RESUMEN
Good zoo animal welfare is commonly promoted with environmental enrichment; however, some species are less likely to be offered enrichment than others. This study tested the effect of enrichment on a group of scarlet ibises from Zoomarine Algarve, Portugal. The study consisted of a first baseline condition, followed by four types of enrichment displays with individual presentations, a post-enrichment condition, and a post-enrichment with all enrichment types presented simultaneously. The enrichment types chosen were physical, with a tidal simulation in the lakes of the enclosure; nutritional, presenting mussels in a plastic mesh tube; sensory, by playing scarlet ibises calls; and tactile, with brushes through the habitat. The data collection was performed for 21 days between January and March 2021, 3 times a day, using scan sampling and instantaneous time sampling every 2 min. The comparison between conditions revealed that most behaviors showed similarity between the baseline and post-enrichment conditions, suggesting that after removing the enrichment, the behaviors returned to their initial baseline. It was also found that each enrichment influenced different types of behaviors and these behaviors also changed depending on the time of day. Exploratory behavior was only associated with the presence of enrichment, and vocalizations were only heard after the sensory enrichment was performed. This study demonstrates that the use of physical and tactile enrichments increased activity and decreased stationary behaviors in this group of ibises and may be used to improve their lives in zoological contexts if included in the housing and husbandry protocols.
RESUMEN
With the growing demand for sustainable and safe agricultural practices, plant compounds emerge as a solution for biological activities. Here, we evaluated the potential of using Morinda citrifolia essential oil to induce plant resistance and to control phytopathogens (Curvularia lunata) and insect pests (Daubulus maidis). We conducted a chromatographic analysis to unveil the essential oil components. We also quantified the activity levels of antioxidant enzymes and chitinase for resistance induction. The antifungal action was evaluated through disease progression and the inhibition of mycelial growth in addition to in silico studies that made it possible to predict the interaction site between the fungal protein and the compounds. We assessed the toxicity and repellent actions towards the D. maidis. Octanoic acid (58.43%) was identified as the essential oil major compound. Preventive treatment with essential oil and octanoic acid (25.0 µL mL-1) increased not only the plant defense activities (i.e., the activity of the enzymes superoxide dismutase, catalase, phenol peroxidase, ascorbate peroxidase, and chitinase) but also controlled Curvularia leaf spot. The stable interactions between octanoic acid and tyrosine-tRNA ligase from C. lunata suggested protein synthesis inactivation. The essential oil inhibited 51.6% of mycelial growth, and this effect was increased to 75.9% with the addition of adjuvants (i.e., angico gum). The essential oil reduced 76% of the population of D. maidis adults and repelled 50% of the number of D. maidis after 48 h under field conditions. The repellency effect in the field reduced the population of D. maidis adults, transmitters of the stunting complex, by 50%. The results highlight the potential of M. citrifolia as a resistance activator, fungicide, insecticide, and an effective biorational alternative.
RESUMEN
Reliable in-vitro digestion models that are able to successfully replicate the conditions found in the human gastrointestinal tract are key to assess the fate and efficiency of new formulations aimed for oral consumption. However, current in-vitro models either lack the capability to replicate crucial dynamics of digestion or require large volumes of sample/reagents, which can be scarce when working with nanomaterials under development. Here, we propose a miniaturised digestion system, a digestion-chip, based on incubation chambers integrated on a polymethylmethacrylate device. The digestion-chip incorporates key dynamic features of human digestion, such as gradual acidification and gradual addition of enzymes and simulated fluids in the gastric phase, and controlled gastric emptying, while maintaining low complexity and using small volumes of sample and reagents. In addition, the new approach integrates real-time automated closed-loop control of two key parameters, pH and temperature, during the two main phases of digestion (gastric and intestinal) with an accuracy down to ± 0.1 °C and ± 0.2 pH points. The experimental results demonstrate that the digestion-chip successfully replicates the gold standard static digestion INFOGEST protocol and that the semi-dynamic digestion kinetics can be reliably fitted to a first kinetic order model. These devices can be easily adapted to dynamic features in an automated, sensorised, and inexpensive platform and will enable reliable, low-cost and efficient assessment of the bioaccessibility of new and expensive drugs, bioactive ingredients or nanoengineered materials aimed for oral consumption, thereby avoiding unnecessary animal testing.
Asunto(s)
Digestión , Modelos Biológicos , Humanos , Digestión/fisiología , Concentración de Iones de Hidrógeno , Cinética , Tracto Gastrointestinal/metabolismo , Temperatura , Miniaturización , Dispositivos Laboratorio en un ChipRESUMEN
The chemical composition, antioxidant capacity and functional properties of mixtures of baru by-products, named baru food ingredients (BFI), were investigated and applied in a plant-based burger formulation. BFI were prepared from wasted baru by-products - partially defatted baru nut cake and baru pulp plus peel. A plant-based burger was developed and its chemical composition, antioxidant capacity, cooking and texture parameters were determined. BFI1 (50% partially defatted baru nut cake + 50% baru pulp plus peel) had the highest content of carbohydrate (31.9%), and dietary fibre (28.3%). BFI2 (75% partially defatted baru nut cake + 25% baru pulp plus peel) and BFI3 (90% partially defatted baru nut cake + 10% baru pulp plus peel) showed high concentration of protein and dietary fibre, and BFI3 had the highest protein content (29.5%). All BFI showed high concentration of total phenolics (402-443 mg GAE/100 g). Replacing textured pea protein of control burger (PPB) with 35% of BFI3 in the formulation of baru protein burger (BPB) resulted in a low-fat product (2.9%), with protein content (19.2%) comparable to the PPB (15.9%) and the commercial burger (mixed plant proteins - 16.3%). The BPB also showed a higher concentration of dietary fibre (4.9%) and phenolic compounds (128 mg GAE/100 g) than the control burger. BPB's cooking yield was the highest among the tested burgers. BPB had a softer texture when compared to other burgers. Baru food ingredients can be used as nutritive ingredients of health-promoting foods, especially in plant-based products, such as burger and meat analogues, or in hybrid meat products. BPB showed a healthy and nutritious profile.
RESUMEN
Keystroke dynamics can valuably contribute to the development of intelligent authentication systems by enabling a single and continuous authentication process in a passive and non-intrusive manner by continuously verifying a user's identity. This work describes the KeyRecs dataset, which contains fixed-text and free-text samples of user typing behavior and demographic information of the participants age, gender, handedness, and nationality. The keystroke data was obtained from 99 participants of various nationalities who completed password retype and transcription exercises. The recorded samples consist of inter-key latencies computed in a digraph fashion measuring the time between each key press and release during an exercise. KeyRecs can be leveraged to improve the recognition of authorized users and prevent unauthorized access in biometric authentication software.
RESUMEN
The accelerating transition of traditional industrial processes towards fully automated and intelligent manufacturing is being witnessed in almost all segments. This major adoption of enhanced technology and digitization processes has been originally embraced by the Factories of the Future and Industry 4.0 initiatives. The overall aim is to create smarter, more sustainable, and more resilient future-oriented factories. Unsurprisingly, introducing new production paradigms based on technologies such as machine learning (ML), the Internet of Things (IoT), and robotics does not come at no cost as each newly incorporated technique poses various safety and security challenges. Similarly, the integration required between these techniques to establish a unified and fully interconnected environment contributes to additional threats and risks in the Factories of the Future. Accumulating and analyzing seemingly unrelated activities, occurring simultaneously in different parts of the factory, is essential to establish cyber situational awareness of the investigated environment. Our work contributes to these efforts, in essence by envisioning and implementing the SMS-DT, an integrated platform to simulate and monitor industrial conditions in a digital twin-based architecture. SMS-DT is represented in a three-tier architecture comprising the involved data and control flows: edge, platform, and enterprise tiers. The goal of our platform is to capture, analyze, and correlate a wide range of events being tracked by sensors and systems in various domains of the factory. For this aim, multiple components have been developed on the basis of artificial intelligence to simulate dominant aspects in industries, including network analysis, energy optimization, and worker behavior. A data lake was also used to store collected information, and a set of intelligent services was delivered on the basis of innovative analysis and learning approaches. Finally, the platform was tested in a textile industry environment and integrated with its ERP system. Two misuse cases were simulated to track the factory machines, systems, and people and to assess the role of SMS-DT correlation mechanisms in preventing intentional and unintentional actions. The results of these misuse case simulations showed how the SMS-DT platform can intervene in two domains in the first scenario and three in the second one, resulting in correlating the alerts and reporting them to security operators in the multi-domain intelligent correlation dashboard.
Asunto(s)
Inteligencia Artificial , Concienciación , Humanos , Comercio , Industrias , Inteligencia , Seguridad ComputacionalRESUMEN
Human induced pluripotent stem cells (hiPSCs) can be efficiently differentiated into cardiomyocytes (CMs), which can be used for cardiac disease modeling, for drug screening, and to regenerate damaged myocardium. Implementation of xeno-free culture systems is essential to fully explore the potential of these cells. However, differentiation using xeno-free adhesion matrices often results in low CM yields and lack of functional CM sheets, capable of enduring additional maturation stages. Here, we established a xeno-free CM differentiation platform using TeSR/Synthemax, including a replating step and integrated with two versatile purification/enrichment metabolic approaches. Results showed that the replating step was essential to reestablish a fully integrated, closely-knit CM sheet. In addition, replating contributed to increase the cTnT expression from 65% to 75% and the output from 2.2 to 3.1 CM per hiPSC, comparable with the efficiency observed when using TeSR/Matrigel. In addition, supplementation with PluriSin1 and Glu-Lac+ medium allowed increasing the CM content over 80% without compromising CM sheet integrity or functionality. Thus, this xeno-free differentiation platform is a reliable and robust method to produce hiPSC-derived CMs, increasing the possibility of using these cells safely for a wide range of applications.
RESUMEN
Human iPSC-derived self-organized cardiac tissues can be valuable for the development of platforms for disease modeling and drug screening, enhancing test accuracy and reducing pharmaceutical industry financial burden. However, current differentiation systems still rely on static culture conditions and specialized commercial microwells for aggregation, which hinders the full potential of hiPSC-derived cardiac tissues. Herein, we integrate cost-effective and reproducible manual aggregation of hiPSC-derived cardiac progenitors with Matrigel encapsulation and a dynamic culture to support hiPSC cardiac differentiation and self-organization. Manual aggregation at day 7 of cardiac differentiation resulted in 97% of beating aggregates with 78% of cTnT-positive cells. Matrigel encapsulation conjugated with a dynamic culture promoted cell migration and the creation of organized structures, with observed cell polarization and the creation of lumens. In addition, encapsulation increased buoyancy and decreased coalescence of the hiPSC-derived cardiac aggregates. Moreover, VEGF supplementation increased over two-fold the percentage of CD31-positive cells resulting in the emergence of microvessel-like structures. Thus, this study shows that the explored culture parameters support the self-organization of hiPSC-derived cardiac microtissues containing multiple cardiac cell types. Additional stimuli (e.g., BMP) in long-term scalable and fully automatized cultures can further potentiate highly structured and mature hiPSC-derived cardiac models, contributing to the development of reliable platforms for high-throughput drug screening and disease modeling.
Asunto(s)
Células Madre Pluripotentes Inducidas , Miocitos Cardíacos , Humanos , Miocitos Cardíacos/metabolismo , Células Cultivadas , Análisis Costo-Beneficio , Colágeno/metabolismo , Diferenciación CelularRESUMEN
The epicardium, the outer epithelial layer that covers the myocardium, derives from a transient organ known as pro-epicardium, crucial during heart organogenesis. The pro-epicardium develops from lateral plate mesoderm progenitors, next to septum transversum mesenchyme, a structure deeply involved in liver embryogenesis. Here we describe a self-organized human multilineage organoid that recreates the co-emergence of pro-epicardium, septum transversum mesenchyme and liver bud. Additionally, we study the impact of WNT, BMP and retinoic acid signaling modulation on multilineage organoid specification. By co-culturing these organoids with cardiomyocyte aggregates, we generated a self-organized heart organoid comprising an epicardium-like layer that fully surrounds a myocardium-like tissue. These heart organoids recapitulate the impact of epicardial cells on promoting cardiomyocyte proliferation and structural and functional maturation. Therefore, the human heart organoids described herein, open the path to advancing knowledge on how myocardium-epicardium interaction progresses during heart organogenesis in healthy or diseased settings.
Asunto(s)
Organoides , Pericardio , Humanos , Miocardio , Endodermo , OrganogénesisRESUMEN
The Research Octane Number (RON) is a key quality parameter for gasoline, obtained offline through complex, time-consuming, and expensive standard methods. Measurements are usually only available a few times per week and after long delays, making process control very challenging. Therefore, alternative methods have been proposed to predict RON from readily available data. In this work, we report the development of inferential models for predicting RON from process data collected in a real catalytic reforming process. Data resolution and synchronization were explicitly considered during the modelling stage, where 20 predictive linear and non-linear machine learning models were assessed and compared using a robust Monte Carlo double cross-validation approach. The workflow also handles outliers, missing data, multirate and multiresolution observations, and processes dynamics, among other features. Low RMSE were obtained under testing conditions (close to 0.5), with the best methods belonging to the class of penalized regression methods and partial least squares. The developed models allow for improved management of the operational conditions necessary to achieve the target RON, including a more effective use of the heating utilities, which improves process efficiency while reducing costs and emissions.
Asunto(s)
Gasolina , Octanos , Análisis de los Mínimos Cuadrados , Aprendizaje AutomáticoRESUMEN
The generation of cardiomyocytes (CMs) from human pluripotent stem cells (hPSCs) represents a valuable tool for a myriad of in vitro applications, including drug screening, disease modeling and regenerative medicine. However, the success of these applications is dependent on the establishment of reliable, efficient, simple, and cost-effective differentiation methods. In this chapter, we describe an efficient and robust 3D platform for the generation of hPSC-CMs based on the use of a microwell culture system, which can be applied in any laboratory environment. Additionally, we will also describe protocols for the structural and functional characterization of the obtained CMs for further quality control upon differentiation.
Asunto(s)
Miocitos Cardíacos , Células Madre Pluripotentes , Técnicas de Cultivo de Célula/métodos , Diferenciación Celular , HumanosRESUMEN
Phosphorus is an essential nutrient for crops. Precise spatiotemporal application of P fertilizer can improve plant P acquisition and reduce run-off losses of P. Optimizing application would benefit from understanding the dynamics of P release from a fertilizer pellet into bulk soil, which requires space- and time-resolved measurements of P concentration in soil solutions. In this study, we combined microdialysis and X-ray computed tomography to investigate P transport in soil. Microdialysis probes enabled repeated solute sampling from one location with minimal physical disturbance, and their small dimensions permitted spatially resolved monitoring. We observed a rapid initial release of P from the source, producing high dissolved P concentrations within the first 24 h, followed by a decrease in dissolved P over time compatible with adsorption onto soil particles. Soils with greater bulk density (i.e., reduced soil porosity) impeded the P pulse movement, which resulted in a less homogeneous distribution of total P in the soil column at the end of the experiment. The model fit to the data showed that the observed phenomena can be explained by diffusion and adsorption. The results showed that compared with conventional measurement techniques (e.g., suction cups), microdialysis measurements present a less invasive alternative. The time-resolved measurements ultimately highlighted rapid P dynamics that require more attention for improving P use efficiency.
RESUMEN
Nutrition is an undeniable part of promoting health and performance among football (soccer) players. Nevertheless, nutritional strategies adopted in elite football can vary significantly depending on culture, habit and practical constraints and might not always be supported by scientific evidence. Therefore, a group of 28 Portuguese experts on sports nutrition, sports science and sports medicine sought to discuss current practices in the elite football landscape and review the existing evidence on nutritional strategies to be applied when supporting football players. Starting from understanding football's physical and physiological demands, five different moments were identified: preparing to play, match-day, recovery after matches, between matches and during injury or rehabilitation periods. When applicable, specificities of nutritional support to young athletes and female players were also addressed. The result is a set of practical recommendations that gathered consensus among involved experts, highlighting carbohydrates periodisation, hydration and conscious use of dietary supplements.
RESUMEN
Peptides have been thoroughly studied as new therapeutic strategies for cancer treatment. In this work, we explored in vitro the anticancer potential of three novel peptides derived from the C-terminal of azurin, an anticancer bacterial protein produced by Pseudomonas aeruginosa. CT-p26, CT-p19 and CT-p19LC peptides were previously obtained through an in silico peptide design optimization process, CT-p19LC being the most promising as it presented higher hydrophobicity and solubility, positive total charge and, most importantly, greater propensity for anticancer activity. Therefore, in this study, through proliferation and apoptosis assays, CT-p19LC was tested in four cancer cell lines-A549, MCF-7, HeLa and HT-29-and in two non-cancer cell lines-16HBE14o- and MCF10A. Its membrane-targeting activity was further evaluated with zeta potential measurements and membrane order was assessed with the Laurdan probe. The results obtained demonstrated that CT-p19LC decreases cell viability through induction of cell death and binds to the plasma membrane of cancer cells, but not to non-cancer cells, making them less rigid. Overall, this study reveals that CT-p19LC is an auspicious selective anticancer peptide able to react with cancer cell membranes and cause effective action.
RESUMEN
Lung cancer is still the main cause of cancer-related deaths worldwide. Its treatment generally includes surgical resection, immunotherapy, radiotherapy, and chemo-targeted therapies such as the application of tyrosine kinase inhibitors. Gefitinib (GEF) is one of them, but its poor solubility in gastric fluids weakens its bioavailability and therapeutic activity. In addition, like all other chemotherapy treatments, GEF administration can cause damage to healthy tissues. Therefore, the development of novel GEF delivery systems to increase its bioavailability and distribution in tumor site is highly demanded. Herein, an innovative strategy for GEF delivery, by functionalizing PLGA nanoparticles with p28 (p28-NPs), a cell-penetrating peptide derived from the bacterial protein azurin, was developed. Our data indicated that p28 potentiates the selective interaction of these nanosystems with A549 lung cancer cells (active targeting). Further p28-NPs delivering GEF (p28-NPs-GEF) were able to selectively reduce the metabolic activity of A549 cells, while no impact was observed in non-tumor cells (16HBE14o-). In vivo studies using A549 subcutaneous xenograft showed that p28-NPs-GEF reduced A549 primary tumor burden and lung metastases formation. Overall, the design of a p28-functionalized delivery nanosystem to effectively penetrate the membranes of cancer cells while deliver GEF could provide a new strategy to improve lung cancer therapy.
Asunto(s)
Antineoplásicos , Neoplasias Pulmonares , Nanopartículas , Antineoplásicos/uso terapéutico , Línea Celular Tumoral , Gefitinib , Humanos , Neoplasias Pulmonares/tratamiento farmacológico , Carga TumoralRESUMEN
INTRODUCTION: Transcatheter aortic valve implantation (TAVI) is associated with cardiac electrical disturbances. However, beyond the risks of pacemaker implantation, few studies have performed a detailed assessment of the effects of TAVI on several cardiac electrical properties. OBJECTIVES: To assess the frequency and type of electrocardiographic disturbances following TAVI, according to the type of prostheses and to assess predictors of these disturbances. METHODS: We performed a detailed retrospective analysis of all electrocardiograms in patients who underwent TAVI, before and after the procedure, at a tertiary center from August 2007 to October 2016. Patients with permanent pacemakers were excluded. RESULTS: We included 182 patients (78±8 years; 56% female) and self-expanding prostheses (SEP) were implanted in 54%. Most patients (80%) were in sinus rhythm at baseline. After TAVI, 21% of patients developed new-onset atrial fibrillation and there was a significant increase in PR interval at discharge (186±41 ms vs. 176±32; p=0.003), which was not maintained after at six-month follow-up (181±35 ms, p=0.06). There was also a significant increase in QRS duration at discharge (129±28 ms vs. 114±25 at baseline p<0.0001), which persisted at six-months (122±28 ms, p<0.0001). New-onset left-bundle branch block (LBBB) was observed in 25% of patients. The depth of valve implantation was a predictor of new LBBB at discharge after multivariate analysis (OR 37.6, 95% CI 14.6-65.2, p=0.001). CONCLUSIONS: The main electrocardiographic disturbances post TAVI were PR prolongation, increased QRS and new-onset LBBB. These disturbances were more pronounced in patients undergoing SEP implantation and tended to improve at six-month follow-up. The depth of valve implantation was a predictor of conduction disturbances.
Asunto(s)
Prótesis Valvulares Cardíacas , Reemplazo de la Válvula Aórtica Transcatéter , Válvula Aórtica/cirugía , Femenino , Humanos , Masculino , Estudios Retrospectivos , Reemplazo de la Válvula Aórtica Transcatéter/efectos adversos , Resultado del TratamientoRESUMEN
The relative age effect (RAE), within the sporting scope, refers to the possible advantages of participation and performance of athletes born in the first months of the year of selection in relation to others within the same age category. The aim of the present study was to investigate the RAE in girls' volleyball players participating in the U-18 World Championship, analysing the differences between the medal teams and other teams in the tournament, and considering this phenomenon in relation to the continents. Data collection was obtained from the website of the International Volleyball Federation with a sample made of 1654 youth players in the last six world championships (2007, 2009, 2011, 2013, 2015 and 2017). A greater representation of athletes born in the first months of the year of all the world championships was observed. In the comparison among the continents, it was observed that in Africa, there was a more equal distribution of quartiles compared to America, Asia and Europe. It should be noted that there was a higher percentage of medalist athletes born at the beginning of the year in comparison to the countries that placed in the last three positions of the championship. Therefore, in U-18 female volleyball, there is an advantage to have the closest birth age at the beginning of the competitive biennium.
RESUMEN
Root citrate exudation is thought to be important for phosphate solubilization. Previous research has concluded that cluster-like roots benefit most from this exudation in terms of increased phosphate uptake, suggesting that root structure plays an important role in citrate-enhanced uptake (additional phosphate uptake due to citrate exudation). Time-resolved computed tomography images of wheat root systems were used as the geometry for 3D citrate-phosphate solubilization models. Citrate-enhanced uptake was correlated with morphological measures of the root systems to determine which had the most benefit. A large variation of citrate-enhanced uptake over 11 root structures was observed. Root surface area dominated absolute phosphate uptake, but did not explain citrate-enhanced uptake. Number of exuding root tips correlated well with citrate-enhanced uptake. Root tips in close proximity could collectively exude high amounts of citrate, resulting in a delayed spike in citrate-enhanced uptake. Root system architecture plays an important role in citrate-enhanced uptake. Singular morphological measurements of the root systems cannot entirely explain variations in citrate-enhanced uptake. Root systems with many tips would benefit greatly from citrate exudation. Quantifying citrate-enhanced uptake experimentally is difficult as variations in root surface area would overwhelm citrate benefits.
Asunto(s)
Ácido Cítrico , Fosfatos , Transporte Biológico , Meristema , Raíces de PlantasAsunto(s)
Anomalías Múltiples/diagnóstico por imagen , Angiografía por Tomografía Computarizada , Defectos del Tabique Interatrial/diagnóstico por imagen , Flebografía , Venas Pulmonares/diagnóstico por imagen , Síndrome de Cimitarra/diagnóstico por imagen , Humanos , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Venas Pulmonares/anomalíasRESUMEN
AIMS: Cellular schwannoma is a specific subtype of schwannoma, prone to misinterpretation as a malignant neoplasm. Involvement of the intracranial compartment by these tumours is extremely rare. We aim to characterise this clinicopathological subgroup. METHODS AND RESULTS: We identified a total of 20 cellular schwannomas with predominant intracranial involvement. The mean age of the patients at the time of surgery was 37 years (range = 16-81), with a slight female predominance (1.5:1 ratio). The most common sites were the eighth (n = 8) and fifth (n = 6) cranial nerves. Three tumours involved the anterior cranial fossa/olfactory groove, and a single case involved the glossopharyngeal nerve. All tumours met established criteria for cellular schwannoma, and were composed of interlacing fascicles of spindle cells lacking Verocay bodies with minimal Antoni B pattern and variable chronic inflammation and foamy histiocytes. Rare findings included haemosiderin deposition (n = 6), necrosis (n = 4), brisk mitotic activity (>10 mitoses per 10 high-power fields) (n = 2), focal epithelioid morphology (n = 2), myxoid areas (n = 2), neuroblastoma-like pattern (n = 1) and granular cells (n = 1). Immunohistochemical stains demonstrated expression of Schwann cell markers (S100 protein, SOX10, collagen IV) and preserved H3 K27 trimethylation in all cases tested. Fourteen patients had postoperative follow-up, ranging from 2 months to 21 years (mean = 66 months). In patients with follow-up, local recurrence/persistence developed in six cases; five tumours were initially incompletely resected. No metastatic disease or deaths were reported. CONCLUSIONS: Intracranial cellular schwannomas share morphological and immunophenotypical features with cellular schwannomas at others sites may demonstrate locally aggressive growth but appear to lack metastatic potential.