Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 13 de 13
Filtrar
1.
Anal Chem ; 96(15): 5852-5859, 2024 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-38556977

RESUMEN

A multicolor electrochemiluminescence (ECL) biosensor based on a closed bipolar electrode (BPE) array was proposed for the rapid and intuitive analysis of three prostate cancer staging indicators. First, [Irpic-OMe], [Ir(ppy)2(acac)], and [Ru(bpy)3]2+ were applied as blue, green, and red ECL emitters, respectively, whose mixed ECL emission colors covered the whole visible region by varying the applied voltages. Afterward, we designed a simple Mg2+-dependent DNAzyme (MNAzyme)-driven tripedal DNA walker (TD walker) to release three output DNAs. Immediately after, three output DNAs were added to the cathodic reservoirs of the BPE for incubation. After that, we found that the emission colors from the anode of the BPE changed as a driving voltage of 8.0 V was applied, mainly due to changes in the interfacial potential and faradaic currents at the two poles of the BPE. Via optimization of the experimental parameters, cutoff values of such three indicators at different clinical stages could be identified instantly with the naked eye, and standard precision swatches with multiple indicators could be prepared. Finally, in order to precisely determine the prostate cancer stage, the multicolor ECL device was used for clinical analysis, and the resulting images were then compared with standard swatches, laying the way for accurate prostate cancer therapy.


Asunto(s)
Técnicas Biosensibles , Neoplasias de la Próstata , Masculino , Humanos , Mediciones Luminiscentes/métodos , Fotometría , Neoplasias de la Próstata/diagnóstico , Antígeno Prostático Específico , ADN , Técnicas Biosensibles/métodos , Electrodos , Técnicas Electroquímicas/métodos
2.
Inorg Chem ; 62(38): 15641-15650, 2023 Sep 25.
Artículo en Inglés | MEDLINE | ID: mdl-37690055

RESUMEN

When it comes to an efficient catalytic oxygen evolution reaction (OER) in the production of renewable energy and chemicals, the construction of heterogeneous structures is crucial to break the linear scalar relationship of a single catalyst. This heterogeneous structure construction helps creatively achieve high activity and stability. However, the synthesis process of heterogeneous crystalline materials is often complex and challenging to capture and reproduce, which limits their application. Here, the dynamic process of structural changes in Co-MOFs in alkali was captured by in situ powder X-ray diffraction, FT-IR spectroscopy, and Raman spectroscopy, and several self-reconfigured MOF heterogeneous materials with different structures were stably isolated. The created ß-Co(OH)2/Co-MOF heterojunction structure facilitates rapid mass-charge transfer and exposure of active sites, which significantly enhanced OER activity. Experimental results show that this heterogeneous structure achieves a low overpotential of 333 mV at 10 mA cm-2. The findings provide new insights and directions for the search for highly reactive cobalt-based MOFs for sustainable energy technologies.

3.
Inorg Chem ; 61(46): 18743-18751, 2022 Nov 21.
Artículo en Inglés | MEDLINE | ID: mdl-36356227

RESUMEN

Basic requirements for advanced and practical supercapacitors need electrode materials with strong stability, high surface area, well-defined porosity, and enhanced capability of ion insertion and electron transfer. It is worth mentioning that the two-dimensional cluster-based Ni/Co-organic layer (Ni0.7Co0.3-CMOL) inherits high stability from the Kagóme lattice and shows excellent pseudocapacitance behavior. As an optimized atomic composition, this crystalline CMOL exhibits excellent performance and stability both in 1.0 M KOH and All-Solid-State Flexible Asymmetric Supercapacitor (ASCs). The specific capacitance values are 1211 and 394 F g-1 and the energy density is 54.67 Wh kg-1 at 1 A g-1. Good cycling stability is characterized by its capacitance retention, maintained at 92.4% after 5000 cycles in a three-electrode system and 90% after 2000 cycles at 20 A g-1 for assembled All-Solid-State Flexible ASCs. An in situ XRD technique was used in the three-electrode system, which showed that there was no signal of crystalline substance that affected the cyclic stability of the material while charging and discharging. These superior results prove that Ni0.7Co0.3-CMOL is a promising candidate for supercapacitor applications.

4.
PLoS One ; 19(4): e0302235, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38635544

RESUMEN

INTRODUCTION: Physical exercise (PE) is essential for alleviating the symptoms of sarcopenia. Low motivation is a major barrier to PE. Mindfulness-based intervention (MBI) has the potential to improve motivation. However, few studies have used a mindfulness-based PE (MBPE) intervention among older people with sarcopenia. OBJECTIVES: To assess the feasibility, acceptability and preliminary effects of the MBPE program among community-dwelling older people with sarcopenia. METHODS AND ANALYSIS: A two-arm pilot randomised controlled trial will be conducted to assess the feasibility, acceptability and preliminary effects of an MBPE program among community-dwelling older people with sarcopenia. A total of 60 participants will be randomised into the intervention group, receiving the MBPE intervention twice a week over 12 weeks, or the control group, receiving health education with the same duration, number of sessions and frequency as the intervention group. Each session of the MBPE program will last about 60 min, including 5-10- min introduction, 20-min MBI, 30-min PE and 5-10-min sharing and discussion. The primary outcomes will be the feasibility (i.e., the time spent recruiting participants, the eligibility rate and the recruitment rate) and acceptability (i.e., the attendance rate, completion rate and attrition rate) of the MBPE program. The secondary outcomes will be the preliminary effects of the MBPE program on symptoms of sarcopenia, motivation for PE, psychological well-being, mindfulness level, physical activity level and quality of life. Individual interviews will be conducted to identify the strengths, limitations and therapeutic components of the intervention. The quantitative data will be analysed by generalised estimating equations. The qualitative data will be analysed by Braun and Clarke's thematic approach. CONCLUSION: The findings of this study will be able to provide evidence for the health professionals in adopting MBPE as a supportive intervention for the older adults with sarcopenia and the groundworks for the researchers in developing non-pharmacological intervention for older adults. The positive effects could facilitate healthy ageing and relief the burden of the medical system, especially in the countries facing the ageing population. TRIAL REGISTRATION NUMBER: NCT05982067; ClinicalTrials.gov.


Asunto(s)
Atención Plena , Sarcopenia , Humanos , Anciano , Sarcopenia/terapia , Calidad de Vida , Vida Independiente , Estudios de Factibilidad , Proyectos Piloto , Ejercicio Físico , Ensayos Clínicos Controlados Aleatorios como Asunto
5.
Biosens Bioelectron ; 253: 116162, 2024 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-38437748

RESUMEN

An electrochemiluminescence (ECL) biosensor with a pair of new ECL emitters and a novel sensing mechanism was designed for the high-sensitivity detection of microRNA-141 (miRNA-141). Sulfur-doped boron nitrogen quantum dots (S-BN QDs) were initially employed to modify the cathode of the bipolar electrode (BPE), while the anode reservoir was [Ir(dfppy)2(bpy)]PF6/TPrA system. The next step involved attaching H1-bound ultra-small WO3-x nanodots (WO3-x NDs) to the S-BN QDs-modified BPE cathode via DNA hybridization. A strong surface plasmon coupling (SPC) effect was observed between S-BN QDs and WO3-x NDs, which allowed for the enhancement of the red and visible ECL emission from S-BN QDs. After target-induced cyclic amplification to produce abundant Zn2+ and Au NPs-DNA3-Au NPs (Au NPs-S3-Au NPs), Zn2+ could cleave DNA at a nucleotide sequence-specific recognition site to release the WO3-x NDs, resulting in the first diminution of cathode ECL signal and the first enhancement of anode ECL signal. Moreover, the ECL signal at cathode decreased for the second time and the emission of [Ir(dfppy)2(bpy)]PF6 was continuously enhanced after the introduction of Au nanoparticles-S3-Au nanoparticles on the cathode surface. Our sensing mode with a dual "on-off" signal conversion strategy shows a good detection capability for miRNAs ranging from 10-17 to 10-10 M, with a limit of detection (LOD) as low as 10-17 M, which has great application potential in biomedical research and clinical diagnosis.


Asunto(s)
Técnicas Biosensibles , Nanopartículas del Metal , MicroARNs , Oro , Boro , Transferencia de Energía , Nitrógeno , Azufre , ADN
6.
Anal Chim Acta ; 1315: 342822, 2024 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-38879216

RESUMEN

In this study, a novel electrochemiluminescence (ECL) biosensor was developed to detect microRNA-21 (miRNA-21) with high sensitivity by leveraging the combined mechanisms of resonance energy transfer (RET) and surface plasmon coupling (SPC). Initially, the glassy carbon electrode (GCE) were coated with Cu-Zn-In-S quantum dots (CZIS QDs), known for their defect-related emission suitable for ECL sensing. Subsequently, a hairpin DNA H3 with gold nanoparticles (Au NPs) attached at the end was modified over the surface of the quantum dots. The Au NPs could effectively quench the ECL signals of CZIS QDs via RET. Further, a significant amount of report DNA was generated through the action of a 3D DNA walker. When the report DNA opened H3-Au NPs, the hairpin structure experienced a conformational change to a linear shape, increasing the gap between the CZIS QDs and the Au NPs. Consequently, the localized surface plasmon resonance ECL (LSPR-ECL) effect replaced ECL resonance energy transfer (ECL-RET). Moreover, the report DNA was released following the addition of H4-Au NPs, resulting in the formation of Au dimers and a surface plasma-coupled ECL (SPC-ECL) effect that enhanced the ECL intensity to 6.97-fold. The integration of new ECL-RET and SPC-ECL biosensor accurately quantified miRNA-21 concentrations from 10-8 M to 10-16 M with a limit of detection (LOD) of 0.08 fM, as well as successfully applied to validate human serum samples.


Asunto(s)
Técnicas Biosensibles , ADN , Técnicas Electroquímicas , Mediciones Luminiscentes , MicroARNs , Puntos Cuánticos , Resonancia por Plasmón de Superficie , MicroARNs/análisis , MicroARNs/sangre , Humanos , Técnicas Electroquímicas/métodos , Técnicas Biosensibles/métodos , ADN/química , Puntos Cuánticos/química , Resonancia por Plasmón de Superficie/métodos , Mediciones Luminiscentes/métodos , Oro/química , Límite de Detección , Transferencia de Energía , Nanopartículas del Metal/química
7.
Biosens Bioelectron ; 261: 116495, 2024 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-38878699

RESUMEN

In this study, we have for the first time constructed a ratiometric ECL biosensor for the ultrasensitive detection of microRNAs (miRNAs) using gold nanoparticles (Au NPs) to trigger both the low-potential emission from conjugated polymer poly(9,9-dioctylfluorene-2,7-diyl) dots (PFO Pdots) and the LSPR-ECL effect with sulfur-doped boron nitride quantum dots (S-BN QDs). PFO Pdots were first applied to the Au NPs-modified electrode, followed by covalent binding to capture the hairpin H1. Immediately thereafter, a small amount of miRNA-141 was able to generate a large amount of output DNA (OP) by traversing the target cycle. OP, H3-S-BN QDs, and H4-glucose oxidase (H4-GOD) were then added sequentially to the Au NPs-modified electrode surface, and the hybridization chain reaction (HCR) was initiated. This resulted in the introduction of a large amount of GOD into the system, which catalyzed the in situ formation of the co-reactant hydrogen peroxide (H2O2) from the substrate glucose. Due to the electron transfer effect, the production of H2O2 led to the ECL quenching of PFO Pdots. Meanwhile, H2O2 served as a co-reactant of S-BN QDs, resulting in strong ECL emission of S-BN QDs at the cathode. Furthermore, the cathodic ECL intensity of S-BN QDs was further enhanced by an LSPR-ECL mechanism between Au NPs and S-BN QDs. By measuring the ratio of ECL intensities at two excitation potentials, this approach could provide sensitive and reliable detection of miRNA-141 in the range of 0.1 fM ∼10 nM, with a detection limit of 0.1 fM.


Asunto(s)
Técnicas Biosensibles , Técnicas Electroquímicas , Oro , Límite de Detección , Mediciones Luminiscentes , Nanopartículas del Metal , MicroARNs , Puntos Cuánticos , Técnicas Biosensibles/métodos , Oro/química , MicroARNs/análisis , Nanopartículas del Metal/química , Puntos Cuánticos/química , Técnicas Electroquímicas/métodos , Humanos , Mediciones Luminiscentes/métodos , Fluorenos/química , Glucosa Oxidasa/química , Peróxido de Hidrógeno/química
8.
Exp Gerontol ; 174: 112128, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36804363

RESUMEN

BACKGROUND: The COVID-19 pandemic has greatly impacted people's lifestyles and changed the delivery of health interventions, especially interventions for community-dwelling older people with sarcopenia. OBJECTIVE: To summarize the components and explore the effectiveness of home-based interventions for improving sarcopenia and other health-related outcomes among community-dwelling older people with sarcopenia. DESIGN: Systematic review and meta-analysis. METHODS: The Cochrane Library, Scopus, EMBASE, Web of Science, CINAHL, Medline (via PubMed), and PsycINFO were searched for relevant papers published from January 1, 2010 to March 29, 2022. Only papers written in English were included. The modified version of Cochrane's risk-of-bias tool was used to assess the risks of bias in the included studies. The template for intervention description and replication checklist was used to summarize the intervention components. The mean difference (MD) or standard mean difference with a 95 % confidence interval (CI) was used to determine the effect size of studies using the same or different measuring methods. Random-effects models were in meta-analyses to pool the effects of home-based interventions on the included outcomes. RESULTS: After detailed screening and exclusion, 11 randomized controlled trials including 1136 older people with sarcopenia were included in our analyses. Three categories of home-based interventions were identified: exercise interventions, nutritional interventions, and combined exercise and nutritional interventions. The overall analysis of the outcomes (e.g., appendicular skeletal muscle mass index, lean mass, body fat mass, handgrip strength, and gait speed), showed that the effects of home-based exercise interventions were inconclusive. Compared with passive controls, home-based exercise interventions significantly improved knee extension strength (MD = 0.56 kg, 95 % CI: 0.09, 1.03, p = 0.020) and reduced the time required to complete the Timed Up and Go Test (MD = -1.41 s, 95 % CI: -2.28, -0.54, p = 0.001). Home-based nutritional interventions were effective in improving appendicular skeletal muscle mass (MD = 0.25 kg, 95 % CI: 0.02, 0.49, p = 0.030), gait speed (MD = 0.06 m/s, 95 % CI: 0.03, 0.09, p = 0.0001), and quality of life in terms of both the physical component summary (MD = 13.54, 95 % CI: 0.73, 26.34, p = 0.040) and mental component summary scores (MD = 8.69, 95 % CI: 2.98, 14.41, p = 0.003). CONCLUSION: Home-based exercise interventions have the potential to improve muscle strength and physical function, while home-based nutritional interventions are effective in increasing muscle mass, physical function, and quality of life. Both of these can be applied at home during and after the COVID-19 pandemic to alleviate sarcopenia and improve health-related outcomes in community-dwelling older people.


Asunto(s)
COVID-19 , Sarcopenia , Humanos , Anciano , Sarcopenia/terapia , Vida Independiente , Calidad de Vida , Fuerza de la Mano , Equilibrio Postural , Pandemias , Estudios de Tiempo y Movimiento
9.
Ann Med ; 55(1): 2205168, 2023 12.
Artículo en Inglés | MEDLINE | ID: mdl-37141250

RESUMEN

The chemokine CCL5 plays a potential role in the occurrence and development of colorectal cancer (CRC). Previous studies have shown that CCL5 directly acts on tumor cells to change tumor metastatic rates. In addition, CCL5 recruits immune cells and immunosuppressive cells into the tumor microenvironment (TME) and reshapes the TME to adapt to tumor growth or increase antitumor immune efficacy, depending on the type of secretory cells releasing CCL5, the cellular function of CCL5 recruitment, and the underlying mechanisms. However, at present, research on the role played by CCL5 in the occurrence and development of CRC is still limited, and whether CCL5 promotes the occurrence and development of CRC and its role remain controversial. This paper discusses the cells recruited by CCL5 in patients with CRC and the specific mechanism of this recruitment, as well as recent clinical studies of CCL5 in patients with CRC.Key MessagesCCL5 plays dual roles in colorectal cancer progression.CCL5 remodels the tumor microenvironment to adapt to colorectal cancer tumor growth by recruiting immunosuppressive cells or by direct action.CCL5 inhibits colorectal cancer tumor growth by recruiting immune cells or by direct action.


Asunto(s)
Quimiocina CCL5 , Neoplasias Colorrectales , Humanos , Línea Celular Tumoral , Microambiente Tumoral
10.
Front Endocrinol (Lausanne) ; 14: 1189570, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37711894

RESUMEN

Object: There is mounting clinical evidence that an increase in obesity is linked to an increase in cancer incidence and mortality. Although studies have shown a link between obesity and colon cancer, the particular mechanism of the interaction between obesity and colon cancer in females remains unknown. The goal of this work is to use bioinformatics to elucidate the genetic link between obesity and colon cancer in females and to investigate probable molecular mechanisms. Methods: GSE44076 and GSE199063 microarray datasets were obtained from the Gene Expression Omnibus (GEO) database. In the two microarray datasets and healthy controls, the online tool GEO2R was utilized to investigate the differential genes between obesity and colon cancer. The differential genes (DEGs) identified in the two investigations were combined. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment studies were performed on the DEGs. The STRING database and Cytoscape software were then used to build protein-protein interaction (PPI) networks to discover hub genes. NetworkAnalyst was also used to build networks of target microRNAs (miRNAs) and hub genes, as well as networks of transcriptions. Results: Between the two datasets, 146 DEGs were shared. The DEGs are primarily enriched in inflammatory and immune-related pathways, according to GO analysis and KEGG. 14 hub genes were identified via PPI building using the Cytoscape software's MCODE and CytoNCA plug-ins: TYROBP, CD44, BGN, FCGR3A, CD53, CXCR4, FN1, SPP1, IGF1, CCND1, MMP9, IL2RG, IL6 and CTGF. Key transcription factors for these hub genes include WRNIP1, ATF1, CBFB, and NR2F6. Key miRNAs for these hub genes include hsa-mir-1-3p, hsa-mir-26b-5p, hsa-mir-164a-5p and hsa-mir-9-5p. Conclusion: Our research provides evidence that changed genes are shared by female patients with colon cancer and obesity. Through pathways connected to inflammation and the immune system, these genes play significant roles in the emergence of both diseases. We created a network between hub genes and miRNAs that target transcription factors, which may offer suggestions for future research in this area.


Asunto(s)
Neoplasias del Colon , MicroARNs , Humanos , Femenino , MicroARNs/genética , Neoplasias del Colon/epidemiología , Neoplasias del Colon/genética , Obesidad/complicaciones , Obesidad/genética , Biología Computacional , Bases de Datos Factuales , Proteínas Represoras
11.
BMC Psychol ; 10(1): 178, 2022 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-35854347

RESUMEN

BACKGROUND: Mindfulness-based intervention (MBI), an emotion-focused approach, has been shown promising and sustainable effects on enhancing the well-being of caregivers of patients with dementia (PWD). However, the conventional MBI was quite demanding, had high rates of attrition and inconsistent long-term effect. The social distancing measures introduced during the COVID-19 pandemic also restricted face-to-face psychosocial intervention. The study aims to evaluate the effectiveness of a 6-week hybrid MBI in caregivers of PWD over a 6-month follow up. METHODS: This is a single-blinded, parallel-group randomized controlled trial (RCT). Eligible participants from three local nongovernmental organizations (NGOs) will be randomly divided into intervention groups and control groups in a ratio of 1:1. The participants in the intervention group will receive 6 weekly 90-min group-based sessions delivered through a face-to-face and online approach. The participants in the control group will receive brief education on dementia care with the same group size, duration, and frequency as the sessions in the intervention group. Immediately after the intervention and at the 6-month follow-up, caring stress and other outcomes will be assessed. Besides, a focus group interview will be conducted to identify the strengths, limitations, and therapeutic components of the intervention from their perspectives. For quantitative data, intention-to-treat analysis and Generalized Estimating Equations (GEE) will be used. For qualitative data, content analysis will be used. DISCUSSION: This proposed hybrid model of MBI has several advantages, such as lower duration, longer follow-up period and easier access by family caregivers. Also, physiological indicators (e.g., heart rate viability and neuropsychiatric symptoms) will be measured in this study to show the body change after MBI. The quantitative and qualitative data of this research can also benefit the development of online or hybrid MBI for caregivers of PWD during the COVID-19 pandemic. Despite these strengths, it does have practical challenges and limitations. However, this proposed intervention has the potential to benefit not only the participants, but also the researcher as well as public health providers. TRIAL REGISTRATION: NCT05242614. Registered on 2022-02-16, https://clinicaltrials.gov/ct2/show/NCT05242614.


Asunto(s)
COVID-19 , Demencia , Atención Plena , Cuidadores/psicología , Demencia/terapia , Emociones , Humanos , Atención Plena/métodos , Ensayos Clínicos Controlados Aleatorios como Asunto
12.
Eur J Cardiovasc Nurs ; 20(8): 736-744, 2021 11 28.
Artículo en Inglés | MEDLINE | ID: mdl-34160024

RESUMEN

AIMS: Older patients with cardiovascular diseases (CVDs) are more likely to develop frailty. Few studies have investigated frailty status, and its multiple associated factors, in this population. The aim of the present study was to explore frailty status, and its multidimensional associated factors, in elderly inpatients with CVDs. METHODS AND RESULTS: In this cross-sectional study, 1021 inpatients with CVDs aged ≥60 years old were recruited through convenience sampling from multiple hospitals in Suzhou, China. The FRAIL scale was used to assess frailty. A self-designed questionnaire gathered sociodemographic, clinical, and health-related information related to the physiological, psychological, and social dimensions of frailty. Among the 629 elderly inpatients with CVDs (73.64 ± 7.93 years old) who met inclusion criteria and completed the assessments, 176 (28.0%) were classified as frail. Univariate analyses demonstrated that the proportion of frailty was significantly associated with multiple factors. Logistic regression analysis indicated that, compared to their counterparts, the risk of frailty was higher in participants with cardiac function classes II, III, and IV [odds ratio (OR) = 1.866, 3.393, and 6.351, respectively]; average and bad mastication function (OR = 2.534 and 2.945, respectively); and often or always using walking aids (OR = 2.713). Conversely, the risk of frailty was lower in participants with good nutritional status (OR = 0.879) and regular exercise habits (OR = 0.573), as compared with their counterparts. CONCLUSION: Frailty in elderly inpatients with CVDs is common and associated with multiple physiological factors including cardiac function, mastication function, nutritional status, use of walking aids, and regular exercise habits.


Asunto(s)
Enfermedades Cardiovasculares , Fragilidad , Anciano , Anciano de 80 o más Años , Estudios Transversales , Anciano Frágil , Evaluación Geriátrica/métodos , Humanos , Pacientes Internos , Persona de Mediana Edad
13.
ACS Appl Mater Interfaces ; 12(4): 4423-4431, 2020 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-31850743

RESUMEN

Production of hydrogen peroxide (H2O2) via in situ electrochemical water oxidation possesses great potential applications in the energy and environment fields. In this work, for the first time, we reported a C,N codoped TiO2 electrode for selective electrocatalytic water oxidation to produce H2O2 in an acidic electrolyte. An electrochemical anodic oxidation method combined with postcalcination in the presence of urea was applied to fabricate such a C,N codoped TiO2 electrode, which was evidenced by detail structural characterizations. The calcination temperature and urea atmosphere were found to play key roles in its catalytic performances; the optimized 600N sample exhibited an onset potential of 2.66 V (vs Ag/AgCl) and a Tafel slope of 51 mV dec-1 at pH 3. Under the optimal applied potential, the cumulative H2O2 concentration for this sample reached 0.29 µmol L-1 cm-2 h-1. More importantly, a simple recalcination strategy was developed to recover the deactivation electrode. This study proposed an efficient C,N codoped TiO2 electrode toward water oxidation to selectively produce H2O2 in the acidic electrolyte, which could be further used to in situ generate H2O2 for the energy- and environment-related fields with water as the precursor.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA