Portal vein thrombosis (PVT) represents a well-known complication during the natural course of liver cirrhosis (LC), ranging from asymptomatic cases to life-threating conditions related to portal ...hypertension and hepatic decompensation. Portal flow stasis, complex acquired hypercoagulable disorders and exogenous factors leading to endothelial dysfunction have emerged as key factors for PVT development. However, PVT occurrence remains unpredictable and many issues regarding its natural history, prognostic significance and treatment are still elusive. In particular although spontaneous resolution or disease stability occur in most cases of PVT, factors predisposing to disease progression or recurrence after spontaneous recanalization are not clarified as yet. Moreover, PVT impact on LC outcome is still debated, as PVT may represent itself a consequence of liver fibrosis and hepatic dysfunction progression. Anticoagulation and transjugular intrahepatic portosystemic shunt are considered safe and effective in this setting and are recommended in selected cases, even if the safer therapeutic option and the optimal therapy duration are still unknown. Nevertheless, their impact on mortality rates should be addressed more extensively. In this review we present the most debated questions regarding PVT, whose answers should come from prospective cohort studies and large sample-size randomized trials.
Hydrophobins, produced by filamentous fungi, are small amphipathic proteins whose biological functions rely on their unique surface-activity properties. Understanding the mechanistic details of the ...multimerization process is of primary importance to clarify the interfacial activity of hydrophobins. We used free energy calculations to study the role of a flexible β-hairpin in the multimerization process in hydrophobin II from Trichoderma reesei (HFBI). We characterized how the displacement of this β-hairpin controls the stability of the monomers/dimers/tetramers in solution. The regulation of the oligomerization equilibrium of HFBI will necessarily affect its interfacial properties, fundamental for its biological function and for technological applications. Moreover, we propose possible routes for the multimerization process of HFBI in solution. This is the first case where a mechanism by which a flexible loop flanking a rigid patch controls the protein-protein binding equilibrium, already known for proteins with charged binding hot-spots, is described within a hydrophobic patch.
The transfer of chirality between nanomolecules is at the core of several applications in chiral technology such as sensing and catalysis. However, the origin of this phenomenon and how exactly ...nanoscale objects transfer chirality to molecules in their vicinity remain largely obscure. Here, we show that the transfer of chirality for the intrinsically chiral gold cluster Au38(SR)24 is site dependent; that is, it differs depending on the ligand-binding sites. This is closely related to the dynamic nature of the ligands on the cluster surface. Using a combination of NMR techniques and molecular dynamics simulations, we could assign the four symmetry-unique ligands on the cluster. The study reveals largely different conformational dynamics of the bound ligands, explaining the diverse diastereotopicities observed for the CH2 protons of the ligands. Although chirality is a structural property, our study reveals the importance of dynamics for the transfer of chirality.
The capacity of contrast-enhanced ultrasound (CEUS) to detect microvessel perfusion has received much attention in cancer imaging since it can be used to evaluate the enhancement patterns of the ...lesions during all vascular phases in real time, with higher temporal resolution as compared other imaging modalities. A rich body of literature has demonstrated the potential usefulness of CEUS in the assessment of HCC in response to both locoregional and systemic therapies. It is useful to evaluate the efficacy of ablation immediately after treatment to provide guidance for the retreatment of residual unablated tumors. In patients treated with transarterial chemoembolization (TACE), CEUS showed a high degree of concordance with computed tomography and magnetic resonance for the differentiation of responders from non-responders. Dynamic CEUS (D-CEUS) has emerged as a promising tool for the depicting changes in tumor perfusion during anti-angiogenetic treatment that can be associated with tumor response and clinical outcome. This article provides a general review of the current literature regarding the usefulness of CEUS in monitoring HCC response to therapy, highlighting the role of the procedure in different stages of the disease.
A correct differentiation between hepatocellular carcinoma (HCC) and intracellular cholangiocarcinoma (ICC) is essential for clinical management and prognostic prediction. However, non-invasive ...differential diagnosis between HCC and ICC remains highly challenging. Dynamic contrast-enhanced ultrasound (D-CEUS) with standardized software is a valuable tool in the diagnostic approach to focal liver lesions and could improve accuracy in the evaluation of tumor perfusion. Moreover, the measurement of tissue stiffness could add more information concerning tumoral environment. To explore the diagnostic performance of multiparametric ultrasound (MP-US) in differentiating ICC from HCC. Our secondary aim was to develop an US score for distinguishing ICC and HCC. Between January 2021 and September 2022 consecutive patients with histologically confirmed HCC and ICC were enrolled in this prospective monocentric study. A complete US evaluation including B mode, D-CEUS and shear wave elastography (SWE) was performed in all patients and the corresponding features were compared between the tumor entities. For better inter-individual comparability, the blood volume-related D-CEUS parameters were analyzed as a ratio between lesions and surrounding liver parenchyma. Univariate and multivariate regression analysis was performed to select the most useful independent variables for the differential diagnosis between HCC and ICC and to establish an US score for non-invasive diagnosis. Finally, the diagnostic performance of the score was evaluated by receiver operating characteristic (ROC) curve analysis. A total of 82 patients (mean age ± SD, 68 ± 11 years, 55 men) were enrolled, including 44 ICC and 38 HCC. No statistically significant differences in basal US features were found between HCC and ICC. Concerning D-CEUS, blood volume parameters (peak intensity, PE; area under the curve, AUC; and wash-in rate, WiR) showed significantly higher values in the HCC group, but PE was the only independent feature associated with HCC diagnosis at multivariate analysis (
= 0.02). The other two independent predictors of histological diagnosis were liver cirrhosis (
< 0.01) and SWE (
= 0.01). A score based on those variables was highly accurate for the differential diagnosis of primary liver tumors, with an area under the ROC curve of 0.836 and the optimal cut-off values of 0.81 and 0.20 to rule in or rule out ICC respectively. MP-US seems to be a useful tool for non-invasive discrimination between ICC and HCC and could prevent the need for liver biopsy at least in a subgroup of patients.
Intrahepatic cholangiocarcinoma (iCCA) represents the second most common liver cancer after hepatocellular carcinoma, accounting for 15% of primary liver neoplasms. Its incidence and mortality rate ...have been rising during the last years, and total new cases are expected to increase up to 10-fold during the next two or three decades. Considering iCCA's poor prognosis and rapid spread, early diagnosis is still a crucial issue and can be very challenging due to the heterogeneity of tumor presentation at imaging exams and the need to assess a correct differential diagnosis with other liver lesions. Abdominal contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) plays an irreplaceable role in the evaluation of liver masses. iCCA's most typical imaging patterns are well-described, but atypical features are not uncommon at both CT and MRI; on the other hand, contrast-enhanced ultrasound (CEUS) has shown a great diagnostic value, with the interesting advantage of lower costs and no renal toxicity, but there is still no agreement regarding the most accurate contrastographic patterns for iCCA detection. Besides diagnostic accuracy, all these imaging techniques play a pivotal role in the choice of the therapeutic approach and eligibility for surgery, and there is an increasing interest in the specific imaging features which can predict tumor behavior or histologic subtypes. Further prognostic information may also be provided by the extraction of quantitative data through radiomic analysis, creating prognostic multi-parametric models, including clinical and serological parameters. In this review, we aim to summarize the role of contrast-enhanced imaging in the diagnosis and management of iCCA, from the actual issues in the differential diagnosis of liver masses to the newest prognostic implications.
The self-assembly of a monolayer of ligands on the surface of noble-metal nanoparticles dictates the fundamental nanoparticle's behavior and its functionality. In this combined ...computational-experimental study, we analyze the structure, organization, and dynamics of functionalized coating thiols in monolayer-protected gold nanoparticles (AuNPs). We explain how functionalized coating thiols self-organize through a delicate and somehow counterintuitive balance of interactions within the monolayer itself and with the solvent. We further describe how the nature and plasticity of these interactions modulate nanoparticle-based chemosensing. Importantly, we found that self-organization of coating thiols can induce the formation of binding pockets in AuNPs. These transient cavities can accommodate small molecules, mimicking protein-ligand recognition, which could explain the selectivity and sensitivity observed for different organic analytes in NMR chemosensing experiments. Thus, our findings advocate for the rational design of tailored coating groups to form specific recognition binding sites on monolayer-protected AuNPs.
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•Synthesis and molecular simulations of AuNPs for chemosensing•A rationale for the molecular recognition ability of functionalized AuNPs•Functionalized coating ligands form transient protein-like binding pockets•Toward the computational nanodesign of intelligent nanoreceptors for chemosensing
The functionalization of monolayer-protected nanoparticles is at the frontier of nanotechnology, such that innovative applications are emerging in fields such as nanomedicine, chemosensing, and even catalysis. Importantly, the nanoparticle's functionality is mainly defined by the nature of the ligands forming the coating monolayer. Here, we show how the self-organization of functionalized coating ligands in monolayer-protected gold nanoparticles (AuNPs) affects their solubility and molecular recognition abilities. We found that coating ligands form transient, protein-like binding pockets in functionalized AuNPs. Thus, we reveal that nanoparticle-based chemosensing operates through a recognition process that is similar to that for protein-ligand complex formation. These findings could now herald the arrival of the computational nanodesign of intelligent nanodevices with recognition abilities toward small molecules such as drugs, metabolites, illegal drugs, and small molecular markers for cancer.
Functionalized gold nanoparticles (AuNPs) can perform different tasks, which depend on the coating ligands that cover the metal core. By combining NMR experiments and molecular-dynamics simulations, De Vivo and colleagues reveal how different ligands can self-organize to modulate molecular recognition ability in AuNPs. Results show how the composition, organization, and plasticity of coating ligands affect the selectivity and sensitivity observed for different organic analytes in NMR chemosensing experiments. These findings offer a unique perspective for the rational design of intelligent nanodevices.
Human monoacylglycerol lipase (MAGL) is a membrane-interacting enzyme that generates pro-inflammatory signaling molecules. For this reason, MAGL inhibition is a promising strategy to treat pain, ...cancer, and neuroinflammatory diseases. MAGL can hydrolyze monoacylglycerols bearing an acyl chain of different lengths and degrees of unsaturation, cleaving primarily the endocannabinoid 2-arachidonoylglycerol. Importantly, the enzymatic binding site of MAGL is confined by a 75-amino-acid-long, flexible cap domain, named ‘lid domain’, which is structurally similar to that found in several other lipases. However, it is unclear how lid domain plasticity affects catalysis in MAGL. By integrating extensive molecular dynamics simulations and free-energy calculations with mutagenesis and kinetic experiments, we here define a lid-domain-mediated mechanism for substrate selection and binding in MAGL catalysis. In particular, we clarify the key role of Phe159 and Ile179, two conserved residues within the lid domain, in regulating substrate specificity in MAGL. We conclude by proposing that other structurally related lipases may share this lid-domain-mediated mechanism for substrate specificity.
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•Computational/experimental characterization of MAGL catalysis.•Lid domain plasticity is coupled to substrate flexibility in MAGL.•A lid-domain-mediated mechanism modulates substrate specificity in MAGL.•Phe159 and Ile179 in MAGL are key to the proposed lid-domain-mediated mechanism.•Possible extension of this mechanism to other structurally similar lipases.
To describe the structure and dynamics of oligomers during peptide aggregation, a method is proposed that considers both the intramolecular and intermolecular structures of the multimolecule system ...and correctly accounts for its degeneracy. The approach is based on the “by-parts” strategy, which partitions a complex molecular system into parts, determines the metastable conformational states of each part, and describes the overall conformational state of the system in terms of a product basis of the states of the parts. Starting from a molecular dynamics simulation of n molecules, the method consists of three steps: (i) characterization of the intramolecular structure, that is, of the conformational states of a single molecule in the presence of the other molecules (e.g., β-strand or random coil); (ii) characterization of the intermolecular structure through the identification of all occurring aggregate states of the peptides (dimers, trimers, etc.); and (iii) construction of the overall conformational states of the system in terms of a product basis of the n “single-molecule” states and the aggregate states. Considering the Alzheimer β-amyloid peptide fragment Aβ16–22 as a first application, about 700 overall conformational states of the trimer (Aβ16–22)3 were constructed from all-atom molecular dynamics simulation in explicit water. Based on these states, a transition network reflecting the free energy landscape of the aggregation process can be constructed that facilitates the identification of the aggregation pathways.
Minimal hepatic encephalopathy (MHE) is a subclinical complication of liver cirrhosis with a relevant social impact. Thus, there is urgent need to implement easy to use diagnostic tools for the early ...identification of affected patients. The aim of this study was to investigate cerebral blood flow, systemic hemodynamics as well as endothelial function of cirrhotic patients with MHE, and to verify their change after treatment with rifaximin. Fifty cirrhotic patients with or without MHE and an equal number of healthy controls underwent transcranial Doppler ultrasound (TCD), abdominal Doppler ultrasound (US), and measurement of flow mediated dilation (FMD). In cirrhotic patients diagnosed with MHE receiving rifaximin, the tests were repeated at the end of treatment. Middle (MCA) and posterior (PCA) cerebral artery resistive (RI) and pulsatility (PI) indices were higher in cirrhotic patients than controls, as well as renal and splenic artery RI. Conversely, FMD was reduced. MCA-RI and PI were even higher in cirrhotic patients with MHE compared to those without; a MCA-RI cut-off of 0.65 showed an accuracy of 74% in discriminating the presence of MHE, with 65% sensitivity and 76% specificity. Rifaximin treatment showed no efficacy in the modulation of cerebral vascular flow. In conclusion, cirrhotic patients with MHE have significantly increased cerebral vascular resistances that are not improved by rifaximin treatment. MCA-RI measurement has a good accuracy for the diagnosis of MHE and can be useful for the early identification of this harmful complication of liver cirrhosis.
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