiographies of the right knee revealed no signs of displacement or loosening of the prothesis. After multiple radical debridements including VAC therapy and targeted antibiotic therapy we have managed to defeat the infection without exchange arthroplasty. Although we could not demonstrate the source of infection, we can only presume that in our case the source of infection was represented by the ingestion of possibly contaminated food. The patient had a habit of eating Nile perch fish (Lates niloticus) every 4 weeks. We illustrated once more the possibility of a late onset L. garvieae related orthopedic periprosthetic joint infection by multiple comorbidities.

Histopathological Analysis of PEEK Wear Particle Effects on the Synovial Tissue of Patients.

Introduction. Increasing interest developed in the use of carbon-fiber-reinforced-poly-ether-ether-ketones (CFR-PEEK) as an alternative bearing material in knee arthroplasty. The effects of CFR-PEEK wear in in vitro and animal studies are controversially discussed, as there are no data available concerning human tissue. The aim of this study was to analyze human tissue containing CFR-PEEK as well as UHMWPE wear debris. The authors hypothesized no difference between the used biomaterials. Methods and Materials. In 10 patients during knee revision surgery of a rotating-hinge-knee-implant-design, synovial tissue samples were achieved (tibial inserts: UHMWPE; bushings and flanges: CFR-PEEK). One additional patient received revision surgery without any PEEK components as a control. The tissue was paraffin-embedded, sliced into 2 µm thick sections, and stained with hematoxylin and eosin in a standard process. A modified panoptical staining was also done. Results. A "wear-type" reaction was seen in the testing and the control group. In all samples, the UHMWPE particles were scattered in the tissue or incorporated in giant cells. CFR-PEEK particles were seen as conglomerates and only could be found next to vessels. CFR-PEEK particles showed no giant-cell reactions. In conclusion, the hypothesis has to be rejected. UHMWPE and PEEK showed a different scatter-behavior in human synovial tissue.

Endoscopic therapy for infected pancreatic necrosis using fully covered self-expandable metal stents: combination of transluminal necrosectomy, transluminal and percutaneous drainage.

BACKGROUND/AIMS: Endoscopic transluminal therapy has become the standard of care as a less invasive alternative to surgery. In a retrospective case series of two tertiary referral centers we report on an individualized concept combining EUS-guided drainage with self-expanding metal stents, direct transluminal debridement und percutaneous drainage. METHODS: We treated 13 patients with infected pancreatic necrosis. Initially in all patients an EUS-guided drainage with plastic stents was performed under antibiotic protection (transduodenal: 2, transgastral: 11). After clinical consolidation (after 9.6 ±â€Š9.4 days) a covered self-expanding metal stent (Niti-S, Taewoong medical Co., Seoul, Korea) was inserted by performing direct endoscopic necrosectomy in 2.9 ±â€Š1.7 sessions through the stent. In cases of disrupted duct syndromes a pancreatic plastic stent was inserted (5 of 13 patients). In 5 of 13 cases additional percutaneous drainage was applied because of extended necrosis. In one patient percutaneous endoscopic drainage using the percutaneous access was needed. RESULTS: A sustained clinical success was achieved in 12 of 13 cases (CRP before therapy 23.5 ±â€Š14.4 mg/L, after 3.1 ±â€Š2.6 mg/lL). Discharge occurred after 2.5 ±â€Š22.4 days. The self-expanding metal stent was extracted after 82.5 ±â€Š56.6 days. Mean follow up was 8.5 ±â€Š5.9 months. CONCLUSION: Our concept of combining transluminal drainage, direct endoscopic necrosectomy and percutaneuos drainage offers a safe and reliable alternative to surgery, even in case of extended necrosis.

In vitro analyses of mitochondrial ATP/phosphate carriers from Arabidopsis thaliana revealed unexpected Ca(2+)-effects.

BACKGROUND: Adenine nucleotide/phosphate carriers (APCs) from mammals and yeast are commonly known to adapt the mitochondrial adenine nucleotide pool in accordance to cellular demands. They catalyze adenine nucleotide--particularly ATP-Mg--and phosphate exchange and their activity is regulated by calcium. Our current knowledge about corresponding proteins from plants is comparably limited. Recently, the three putative APCs from Arabidopsis thaliana were shown to restore the specific growth phenotype of APC yeast loss-of-function mutants and to interact with calcium via their N-terminal EF--hand motifs in vitro. In this study, we performed biochemical characterization of all three APC isoforms from A. thaliana to gain further insights into their functional properties. RESULTS: Recombinant plant APCs were functionally reconstituted into liposomes and their biochemical characteristics were determined by transport measurements using radiolabeled substrates. All three plant APCs were capable of ATP, ADP and phosphate exchange, however, high preference for ATP-Mg, as shown for orthologous carriers, was not detectable. By contrast, the obtained data suggest that in the liposomal system the plant APCs rather favor ATP-Ca as substrate. Moreover, investigation of a representative mutant APC protein revealed that the observed calcium effects on ATP transport did not primarily/essentially involve Ca(2+)-binding to the EF-hand motifs in the N-terminal domain of the carrier. CONCLUSION: Biochemical characteristics suggest that plant APCs can mediate net transport of adenine nucleotides and hence, like their pendants from animals and yeast, might be involved in the alteration of the mitochondrial adenine nucleotide pool. Although, ATP-Ca was identified as an apparent import substrate of plant APCs in vitro it is arguable whether ATP-Ca formation and thus the corresponding transport can take place in vivo.

[Evaluation of endoscopic live case demonstrations--the patient's and participant's perspective]. / Beurteilung von endoskopischen Liveübertragungen aus Sicht von Patienten und Teilnehmer.

INTRODUCTION: Benefits and ethics of live demonstrations of endoscopic interventions as part of educational meetings are controversial. Of particular importance is the acceptance and satisfaction of patients treated and the opinion of the participants of the courses. METHODS: A validated questionnaire was sent to all patients who were treated in live demonstrations at the Düsseldorf International Endoscopy Symposium (DIES) in the years 2008-2014. In addition, all participants completed evaluation forms of the same events were evaluated in order to determine the benefits of live performances. The assessments were carried out with evaluations 1-6 (1=very good, 6=very poor). RESULTS: Of 174 patients, 76 written questionnaires were returned, of which 70 were evaluable (40.2%). The rate of satisfaction with the course of treatment and stay in the endoscopy department was 80.8%. The vast majority of patients (84.1%) did not feel that a wrong treatment option was chosen, and only a few (6.7%) questioned the expertise of the treating physician. 83% of respondents felt also at the nurses in good hands. For three-quarters of patients surveyed (74.3%), the quality of life has improved as a result of the measures in the live demonstrations. Of 10,004 participants of the symposia, 6770 evaluation forms were filled out. Mean scores of below 2 were rated for questions about the quality of patient care from a medical and ethical point of view as well as for questions about the learning effect through live demonstrations compared to canned videos. CONCLUSION: The vast majority of patients treated within live demonstrations as part of the DIES is satisfied with the course, treatment and patient care and outcomes. Congress participants assess the educational value of the live broadcasts as well as patient care in medical and ethical terms as good to very good.

Efficacy and safety of a novel submucosal lifting gel used for endoscopic submucosal dissection: a study in a porcine model.

BACKGROUND AND STUDY AIMS: Endoscopic submucosal dissection (ESD) is technically demanding. A viscous gel for submucosal lifting might induce mechanical submucosal dissection facilitating easier and safer ESD. METHODS: In 12 female pigs (median 64 kg), ESDs of simulated lesions were performed at the posterior wall and greater curvature in the gastric body (one ESD per location) with randomly assigned injection fluids: gel or control fluid (0.9% saline with hydroxypropyl methylcellulose 3 mg/ml [7:1] and indigo carmine droplets). Additionally, 10 cc gel was injected into the submucosa at the anterior wall without ESD to assess effects of inappropriate injection. Pigs were euthanized at day 0, 3 or 28. In four additional pigs (euthanized day 3 or 28) 10 cc gel was injected into the muscularis propria (MP) after four endoscopic mucosal resections in the gastric body. RESULTS: Both fluid groups showed equal ESD-procedure times (28 [gel] vs. 26 min [control]) and complications. Gel-ESDs required less accessory interchanges (3.5 vs. 5.5; p = 0.01). Mechanical dissection after circumferential incision was achieved in 25% of gel-ESDs; none in control-ESDs. The severity of inflammation and fibrosis was equal in both fluid groups. Normal architecture and vital mucosa were found after inappropriate submucosal injection. MP-injections resulted in one transmural hematoma (day 3), and intramuscular encapsulation in 25% of the sites (day 28). LIMITATIONS: A pig's stomach differs from the human stomach. CONCLUSIONS: The mechanical dissection properties of the gel may reduce the need for submucosal dissection during ESD. The gel is safe when advertently injected in the submucosa and MP. The porcine model appeared suboptimal to evaluate the true mechanical dissection properties of the gel.

[The role of peroral endoscopic myotomy (POEM) in achalasia]. / Die Rolle der peroralen endoskopischen Myotomie (POEM) bei der ösophagealen Achalasie.

Achalasia is a rare motility disorder of the oesophagus. Classic achalasia is characterised by a lack of propulsive peristalsis of the distal oesophagus and incomplete relaxation of the lower oesophageal sphincter (LES). Traditionally achalasia is treated either endoscopically by pneumatic balloon dilatation or laparoscopically by Heller's myotomy. Both therapeutic procedures show a comparable effectiveness. Recently, peroral endoscopic myotomy was introduced as a new definitive treatment option. So far, this minimally invasive therapy was evaluated in a few clinical studies only. In this survey, peroral endoscopic myotomy is presented and compared to the well established surgical treatment. The diagnosis of achalasia is based on the patient's medical history and analysis of symptoms and particularly on oesophageal manometry. In addition, a barium swallow (oesophagram) and upper endoscopy are performed to rule out other reasons causing dysphagia. The patient's complaints should be recorded by use of a symptoms score. The POEM procedure starts with an incision of the mucosa at the level of the mid-oesophagus. Then, a submucosal tunnel is created distally passing approximately 2 cm over the oesophagogastric junction. After this step, myotomy of (at least) the circular muscle bundle of the distal oesophagus is performed and should be extended to a distance of 2 cm over the cardiac. Finally the mucosal entry site at the level of the mid-oesophagus is closed with endoscopic clips. First results of this technique are very promising with significant symptom relief and reduction of the mean LES pressure. In conclusion, POEM is a new, minimally invasive therapeutic option for the treatment of oesophageal achalasia. First results are very promising; long-term results and results of comparative clinical trials with established treatment methods must be awaited.

Profiling carbohydrate composition, biohydrogen capacity, and disease resistance in potato

Background: Potato (Solanum tuberosum) is one of the most important sources of carbohydrates in human diet. Because of its high carbohydrate levels it recently has also received attention in biohydrogen production. To exploit the natural variation of potato with respect to resistance to major diseases, carbohydrate levels and composition, and capacity for biohydrogen production we analyzed tubers of native, improved, and genetically modified potatoes, and two other tuberous species for their glucose, fructose, sucrose, and starch content. Results: High-starch potato varieties were evaluated for their potential for Caldicellulosiruptor saccharolyticus-mediated biohydrogen production with Desirée and Rosita varieties delivering the highest biohydrogen amounts. Native line Vega1 and improved line Yagana were both immune to two isolates (A291, A287) of Phytophthora infestans. Conclusions: Our data demonstrate that native potato varieties might have great potential for further improving the multifaceted use of potato in worldwide food and biohydrogen production.

From endoplasmic reticulum to mitochondria: absence of the Arabidopsis ATP antiporter endoplasmic Reticulum Adenylate Transporter1 perturbs photorespiration.

The carrier Endoplasmic Reticulum Adenylate Transporter1 (ER-ANT1) resides in the endoplasmic reticulum (ER) membrane and acts as an ATP/ADP antiporter. Mutant plants lacking ER-ANT1 exhibit a dwarf phenotype and their seeds contain reduced protein and lipid contents. In this study, we describe a further surprising metabolic peculiarity of the er-ant1 mutants. Interestingly, Gly levels in leaves are immensely enhanced (26×) when compared with that of wild-type plants. Gly accumulation is caused by significantly decreased mitochondrial glycine decarboxylase (GDC) activity. Reduced GDC activity in mutant plants was attributed to oxidative posttranslational protein modification induced by elevated levels of reactive oxygen species (ROS). GDC activity is crucial for photorespiration; accordingly, morphological and physiological defects in er-ant1 plants were nearly completely abolished by application of high environmental CO(2) concentrations. The latter observation demonstrates that the absence of ER-ANT1 activity mainly affects photorespiration (maybe solely GDC), whereas basic cellular metabolism remains largely unchanged. Since ER-ANT1 homologs are restricted to higher plants, it is tempting to speculate that this carrier fulfils a plant-specific function directly or indirectly controlling cellular ROS production. The observation that ER-ANT1 activity is associated with cellular ROS levels reveals an unexpected and critical physiological connection between the ER and other organelles in plants.

Predictive factors for initial treatment response after circumferential radiofrequency ablation for Barrett's esophagus with early neoplasia: a prospective multicenter study.

BACKGROUND AND STUDY AIMS: Radiofrequency ablation (RFA) is safe and effective for the eradication of neoplastic Barrett's esophagus; however, occasionally there is minimal regression after initial circumferential balloon-based RFA (c-RFA). This study aimed to identify predictive factors for a poor response 3 months after c-RFA, and to relate the percentage regression at 3 months to the final treatment outcome. METHODS: We included consecutive patients from 14 centers who underwent c-RFA for high grade dysplasia at worst. Patient and treatment characteristics were registered prospectively. "Poor initial response" was defined as < 50 % regression of the Barrett's esophagus 3 months after c-RFA, graded by two expert endoscopists using endoscopic images. Predictors of initial response were identified through logistic regression analysis. RESULTS: There were 278 patients included (median Barrett's segment C4M6). In poor initial responders (n = 36; 13 %), complete response for neoplasia (CR-neoplasia) was ultimately achieved in 86 % (vs. 98 % in good responders; P < 0.01) and complete response for intestinal metaplasia (CR-IM) in 66 % (vs. 95 %; P < 0.01). Poor responders required 13 months treatment (vs. 7 months; P < 0.01) for a median of four RFA sessions (vs. three; P < 0.01). We identified four independent baseline predictors of poor response: active reflux esophagitis (odds ratio [OR] 37.4; 95 % confidence interval [CI] 3.2 - 433.2); endoscopic resection scar regeneration with Barrett's epithelium (OR 4.7; 95 %CI 1.1 - 20.0); esophageal narrowing pre-RFA (OR 3.9; 95 %CI 1.0 - 15.1); and years of neoplasia pre-RFA (OR 1.2; 95 %CI 1.0 - 1.4). CONCLUSIONS: Patients with a poor initial response to c-RFA have a lower ultimate success rate for CR-neoplasia/CR-IM, require more treatment sessions, and a longer treatment period. A poor initial response to c-RFA occurs more frequently in patients who regenerate their endoscopic resection scar with Barrett's epithelium, and those with ongoing reflux esophagitis, neoplasia in Barrett's esophagus for a longer time, or a narrow esophagus.

NOTES in Europe: summary of the working group reports of the 2012 EURO-NOTES meeting.

The sixth EURO-NOTES workshop (4 - 6 October 2012, Prague, Czech Republic) focused on enabling intensive scientific dialogue and interaction between surgeons, gastroenterologists, and engineers/industry representatives and discussion of the state of the practice and development of natural orifice transluminal endoscopic surgery (NOTES) in Europe. In accordance with previous meetings, five working groups were formed. In 2012, emphasis was put on specific indications for NOTES and interventional endoscopy. Each group was assigned an important indication related to ongoing research in NOTES and interventional endoscopy: cholecystectomy and appendectomy, therapy of colorectal diseases, therapy of adenocarcinoma and neoplasia in the upper gastrointestinal tract, treating obesity, and new therapeutic approaches for achalasia. This review summarizes consensus statements of the working groups.