Summary Acute upper gastrointestinal bleeding is a common medical emergency worldwide, a major cause of which are bleeding peptic ulcers. Endoscopic treatment and acid suppression with proton-pump ...inhibitors are cornerstones in the management of the disease, and both treatments have been shown to reduce mortality. The role of emergency surgery continues to diminish. In specialised centres, radiological intervention is increasingly used in patients with severe and recurrent bleeding who do not respond to endoscopic treatment. Despite these advances, mortality from the disorder has remained at around 10%. The disease often occurs in elderly patients with frequent comorbidities who use antiplatelet agents, non-steroidal anti-inflammatory drugs, and anticoagulants. The management of such patients, especially those at high cardiothrombotic risk who are on anticoagulants, is a challenge for clinicians. We summarise the published scientific literature about the management of patients with bleeding peptic ulcers, identify directions for future clinical research, and suggest how mortality can be reduced.
Background & Aims The epidemiology of Helicobacter pylori infection has changed with improvements in sanitation and methods of eradication. We performed a systematic review and meta-analysis to ...evaluate changes in the global prevalence of H pylori infection. Methods We performed a systematic search of the MEDLINE and EMBASE databases for studies of the prevalence of H pylori infection published from January 1, 1970 through January 1, 2016. We analyzed data based on United Nations geoscheme regions and individual countries. We used a random effects model to calculate pooled prevalence estimates with 95% confidence intervals (CIs), weighted by study size. We extrapolated 2015 prevalence estimates to obtain the estimated number of individuals with H pylori infection. Results Among 14,006 reports screened, we identified 263 full-text articles on the prevalence of H pylori infection; 184 were included in the final analysis, comprising data from 62 countries. Africa had the highest pooled prevalence of H pylori infection (70.1%; 95% CI, 62.6−77.7), whereas Oceania had the lowest prevalence (24.4%; 95% CI, 18.5−30.4). Among individual countries, the prevalence of H pylori infection varied from as low as 18.9% in Switzerland (95% CI, 13.1−24.7) to 87.7% in Nigeria (95% CI, 83.1−92.2). Based on regional prevalence estimates, there were approximately 4.4 billion individuals with H pylori infection worldwide in 2015. Conclusions In a systematic review and meta-analysis to assess the prevalence of H pylori infection worldwide, we observed large amounts of variation among regions—more than half the world’s population is infected. These data can be used in development of customized strategies for the global eradication.
Upper gastrointestinal bleeding (UGIB), especially peptic ulcer bleeding, remains one of the most important cause of hospitalisation and mortality world wide. In Asia, with a high prevalence of ...Helicobacter pylori infection, a potential difference in drug metabolism, and a difference in clinical management of UGIB due to variable socioeconomic environments, it is considered necessary to re-examine the International Consensus of Non-variceal Upper Gastrointestinal Bleeding with emphasis on data generated from the region. The working group, which comprised experts from 12 countries from Asia, recommended the use of the Blatchford score for selection of patients who require endoscopic intervention and which would allow early discharge of patients at low risk. Patients' comorbid conditions should be included in risk assessment. A pre-endoscopy proton pump inhibitor (PPI) is recommended as a stop-gap treatment when endoscopy within 24 h is not available. An adherent clot on a peptic ulcer should be treated with endoscopy combined with a PPI if the clot cannot be removed. Routine repeated endoscopy is not recommended. High-dose intravenous and oral PPIs are recommended but low-dose intravenous PPIs should be avoided. COX-2 selective non-steroidal anti-inflammatory drugs combined with a PPI are recommended for patients with very high risk of UGIB. Aspirin should be resumed soon after stabilisation and clopidogrel alone is no safer than aspirin plus a PPI. When dual antiplatelet agents are used, prophylactic use of a PPI reduces the risk of adverse gastrointestinal events.
Patients with acute upper gastrointestinal bleeding were assigned to receive endoscopy within 6 hours or between 6 and 24 hours after gastroenterologic consultation. Mortality at 30 days was 8.9% in ...the former group and 6.6% in the latter group; earlier endoscopy did not lower mortality.
Deep neural networks currently provide the best quantitative models of the response patterns of neurons throughout the primate ventral visual stream. However, such networks have remained implausible ...as a model of the development of the ventral stream, in part because they are trained with supervised methods requiring many more labels than are accessible to infants during development. Here, we report that recent rapid progress in unsupervised learning has largely closed this gap. We find that neural network models learned with deep unsupervised contrastive embedding methods achieve neural prediction accuracy in multiple ventral visual cortical areas that equals or exceeds that of models derived using today's best supervised methods and that the mapping of these neural network models' hidden layers is neuroanatomically consistent across the ventral stream. Strikingly, we find that these methods produce brain-like representations even when trained solely with real human child developmental data collected from head-mounted cameras, despite the fact that these datasets are noisy and limited. We also find that semisupervised deep contrastive embeddings can leverage small numbers of labeled examples to produce representations with substantially improved error-pattern consistency to human behavior. Taken together, these results illustrate a use of unsupervised learning to provide a quantitative model of a multiarea cortical brain system and present a strong candidate for a biologically plausible computational theory of primate sensory learning.
Fueled by innovation in the computer vision and artificial intelligence communities, recent developments in computational neuroscience have used goal-driven hierarchical convolutional neural networks ...(HCNNs) to make strides in modeling neural single-unit and population responses in higher visual cortical areas. In this Perspective, we review the recent progress in a broader modeling context and describe some of the key technical innovations that have supported it. We then outline how the goal-driven HCNN approach can be used to delve even more deeply into understanding the development and organization of sensory cortical processing.
The contact resistance in organic thin-film transistors (TFTs) is the limiting factor in the development of high-frequency organic TFTs. In devices fabricated in the inverted (bottom-gate) device ...architecture, staggered (top-contact) organic TFTs have usually shown or are predicted to show lower contact resistance than coplanar (bottom-contact) organic TFTs. However, through comparison of organic TFTs with different gate-dielectric thicknesses based on the small-molecule organic semiconductor 2,9-diphenyl-dinaphtho2,3-b:2',3'-fthieno3,2-bthiophene, we show the potential for bottom-contact TFTs to have lower contact resistance than top-contact TFTs, provided the gate dielectric is sufficiently thin and an interface layer such as pentafluorobenzenethiol is used to treat the surface of the source and drain contacts. We demonstrate bottom-contact TFTs fabricated on flexible plastic substrates with record-low contact resistance (29 Ωcm), record subthreshold swing (62 mV/decade), and signal-propagation delays in 11-stage unipolar ring oscillators as short as 138 ns per stage, all at operating voltages of about 3 V.
The primate visual system achieves remarkable visual object recognition performance even in brief presentations, and under changes to object exemplar, geometric transformations, and background ...variation (a.k.a. core visual object recognition). This remarkable performance is mediated by the representation formed in inferior temporal (IT) cortex. In parallel, recent advances in machine learning have led to ever higher performing models of object recognition using artificial deep neural networks (DNNs). It remains unclear, however, whether the representational performance of DNNs rivals that of the brain. To accurately produce such a comparison, a major difficulty has been a unifying metric that accounts for experimental limitations, such as the amount of noise, the number of neural recording sites, and the number of trials, and computational limitations, such as the complexity of the decoding classifier and the number of classifier training examples. In this work, we perform a direct comparison that corrects for these experimental limitations and computational considerations. As part of our methodology, we propose an extension of "kernel analysis" that measures the generalization accuracy as a function of representational complexity. Our evaluations show that, unlike previous bio-inspired models, the latest DNNs rival the representational performance of IT cortex on this visual object recognition task. Furthermore, we show that models that perform well on measures of representational performance also perform well on measures of representational similarity to IT, and on measures of predicting individual IT multi-unit responses. Whether these DNNs rely on computational mechanisms similar to the primate visual system is yet to be determined, but, unlike all previous bio-inspired models, that possibility cannot be ruled out merely on representational performance grounds.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This update of the 2010 International Consensus Recommendations on the Management of Patients With Nonvariceal Upper Gastrointestinal Bleeding (UGIB) refines previous important statements and ...presents new clinically relevant recommendations.
An international multidisciplinary group of experts developed the recommendations. Data sources included evidence summarized in previous recommendations, as well as systematic reviews and trials identified from a series of literature searches of several electronic bibliographic databases from inception to April 2018. Using an iterative process, group members formulated key questions. Two methodologists prepared evidence profiles and assessed quality (certainty) of evidence relevant to the key questions according to the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. Group members reviewed the evidence profiles and, using a consensus process, voted on recommendations and determined the strength of recommendations as strong or conditional.
Preendoscopic management: The group suggests using a Glasgow Blatchford score of 1 or less to identify patients at very low risk for rebleeding, who may not require hospitalization. In patients without cardiovascular disease, the suggested hemoglobin threshold for blood transfusion is less than 80 g/L, with a higher threshold for those with cardiovascular disease. Endoscopic management: The group suggests that patients with acute UGIB undergo endoscopy within 24 hours of presentation. Thermocoagulation and sclerosant injection are recommended, and clips are suggested, for endoscopic therapy in patients with high-risk stigmata. Use of TC-325 (hemostatic powder) was suggested as temporizing therapy, but not as sole treatment, in patients with actively bleeding ulcers. Pharmacologic management: The group recommends that patients with bleeding ulcers with high-risk stigmata who have had successful endoscopic therapy receive high-dose proton-pump inhibitor (PPI) therapy (intravenous loading dose followed by continuous infusion) for 3 days. For these high-risk patients, continued oral PPI therapy is suggested twice daily through 14 days, then once daily for a total duration that depends on the nature of the bleeding lesion. Secondary prophylaxis: The group suggests PPI therapy for patients with previous ulcer bleeding who require antiplatelet or anticoagulant therapy for cardiovascular prophylaxis.
Extensive research has revealed that the ventral visual stream hierarchically builds a robust representation for supporting visual object categorization tasks. We systematically explored the ability ...of multiple ventral visual areas to support a variety of 'category-orthogonal' object properties such as position, size and pose. For complex naturalistic stimuli, we found that the inferior temporal (IT) population encodes all measured category-orthogonal object properties, including those properties often considered to be low-level features (for example, position), more explicitly than earlier ventral stream areas. We also found that the IT population better predicts human performance patterns across properties. A hierarchical neural network model based on simple computational principles generates these same cross-area patterns of information. Taken together, our empirical results support the hypothesis that all behaviorally relevant object properties are extracted in concert up the ventral visual hierarchy, and our computational model explains how that hierarchy might be built.
PDF
