Nonalcoholic fatty liver disease (NAFLD) has emerged as the most common chronic liver disease worldwide and is strongly associated with the presence of oxidative stress. Disturbances in lipid ...metabolism lead to hepatic lipid accumulation, which affects different reactive oxygen species (ROS) generators, including mitochondria, endoplasmic reticulum, and NADPH oxidase. Mitochondrial function adapts to NAFLD mainly through the downregulation of the electron transport chain (ETC) and the preserved or enhanced capacity of mitochondrial fatty acid oxidation, which stimulates ROS overproduction within different ETC components upstream of cytochrome c oxidase. However, non-ETC sources of ROS, in particular, fatty acid β-oxidation, appear to produce more ROS in hepatic metabolic diseases. Endoplasmic reticulum stress and NADPH oxidase alterations are also associated with NAFLD, but the degree of their contribution to oxidative stress in NAFLD remains unclear. Increased ROS generation induces changes in insulin sensitivity and in the expression and activity of key enzymes involved in lipid metabolism. Moreover, the interaction between redox signaling and innate immune signaling forms a complex network that regulates inflammatory responses. Based on the mechanistic view described above, this review summarizes the mechanisms that may account for the excessive production of ROS, the potential mechanistic roles of ROS that drive NAFLD progression, and therapeutic interventions that are related to oxidative stress.
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•Oxidative stress plays a central role in the pathogenesis of NAFLD.•Mechanisms for ROS production include alterations in the mitochondria, ER, and NOX.•Non-ETC sources, especially β-oxidation, are important sources of mitochondrial ROS.•ROS signaling modulates lipid metabolism, insulin signaling, and inflammation.•Targeting hepatic oxidative stress is a promising strategy to treat NAFLD.
A Co-Saliency Model of Image Pairs Li, Hongliang; Ngan, King Ngi
IEEE transactions on image processing,
12/2011, Volume:
20, Issue:
12
Journal Article
Peer reviewed
In this paper, we introduce a method to detect co-saliency from an image pair that may have some objects in common. The co-saliency is modeled as a linear combination of the single-image saliency map ...(SISM) and the multi-image saliency map (MISM). The first term is designed to describe the local attention, which is computed by using three saliency detection techniques available in literature. To compute the MISM, a co-multilayer graph is constructed by dividing the image pair into a spatial pyramid representation. Each node in the graph is described by two types of visual descriptors, which are extracted from a representation of some aspects of local appearance, e.g., color and texture properties. In order to evaluate the similarity between two nodes, we employ a normalized single-pair SimRank algorithm to compute the similarity score. Experimental evaluation on a number of image pairs demonstrates the good performance of the proposed method on the co-saliency detection task.
Inflammation and metabolic dysfunction are hallmarks of nonalcoholic steatohepatitis (NASH), which is one of the fastest‐growing liver diseases worldwide. Emerging evidence indicates that innate ...immune mechanisms are pivotal drivers of inflammation and other pathological manifestations observed in NASH, such as hepatosteatosis, insulin resistance (IR), and fibrosis. This robust innate immune reaction is intrinsic to the liver, which is an important immunological organ that contains a coordinated network of innate immune cells, including Kupffer cells (KCs), dendritic cells (DCs), and lymphocytes. Hepatocytes and liver sinusoidal endothelial cells (LSECs) are not formally innate immune cells, but they take on immune cell function when stressed. These cells can sense excess metabolites and bacterial products and translate those signals into immune responses and pathological hepatic changes during the development of NASH. In this review, we take a historical perspective in describing decades of research that aimed to identify the key molecular and cellular players in the innate immune system in the setting of NASH. Furthermore, we summarize the innate immune cells that are involved in the progression of NASH and illustrate how they sense disturbances in circulating metabolic factors by innate immune receptors and subsequently initiate the intercellular signaling cascades that lead to persistent inflammation and progression of hepatic complications.
The great content diversity of real-world digital images poses a grand challenge to image quality assessment (IQA) models, which are traditionally designed and validated on a handful of commonly used ...IQA databases with very limited content variation. To test the generalization capability and to facilitate the wide usage of IQA techniques in real-world applications, we establish a large-scale database named the Waterloo Exploration Database, which in its current state contains 4744 pristine natural images and 94 880 distorted images created from them. Instead of collecting the mean opinion score for each image via subjective testing, which is extremely difficult if not impossible, we present three alternative test criteria to evaluate the performance of IQA models, namely, the pristine/distorted image discriminability test, the listwise ranking consistency test, and the pairwise preference consistency test (P-test). We compare 20 well-known IQA models using the proposed criteria, which not only provide a stronger test in a more challenging testing environment for existing models, but also demonstrate the additional benefits of using the proposed database. For example, in the P-test, even for the best performing no-reference IQA model, more than 6 million failure cases against the model are "discovered" automatically out of over 1 billion test pairs. Furthermore, we discuss how the new database may be exploited using innovative approaches in the future, to reveal the weaknesses of existing IQA models, to provide insights on how to improve the models, and to shed light on how the next-generation IQA models may be developed. The database and codes are made publicly available at: https://ece.uwaterloo.ca/~k29ma/exploration/.
This study used data from the National Health and Nutrition Examination Survey (NHANES) to investigate the relationship between the triglyceride-glucose (TyG) index and gallstones. We evaluated the ...data collected between 2017 to 2020. To evaluate the relationship between TyG index and gallstones, logistic regression analysis, basic characteristics of participants, subgroup analysis, and smooth curve fitting were utilized. The study included 3870 participants over the age of 20 years, 403 of whom reported gallstones, with a prevalence rate of 10.4%. After adjusting for all confounding factors, the risk of gallstones increased by 41% for each unit increase in the TyG index (OR 1.41, 95% CI 1.07, 1.86). The smooth curve fitting also showed a positive correlation between the TyG index and gallstones. Subgroup analysis revealed a significant positive relationship between the TyG index and the risk of gallstones in those aged < 50 years, women, individuals with total cholesterol levels > 200 mg/dL, individuals with body mass index (BMI) > 25, and individuals without diabetes. The risk of gallstones is positively correlated with a higher TyG index. Thus, the TyG index can be used as a predictor of the risk of gallstones.
Classifying texture images, especially those with significant rotation, illumination, scale, and viewpoint changes, is a fundamental and challenging problem in computer vision. This paper proposes a ...simple yet effective image descriptor, called Locally Encoded TRansform feature hISTogram (LETRIST), for texture classification. LETRIST is a histogram representation that explicitly encodes the joint information within an image across feature and scale spaces. The proposed representation is training-free, low-dimensional, yet discriminative and robust for texture description. It consists of the following major steps. First, a set of transform features is constructed to characterize local texture structures and their correlation by applying linear and non-linear operators on the extremum responses of directional Gaussian derivative filters in scale space. Established on the basis of steerable filters, the constructed transform features are exactly rotationally invariant as well as computationally efficient. Second, the scalar quantization via binary or multi-level thresholding is adopted to quantize these transform features into texture codes. Two quantization schemes are designed, both of which are robust to image rotation and illumination changes. Third, the cross-scale joint coding is explored to aggregate the discrete texture codes into a compact histogram representation, i.e., LETRIST. Experimental results on the Outex, CUReT, KTH-TIPS, and UIUC texture data sets show that LETRIST consistently produces better or comparable classification results than the state-of-the-art approaches. Impressively, recognition rates of 100.00% and 99.00% have been achieved on the Outex and KTH-TIPS data sets, respectively. In addition, the noise robustness is evaluated on the Outex and CUReT data sets. The source code is publicly available at https://github.com/stc-cqupt/letrist .
As the key for biological sequence structure and function prediction, disease diagnosis and treatment, biological sequence similarity analysis has attracted more and more attentions. However, the ...exiting computational methods failed to accurately analyse the biological sequence similarities because of the various data types (DNA, RNA, protein, disease, etc) and their low sequence similarities (remote homology). Therefore, new concepts and techniques are desired to solve this challenging problem. Biological sequences (DNA, RNA and protein sequences) can be considered as the sentences of "the book of life", and their similarities can be considered as the biological language semantics (BLS). In this study, we are seeking the semantics analysis techniques derived from the natural language processing (NLP) to comprehensively and accurately analyse the biological sequence similarities. 27 semantics analysis methods derived from NLP were introduced to analyse biological sequence similarities, bringing new concepts and techniques to biological sequence similarity analysis. Experimental results show that these semantics analysis methods are able to facilitate the development of protein remote homology detection, circRNA-disease associations identification and protein function annotation, achieving better performance than the other state-of-the-art predictors in the related fields. Based on these semantics analysis methods, a platform called BioSeq-Diabolo has been constructed, which is named after a popular traditional sport in China. The users only need to input the embeddings of the biological sequence data. BioSeq-Diabolo will intelligently identify the task, and then accurately analyse the biological sequence similarities based on biological language semantics. BioSeq-Diabolo will integrate different biological sequence similarities in a supervised manner by using Learning to Rank (LTR), and the performance of the constructed methods will be evaluated and analysed so as to recommend the best methods for the users. The web server and stand-alone package of BioSeq-Diabolo can be accessed at http://bliulab.net/BioSeq-Diabolo/server/.
The newly developed HEVC video coding standard can achieve higher compression performance than the previous video coding standards, such as MPEG-4, H.263 and H.264/AVC. However, HEVC's high ...computational complexity raises concerns about the computational burden on real-time application. In this paper, a fast pyramid motion divergence (PMD) based CU selection algorithm is presented for HEVC inter prediction. The PMD features are calculated with estimated optical flow of the downsampled frames. Theoretical analysis shows that PMD can be used to help selecting CU size. A k nearest neighboring like method is used to determine the CU splittings. Experimental results show that the fast inter prediction method speeds up the inter coding significantly with negligible loss of the peak signal-to-noise ratio.
Abstract
To date, the effect of oxidation state on activity remains controversial in whether higher or lower oxidation states benefit the enhancement of catalytic activity. Herein, we discover a ...volcanic relationship between oxidation state and hydrogen evolution reaction activity based on Os single-atom catalysts. Firstly, a series of Os SACs with oxidation states ranging from + 0.9 to + 2.9 are synthesized via modifying the coordination environments, including Os-N
3
S
1
, Os-N
4
, Os-S
6
, Os-C
3
, and Os-C
4
S
2
. A volcano-type relation between oxidation states and hydrogen evolution activity emerge with a summit at a moderate experimental oxidation state of + 1.3 (Os-N
3
S
1
). Mechanism studies illustrate that with increasing oxidation states, the adsorption of H atoms on Os is strengthened due to increased energy level and decreased occupancy of anti-bonding states of Os-H bond until the anti-bonding states become empty. Further increasing the oxidation states weakens hydrogen adsorption because of the decreased occupancy of Os-H bonding states. In this work, we emphasize the essential role of oxidation state in manipulating activity, which offers insightful guidance for the rational design of single-atom catalysts.
With dramatic changes in lifestyles over the last 20 years, nonalcoholic fatty liver disease (NAFLD) has become the most prevalent liver disorder in China but has not received sufficient attention. ...NAFLD‐related advanced liver disease and its mortality along with its overall disease burden are expected to increase substantially. There is thus an imperative need to clarify the epidemiological features of NAFLD to guide a holistic approach to management. We summarize eight epidemiological features of NAFLD in China over the past two decades using systematic review and meta‐analysis methodology. Our data reveal a rapid growth in the NAFLD population, especially among younger individuals. Importantly, there is a strong ethnic difference in body mass index (BMI) and genetic risk of NAFLD compared with the US population. The etiology of advanced liver disease and its complications (e.g., hepatocellular carcinoma) has been altered because of a Westernized lifestyle and the implementation of effective vaccination strategies against viral hepatitis. Regional epidemiological patterns of NAFLD indicate that economics, environment, and lifestyle are critical factors in disease progression. The analysis also indicates that a large number of patients remain undiagnosed and untreated because of the inadequacy of diagnostic tools and the absence of effective pharmacologic therapies. Given the burden of NAFLD, future policy and research efforts need to address knowledge gaps to mitigate the risk burden.
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