Non-alcoholic fatty liver disease (NAFLD) is characterized by hepatic lipid accumulation in the absence of excess alcohol intake. NAFLD is the most common chronic liver disease, and ongoing research ...efforts are focused on understanding the underlying pathobiology of hepatic steatosis with the anticipation that these efforts will identify novel therapeutic targets. Under physiological conditions, the low steady-state triglyceride concentrations in the liver are attributable to a precise balance between acquisition by uptake of non-esterified fatty acids from the plasma and by de novo lipogenesis, versus triglyceride disposal by fatty acid oxidation and by the secretion of triglyceride-rich lipoproteins. In NAFLD patients, insulin resistance leads to hepatic steatosis by multiple mechanisms. Greater uptake rates of plasma non-esterified fatty acids are attributable to increased release from an expanded mass of adipose tissue as a consequence of diminished insulin responsiveness. Hyperinsulinemia promotes the transcriptional upregulation of genes that promote de novo lipogenesis in the liver. Increased hepatic lipid accumulation is not offset by fatty acid oxidation or by increased secretion rates of triglyceride-rich lipoproteins. This review discusses the molecular mechanisms by which hepatic triglyceride homeostasis is achieved under normal conditions, as well as the metabolic alterations that occur in the setting of insulin resistance and contribute to the pathogenesis of NAFLD.
Understanding the etiology of metastasis is very important in clinical perspective, since it is estimated that metastasis accounts for 90% of cancer patient mortality. Metastasis results from a ...sequence of multiple steps including invasion and migration. The early stages of metastasis are tightly controlled in normal cells and can be drastically affected by malignant mutations; therefore, they might constitute the principal determinants of the overall metastatic rate even if the later stages take long to occur. To elucidate the role of individual mutations or their combinations affecting the metastatic development, a logical model has been constructed that recapitulates published experimental results of known gene perturbations on local invasion and migration processes, and predict the effect of not yet experimentally assessed mutations. The model has been validated using experimental data on transcriptome dynamics following TGF-β-dependent induction of Epithelial to Mesenchymal Transition in lung cancer cell lines. A method to associate gene expression profiles with different stable state solutions of the logical model has been developed for that purpose. In addition, we have systematically predicted alleviating (masking) and synergistic pairwise genetic interactions between the genes composing the model with respect to the probability of acquiring the metastatic phenotype. We focused on several unexpected synergistic genetic interactions leading to theoretically very high metastasis probability. Among them, the synergistic combination of Notch overexpression and p53 deletion shows one of the strongest effects, which is in agreement with a recent published experiment in a mouse model of gut cancer. The mathematical model can recapitulate experimental mutations in both cell line and mouse models. Furthermore, the model predicts new gene perturbations that affect the early steps of metastasis underlying potential intervention points for innovative therapeutic strategies in oncology.
Nonalcoholic fatty liver disease (NAFLD) is a liver manifestation of metabolic syndrome. Overconsumption of high-fat diet (HFD) and increased intake of sugar-sweetened beverages are major risk ...factors for development of NAFLD. Today the most commonly consumed sugar is high fructose corn syrup. Hepatic lipids may be derived from dietary intake, esterification of plasma free fatty acids (FFA) or hepatic de novo lipogenesis (DNL). A central abnormality in NAFLD is enhanced DNL. Hepatic DNL is increased in individuals with NAFLD, while the contribution of dietary fat and plasma FFA to hepatic lipids is not significantly altered. The importance of DNL in NAFLD is further established in mouse studies with knockout of genes involved in this process. Dietary fructose increases levels of enzymes involved in DNL even more strongly than HFD. Several properties of fructose metabolism make it particularly lipogenic. Fructose is absorbed via portal vein and delivered to the liver in much higher concentrations as compared to other tissues. Fructose increases protein levels of all DNL enzymes during its conversion into triglycerides. Additionally, fructose supports lipogenesis in the setting of insulin resistance as fructose does not require insulin for its metabolism, and it directly stimulates SREBP1c, a major transcriptional regulator of DNL. Fructose also leads to ATP depletion and suppression of mitochondrial fatty acid oxidation, resulting in increased production of reactive oxygen species. Furthermore, fructose promotes ER stress and uric acid formation, additional insulin independent pathways leading to DNL. In summary, fructose metabolism supports DNL more strongly than HFD and hepatic DNL is a central abnormality in NAFLD. Disrupting fructose metabolism in the liver may provide a new therapeutic option for the treatment of NAFLD.
Cardiovascular disease represents the most common cause of death in patients with nonalcoholic fatty liver disease (NAFLD). Patients with NAFLD exhibit an atherogenic dyslipidemia that is ...characterized by an increased plasma concentration of triglycerides, reduced concentration of high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) particles that are smaller and more dense than normal. The pathogenesis of NAFLD-associated atherogenic dyslipidemia is multifaceted, but many aspects are attributable to manifestations of insulin resistance. Here the authors review the structure, function, and metabolism of lipoproteins, which are macromolecular particles of lipids and proteins that transport otherwise insoluble triglyceride and cholesterol molecules within the plasma. They provide a current explanation of the metabolic perturbations that are observed in the setting of insulin resistance. An improved understanding of the pathophysiology of atherogenic dyslipidemia would be expected to guide therapies aimed at reducing morbidity and mortality in patients with NAFLD.
Constraint satisfaction is a simple but powerful tool. Constraints identify the impossible and reduce the realm of possibilities to effectively focus on the possible, allowing for a natural ...declarative formulation of what must be satisfied, without expressing how. The field of constraint reasoning has matured over the last three decades with contributions from a diverse community of researchers in artificial intelligence, databases and programming languages, operations research, management science, and applied mathematics. Today, constraint problems are used to model cognitive tasks in vision, language comprehension, default reasoning, diagnosis, scheduling, temporal and spatial reasoning. In Constraint Processing, Rina Dechter, synthesizes these contributions, along with her own significant work, to provide the first comprehensive examination of the theory that underlies constraint processing algorithms. Throughout, she focuses on fundamental tools and principles, emphasizing the representation and analysis of algorithms. * Examines the basic practical aspects of each topic and then tackles more advanced issues, including current research challenges * Builds the reader's understanding with definitions, examples, theory, algorithms and complexity analysis * Synthesizes three decades of researchers work on constraint processing in AI, databases and programming languages, operations research, management science, and applied mathematics
Despite the substantial gains in our understanding of NAFLD/NASH over the past 2 decades, there has been some dissatisfaction with the terminology “non‐alcoholic” which overemphasizes “alcohol” and ...underemphasizes the root cause of this liver disease, namely, the predisposing metabolic risk factors. As a potential remedy, a name change from NAFLD to metabolic associated fatty liver disease (MAFLD) has been proposed. Although MAFLD reflects the relevant risk factors for this liver disease, this term is still suboptimal, leaving a great deal of ambiguity. Here, we caution that changing the name without understanding its broad implications can have a negative impact on the field. In this context, changing the terminology without new understanding of the molecular basis of the disease entity, new insights in risk stratification or other important aspect of this liver disease, can create unnecessary confusion which could negatively impact the field. At a time when the field is facing substantial challenges around disease awareness as well as clarity of acceptable endpoints for drug development and biomarker discovery, changing the terminology from one suboptimal name to another suboptimal name without full assessment is expected to deepen these challenges. In the context of this debate about terminology, we recommend the creation of a true international consensus group to include all the relevant scientific liver societies (AASLD, EASL, ALEH, APASL), patient advocacy organizations, bio‐pharmaceutical industry, regulatory agencies and policy makers. A consensus meeting must assess the impact and consequences of changing the terminology based on the available evidence and make recommendations that will move the field forward. By this approach, a true collaborative international and inclusive consensus can be adopted by all stakeholders dealing with this important global liver disease.
Abstract
Tumor progression and the efficacy of immunotherapy are strongly influenced by the composition and abundance of immune cells in the tumor microenvironment. Due to the limitations of direct ...measurement methods, computational algorithms are often used to infer immune cell composition from bulk tumor transcriptome profiles. These estimated tumor immune infiltrate populations have been associated with genomic and transcriptomic changes in the tumors, providing insight into tumor–immune interactions. However, such investigations on large-scale public data remain challenging. To lower the barriers for the analysis of complex tumor–immune interactions, we significantly improved our previous web platform TIMER. Instead of just using one algorithm, TIMER2.0 (http://timer.cistrome.org/) provides more robust estimation of immune infiltration levels for The Cancer Genome Atlas (TCGA) or user-provided tumor profiles using six state-of-the-art algorithms. TIMER2.0 provides four modules for investigating the associations between immune infiltrates and genetic or clinical features, and four modules for exploring cancer-related associations in the TCGA cohorts. Each module can generate a functional heatmap table, enabling the user to easily identify significant associations in multiple cancer types simultaneously. Overall, the TIMER2.0 web server provides comprehensive analysis and visualization functions of tumor infiltrating immune cells.
Nonalcoholic fatty liver disease (NAFLD) is an increasingly common condition that is believed to affect >25% of adults worldwide. Unless specific testing is done to identify NAFLD, the condition is ...typically silent until advanced and potentially irreversible liver impairment occurs. For this reason, the majority of patients with NAFLD are unaware of having this serious condition. Hepatic complications from NAFLD include nonalcoholic steatohepatitis, hepatic cirrhosis, and hepatocellular carcinoma. In addition to these serious complications, NAFLD is a risk factor for atherosclerotic cardiovascular disease, which is the principal cause of death in patients with NAFLD. Accordingly, the purpose of this scientific statement is to review the underlying risk factors and pathophysiology of NAFLD, the associations with atherosclerotic cardiovascular disease, diagnostic and screening strategies, and potential interventions.
Transcatheter aortic valve implantation (TAVI) has spawned the evolution of novel catheter-based therapies for a variety of cardiovascular conditions. Newer device iterations are delivering lower ...peri- and early post-procedural complication rates in patients with aortic stenosis, who were otherwise deemed too high risk for conventional surgical valve replacement. Yet beyond the post-procedural period, a considerable portion of current TAVI recipients fail to derive a benefit from TAVI, either dying or displaying a lack of clinical and functional improvement. Considerable interest now lies in better identifying factors likely to predict futility post-TAVI. Implicit in this are the critical roles of frailty, disability, and a multimorbidity patient assessment. In this review, we outline the roles that a variety of medical comorbidities play in determining futile post-TAVI outcomes, including the critical role of frailty underlying the identification of patients unlikely to benefit from TAVI. We discuss various TAVI risk scores, and further propose that by combining such scores along with frailty parameters and the presence of specific organ failure, a more accurate and holistic assessment of potential TAVI-related futility could be achieved.
There are scant data on long-term clinical outcomes and bioprosthetic-valve function after transcatheter aortic-valve replacement (TAVR) as compared with surgical aortic-valve replacement in patients ...with severe aortic stenosis and intermediate surgical risk.
We enrolled 2032 intermediate-risk patients with severe, symptomatic aortic stenosis at 57 centers. Patients were stratified according to intended transfemoral or transthoracic access (76.3% and 23.7%, respectively) and were randomly assigned to undergo either TAVR or surgical replacement. Clinical, echocardiographic, and health-status outcomes were followed for 5 years. The primary end point was death from any cause or disabling stroke.
At 5 years, there was no significant difference in the incidence of death from any cause or disabling stroke between the TAVR group and the surgery group (47.9% and 43.4%, respectively; hazard ratio, 1.09; 95% confidence interval CI, 0.95 to 1.25; P = 0.21). Results were similar for the transfemoral-access cohort (44.5% and 42.0%, respectively; hazard ratio, 1.02; 95% CI, 0.87 to 1.20), but the incidence of death or disabling stroke was higher after TAVR than after surgery in the transthoracic-access cohort (59.3% vs. 48.3%; hazard ratio, 1.32; 95% CI, 1.02 to 1.71). At 5 years, more patients in the TAVR group than in the surgery group had at least mild paravalvular aortic regurgitation (33.3% vs. 6.3%). Repeat hospitalizations were more frequent after TAVR than after surgery (33.3% vs. 25.2%), as were aortic-valve reinterventions (3.2% vs. 0.8%). Improvement in health status at 5 years was similar for TAVR and surgery.
Among patients with aortic stenosis who were at intermediate surgical risk, there was no significant difference in the incidence of death or disabling stroke at 5 years after TAVR as compared with surgical aortic-valve replacement. (Funded by Edwards Lifesciences; PARTNER 2 ClinicalTrials.gov number, NCT01314313.).
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