Higher Plant-Derived Biostimulants: Mechanisms of Action and Their Role in Mitigating Plant Abiotic Stress.

Modern agriculture is being challenged by deteriorating edaphoclimatic conditions and increasing anthropogenic pressure. This necessitates the development of innovative crop production systems that can sustainably meet the demands of a growing world population while minimizing the environmental impact. The use of plant biostimulants is gaining ground as a safe and ecologically sound approach to improving crop yields. In this review, biostimulants obtained from different higher plant sources are presented under the term higher plant-derived biostimulants (hPDBs). Their mechanisms of action regulate physiological processes in plants from germination to fructification, conditioned by responses induced in plant mineral nutrition and primary metabolism, specialized metabolism, photosynthetic processes, oxidative metabolism, and signaling-related processes. The aim of this review is to collect and unify the abundant information dispersed in the literature on the effects of these biostimulants, focusing on crops subjected to abiotic stress conditions and the underlying mechanisms of action.

Recruitment of the 40S ribosomal subunit by the West Nile virus 3' UTR promotes the cross-talk between the viral genomic ends for translation regulation.

Flaviviral RNA genomes are composed of discrete RNA structural units arranged in an ordered fashion and grouped into complex folded domains that regulate essential viral functions, e.g. replication and translation. This is achieved by adjusting the overall structure of the RNA genome via the establishment of inter- and intramolecular interactions. Translation regulation is likely the main process controlling flaviviral gene expression. Although the genomic 3' UTR is a key player in this regulation, little is known about the molecular mechanisms underlying this role. The present work provides evidence for the specific recruitment of the 40S ribosomal subunit by the 3' UTR of the West Nile virus RNA genome, showing that the joint action of both genomic ends contributes the positioning of the 40S subunit at the 5' end. The combination of structural mapping techniques revealed specific conformational requirements at the 3' UTR for 40S binding, involving the highly conserved SL-III, 5'DB, 3'DB and 3'SL elements, all involved in the translation regulation. These results point to the 40S subunit as a bridge to ensure cross-talk between both genomic ends during viral translation and support a link between 40S recruitment by the 3' UTR and translation control.

Clinical profile of Spanish hepatitisC virus-infected treatment-naïve patients with compensated cirrhosis in the CREST study. / Perfil clínico de los pacientes españoles con hepatitisC naïve con cirrosis compensada tratados en el estudio CREST.

BACKGROUND AND AIM OF THE STUDY: There are still patients with hepatitisC in Spain who have yet to be diagnosed, but their clinical profile is unclear. In 2021, 21.93% of patients diagnosed had cirrhosis and were mostly treatment-naïve. METHODS: This sub-analysis describes the clinical profile of the 60Spanish treatment-naïve patients with compensated cirrhosis who were included in the CREST study. MAJOR RESULTS: Sixty percent of patients were male, median age 56years, and 33% had a history of drug use. Almost three-quarters (71.3%) had more than one comorbidity and 78.3% took concomitant medication. At treatment initiation, median platelet count was 139×103/µL and FibroScan® 17kPa. No virological failure was observed and no patient discontinued treatment due to adverse events. No clinically significant changes were noted during or after treatment in the median platelet, albumin, bilirubin, and transaminase levels. CONCLUSIONS: Treatment with glecaprevir/pibrentasvir for 8weeks in this cohort of treatment-naïve patients with compensated cirrhosis in Spain was safe and effective. This information reinforces the use of this short antiviral regimen even when there is compensated cirrhosis, simplifying the approach to hepatitisC among those patients still to be diagnosed and treated in Spain.

Screening and risk of hepatocellular carcinoma in patients with advanced fibrosis after hepatitis C virus eradication.

INTRODUCTION: The risk of hepatocellular carcinoma (HCC) after eradication of the hepatitis C virus (HCV) is highly variable in patients with advanced fibrosis (F3). Long-term surveillance for HCC after sustained virological response (SVR) is controversial in these patients. Our objective is to describe the post-SVR follow-up in clinical practice in patients with F3 and determine the predictive factors for the development of HCC. PATIENTS AND METHODS: a multicenter, observational, and retrospective study, which included HCV-monoinfected patients with F3 fibrosis determined by transient elastography who achieved SVR between 2015 and 2022 and with follow-up until May 2023. Clinical-demographic, laboratory, elastography, and ultrasound variables were recorded before and after treatment. A descriptive and inferential analysis, Cox regression analysis, and survival analysis were carried out with the R statistical software. RESULTS: 219 patients were included (65.3% men, median age 57 years). 175 (79.9%) received ultrasound screening after SVR for 62 [6-90] months. The prescribing service was the only independent variable related to performing ultrasound surveillance (p=0.004). Eight patients developed HCC. In multivariate analysis adjusted for sex, age, presence of diabetes, and alcohol consumption, a post-SVR FIB-4 ≥ 3.25 was associated with a 12-fold increase in HCC risk. The cumulative probability of HCC was higher in the group of patients with FIB-4 ≥ 3.25 after SVR (p<0.001). CONCLUSION: post-SVR follow-up of patients with F3 fibrosis is variable in clinical practice. Using the FIB-4 after SVR allows us to identify those patients with a higher risk of HCC who benefit from biannual ultrasound screening.

Inter- and Intramolecular RNA-RNA Interactions Modulate the Regulation of Translation Mediated by the 3' UTR in West Nile Virus.

RNA viruses rely on genomic structural elements to accomplish the functions necessary to complete the viral cycle. These elements participate in a dynamic network of RNA-RNA interactions that determine the overall folding of the RNA genome and may be responsible for the fine regulation of viral replication and translation as well as the transition between them. The genomes of members of the genus Flavivirus are characterized by a complexly folded 3' UTR with a number of RNA structural elements that are conserved across isolates of each species. The present work provides evidence of intra- and intermolecular RNA-RNA interactions involving RNA structural elements in the 3' UTR of the West Nile virus genome. The intermolecular interactions can be visualized in vitro by the formation of molecular dimers involving the participation of at least the SLI and 3'DB elements. Certainly, the 3' UTR of dengue virus, which lacks the SLI element, forms molecular dimers in lower quantities via a single interaction site, probably 3'DB. The functional analysis of sequence or deletion mutants revealed an inverse relationship between 3' UTR dimerization and viral translation efficiency in cell cultures. A network of RNA-RNA interactions involving 3' UTR structural elements might therefore exist, helping to regulate viral translation.

Significant heterogeneity in the diagnosis and long-term management of Wilson disease: Results from a large multicenter Spanish study.

There is uncertainty regarding Wilson's disease (WD) management. OBJECTIVES: To assess, in a multicenter Spanish retrospective cohort study, whether the approach to WD is homogeneous among centers. METHODS: Data on WD patients followed at 32 Spanish hospitals were collected. RESULTS: 153 cases, 58% men, 20.6 years at diagnosis, 69.1% hepatic presentation, were followed for 15.5 years. Discordant results in non-invasive laboratory parameters were present in 39.8%. Intrahepatic copper concentration was pathologic in 82.4%. Genetic testing was only done in 56.6% with positive results in 83.9%. A definite WD diagnosis (Leipzig score ≥4) was retrospectively confirmed in 92.5% of cases. Chelating agents were standard initial therapy (75.2%) with frequent modifications (57%), particularly to maintenance zinc. Enzyme normalization was not achieved by one third, most commonly in the setting of poor compliance, lack of genetic mutations and/or presence of cardiometabolic risk factors. Although not statistically significant, there were trends for sex differences in number of diagnosed cases, age at diagnosis and biochemical response. CONCLUSIONS: Significant heterogeneity in diagnosis and management of WD patients emerges from this multicenter study that includes both small and large reference centers. The incorporation of genetic testing will likely improve diagnosis. Sex differences need to be further explored.

Nivolumab after selective internal radiation therapy for the treatment of hepatocellular carcinoma: a phase 2, single-arm study.

PURPOSE: To evaluate the safety and efficacy of selective internal radiation therapy (SIRT) in combination with a PD-1 inhibitor in patients with unresectable hepatocellular carcinoma (uHCC) and liver-only disease ineligible for chemoembolization. PATIENTS AND METHODS: NASIR-HCC is a single-arm, multicenter, open-label, phase 2 trial that recruited from 2017 to 2019 patients who were naïve to immunotherapy and had tumors in the BCLC B2 substage (single or multiple tumors beyond the up-to-7 rule), or unilobar tumors with segmental or lobar portal vein invasion (PVI); no extrahepatic spread; and preserved liver function. Patients received SIRT followed 3 weeks later by nivolumab (240 mg every 2 weeks) for up to 24 doses or until disease progression or unacceptable toxicity. Safety was the primary endpoint. Secondary objectives included objective response rate (ORR), time to progression (TTP), and overall survival (OS). RESULTS: 42 patients received SIRT (31 BCLC-B2, 11 with PVI) and were followed for a median of 22.2 months. 27 patients discontinued and 1 never received Nivolumab. 41 patients had any-grade adverse events (AE) and 21 had serious AEs (SAE). Treatment-related AEs and SAEs grade 3-4 occurred in 8 and 5 patients, respectively. Using RECIST 1.1 criteria, ORR reported by investigators was 41.5% (95% CI 26.3% to 57.9%). Four patients were downstaged to partial hepatectomy. Median TTP was 8.8 months (95% CI 7.0 to 10.5) and median OS was 20.9 months (95% CI 17.7 to 24.1). CONCLUSIONS: The combination of SIRT and nivolumab has shown an acceptable safety profile and signs of antitumor activity in the treatment of patients with uHCC that were fit for SIRT. TRIAL REGISTRATION NUMBER: NCT03380130.

Redox post-translational modifications and their interplay in plant abiotic stress tolerance.

The impact of climate change entails a progressive and inexorable modification of the Earth's climate and events such as salinity, drought, extreme temperatures, high luminous intensity and ultraviolet radiation tend to be more numerous and prolonged in time. Plants face their exposure to these abiotic stresses or their combination through multiple physiological, metabolic and molecular mechanisms, to achieve the long-awaited acclimatization to these extreme conditions, and to thereby increase their survival rate. In recent decades, the increase in the intensity and duration of these climatological events have intensified research into the mechanisms behind plant tolerance to them, with great advances in this field. Among these mechanisms, the overproduction of molecular reactive species stands out, mainly reactive oxygen, nitrogen and sulfur species. These molecules have a dual activity, as they participate in signaling processes under physiological conditions, but, under stress conditions, their production increases, interacting with each other and modifying and-or damaging the main cellular components: lipids, carbohydrates, nucleic acids and proteins. The latter have amino acids in their sequence that are susceptible to post-translational modifications, both reversible and irreversible, through the different reactive species generated by abiotic stresses (redox-based PTMs). Some research suggests that this process does not occur randomly, but that the modification of critical residues in enzymes modulates their biological activity, being able to enhance or inhibit complete metabolic pathways in the process of acclimatization and tolerance to the exposure to the different abiotic stresses. Given the importance of these PTMs-based regulation mechanisms in the acclimatization processes of plants, the present review gathers the knowledge generated in recent years on this subject, delving into the PTMs of the redox-regulated enzymes of plant metabolism, and those that participate in the main stress-related pathways, such as oxidative metabolism, primary metabolism, cell signaling events, and photosynthetic metabolism. The aim is to unify the existing information thus far obtained to shed light on possible fields of future research in the search for the resilience of plants to climate change.

The Genomic 3' UTR of Flaviviruses Is a Translation Initiation Enhancer.

Viruses rely on the cellular machinery of host cells to synthesize their proteins, and have developed different mechanisms enabling them to compete with cellular mRNAs for access to it. The genus Flavivirus is a large group of positive, single-stranded RNA viruses that includes several important human pathogens, such as West Nile, Dengue and Zika virus. The genome of flaviviruses bears a type 1 cap structure at its 5' end, needed for the main translation initiation mechanism. Several members of the genus also use a cap-independent translation mechanism. The present work provides evidence that the WNV 5' end also promotes a cap-independent translation initiation mechanism in mammalian and insect cells, reinforcing the hypothesis that this might be a general strategy of flaviviruses. In agreement with previous reports, we show that this mechanism depends on the presence of the viral genomic 3' UTR. The results also show that the 3' UTR of the WNV genome enhances translation of the cap-dependent mechanism. Interestingly, WNV 3' UTR can be replaced by the 3' UTR of other flaviviruses and the translation enhancing effect is maintained, suggesting a molecular mechanism that does not involve direct RNA-RNA interactions to be at work. In addition, the deletion of specific structural elements of the WNV 3' UTR leads to increased cap-dependent and cap-independent translation. These findings suggest the 3' UTR to be involved in a fine-tuned translation regulation mechanism.

Interaction between Melatonin and NO: Action Mechanisms, Main Targets, and Putative Roles of the Emerging Molecule NOmela.

Melatonin (MEL), a ubiquitous indolamine molecule, has gained interest in the last few decades due to its regulatory role in plant metabolism. Likewise, nitric oxide (NO), a gasotransmitter, can also affect plant molecular pathways due to its function as a signaling molecule. Both MEL and NO can interact at multiple levels under abiotic stress, starting with their own biosynthetic pathways and inducing a particular signaling response in plants. Moreover, their interaction can result in the formation of NOmela, a very recently discovered nitrosated form of MEL with promising roles in plant physiology. This review summarizes the role of NO and MEL molecules during plant development and fruit ripening, as well as their interactions. Due to the impact of climate-change-related abiotic stresses on agriculture, this review also focuses on the role of these molecules in mediating abiotic stress tolerance and the main mechanisms by which they operate, from the upregulation of the entire antioxidant defense system to the post-translational modifications (PTMs) of important molecules. Their individual interaction and crosstalk with phytohormones and H2S are also discussed. Finally, we introduce and summarize the little information available about NOmela, an emerging and still very unknown molecule, but that seems to have a stronger potential than MEL and NO separately in mediating plant stress response.

How Donor and Surgical Factors Affect the Viability and Functionality of Human Hepatocytes Isolated From Liver Resections.

Liver resections are a significant source of primary human hepatocytes used mainly in artificial liver devices and pharmacological and biomedical studies. However, it is not well known how patient-donor and surgery-dependent factors influence isolated hepatocytes' yield, viability, and function. Hence, we aimed to analyze the impact of all these elements on the outcome of human hepatocyte isolation. Patients and methods: Hepatocytes were isolated from liver tissue from patients undergoing partial hepatectomy using a two-step collagenase method. Hepatocyte viability, cell yield, adhesion, and functionality were measured. In addition, clinical and analytical patient variables were collected and the use or absence of vascular clamping and its type (continuous or intermittent) plus the ischemia times during surgery. Results: Malignant disease, previous chemotherapy, and male gender were associated with lower hepatocyte viability and isolation cell yields. The previous increase in transaminases was also associated with lower yields on isolation and lower albumin production. Furthermore, ischemia secondary to vascular clamping during surgery was inversely correlated with the isolated hepatocyte viability. An ischemia time higher than 15 min was related to adverse effects on viability. Conclusion: Several factors correlated with the patient and the surgery directly influence the success of human hepatocyte isolation from patients undergoing liver resection.

Mortality and Causes of Death After Liver Transplantation: Analysis of Sex Differences in a Large Nationwide Cohort.

In the last few years, several studies have analyzed sex and gender differences in liver transplantation (LT), but none have performed a disaggregated analysis of both mortality and causes of death. Data from 15,998 patients, 11,914 (74.5%) males and 4,069 (25.5%) females, transplanted between 2000 and 2016 were obtained from the Liver Transplantation Spanish Registry. Survival analysis was applied to explore recipient sex as a risk factor for death. The causes of death at different follow-up duration were disaggregated by recipient sex for analysis. Short-term survival was higher in males, whereas long-term survival was higher in females. Survival at 1, 5 and 10 years post-transplant was 87.43%, 73.83%, and 61.23%, respectively, in males and 86.28%, 74.19%, and 65.10%, respectively, in females (p = 0.05). Post-LT mortality related to previous liver disease also presented sex differences. Males had 37% increased overall mortality from acute liver failure (p = 0.035) and 37% from HCV-negative cirrhosis (p < 0.001). Females had approximately 16% increased mortality when the liver disease was HCV-positive cirrhosis (p = 0.003). Regarding causes of death, non-malignancy HCV+ recurrence (6.3% vs. 3.9% of patients; p < 0.001), was more frequently reported in females. By contrast, death because of malignancy recurrence (3.9% vs. 2.2% of patients; p = 0.003) and de novo malignancy (4.8% vs. 2.5% of patients; p < 0.001) were significantly more frequent in male recipients. Cardiovascular disease, renal failure, and surgical complications were similar in both. In summary, male patients have lower short-term mortality than females but higher long-term and overall mortality. In addition, the post-LT mortality risk related to previous liver disease and the causes of mortality differ between males and females.

Cumulative exposure to tacrolimus and incidence of cancer after liver transplantation.

Cancer is the leading cause of death after liver transplantation (LT). This multicenter case-control nested study aimed to evaluate the effect of maintenance immunosuppression on post-LT malignancy. The eligible cohort included 2495 LT patients who received tacrolimus-based immunosuppression. After 13 922 person/years follow-up, 425 patients (19.7%) developed malignancy (cases) and were matched with 425 controls by propensity score based on age, gender, smoking habit, etiology of liver disease, and hepatocellular carcinoma (HCC) before LT. The independent predictors of post-LT malignancy were older age (HR = 1.06 [95% CI 1.05-1.07]; p < .001), male sex (HR = 1.50 [95% CI 1.14-1.99]), smoking habit (HR = 1.96 [95% CI 1.42-2.66]), and alcoholic liver disease (HR = 1.53 [95% CI 1.19-1.97]). In selected cases and controls (n = 850), the immunosuppression protocol was similar (p = .51). An increased cumulative exposure to tacrolimus (CET), calculated by the area under curve of trough concentrations, was the only immunosuppression-related predictor of post-LT malignancy after controlling for clinical features and baseline HCC (CET at 3 months p = .001 and CET at 12 months p = .004). This effect was consistent for de novo malignancy (after excluding HCC recurrence) and for internal neoplasms (after excluding non-melanoma skin cancer). Therefore, tacrolimus minimization, as monitored by CET, is the key to modulate immunosuppression in order to prevent cancer after LT.

In Vitro Methods to Decipher the Structure of Viral RNA Genomes.

RNA viruses encode essential information in their genomes as conserved structural elements that are involved in efficient viral protein synthesis, replication, and encapsidation. These elements can also establish complex networks of RNA-RNA interactions, the so-called RNA interactome, to shape the viral genome and control different events during intracellular infection. In recent years, targeting these conserved structural elements has become a promising strategy for the development of new antiviral tools due to their sequence and structural conservation. In this context, RNA-based specific therapeutic strategies, such as the use of siRNAs have been extensively pursued to target the genome of different viruses. Importantly, siRNA-mediated targeting is not a straightforward approach and its efficiency is highly dependent on the structure of the target region. Therefore, the knowledge of the viral structure is critical for the identification of potentially good target sites. Here, we describe detailed protocols used in our laboratory for the in vitro study of the structure of viral RNA genomes. These protocols include DMS (dimethylsulfate) probing, SHAPE (selective 2'-hydroxyl acylation analyzed by primer extension) analysis, and HMX (2'-hydroxyl molecular interference). These methodologies involve the use of high-throughput analysis techniques that provide extensive information about the 3D folding of the RNA under study and the structural tuning derived from the interactome activity. They are therefore a good tool for the development of new RNA-based antiviral compounds.

ROS and NO Phytomelatonin-Induced Signaling Mechanisms under Metal Toxicity in Plants: A Review.

Metal toxicity in soils, along with water runoff, are increasing environmental problems that affect agriculture directly and, in turn, human health. In light of finding a suitable and urgent solution, research on plant treatments with specific compounds that can help mitigate these effects has increased, and thus the exogenous application of melatonin (MET) and its role in alleviating the negative effects of metal toxicity in plants, have become more important in the last few years. MET is an important plant-related response molecule involved in growth, development, and reproduction, and in the induction of different stress-related key factors in plants. It has been shown that MET plays a protective role against the toxic effects induced by different metals (Pb, Cd, Cu, Zn, B, Al, V, Ni, La, As, and Cr) by regulating both the enzymatic and non-enzymatic antioxidant plant defense systems. In addition, MET interacts with many other signaling molecules, such as reactive oxygen species (ROS) and nitric oxide (NO) and participates in a wide variety of physiological reactions. Furthermore, MET treatment enhances osmoregulation and photosynthetic efficiency, and increases the concentration of other important antioxidants such as phenolic compounds, flavonoids, polyamines (PAs), and carotenoid compounds. Some recent studies have shown that MET appeared to be involved in the regulation of metal transport in plants, and lastly, various studies have confirmed that MET significantly upregulated stress tolerance-related genes. Despite all the knowledge acquired over the years, there is still more to know about how MET is involved in the metal toxicity tolerance of plants.

Information Encoded by the Flavivirus Genomes beyond the Nucleotide Sequence.

The genus Flavivirus comprises numerous, small, single positive-stranded RNA viruses, many of which are important human pathogens. To store all the information required for their successful propagation, flaviviruses use discrete structural genomic RNA elements to code for functional information by the establishment of dynamic networks of long-range RNA-RNA interactions that promote specific folding. These structural elements behave as true cis-acting, non-coding RNAs (ncRNAs) and have essential regulatory roles in the viral cycle. These include the control of the formation of subgenomic RNAs, known as sfRNAs, via the prevention of the complete degradation of the RNA genome. These sfRNAs are important in ensuring viral fitness. This work summarizes our current knowledge of the functions performed by the genome conformations and the role of RNA-RNA interactions in these functions. It also reviews the role of RNA structure in the production of sfRNAs across the genus Flavivirus, and their existence in related viruses.

Gas venoso portal hepático, un hallazgo radiológico potencialmente grave / Hepatic portal venous gas, a potentially serious radiological finding

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Impact of sustained virological response with DAAs on gastroesophageal varices and Baveno criteria in HCV-cirrhotic patients.

BACKGROUND: Direct-acting antivirals (DAAs) show high efficacy and safety in HCV-cirrhotic patients, but most maintain clinically significant portal hypertension after sustained virological response (SVR). Non-invasive Baveno and expanded-Baveno criteria can identify patients without high-risk gastroesophageal varices (GEV) who have no need for endoscopic surveillance. However, data after SVR are scarce. We performed a multicenter study to evaluate SVR effects over GEV and diagnostic accuracy of non-invasive criteria after SVR. METHODS: HCV-cirrhotic patients receiving DAAs and baseline endoscopic evaluation were included (November 2014-October 2015). GEV were classified as low risk (LR-GEV) (< 5 mm) or high risk (HR-GEV) (≥ 5 mm or with risk signs). Transient elastography (TE) and endoscopy were performed during follow-up. RESULTS: SVR was achieved in 230 (93.1%) of 247 included patients, 151 (65.7%) with endoscopic follow-up. Among 64/151 (42.4%) patients without baseline GEV, 8 (12.5%) developed GEV after SVR. Among 50/151 (33.1%) with baseline LR-GEV, 12 (24%) developed HR-GEV. Patients with GEV progression showed TE ≥ 25 kPa before treatment (64.7%) or ≥ 20 kPa after SVR (66.7%). Only 6% of patients without GEV and LSM < 25 kPa before treatment, and 10% of those with baseline LSM < 25 kPa and LSM < 20 kPa after SVR showed GEV progression after 36 months. The negative predictive value of Baveno and expanded-Baveno criteria to exclude HR-GEV was maintained after SVR (100% and 90.7%, respectively). CONCLUSIONS: HCV-cirrhotic patients can develop HR-GEV after SVR. Surveillance is especially recommended in those with GEV before antiviral treatment. Baveno and expanded-Baveno criteria can be safely applied after SVR. https://clinicaltrials.gov: NCT02758509.