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BACKGROUND & AIMS: Both metabolic dysfunction and alcohol consumption cause steatotic liver disease (SLD). New nomenclature and distinction of metabolic dysfunction-associated SLD (MASLD) and MetALD categories is based on arbitrary thresholds of alcohol intake. We assessed the impact of different levels of alcohol consumption on SLD severity and its interaction with metabolic comorbidities. METHODS: Population-based study with transient elastography (FibroScan®) data from participants in Spain (derivation) and U.S. (validation) cohorts. Controlled attenuation parameter (CAP≥275 dB/m) identified SLD. At least one cardiometabolic risk factor was required to define MASLD. Among MASLD patients, low alcohol consumption was defined as an average of 5-9 drinks/week, moderate consumption as 10-13 drinks/week for females and 10-20 drinks/week for males, and increased alcohol intake (MetALD) as 14-35 drinks/week for females and 21-42 drinks/week for males. Significant fibrosis was defined as LSM≥8 kPa and at-risk MASH as FAST score≥0.35. RESULTS: The derivation cohort included 2,227 subjects with MASLD (9% reported low, 14% moderate alcohol consumption), and 76 cases with MetALD. Overall prevalence of significant fibrosis and at-risk MASH were 7.6% and 14.8%, respectively. In the multivariable analysis, alcohol consumption was independently associated with significant fibrosis and at-risk MASH. A dose-dependent increase in the prevalence of significant fibrosis and at-risk MASH was observed between the number of drinks/week and the number of cardiometabolic factors. The validation cohort included 1,732 participants with MASLD, of whom 17% had significant fibrosis and 13% at-risk MASH. This cohort validated the association between moderate intake and MASLD at risk of progression (OR=1.69 [95%CI 1.06-2.71]). CONCLUSIONS: Moderate alcohol intake is commonly seen in MASLD and increases the risk of advanced disease, in a similar magnitude to MetALD spectrum. IMPACT AND IMPLICATIONS: Metabolic risk factors such as overweight, diabetes or dyslipidemia, and alcohol consumption can cause liver disease. These factors frequently co-exist, but their joint effects on liver fibrosis remain uncertain. This study analyzes subjects form the general population with metabolic dysfunction-associated steatotic liver disease (MASLD) enrolled in Spain and U.S. We show that moderate alcohol consumption has a supra-additive effect with metabolic risk factors, exponentially increasing the risk of liver fibrosis. These results suggest that patients with unhealthy metabolic status and MASLD have no safe limits of daily alcohol intake.
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BACKGROUND & AIMS: Metabolic dysfunction-associated steatotic liver disease (MASLD) is a leading cause of advanced chronic liver disease (ACLD). Portal hypertension drives hepatic decompensation and is best diagnosed by hepatic venous pressure gradient (HVPG) measurement. Here, we investigate the prognostic value of HVPG in MASLD-related compensated ACLD (MASLD-cACLD). METHODS: This European multicentre study included patients with MASLD-cACLD characterised by HVPG at baseline. Hepatic decompensation (variceal bleeding/ascites/hepatic encephalopathy) and liver-related mortality were considered the primary events of interest. RESULTS: A total of 340 patients with MASLD-cACLD (56.2% male; median age 62 [55-68] years, median MELD 8 [7-9], 71.2% with diabetes) were included. Clinically significant portal hypertension (CSPH: i.e., HVPG ≥10 mmHg) was found in 209 patients (61.5%). During a median follow-up of 41.5 (27.5-65.8) months, 65 patients developed hepatic decompensation with a cumulative incidence of 10.0% after 2 years (2Y) and 30.7% after 5 years (5Y) in those with MASLD-cACLD with CSPH, compared to 2.4% after 2Y and 9.4% after 5Y in patients without CSPH. Variceal bleeding did not occur without CSPH. CSPH (subdistribution hazard ratio [SHR] 5.13; p <0.001) was associated with an increased decompensation risk and a higher HVPG remained an independent risk factor in the multivariable model (adjusted SHR per mmHg: 1.12, p <0.001). Liver-related mortality occurred in 37 patients at a cumulative incidence of 3.3% after 2Y and 21.4% after 5Y in CSPH. Without CSPH, the incidence after 5Y was 0.8%. Accordingly, a higher HVPG was also independently associated with a higher risk of liver-related death (adjusted SHR per mmHg: 1.20, p <0.001). CONCLUSION: HVPG measurement is of high prognostic value in MASLD-cACLD. In patients with MASLD-cACLD without CSPH, the short-term risk of decompensation is very low and liver-related mortality is rare, while the presence of CSPH substantially increases the risk of both. IMPACT AND IMPLICATIONS: While the incidence of compensated advanced chronic liver disease (cACLD) due to metabolic dysfunction-associated steatotic liver disease (MASLD) is increasing worldwide, insights into the impact of clinically significant portal hypertension (CSPH) on the risk of liver-related events in MASLD-cACLD remain limited. Based on the findings of this European multicentre study including 340 MASLD-cACLD patients, we could show that increasing HVPG values and the presence of CSPH in particular were associated with a significantly higher risk of first hepatic decompensation and liver-related mortality. In contrast, the short-term incidence of decompensation in patients with MASLD-cACLD without CSPH was low and the risk of liver-mortality remained negligible. Thus, HVPG measurements can provide important prognostic information for individualised risk stratification in MASLD-cACLD and may help facilitate the study of novel and promising treatment possibilities for MASLD.
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Hepatocellular carcinoma (HCC) typically develops as a consequence of liver cirrhosis, but HCC epidemiology has evolved drastically in recent years. Metabolic dysfunction-associated steatotic liver disease (MASLD), including metabolic dysfunction-associated steatohepatitis, has emerged as the most common chronic liver disease worldwide and a leading cause of HCC. A substantial proportion of MASLD-associated HCC (MASLD-HCC) also can develop in patients without cirrhosis. The specific pathways that trigger carcinogenesis in this context are not elucidated completely, and recommendations for HCC surveillance in MASLD patients are challenging. In the era of precision medicine, it is critical to understand the processes that define the profiles of patients at increased risk of HCC in the MASLD setting, including cardiometabolic risk factors and the molecular targets that could be tackled effectively. Ideally, defining categories that encompass key pathophysiological features, associated with tailored diagnostic and treatment strategies, should facilitate the identification of specific MASLD-HCC phenotypes. In this review, we discuss MASLD-HCC, including its epidemiology and health care burden, the mechanistic data promoting MASLD, metabolic dysfunction-associated steatohepatitis, and MASLD-HCC. Its natural history, prognosis, and treatment are addressed specifically, as the role of metabolic phenotypes of MASLD-HCC as a potential strategy for risk stratification. The challenges in identifying high-risk patients and screening strategies also are discussed, as well as the potential approaches for MASLD-HCC prevention and treatment.
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Carcinoma Hepatocelular , Neoplasias Hepáticas , Fenótipo , Humanos , Carcinoma Hepatocelular/epidemiologia , Neoplasias Hepáticas/epidemiologia , Fígado Gorduroso/complicaçõesRESUMO
Per- and poly(fluoroalkyl) substances (PFAS) are environmentally persistent pollutants that are of growing concern due to their detrimental effects at ultratrace concentrations (ng·L-1) in human and environmental health. Suitable technologies for on-site ultratrace detection of PFAS do not exist and current methods require complex and specialized equipment, making the monitoring of PFAS in distributed water infrastructures extremely challenging. Herein, we describe amplifying fluorescent polymers (AFPs) that can selectively detect perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) at concentrations of ng·L-1. The AFPs are highly fluorinated and have poly(p-phenylene ethynylene) and polyfluorene backbones bearing pyridine-based selectors that react with acidic PFAS via a proton-transfer reaction. The fluorinated regions within the polymers partition PFAS into polymers, whereas the protonated pyridine units create lower-energy traps for the excitons, and emission from these pyridinium sites results in red-shifting of the fluorescence spectra. The AFPs are evaluated in thin-film and nanoparticle forms and can selectively detect PFAS concentrations of â¼1 ppb and â¼100 ppt, respectively. Both polymer films and nanoparticles are not affected by the type of water, and similar responses to PFAS were found in milliQ water, DI water, and well water. These results demonstrate a promising sensing approach for on-site detection of aqueous PFAS in the ng·L-1 range.
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BACKGROUND & AIMS: Individual risk prediction of liver-related events (LRE) is needed for clinical assessment of nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH) patients. We aimed to provide point-of-care validated liver stiffness measurement (LSM)-based risk prediction models for the development of LRE in patients with NAFLD, focusing on selecting patients for clinical trials at risk of clinical events. METHODS: Two large multicenter cohorts were evaluated, 2638 NAFLD patients covering all LSM values as the derivation cohort and 679 more advanced patients as the validation cohort. We used Cox regression to develop and validate risk prediction models based on LSM alone, and the ANTICIPATE and ANTICIPATE-NASH models for clinically significant portal hypertension. The main outcome of the study was the rate of LRE in the first 3 years after initial assessment. RESULTS: The 3 predictive models had similar performance in the derivation cohort with a very high discriminative value (c-statistic, 0.87-0.91). In the validation cohort, the LSM-LRE alone model had a significant inferior discrimination (c-statistic, 0.75) compared with the other 2 models, whereas the ANTICIPATE-NASH-LRE model (0.81) was significantly better than the ANTICIPATE-LRE model (0.79). In addition, the ANTICIPATE-NASH-LRE model presented very good calibration in the validation cohort (integrated calibration index, 0.016), and was better than the ANTICIPATE-LRE model. CONCLUSIONS: The ANTICIPATE-LRE models, and especially the ANTICIPATE-NASH-LRE model, could be valuable validated clinical tools to individually assess the risk of LRE at 3 years in patients with NAFLD/NASH.
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BACKGROUND & AIMS: Pathogenesis of hepatocellular carcinoma (HCC), which kills millions annually, is poorly understood. Identification of risk factors and modifiable determinants and mechanistic understanding of how they impact HCC are urgently needed. METHODS: We sought early prognostic indicators of HCC in C57BL/6 mice, which we found were prone to developing this disease when fed a fermentable fiber-enriched diet. Such markers were used to phenotype and interrogate stages of HCC development. Their human relevance was tested using serum collected prospectively from an HCC/case-control cohort. RESULTS: HCC proneness in mice was dictated by the presence of congenitally present portosystemic shunt (PSS), which resulted in markedly elevated serum bile acids (BAs). Approximately 10% of mice from various sources exhibited PSS/cholemia, but lacked an overt phenotype when fed standard chow. However, PSS/cholemic mice fed compositionally defined diets, developed BA- and cyclooxygenase-dependent liver injury, which was exacerbated and uniformly progressed to HCC when diets were enriched with the fermentable fiber inulin. Such progression to cholestatic HCC associated with exacerbated cholemia and an immunosuppressive milieu, both of which were required in that HCC was prevented by impeding BA biosynthesis or neutralizing interleukin-10 or programmed death protein 1. Analysis of human sera revealed that elevated BA was associated with future development of HCC. CONCLUSIONS: PSS is relatively common in C57BL/6 mice and causes silent cholemia, which predisposes to liver injury and HCC, particularly when fed a fermentable fiber-enriched diet. Incidence of silent PSS/cholemia in humans awaits investigation. Regardless, measuring serum BA may aid HCC risk assessment, potentially alerting select individuals to consider dietary or BA interventions.
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Carcinoma Hepatocelular , Doenças do Sistema Digestório , Neoplasias Hepáticas , Humanos , Camundongos , Animais , Neoplasias Hepáticas/etiologia , Carcinoma Hepatocelular/etiologia , Camundongos Endogâmicos C57BL , Próteses e Implantes , Fibras na DietaRESUMO
Open-shell graphene nanoribbons have become promising candidates for future applications, including quantum technologies. Here, we characterize magnetic states hosted by chiral graphene nanoribbons (chGNRs). The substitution of a hydrogen atom at the chGNR edge by a ketone effectively adds one pz electron to the π-electron network, producing an unpaired π-radical. A similar scenario occurs for regular ketone-functionalized chGNRs in which one ketone is missing. Two such radical states can interact via exchange coupling, and we study those interactions as a function of their relative position, which includes a remarkable dependence on the chirality, as well as on the nature of the surrounding ribbon, that is, with or without ketone functionalization. Besides, we determine the parameters whereby this type of system with oxygen heteroatoms can be adequately described within the widely used mean-field Hubbard model. Altogether, we provide insight to both theoretically model and devise GNR-based nanostructures with tunable magnetic properties.
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A 48 year old male was referred to our center due to a gastrointestinal bleeding with melena secondary to a Forrest IIb gastric ulcer treated endoscopically. Physical examination revealed bilateral conjunctival suffusion, bradypsychia, and asterixis. Epidemiological history included a trip to Dominican Republic two weeks before, presenting later a flu-like syndrome. He had no history of NSAID use. Laboratory tests showed a normocytic anemia, leukocytosis with neutrophilia, acute renal failure, severe hyponatremia, a predominant direct hyperbilirubinemia, hyperamylasemia, and mild coagulopathy (Table 1). An abdominal ultrasound was performed, with no pathological findings, and a chest-abdominal computed tomography (CT), bilateral diffuse ground glass pulmonary opacities and pleural effusion, mild hepatomegaly, and peritoneal and gastrohepatic ligament lymphadenopathy, with no signs of acute pancreatitis. A second look upper endoscopy revealed a Forrest III gastric ulcer. Gastric biopsies results ruled out malignancy and Helicobacter pylori infection. Due to his recent travel history combined with his characteristic signs and symptoms a clinical diagnosis of leptospirosis was made and empirical antibiotic therapy with meropenem was started. The serology for Leptospira was positive (IgG 1/1600) and antibiotic therapy was de-escalated to ceftriaxone with clinical and analytical remission on day five of his hospital stay with complete radiological resolution at 6 months.
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Infecções por Helicobacter , Helicobacter pylori , Pancreatite , Úlcera Gástrica , Masculino , Humanos , Pessoa de Meia-Idade , Infecções por Helicobacter/tratamento farmacológico , Úlcera Gástrica/complicações , Doença Aguda , Pancreatite/complicações , Hemorragia Gastrointestinal/complicações , Antibacterianos/uso terapêutico , Endoscopia GastrointestinalRESUMO
BACKGROUND & AIMS: Non-alcoholic fatty liver disease (NAFLD) is associated with poorer glycemic control and a higher risk of type-2 diabetes (T2D) complications, extrahepatic and cardiovascular disease (CVD). Our study aim was to evaluate the association between NAFLD, T2D complications, and the development of overall clinical events (OCE) (CV, liver-related, and mortality) in patients with T2D. METHODS: Prospective single-center study comprising T2D subjects with no history of CVD and non-T2D matched controls. Patients were selected from the Outpatient Diabetes Clinic of Vall d'Hebron Hospital and related primary care centers. RESULTS: 186 diabetics and 57 controls were included. Amongst T2D, 124/186 subjects had NAFLD (66.6%). T2D-NAFLD subjects showed a heavier metabolic burden and higher median liver stiffness (5.6kPa [4.5-7.3] vs 4.8 [4.2-5.8]; p=0.004) compared to non-NAFLD diabetics. During a median follow-up of 5.6 years, 33 (17.7%) T2D patients developed OCE vs 4 (7.0%) controls (p=0.049). No differences were found for OCE between NAFLD and non-NAFLD diabetics (16.9% vs 19.4%; p=0.68). CV was the most reported outcome and only one liver event occurred. NAFLD diabetics showed more often chronic kidney disease (CKD), whereas T2D complications and subclinical CVD rates were similar. A higher liver stiffness, older age, and male gender were independently associated with OCE amongst the entire T2D population and NAFLD diabetics. CONCLUSIONS: NAFLD and liver stiffness were associated with CKD and clinical outcomes in diabetics, respectively. A hepatic evaluation is recommended to identify high-risk T2D patients that would benefit from early referral to specialized care.
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Doenças Cardiovasculares , Complicações do Diabetes , Diabetes Mellitus Tipo 2 , Hepatopatia Gordurosa não Alcoólica , Insuficiência Renal Crônica , Humanos , Masculino , Hepatopatia Gordurosa não Alcoólica/complicações , Hepatopatia Gordurosa não Alcoólica/epidemiologia , Fatores de Risco , Estudos Prospectivos , Diabetes Mellitus Tipo 2/complicações , Insuficiência Renal Crônica/complicações , Complicações do Diabetes/epidemiologia , Complicações do Diabetes/complicações , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/etiologiaRESUMO
OBJECTIVE: To investigate the prevalence of metabolic morbidity (MM) amongst prison inmates. DESIGN: Multicentric, cross-sectional observational study. SETTING: All (nine) prisons in Catalonia. PARTICIPANTS: Convicted inmates that are not in an «open regime¼, whose healthcare relies on the Prison Primary Care Teams. INTERVENTIONS: MM was defined as the presence of at least one component of the metabolic syndrome, i.e., obesity, arterial hypertension, type2 diabetes, and/or dyslipidemia. The variables collected included anthropometric measurements, medical history and laboratory values related to MM. The source of information was the Catalan Primary Healthcare Services Information System (SISAP). MAIN MEASUREMENTS: The prevalence of MM, overall and by several participant subcategories, was calculated. To investigate the risk factors associated to a higher prevalence of MM, a multivariable logistic regression analysis was carried out and expressed as adjusted odds ratios and 95% confidence intervals. RESULTS: 4338 inmates were studied, of whom 93.9% were male. Mean age was 38.4years, 51.7% were born in European Union countries, and 6.7% were infected by HIV. The variables associated with a significantly increased risk of presenting MM were older age and HIV infection, whereas certain geographical origins (i.e., non-UE European countries, Maghreb and Sub-Saharan Africa) were associated with lower risk of MM. CONCLUSIONS: In spite of being an overall young population, prison inmates present high rates of MM. Older age, HIV infection and geographic origin appear as the most strongly associated factors with MM in the prison population. MM should be detected early in order to prevent complications. Prevention, screening and treatment of MM ought to be considered a priority in the clinical routine of prison healthcare professionals.
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Infecções por HIV , Humanos , Masculino , Adulto , Feminino , Infecções por HIV/epidemiologia , Infecções por HIV/diagnóstico , Espanha/epidemiologia , Prisões , Estudos Transversais , Morbidade , PrevalênciaRESUMO
BACKGROUND & AIMS: Non-alcoholic fatty liver disease (NAFLD) has become a major public health problem, but the prevalence of fibrosis associated with non-alcoholic steatohepatitis (NASH) is largely unknown in the general population. This study aimed to provide an updated estimation of the prevalence of NASH fibrosis in Spain. METHODS: This was an observational, retrospective, cross-sectional, population-based study with merged data from two Spanish datasets: a large (N = 12 246) population-based cohort (ETHON), including transient elastography (TE) data, and a contemporary multi-centric biopsy-proven NASH cohort with paired TE data from tertiary centres (N = 501). Prevalence for each NASH fibrosis stage was estimated by crossing TE data from ETHON dataset with histology data from the biopsy-proven cohort. RESULTS: From the patients with valid TE in ETHON dataset (N = 11 440), 5.61% (95% confidence interval [95% CI]: 2.53-11.97) had a liver stiffness measurement (LSM) ≥ 8 kPa. The proportion attributable to NAFLD (using clinical variables and Controlled Attenuation Parameter) was 57.3% and thus, the estimated prevalence of population with LSM ≥ 8 kPa because of NAFLD was 3.21% (95% CI 1.13-8.75). In the biopsy-proven NASH cohort, 389 patients had LSM ≥ 8 kPa. Among these, 37% did not have significant fibrosis (F2-4). The estimated prevalence of NASH F2-3 and cirrhosis in Spain's adult population were 1.33% (95% CI 0.29-5.98) and 0.70% (95% CI 0.10-4.95) respectively. CONCLUSIONS: These estimations provide an accurate picture of the current prevalence of NASH-related fibrosis in Spain and can serve as reference point for dimensioning the therapeutic efforts that will be required as NASH therapies become available.
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Técnicas de Imagem por Elasticidade , Hepatopatia Gordurosa não Alcoólica , Adulto , Estudos Transversais , Fibrose , Humanos , Fígado/diagnóstico por imagem , Fígado/patologia , Cirrose Hepática/diagnóstico por imagem , Cirrose Hepática/epidemiologia , Cirrose Hepática/etiologia , Hepatopatia Gordurosa não Alcoólica/complicações , Hepatopatia Gordurosa não Alcoólica/diagnóstico por imagem , Hepatopatia Gordurosa não Alcoólica/epidemiologia , Prevalência , Estudos Prospectivos , Estudos Retrospectivos , Espanha/epidemiologiaRESUMO
OBJECTIVE: Despite growing evidence on the benefits of outpatient oncological neurosurgery (OON), it is only performed in a few specialized centers and there are no previous descriptions of established OON programs in Europe. Moreover, increasing application of telemedicine strategies, especially after the start of the coronavirus disease 2019 (COVID-19) pandemic, is drastically changing neurosurgical management, particularly in the case of vulnerable populations such as neuro-oncological patients. In this context, the authors implemented an OON program in their hospital with telematic follow-up. Herein, they describe the protocol and qualitatively analyze the barriers and facilitators of the development process. METHODS: An OON program was developed through the following steps: assessment of hospital needs, specific OON training, multidisciplinary team organization, and OON protocol design. In addition, the implementation phase included training sessions, a pilot study, and continuous improvement sessions. Finally, barriers and facilitators of the protocol's implementation were identified from the feedback of all participants. RESULTS: An OON protocol was successfully designed and implemented for resection or biopsy of supratentorial lesions up to 3 cm in diameter. The protocol included the patient's admission to the day surgery unit, noninvasive anesthetic monitoring, same-day discharge, and admission to the hospital-at-home (HaH) unit for telematic and on-site postoperative care. After a pilot study including 10 procedures in 9 patients, the main barriers identified were healthcare provider resistance to change, lack of experience in outpatient neurosurgery, patient reluctance, and limitations in the recruitment of patients. Key facilitators of the process were the patient education program, the multidisciplinary team approach, and the HaH-based telematic postoperative care. CONCLUSIONS: Initiating an OON program with telematic follow-up in a European clinical setting is feasible. Nevertheless, it poses several barriers that can be overcome by identifying and maximizing key facilitators of the process. Among them, patient education, a multidisciplinary team approach, and HaH-based postoperative care were crucial to the success of the program. Future studies should investigate the cost-effectiveness of telemedicine to assess potential cost savings, from reduced travel and wait times, and the impact on patient satisfaction.
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Neoplasias Encefálicas , COVID-19 , Telemedicina , Neoplasias Encefálicas/cirurgia , Humanos , Pacientes Ambulatoriais , Projetos PilotoRESUMO
Non-alcoholic steatohepatitis has emerged as a major public health problem, and the burden of non-alcoholic steatohepatitis cirrhosis is projected to increase by 64%-156% by 2030. The threat is aggravated by the fact that are currently no approved drugs for the treatment of non-alcoholic steatohepatitis. In this paper, we review the main challenges to drug development in patients with non-alcoholic steatohepatitis cirrhosis, and describe the opportunities brought by the advances in the understanding of the clinical and pathophysiological nuances of cirrhosis. The design of therapeutic regimens for non-alcoholic steatohepatitis cirrhosis will vary according to the specific cirrhosis substage (compensated vs decompensated), and the specific mechanistic basis of therapy, targeted either at improving aetiology-specific pathways and/or at more general aetiology-agnostic processes. The understanding of the probabilistic expectations for the whole range of potential outcomes, rooted at different mechanistic drivers at each specific substage, will be essential in order to choose adequate estimands and therapeutic strategies for clinical trials and individual patients with non-alcoholic steatohepatitis cirrhosis. Finally, we provide a summary of the main pitfalls and uncertainties in the design of clinical trials for non-alcoholic steatohepatitis cirrhosis and discuss potential biomarkers for use in trials and practice for these patients.
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Cirrose Hepática , Hepatopatia Gordurosa não Alcoólica , Biomarcadores , Humanos , Cirrose Hepática/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológicoRESUMO
The on-surface synthesis of non-planar nanographenes is a challenging task. Herein, with the aid of bond-resolving scanning tunneling microscopy (BRSTM) and density functional theory (DFT) calculations, we present a systematic study aiming at the fabrication of corannulene-based nanographenes via intramolecular cyclodehydrogenation on a Au(111) surface. The formation of non-planar targeted products is confirmed to be energetically unfavorable compared to the formation of planar/quasi-planar undesired competing monomer products. In addition, the activation of intermolecular coupling further inhibits the formation of the final targeted product. Although it was not possible to access the corannulene moiety by means of on-surface synthesis, partial cyclodehydrogenation of the molecular precursors was demonstrated.
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The Diels-Alder reaction is one of the most popular reactions in organic chemistry. However, its use in the field of on-surface synthesis is hampered by the spatial restrictions of this cycloaddition reaction. Herein we selected a cyclic strained triyne to demonstrate an on-surface hexadehydro-Diels-Alder reaction in a single molecule. The reaction was studied in detail by means of atomic force microscopy (AFM) with CO-functionalized tips. Our results pave the way to use this iconic pericyclic reaction for on-surface synthesis, introducing the concept of atom economy in the field.
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Graphene can develop large magnetic moments in custom-crafted open-shell nanostructures such as triangulene, a triangular piece of graphene with zigzag edges. Current methods of engineering graphene nanosystems on surfaces succeeded in producing atomically precise open-shell structures, but demonstration of their net spin remains elusive to date. Here, we fabricate triangulenelike graphene systems and demonstrate that they possess a spin S=1 ground state. Scanning tunneling spectroscopy identifies the fingerprint of an underscreened S=1 Kondo state on these flakes at low temperatures, signaling the dominant ferromagnetic interactions between two spins. Combined with simulations based on the meanfield Hubbard model, we show that this S=1 π paramagnetism is robust and can be turned into an S=1/2 state by additional H atoms attached to the radical sites. Our results demonstrate that π paramagnetism of high-spin graphene flakes can survive on surfaces, opening the door to study the quantum behavior of interacting π spins in graphene systems.
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Porous solid materials commonly undergo coating processes during their manufacture, where liquids are put in contact with solids for different purposes. The study of liquid penetration in porous substrates is a process of high relevance in activities in several industries. In particular, powder detergents are subject to coating with surfactants that will boost their performance, although this may affect the flowability and even cause caking of the particulate material, which can be detrimental to consumer acceptance. Here we present a methodology to make compacted preparations of powders relevant to detergent making and evaluate the internal structure of such porous substrates by means of X-ray microcomputed tomography. Liquid penetration in the preparation and the total mass uptake of fluid were monitored by a gravimetric technique based on a modified Wilhelmy plate method consisting of consecutive cycles. Taking into account the geometry of the system, two models were proposed to describe the liquid uptake based on the process being driven by mass (model 1) or pressure (model 2) gradients. A comparison between both from statistical and physical points of view led to the conclusion that the latter was more appropriate for describing the process and retrieving values of the permeability of the solid between 0.03 × 10-12 and 0.95 × 10-12 m2. Finally, with the parameters retrieved from model 2, the force balance observed throughout the experiment was simulated satisfactorily.