Directional uncertainty in chase and escape dynamics.

Intercepting and avoiding collisions with moving targets are crucial skills for survival. However, little is known about how these behaviors are implemented when the trajectory of the moving target introduces variability and ambiguity into the perceptual-motor system. We developed a simple visuomotor task in which participants used a joystick to interact with a computer-controlled dot that moved along two-dimensional trajectories. This virtual system allowed us to define the role of the moving object (predator or prey) and adjust its speed and directional uncertainty (i.e., magnitude and frequency of random directional changes) during chase and escape trials. These factors had a significant impact on participants' performance in both chasing and escaping trials. We developed a simple geometrical model of potential chaser/escaper interactions to distinguish pursuit from interception chasing trajectories. We found that participants initially pursued the target but switched to a late interception strategy. The amount of late interception strategy followed an inverted U-shaped curve with the highest values at intermediate speeds. We tested the applicability of our task and methods in children who showed a robust developmental improvement in task performance and late interception strategy. Our task constitutes a flexible system in a virtual space for studying chasing and escaping behavior in adults and children. Our analytical methods allow detecting subtle changes in interception strategies, a valuable tool for studying the maturation of predictive and prospective systems, with a high potential to contribute to cognitive and developmental research. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

A Polyvalent Tool for Detecting Coguviruses in Multiple Hosts Allowed the Identification of a Novel Seed-Transmitted Coguvirus Infecting Brassicaceae.

The genus Coguvirus, a recently established genus in the family Phenuiviridae, includes several species whose members infect both woody and herbaceous hosts, suggesting a broader host range and wider distribution than previously. To gain insights into the epidemiology and biology of coguviruses, a polyvalent reverse transcription-PCR assay using degenerate primers was developed. The specificity of the assay for coguviruses was confirmed by testing citrus and apple plants infected by previously reported coguviruses and/or several unrelated viruses. The expected 236-bp amplicon was obtained from citrus, apple, pear, watermelon, and several species of the family Brassicaceae. Sequencing of the PCR amplicons allowed the identification, for the first time in Italy and/or Europe, of several coguviruses in multiple hosts, confirming the effectiveness of the assay. Moreover, a new virus, tentatively named Brassica oleracea Torzella virus 1 (BoTV1), was detected in several plants of Torzella cabbage. The complete +genome of BoTV1, determined by high-throughput sequencing and 5' rapid amplification of cDNA ends, revealed that it has the typical molecular features of coguviruses and fulfils the current criteria to be classified as a member of a new species, for which the tentative name Coguvirus torzellae is proposed. The same polyvalent assay was also used to investigate and confirm that BoTV1 is transmitted through seeds in black cabbage, thus providing the first evidence on the relevance of this natural transmission mode in the epidemiology of coguviruses. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.

A giant cause of recurrent fever

A 73-year-old male patient presented to the Emergency Department with history of weight loss, dysphagia, and recurrent fever. The initial chest radiograph showed a mediastinal hypotransparency and to the complaints of dysphagia the patient did a barium swallow test that revealed a giant Zenker diverticulum. Apart from mildly elevated inflammatory markers and despite the extensive investigation of recurrent fever, no other relevant features were found either in blood analysis, microbiological cultures or computerized tomography. He was submitted to surgical intervention, with no recurrence of fever afterwards. It was assumed that food debris and possible microaspirations were responsible for the recurrence of fever and elevation of inflammatory markers. The patient eventually died due to late complications of surgery. Although recurrent fever is frequently linked to systemic disease, the presence of such a giant diverticulum was probably causing an inflammatory response that is usually not seen in these conditions. (AU)

PSTVd infection in Nicotiana benthamiana plants has a minor yet detectable effect on CG methylation.

Viroids are small circular RNAs infecting a wide range of plants. They do not code for any protein or peptide and therefore rely on their structure for their biological cycle. Observed phenotypes of viroid infected plants are thought to occur through changes at the transcriptional/translational level of the host. A mechanism involved in such changes is RNA-directed DNA methylation (RdDM). Till today, there are contradictory works about viroids interference of RdDM. In this study, we investigated the epigenetic effect of viroid infection in Nicotiana benthamiana plants. Using potato spindle tuber viroid (PSTVd) as the triggering pathogen and via bioinformatic analyses, we identified endogenous gene promoters and transposable elements targeted by 24 nt host siRNAs that differentially accumulated in PSTVd-infected and healthy plants. The methylation status of these targets was evaluated following digestion with methylation-sensitive restriction enzymes coupled with PCR amplification, and bisulfite sequencing. In addition, we used Methylation Sensitive Amplification Polymorphism (MSAP) followed by sequencing (MSAP-seq) to study genomic DNA methylation of 5-methylcytosine (5mC) in CG sites upon viroid infection. In this study we identified a limited number of target loci differentially methylated upon PSTVd infection. These results enhance our understanding of the epigenetic host changes as a result of pospiviroid infection.

High resting energy expenditure, less fat-free mass, and less muscle strength in HIV-infected children: a matched, cross-sectional study.

Background and aims: Many improvements have been made in the treatment of human immunodeficiency virus (HIV) in pediatric patients; however, challenges remain in terms of achieving normal growth, body composition, and metabolism during treatment, etc. Current nutritional recommendations are based on studies performed in adults, with limited data on the HIV-infected pediatric population. Therefore, this study aimed to compare the resting energy expenditure (REE) of asymptomatic HIV-infected pediatric patients with healthy counterparts and to compare body composition, dietary intake, and physical activity between the two groups. Methods: This was a cross-sectional study of asymptomatic HIV-infected children who were receiving antiretroviral therapy; the infected group was compared with the uninfected group, matched by age (± 6 months), sex, and body mass index (± 0.5 z-score). Participants were recruited between 2021 and 2022, as outpatients. In both groups, REE was determined by indirect calorimetry and body composition by bioelectrical impedance analysis and hand strength, measured using a hydraulic hand dynamometer. Results: Seventy-eight participants were enrolled, where n = 39 HIV-infected children and n = 39 controls, with a mean age of 11.6 ± 3.4 years old. REE was significantly higher in the HIV group (1254.4 ± 334.7 kcal/day vs. 1124.7 ± 321 kcal/day, p = 0.013) than in the control group. Fat-free mass (FFM) was lower in the HIV group (28.2 ± 10.5 kg vs. 32 ± 11.2 kg, p = 0.001); this trend continued when the index skeletal muscle was evaluated (7.2 ± 1.2 vs. 7.6 ± 1.5, p = 0.04). The strength of the dominant hand was also lower in the HIV group (12 (8-18) kg vs. 20 (10.5-26) kg, p < 0.0001). Conclusions: Children with asymptomatic HIV infection have higher REE than their uninfected peers. They also present decreased FFM, skeletal muscle mass index, and muscle strength. These parameters should be considered during nutritional assessment in this population to have a favorable impact on nutritional status and growth.

Role of selected salivary inflammatory cytokines in the diagnosis and prognosis of oral squamous cell carcinoma. A Systematic Review and Meta-analysis

Background: Oral squamous cell carcinoma (OSCC) is gradually increasing its incidence in our society. Unfortunately, this entity is diagnosed at an advanced stage in most patients, a fact that implies greater difficulty in its treatment and a worse prognosis. This systematic review aims to assess whether the cytokines IL-6, IL-8 and TNF-α are potential salivary biomarkers that allow early diagnosis of cancer. Material and methods: An electronic search was performed in three databases (Pubmed, Scopus and Web of Science). We used the following keywords: "salivary cytokines", "saliva cytokines", "salivary interleukins", "biomarkers", "oral squamous cell carcinoma" and "diagnosis", combined with the Boolean operators "AND" and "OR". Results: 128 publications were found and finally 23 articles were included in the review and 15 in the meta-analysis. It has been observed that the majority of OSCC patients express higher salivary concentrations of IL-6, IL-8 and TNF-α compared to the control (CL) and premalignant lesion (OPML) groups. It has also been observed that the different premalignant lesions do not have statistically significant differences in the salivary concentration of the cytokines, and on the other hand, differences have been observed between the different TNM stages. The meta-analysis has shown that the difference in concentration of IL-6, IL-8 and TNF-α is statistically significant between the CL group and the OSCC, and also between the CL group and OPML. Conclusions: There is sufficient evidence to affirm that IL-6, IL-8 and TNF-α are useful salivary cytokines in the early diagnosis and prognosis of OSCC. Although future studies are necessary to establish greater reliability of these biomarkers and thus be able to develop a valid diagnostic test. (AU)

Association between phase angle and the nutritional status in pediatric populations: a systematic review.

Background and aims: Malnutrition is prevalent in pediatric populations with any disease, and it is also related to changes in body composition. In addition, recent studies have documented relationships between these changes and phase angle (PhA), an important parameter of functional nutritional assessment. PhA could be a new marker of nutritional status. Many studies have generated information about the association between PhA and malnutrition in various pathologies, although the vast majority of this information is from adult populations. In this systematic review, we answered the following question: What is the association between PhA and the nutritional status in pediatric populations? Methods: We performed a systematic search of the Medline/PubMed and Latin American and Caribbean Health Sciences Literature databases (LILACS) databases for studies published up to October 2022. The inclusion criteria were pediatric subjects, which reported the relationship between PhA and the nutritional status with any objective nutritional indicator, and PhA was measured by electric impedance and reported at 50 kHz. We synthesized data from the studies that reported cutoff analysis of PhA with receiver operating characteristic (ROC) curves, mean PhA values presented by nutritional status strata, and correlations between PhA and nutritional status indicators. We assessed the risk of bias by using the Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies and the Quality Assessment for Diagnostic Accuracy Studies. Results: Of the 126 studies we identified, 15 met the inclusion criteria. The included studies reported the association between PhA and objective indicators of nutritional status, including weight-for-age z-score (WAZ) <-1 standard deviation (SD) for malnutrition, height-for-age z-score (HAZ) for malnutrition-stunting, body mass index (BMI) for the starvation state, body mass index z-score (BMIz) and BMI for malnutrition, mid-upper arm circumference (MUAC) <11 cm for severe acute malnutrition (SAM), and fat-free mass index z-score (FFMIz) <-2 z-score for moderate malnutrition, among others. The report of these associations between PhA and nutritional status was based on cutoff points generated with ROC curve analysis or comparison of mean PhA values, which were reported stratified by the presence or absence of malnutrition, and correlations between PhA and anthropometric indicators for the evaluation of the nutritional status in the pediatric population. It was difficult to compare the studies due to the heterogeneity of the bioelectrical impedance analysis models used, how PhA was reported (standardized, percentiles, or degrees), and the anthropometric indicators used to diagnose malnutrition. Conclusion: The early identification of malnutrition is relevant to establish the correct nutritional treatment; PhA appears to be a sensitive indicator of nutritional status and is easy to obtain. Although the results of this review are inadequate to establish PhA cutoff points associated with malnutrition in pediatric populations, in most of the studies, there was an association between PhA and objective indicators of nutritional status. Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022362413, identifier: PROSPERO 2022 CRD42022362413.

Hybrids of RNA viruses and viroid-like elements replicate in fungi.

Earth's life may have originated as self-replicating RNA, and it has been argued that RNA viruses and viroid-like elements are remnants of such pre-cellular RNA world. RNA viruses are defined by linear RNA genomes encoding an RNA-dependent RNA polymerase (RdRp), whereas viroid-like elements consist of small, single-stranded, circular RNA genomes that, in some cases, encode paired self-cleaving ribozymes. Here we show that the number of candidate viroid-like elements occurring in geographically and ecologically diverse niches is much higher than previously thought. We report that, amongst these circular genomes, fungal ambiviruses are viroid-like elements that undergo rolling circle replication and encode their own viral RdRp. Thus, ambiviruses are distinct infectious RNAs showing hybrid features of viroid-like RNAs and viruses. We also detected similar circular RNAs, containing active ribozymes and encoding RdRps, related to mitochondrial-like fungal viruses, highlighting fungi as an evolutionary hub for RNA viruses and viroid-like elements. Our findings point to a deep co-evolutionary history between RNA viruses and subviral elements and offer new perspectives in the origin and evolution of primordial infectious agents, and RNA life.

Expression of symptoms elicited by a hammerhead viroid through RNA silencing is related to population bottlenecks in the infected host.

Chlorosis is frequently incited by viroids, small nonprotein-coding, circular RNAs replicating in nuclei (family Pospiviroidae) or chloroplasts (family Avsunviroidae). Here, we investigated how chrysanthemum chlorotic mottle viroid (CChMVd, Avsunviroidae) colonizes, evolves and initiates disease. Progeny variants of natural and mutated CChMVd sequence variants inoculated in chrysanthemum plants were characterized, and plant responses were assessed by molecular assays. We showed that: chlorotic mottle induced by CChMVd reflects the spatial distribution and evolutionary behaviour in the infected host of pathogenic (containing a UUUC tetranucleotide) and nonpathogenic (lacking such a pathogenic determinant) variants; and RNA silencing is involved in the initiation of the chlorosis in symptomatic leaf sectors through a viroid-derived small RNA containing the pathogenic determinant that directs AGO1-mediated cleavage of the mRNA encoding the chloroplastic transketolase. This study provides the first evidence that colonization of leaf tissues by CChMVd is characterized by segregating variant populations differing in pathogenicity and with the ability to colonize leaf sectors (bottlenecks) and exclude other variants (superinfection exclusion). Importantly, no specific pathogenic viroid variants were found in the chlorotic spots caused by chrysanthemum stunt viroid (Pospiviroidae), thus establishing a clear distinction on how members of the two viroid families trigger chlorosis in the same host.

Validación del instrumento Infant Malnutrition and Feeding Checklist for Congenital Heart Disease, una herramienta para identificar riesgo de desnutrición y dificultades de alimentación en lactantes con cardiopatías congénitas / Validation of the instrument “Infant Malnutrition and Feeding Checklist for Congenital Heart Disease”, a tool to identify risk of malnutrition and feeding difficulties in infants with congenital heart disease

Introducción: actualmente, se han diseñado diversas herramientas para detectar oportunamente el riesgo de desnutrición en niños hospitalizados. En aquellos con diagnóstico de cardiopatías congénitas (CC), solo existe una herramienta desarrollada en Canadá, llamada Infant Malnutrition and Feeding Checklist for Congenital Heart Disease (IMFC:CHD), la cual fue diseñada en idioma inglés. Objetivo: evaluar la validez y confiabilidad de la adaptación en español de la herramienta IMFC:CHD en lactantes con CC. Métodos: estudio transversal de validación realizado en dos etapas: la primera, de traducción y adaptación transcultural de la herramienta; y la segunda, de validación de la nueva herramienta traducida, donde se obtuvieron las evidencias de confiabilidad y validez. Resultados: en la primera etapa se obtuvo la herramienta traducida y adaptada al idioma español; para la segunda etapa se incluyeron 24 lactantes con diagnóstico de CC. Se evaluó la validez de criterio concurrente entre la herramienta de tamizaje y la evaluación antropométrica, obteniéndose un acuerdo sustancial (κ = 0,660, IC 95 %: 0,36-0,95). Para la validez de criterio predictiva, la cual fue comparada con los días de estancia hospitalaria, se obtuvo un acuerdo moderado (κ = 0,489, IC 95 %: 0,1-0,8). La confiabilidad de la herramienta se evaluó mediante consistencia externa, midiendo la concordancia interobservador, y se obtuvo un acuerdo sustancial (κ = 0,789, IC 95 %: 0,5-0,9); la reproducibilidad de la herramienta mostró un acuerdo casi perfecto (κ = 1, IC 95 %: 0,9-1,0). Conclusiones: la herramienta IMFC:CHD mostró una adecuada validez y confiabilidad, por lo que podría considerarse un recurso útil para la identificación de desnutrición grave. (AU)

Introduction: currently, various tools have been designed to timely detect the risk of malnutrition in hospitalized children. In those with a diagnosis of congenital heart disease (CHD), there is only one tool developed in Canada: Infant Malnutrition and Feeding Checklist for Congenital Heart Disease (IMFC:CHD), which was designed in English. Objective: to evaluate the validity and reliability of the Spanish adaptation of the IMFC:CHD tool in infants with CHD. Methods: cross-sectional validation study carried out in two stages. The first, of translation and cross-cultural adaptation of the tool, and the second, of validation of the new translated tool, where evidence of reliability and validity were obtained. Results: in the first stage, the tool was translated and adapted to the Spanish language; for the second stage, 24 infants diagnosed with CHD were included. The concurrent criterion validity between the screening tool and the anthropometric evaluation was evaluated, obtaining a substantial agreement (κ = 0.660, 95 % CI: 0.36-0.95) and for the predictive criterion validity, which was compared with the days of hospital stay, moderate agreement was obtained (κ = 0.489, 95 % CI: 0.1-0.8). The reliability of the tool was evaluated through external consistency, measuring theinter-observer agreement, obtaining a substantial agreement (κ = 0.789, 95 % CI: 0.5-0.9), and the reproducibility of the tool showed an almost perfect agreement (κ = 1, CI 95 %: 0.9-1.0). Conclusions: the IMFC:CHD tool showed adequate validity and reliability, and could be considered as a useful resource for the identification of severe malnutrition. (AU)

[Validation of the instrument "Infant Malnutrition and Feeding Checklist for Congenital Heart Disease", a tool to identify risk of malnutrition and feeding difficulties in infants with congenital heart disease]. / Validación del instrumento Infant Malnutrition and Feeding Checklist for Congenital Heart Disease, una herramienta para identificar riesgo de desnutrición y dificultades de alimentación en lactantes con cardiopatías congénitas.

Introduction: Introduction: currently, various tools have been designed to timely detect the risk of malnutrition in hospitalized children. In those with a diagnosis of congenital heart disease (CHD), there is only one tool developed in Canada: Infant Malnutrition and Feeding Checklist for Congenital Heart Disease (IMFC:CHD), which was designed in English. Objective: to evaluate the validity and reliability of the Spanish adaptation of the IMFC:CHD tool in infants with CHD. Methods: cross-sectional validation study carried out in two stages. The first, of translation and cross-cultural adaptation of the tool, and the second, of validation of the new translated tool, where evidence of reliability and validity were obtained. Results: in the first stage, the tool was translated and adapted to the Spanish language; for the second stage, 24 infants diagnosed with CHD were included. The concurrent criterion validity between the screening tool and the anthropometric evaluation was evaluated, obtaining a substantial agreement (κ = 0.660, 95 % CI: 0.36-0.95) and for the predictive criterion validity, which was compared with the days of hospital stay, moderate agreement was obtained (κ = 0.489, 95 % CI: 0.1-0.8). The reliability of the tool was evaluated through external consistency, measuring the inter-observer agreement, obtaining a substantial agreement (κ = 0.789, 95 % CI: 0.5-0.9), and the reproducibility of the tool showed an almost perfect agreement (κ = 1, CI 95 %: 0.9-1.0). Conclusions: the IMFC:CHD tool showed adequate validity and reliability, and could be considered as a useful resource for the identification of severe malnutrition.

Introducción: Introducción: actualmente, se han diseñado diversas herramientas para detectar oportunamente el riesgo de desnutrición en niños hospitalizados. En aquellos con diagnóstico de cardiopatías congénitas (CC), solo existe una herramienta desarrollada en Canadá, llamada Infant Malnutrition and Feeding Checklist for Congenital Heart Disease (IMFC:CHD), la cual fue diseñada en idioma inglés. Objetivo: evaluar la validez y confiabilidad de la adaptación en español de la herramienta IMFC:CHD en lactantes con CC. Métodos: estudio transversal de validación realizado en dos etapas: la primera, de traducción y adaptación transcultural de la herramienta; y la segunda, de validación de la nueva herramienta traducida, donde se obtuvieron las evidencias de confiabilidad y validez. Resultados: en la primera etapa se obtuvo la herramienta traducida y adaptada al idioma español; para la segunda etapa se incluyeron 24 lactantes con diagnóstico de CC. Se evaluó la validez de criterio concurrente entre la herramienta de tamizaje y la evaluación antropométrica, obteniéndose un acuerdo sustancial (κ = 0,660, IC 95 %: 0,36-0,95). Para la validez de criterio predictiva, la cual fue comparada con los días de estancia hospitalaria, se obtuvo un acuerdo moderado (κ = 0,489, IC 95 %: 0,1-0,8). La confiabilidad de la herramienta se evaluó mediante consistencia externa, midiendo la concordancia interobservador, y se obtuvo un acuerdo sustancial (κ = 0,789, IC 95 %: 0,5-0,9); la reproducibilidad de la herramienta mostró un acuerdo casi perfecto (κ = 1, IC 95 %: 0,9-1,0). Conclusiones: la herramienta IMFC:CHD mostró una adecuada validez y confiabilidad, por lo que podría considerarse un recurso útil para la identificación de desnutrición grave.

Surgical restaging of patients with early­stage endometrial cancer with lymphovascular invasion does not significantly impact their survival outcomes.

Lymphovascular space invasion (LVSI) is considered to be a poor prognostic factor in endometrial cancer. However, management of patients with early-stage endometrial cancer with positive LVSI remains controversial. The main objective of the present study was to investigate whether surgical restaging of such patients has a significant effect on survival outcomes or may be otherwise omitted. A retrospective cohort study was conducted at the Gynaecologic Oncology Unit, Insitut Bergonie, Bordeaux, France for the period January 2003-December 2019. The present study included patients with definitive histopathological diagnosis of early-stage, grade 1-2 endometrial cancer with positive LVSI. Patients were divided into two groups: Those being restaged with pelvic and para-aortic lymphadenectomy (group 1) and those not restaged and receiving complementary therapy (group 2). The primary outcomes of the study were overall survival and progression-free survival. Epidemiological data, clinical and histopathological characteristics as well as complementary treatment received were also studied. Kaplan-Meier and Cox regression analyses were performed. Data from 30 patients were retrieved, of which restaging with lymphadenectomy was performed in 21 patients (group 1), while another 9 patients (group 2) were not restaged and received complementary therapy. Lymph node metastasis was observed in 23.8% of patients in group 1 (n=5). No significant difference was observed between groups 1 and 2 in terms of survival outcomes. The median overall survival was 91.31 months in group 1 and 90.61 months in group 2 [hazard ratio (HR), 0.71; 95% CI, 0.03-16.58; P=0.829]. The median disease-free survival was 87.95 months in group 1 and 81.52 months in group 2 (HR, 0.85; 95% CI, 0.12-5.91; P=0.869). In conclusion, restaging with lymphadenectomy did not alter prognosis of early-stage, LVSI-positive patients. As there was no clinical and therapeutic benefit, restaging with lymphadenectomy could be omitted in such patients.

Treatment of recurrent aphtous stomatitis: A systematic review

Background: Recurrent Aphtous Stomatitis (RAS) is the most common process affecting the oral mucosa. It is painful, multifactorial and generally recurrent. The aim of this systematic review is to know the last treatment approaches and their effectivity. Material and methods: we compared the outcome of different kind of treatments in terms of the improvement of the lesions, reduction of the size of those lesions and the time needed for their healing. Inclusion criteria were: clinical trials, articles written in English or Spanish and published less than 5 years ago. Results: we used the following keywords: "treatment", "aphtous stomatitis", "canker sores"; combined with Boolean operators AND y OR. We selected 28 articles for reading the whole text, and after applying the eligibility criteria, we selected 17 articles for our revision. Among all the treatments, we emphasize the barrier method based in compound of cellulose rubber and a calcium/sodium copolymer PVM/MA, with which the difference in the 3rd and 7th day was of -6,29 ± 0,14 points in the pain score. The treatment with insulin and chitosan gel, brought a pain suppression on the third day, with no reactivation of the pain during the whole study. The application of a film composed of polyurethane and sesame oil with chitosan, brought a reduction in the size of the lesions of 4,54 ± 2,84mm on the 6th day compared with the situation before the beginning of the treatment. The different kinds of laser, which produced a reduction in the pain score just at the beginning of the treatment up to 8,1 ± 1,6 points, and a reduction of the size of the lesions of 4,42 ± 1,02mm on the 7th day. Conclusions: Besides the classic treatments for RAS, we have to take into account other treatment modalities, above all the different kinds of laser. (AU)

On the early identification and characterization of pear blister canker viroid, apple dimple fruit viroid, peach latent mosaic viroid and chrysanthemum chlorotic mottle viroid.

In the 90's, pear blister canker viroid (PBCVd), apple dimple fruit viroid (ADFVd), peach latent mosaic viroid (PLMVd) and chrysanthemum chlorotic mottle viroid (CChMVd) were identified and characterized in the Ricardo Flores' laboratory. In these studies, the autonomous replication of these infectious RNAs and their involvement in the elicitation of diseases in their natural hosts were also shown. Their discovery was achieved by classical approaches based on the physical purification of the viroid RNAs from polyacrylamide gels followed by the sequencing of their genomic RNAs and by bioassays to assess their autonomous replication and the fulfillment of Koch's postulates. The molecular characterization of these four viroids, including the study of their sequence variability, contributed to the establishment of the concept of quasispecies for viroids and to the development of reliable molecular diagnostic methods that have facilitated the control of the diseases they caused. Most importantly, some of these viroids became valuable experimental model systems that are still used nowadays to study structural-functional relationships in RNAs and to dissect evolutionary and pathogenic pathways underlying plant-viroid interaction. The differences between early viroid discovery strategies, relying on biological and pathogenic issues, and the current high-throughput sequencing-based approaches, that frequently allow the discovery of new viroids and viroid-like RNAs in symptomless hosts, is also discussed, clarifying why the traditional molecular and biological studies mentioned above are still required to conclusively define the nature of any novel viroid-like RNA.

Role of RNA silencing in plant-viroid interactions and in viroid pathogenesis.

Viroids are small, single-stranded, non-protein coding and circular RNAs able to infect host plants in the absence of any helper virus. They may elicit symptoms in their hosts, but the underlying molecular pathways are only partially known. Here we address the role of post-transcriptional RNA silencing in plant-viroid-interplay, with major emphasis on the involvement of this sequence-specific RNA degradation mechanism in both plant antiviroid defence and viroid pathogenesis. This review is a tribute to the memory of Dr. Ricardo Flores, who largely contributed to elucidate this and other molecular mechanisms involved in plant-viroid interactions.

Relation between resilience and personality traits: The role of hopelessness and age.

Resilience refers to the process by which individuals use the ability to cope with challenges to successfully adapt to adverse situations, inclining towards the future and hope. The main aim of this study was to analyze the relation between resilience, personality traits, and hopelessness. Furthermore, we conducted comparisons between two age groups: young and older adults. The sample comprised 439 Spanish participants (66.7% women; M = 43.73, SD = 26.41; age range = 18-98 years). The Connor-Davidson Resilience Scale, NEO-Five Factor Inventory, and Beck Hopelessness Scale were used to measure the main study variables. The results revealed a negative relation between resilience and neuroticism, and a positive association with the other personality traits. Additionally, levels of resilience were found to be negatively related to hopelessness. The group of older adults showed significantly lower resilience levels than the young adults, although age was not a significant predictor of resilience. Neuroticism, extraversion, openness, and hopelessness were the only predictors of resilience for the current study. This work contributes to the study of resilience and related factors, by attempting to understand the role of resilience and resistance to risk and how individuals tackle challenges over time, with important implications for mental health.