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1.
Plant Cell ; 34(10): 3899-3914, 2022 09 27.
Artículo en Inglés | MEDLINE | ID: mdl-35775944

RESUMEN

In eukaryotes, the STRUCTURAL MAINTENANCE OF CHROMOSOME 5/6 (SMC5/6) complex is critical to maintaining chromosomal structures around double-strand breaks (DSBs) in DNA damage repair. However, the recruitment mechanism of this conserved complex at DSBs remains unclear. In this study, using Arabidopsis thaliana as a model, we found that SMC5/6 localization at DSBs is dependent on the protein scaffold containing INVOLVED IN DE NOVO 2 (IDN2), CELL DIVISION CYCLE 5 (CDC5), and ALTERATION/DEFICIENCY IN ACTIVATION 2B (ADA2b), whose recruitment is further mediated by DNA-damage-induced RNAs (diRNAs) generated from DNA regions around DSBs. The physical interactions of protein components including SMC5-ADA2b, ADA2b-CDC5, and CDC5-IDN2 result in formation of the protein scaffold. Further analysis indicated that the DSB localization of IDN2 requires its RNA-binding activity and ARGONAUTE 2 (AGO2), indicating a role for the AGO2-diRNA complex in this process. Given that most of the components in the scaffold are conserved, the mechanism presented here, which connects SMC5/6 recruitment and small RNAs, will improve our understanding of DNA repair mechanisms in eukaryotes.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Roturas del ADN de Doble Cadena , Daño del ADN/genética , Reparación del ADN/genética , ADN de Plantas/metabolismo , ARN/genética , Factores de Transcripción/metabolismo
2.
Opt Lett ; 49(7): 1725-1728, 2024 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-38560847

RESUMEN

Ultrasound coupling is one of the critical challenges for traditional photoacoustic (or optoacoustic) microscopy (PAM) techniques transferred to the clinical examination of chronic wounds and open tissues. A promising alternative potential solution for breaking the limitation of ultrasound coupling in PAM is photoacoustic remote sensing (PARS), which implements all-optical non-interferometric photoacoustic measurements. Functional imaging of PARS microscopy was demonstrated from the aspects of histopathology and oxygen metabolism, while its performance in hemodynamic quantification remains unexplored. In this Letter, we present an all-optical thermal-tagging flowmetry approach for PARS microscopy and demonstrate it with comprehensive mathematical modeling and ex vivo and in vivo experimental validations. Experimental results demonstrated that the detectable range of the blood flow rate was from 0 to 12 mm/s with a high accuracy (measurement error:±1.2%) at 10-kHz laser pulse repetition rate. The proposed all-optical thermal-tagging flowmetry offers an effective alternative approach for PARS microscopy realizing non-contact dye-free hemodynamic imaging.


Asunto(s)
Técnicas Fotoacústicas , Tecnología de Sensores Remotos , Técnicas Fotoacústicas/métodos , Reología/métodos , Ultrasonografía/métodos , Microscopía/métodos
4.
Teach Learn Med ; 36(2): 211-221, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-37092834

RESUMEN

Problem: Since competency-based medical education has gained widespread acceptance to guide curricular reforms, faculty development has been regarded as an indispensable element to make these programs successful. Faculty developers have striven to design and deliver myriad of programs or workshops to better prepare faculty members for fulfilling their teaching roles. However, how faculty developers can improve workshop delivery by researching their teaching practices remains underexplored. Intervention: Action research aims to understand real world practices and advocates for formulation of doable plans through cycles of investigations, and ultimately contributes to claims of knowledge and a progression toward the goal of practice improvement. This methodology aligns with the aim of this study to understand how I could improve a faculty development workshop by researching my teaching practices. Context: In 2016, we conducted four cycles of action research in the context of mini-Clinical Evaluation Exercise (mini-CEX) workshops within a faculty development program aiming for developing teaching and assessment competence in faculty members. We collected multiple sources of qualitative data for thematic analysis, including my reflective journal, field notes taken by a researcher-observer, and post-workshop written reflection and feedback in portfolio from fourteen workshop attendees aiming to develop faculty teaching and assessment competence. Impact: By doing action research, I scrutinized each step as an opportunity for change, enacted adaptive practice and reflection on my teaching practices, and formulated action plans to transform a workshop design through each cycle. In so doing, my workshop evolved from didactic to dialogic with continuous improvement on enhanced engagement, focused discussion and participant empowerment through a collaborative inquiry into feedback practice. Moreover, these processes of action research also supported my growth as a faculty developer. Lessons Learned: The systematic approach of action research serves as a vehicle to enable faculty developers to investigate individual teaching practices as a self-reflective inquiry, to examine, rectify, and transform processes of program delivery, and ultimately introduce themselves as agents for change and improvement.


Asunto(s)
Educación Médica , Docentes , Humanos , Retroalimentación , Desarrollo de Personal/métodos , Investigación sobre Servicios de Salud , Docentes Médicos , Enseñanza
5.
Molecules ; 29(5)2024 Mar 05.
Artículo en Inglés | MEDLINE | ID: mdl-38474673

RESUMEN

1,3,6-Trigalloylglucose is a natural compound that can be extracted from the aqueous extracts of ripe fruit of Terminalia chebula Retz, commonly known as "Haritaki". The potential anti-Helicobacter pylori (HP) activity of this compound has not been extensively studied or confirmed in scientific research. This compound was isolated using a semi-preparative liquid chromatography (LC) system and identified through Ultra-high-performance liquid chromatography-MS/MS (UPLC-MS/MS) and Nuclear Magnetic Resonance (NMR). Its role was evaluated using Minimum inhibitory concentration (MIC) assay and minimum bactericidal concentration (MBC) assay, scanning electron microscope (SEM), inhibiting kinetics curves, urea fast test, Cell Counting Kit-8 (CCK-8) assay, Western blot, and Griess Reagent System. Results showed that this compound effectively inhibits the growth of HP strain ATCC 700392, damages the HP structure, and suppresses the Cytotoxin-associated gene A (Cag A) protein, a crucial factor in HP infection. Importantly, it exhibits selective antimicrobial activity without impacting normal epithelial cells GES-1. In vitro studies have revealed that 1,3,6-Trigalloylglucose acts as an anti-adhesive agent, disrupting the adhesion of HP to host cells, a critical step in HP infection. These findings underscore the potential of 1,3,6-Trigalloylglucose as a targeted therapeutic agent against HP infections.


Asunto(s)
Helicobacter pylori , Terminalia , Extractos Vegetales/química , Terminalia/química , Cromatografía Liquida , Espectrometría de Masas en Tándem , Agua
6.
J Cell Mol Med ; 27(22): 3451-3464, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-37603612

RESUMEN

Pathological myocardial remodelling is the initial factor of chronic heart failure (CHF) and is induced by multiple factors. We previously demonstrated that histone acetylation is involved in CHF in transverse aortic constriction (TAC) mice, a model for pressure overload-induced heart failure. In this study, we investigated whether the histone deacetylase Sirtuin 6 (SIRT6), which mediates deacetylation of histone 3 acetylated at lysine 9 (H3K9ac), is involved pathological myocardial remodelling by regulating myocardial energy metabolism and explored the underlying mechanisms. We generated a TAC mouse model by partial thoracic aortic banding. TAC mice were injected with the SIRT6 agonist MDL-800 at a dose of 65 mg/kg for 8 weeks. At 4, 8 and 12 weeks after TAC, the level of H3K9ac increased gradually, while the expression of SIRT6 and vascular endothelial growth factor A (VEGFA) decreased gradually. MDL-800 reversed the effects of SIRT6 on H3K9ac in TAC mice and promoted the expression of VEGFA in the hearts of TAC mice. MDL-800 also attenuated mitochondria damage and improved mitochondrial respiratory function through upregulating SIRT6 in the hearts of TAC mice. These results revealed a novel mechanism in which SIRT6-mediated H3K9ac level is involved pathological myocardial remodelling in TAC mice through regulating myocardial energy metabolism. These findings may assist in the development of novel methods for preventing and treating pathological myocardial remodelling.


Asunto(s)
Estenosis de la Válvula Aórtica , Insuficiencia Cardíaca , Sirtuinas , Ratones , Animales , Histonas/metabolismo , Factor A de Crecimiento Endotelial Vascular/metabolismo , Sirtuinas/genética , Sirtuinas/metabolismo , Metabolismo Energético
7.
J Hepatol ; 79(3): 605-617, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37217020

RESUMEN

BACKGROUND & AIMS: Disturbed hepatic metabolism frequently results in excessive lipid accumulation in the adipose tissue. However, the specific role of the liver-adipose axis in maintaining lipid homeostasis, as well as the underlying mechanism, has not yet been fully elucidated. In this study, we investigated the role of hepatic glucuronyl C5-epimerase (Glce) in the progression of obesity. METHODS: We determined the association between the expression of hepatic Glce and body mass index (BMI) in obese patients. Obesity models were established in hepatic Glce-knockout and wild-type mice fed a high-fat diet (HFD) to understand the effect of Glce on obesity development. The role of Glce in the progression of disrupted hepatokine secretion was examined via secretome analysis. RESULTS: Hepatic Glce expression was inversely correlated with BMI in obese patients. Moreover, Glce level was found to be decreased in the liver of a HFD murine model. Hepatic Glce deficiency led to impaired thermogenesis in adipose tissue and exacerbated HFD-induced obesity. Interestingly, decreased level of growth differentiation factor 15 (GDF15) was observed in the culture medium of Glce-knockout mouse hepatocytes. Treatment with recombinant GDF15 obstructed obesity progression derived from the absence of hepatic Glce, similar to the effect of Glce or its inactive mutant overexpressed both in vitro and in vivo. Furthermore, liver Glce deficiency led to diminished production and increased degradation of mature GDF15, resulting in reduced hepatic GDF15 secretion. CONCLUSIONS: Hepatic Glce deficiency facilitated obesity development, and decreased Glce expression further reduced hepatic secretion of GDF15, thereby perturbing lipid homeostasis in vivo. Therefore, the novel Glce-GDF15 axis plays an important role in maintaining energy balance and may act as a potential target for combating obesity. IMPACT AND IMPLICATIONS: Evidence suggests that GDF15 plays a key role in hepatic metabolism; however, the molecular mechanism for regulating its expression and secretion is largely unknown. Our work observes that hepatic Glce, as a key Golgi-localised epimerase, may work on the maturation and post-translational regulation of GDF15. Hepatic Glce deficiency reduces the production of mature GDF15 protein and facilitates its ubiquitination, resulting in the aggravation of obesity development. This study sheds light on the new function and mechanism of the Glce-GDF15 axis in lipid metabolism and provides a potential therapeutic target against obesity.


Asunto(s)
Factor 15 de Diferenciación de Crecimiento , Obesidad , Animales , Ratones , Dieta Alta en Grasa , Factor 15 de Diferenciación de Crecimiento/metabolismo , Lípidos , Hígado/metabolismo , Obesidad/metabolismo , Racemasas y Epimerasas/metabolismo
8.
Nanotechnology ; 35(9)2023 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-38035397

RESUMEN

The outstanding electrical conductivity of transition metal carbides Ti3C2Tx(MXene) makes it as an excellent electron transfer medium for fabrication of efficient catalysts. However, the poor stability of MXene may restrict its application. Herein, a novel silver nanoparticles/reduced MXene nanocomposite (AgNPs/rMXene) catalyst was prepared by using L-arginine (L-Arg) as a green reducing agent. In the AgNPs/rMXene catalyst, the silver nanoparticles (AgNPs) and reduced MXene (rMXene) acted as catalytic active species and electron transfer medium, respectively. The composite catalyst exhibited superior catalytic activity in the conversion of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), and the conversion frequency (TOF) was high up to 1109.4 h-1. Notably, the composite catalyst also showed high stability due to the reduction of L-Arg (i.e. the repair of defect groups on MXene surface). The conversion efficiency for 4-NP reduction by AgNPs/rMXene was high up to 90% after five recycles. This present study offers a simple and green approach for the design and development of efficient MXene-based catalysts.

9.
Epilepsy Behav ; 138: 108981, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36470058

RESUMEN

PURPOSE: To explore the localization value of drug-resistant temporal lobe epilepsy (TLE) aura for preoperative evaluation, based on stereoelectroencephalography (SEEG), and its prognostic value on the surgical outcome. METHODS: The data of patients with drug-resistant TLE who had SEEG electrodes implanted during preoperative evaluation at the First Affiliated Hospital of the University of Science and Technology of China (Hefei, China) were retrospectively analyzed. The patients were divided into aura-positive and aura-negative groups according to the presence of aura in seizures. To explore the clinical features of aura, we evaluated the localizing and prognostic values of aura for the outcome of anterior temporal lobectomy based on SEEG. RESULTS: Among forty patients, twenty-seven patients were in the aura-positive group and ten (25.0%) patients had multiple auras. The most common TLE aura was abdominal aura [thirteen (34.2%) patients]. The postoperative seizure frequency was significantly reduced in the preoperative aura-positive patients compared to the preoperative aura-negative patients (P = 0.011). Patients with abdominal (P = 0.029) and single (P = 0.036) auras had better surgical prognoses than aura-negative patients. In the preoperative evaluation, aura-positive patients had a better surgical outcome if the laterality of positron emission tomography-computed tomography (PET-CT) hypometabolism was concordant with the epileptogenic focus identified with SEEG (P = 0.031). A good postoperative epileptic outcome in aura-positive patients was observed among those with hippocampal sclerotic medial temporal lobe epilepsy (P = 0.025). CONCLUSION: Epileptic aura is valuable for the localization of the epileptogenic focus. Abdominal aura and single aura were good predictors of better surgical outcomes. Among patients with a preoperative diagnosis of hippocampal sclerosis or with laterality of PET-CT hypometabolism concordant with the epileptogenic focus identified using SEEG, those with aura are likely to benefit from surgery.


Asunto(s)
Epilepsia Refractaria , Epilepsias Parciales , Epilepsia del Lóbulo Temporal , Epilepsia , Humanos , Epilepsia del Lóbulo Temporal/diagnóstico por imagen , Epilepsia del Lóbulo Temporal/cirugía , Estudios Retrospectivos , Tomografía Computarizada por Tomografía de Emisión de Positrones , Epilepsia/cirugía , Epilepsia Refractaria/diagnóstico por imagen , Epilepsia Refractaria/cirugía , Convulsiones , Electroencefalografía , Resultado del Tratamiento , Imagen por Resonancia Magnética
10.
Environ Res ; 228: 115841, 2023 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-37028538

RESUMEN

BACKGROUND: The existing studies on the relationships of prenatal ambient air pollutants exposure with stillbirth in the Chinese population are very limited and the results are inconsistent, and the susceptible windows and potential modifiers for air pollutants exposure on stillbirth remain unanswered. OBJECTIVE: We aimed to determine the relationships between exposure to ambient air pollutants and stillbirth, and explored the susceptible windows and potential modifiers for air pollutants exposure on stillbirth. METHODS: A population-based cohort was established through the Wuhan Maternal and Child Health Management Information System involving 509,057 mother-infant pairs in Wuhan from January 1, 2011 through September 30, 2017. Personal exposure concentrations of fine particles (PM2.5), inhalable particles (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) for mothers were estimated based on their residential address during pregnancy using the inverse distance weighted (IDW) method. We used the logistic regression models to determine the associations at different stages of pregnancy with adjustment for confounding factors. RESULTS: There were 3218 stillbirths and 505,839 live births among the participants. For each 100 µg/m3 of CO and 10 µg/m3 of O3 increase in the first trimester (conception to 13+6 weeks), the risk of stillbirth increased by 1.0% (OR = 1.01, 95%CI: 1.00-1.03) and 7.0% (OR = 1.07, 95%CI: 1.05-1.09). In the second trimester (14 weeks-27+6 weeks), PM2.5, PM10, CO, and O3 exposure were closely related to the risk of stillbirth (P<0.05). In the third trimester (28 weeks to delivery), for each 10 µg/m3 increase in exposure concentrations of PM2.5, SO2, and O3, the risk of stillbirth increased by 3.4%, 5.9%, and 4.0%, respectively. O3 exposure was positively relevant to the risk of stillbirth (OR = 1.11, 95%CI: 1.08-1.14) in the whole pregnancy. Exposure to NO2 was not significantly associated with the risk of stillbirth. Stratified analyses also presented a stronger association among mothers with boy infant, living in rural areas, delivering between 2011 and 2013, and those without gestational hypertension and history of stillbirth. CONCLUSION: This study provides evidence that maternal exposure to PM2.5, PM10, SO2, CO, and O3 were related to the increased risk of stillbirth. Both the second and third trimesters might be vital susceptible windows for stillbirth. Our findings expand the evidence base for the important impacts of air pollution on fetal growth.


Asunto(s)
Contaminantes Atmosféricos , Contaminación del Aire , Contaminantes Ambientales , Masculino , Embarazo , Femenino , Niño , Humanos , Contaminantes Atmosféricos/análisis , Mortinato/epidemiología , Contaminantes Ambientales/análisis , Contaminación del Aire/análisis , Exposición Materna/efectos adversos , Dióxido de Nitrógeno/análisis , China/epidemiología , Material Particulado/toxicidad , Material Particulado/análisis
11.
Med Educ ; 57(11): 1102-1116, 2023 11.
Artículo en Inglés | MEDLINE | ID: mdl-37394612

RESUMEN

CONTEXT: Assessment plays a key role in competence development and the shaping of future professionals. Despite its presumed positive impacts on learning, unintended consequences of assessment have drawn increasing attention in the literature. Considering professional identities and how these can be dynamically constructed through social interactions, as in assessment contexts, our study sought to understand how assessment influences the construction of professional identities in medical trainees. METHODS: Within social constructionism, we adopted a discursive, narrative approach to investigate the different positions trainees narrate for themselves and their assessors in clinical assessment contexts and the impact of these positions on their constructed identities. We purposively recruited 28 medical trainees (23 students and five postgraduate trainees), who took part in entry, follow-up and exit interviews of this study and submitted longitudinal audio/written diaries across nine-months of their training programs. Thematic framework and positioning analyses (focusing on how characters are linguistically positioned in narratives) were applied using an interdisciplinary teamwork approach. RESULTS: We identified two key narrative plotlines, striving to thrive and striving to survive, across trainees' assessment narratives from 60 interviews and 133 diaries. Elements of growth, development, and improvement were identified as trainees narrated striving to thrive in assessment. Neglect, oppression and perfunctory narratives were elaborated as trainees narrated striving to survive from assessment. Nine main character tropes adopted by trainees with six key assessor character tropes were identified. Bringing these together we present our analysis of two exemplary narratives with elaboration of their wider social implications. CONCLUSION: Adopting a discursive approach enabled us to better understand not only what identities are constructed by trainees in assessment contexts but also how they are constructed in relation to broader medical education discourses. The findings are informative for educators to reflect on, rectify and reconstruct assessment practices for better facilitating trainee identity construction.


Asunto(s)
Educación Médica , Estudiantes de Medicina , Humanos , Aprendizaje , Narración , Educación de Postgrado en Medicina , Competencia Clínica
12.
J Sci Food Agric ; 103(15): 7424-7433, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37385969

RESUMEN

BACKGROUND: This study examined the changes in soil fertility in a maize cropping area when chemical fertilizer was partially replaced with straw or livestock manure over a 33-year period. Four treatments were included: (i) CK (no fertilizer application); (ii) NPK (only chemical fertilizer application); (iii) NPKM (chemical fertilizer partly replaced with livestock manure); (iv) NPKS (chemical fertilizer partly replaced with straw). RESULTS: Soil organic carbon increased by 41.7% and 95.5% in the NPKS and NPKM treatments, respectively, over the 33-year trial compared with the initial concentration. However, soil organic carbon in NPK was significantly reduced by 9.8%. Soil total N, P and K increased in both NPKM and NPKS treatments compared to the original soil. Soil pH was significantly acidified from 7.6 to 5.97 in the NPK treatment during the experimental period. The NPKM and NPKS treatments buffered the acidification compared to NPK. Meta-analysis results showed that, compared with NPK, NPKM significantly raised soil bacteria and fungi populations by 38.7% and 58.6%; enhanced microbial biomass carbon and nitrogen by 66.3% and 63%, respectively; and increased sucrase, urease and catalase activities by 34.2%, 48.2% and 21.5%. NPKS significantly increased soil fungi and actinomycetes populations by 24.3% and 41.2%, respectively; enhanced microbial biomass carbon and nitrogen by 27.1% and 45%; and strengthened sucrase and urease activities by 36% and 20.3%, respectively. CONCLUSION: Long-term chemical fertilizer application led to the deterioration of soil fertility and environment. Partial replacement of chemical fertilizers with organic materials could significantly amend and buffer such negative effects. © 2023 Society of Chemical Industry.


Asunto(s)
Fertilizantes , Suelo , Fertilizantes/análisis , Agricultura , Estiércol/análisis , Carbono/análisis , Ureasa , Nitrógeno/análisis , Sacarasa , China
13.
Soins Gerontol ; 28(161): 24-27, 2023.
Artículo en Francés | MEDLINE | ID: mdl-37328203

RESUMEN

The Assure approach (improvement of emergency care) is a project designed to improve emergency care for the 63,000 residents of homes for the dependent elderly (Ehpad) in the Ile-de-France region. By reinforcing the skills of caregivers in emergency situations and facilitating collaboration between care providers, the Assure approach is mobilizing, alongside all the Ehpad in the Ile-de-France region over a period of two years, the emergency medical assistance services, emergency physicians, mobile geriatric teams and nursing and care assistant training institutes.


Asunto(s)
Servicios Médicos de Urgencia , Casas de Salud , Humanos , Anciano , Cuidadores , Francia
14.
Soins Gerontol ; 28(161): 31-35, 2023.
Artículo en Francés | MEDLINE | ID: mdl-37328205

RESUMEN

Access to care for the population residing in residential facilities for dependent elderly people (Ehpad), i.e. 600,000 people in France in 2019, is a major public health issue. Description of the characteristics and pathways of the residents of Ehpad transferred to the emergency department (SAU) in the Paris 16th district.


Asunto(s)
Hogares para Ancianos , Casas de Salud , Humanos , Anciano , Servicio de Urgencia en Hospital , Francia/epidemiología
15.
Environ Res ; 204(Pt A): 111949, 2022 03.
Artículo en Inglés | MEDLINE | ID: mdl-34478720

RESUMEN

Photocatalysis is regarded as one of the most effective strategies for the removal of the toxic organic pollutants from aqueous solutions. However, a lack of the efficient photocatalysts prevents the widespread practical application. Herein, the electrostatic self-assembly method has been designed for facile synthesis of a novel BaSnO3/PDDA/MXene (BSO/P/MX) nanocomposite as high efficient photocatalyst. In this nanocomposite, the BaSnO3 (BSO), poly (dimethyl-diallylammonium chloride) (PDDA) and MXene (Ti3C2Tx) act as the active species, structure stabilizer and efficient electron transfer medium, respectively. Due to the strong synergy of the nanocomposite, the electron-transferring ability as well as the charge separation efficiency is boosted and thus high catalytic activity achieves towards the photodegradation of 4-nitrophenol. The superior degradation rate of 98.8% and a rate constant K of 0.09113 min-1 have been realized within 75 min of ultraviolet (UV) light irradiation over the BSO/P/MX-8% catalyst. This as-prepared nanocomposite with the excellent catalytic activity can be employed as a promising photocatalyst for treating the organic pollutants from aqueous solutions.


Asunto(s)
Nanocompuestos , Catálisis , Nitrofenoles , Fotólisis , Electricidad Estática
16.
Anal Chem ; 93(3): 1740-1748, 2021 01 26.
Artículo en Inglés | MEDLINE | ID: mdl-33370097

RESUMEN

Natural organic matter (NOM) is a highly complex mixture of natural organic molecules. The recent developments in NOM molecular characterization methods have shown that ESI-FT-ICR hyphenated with liquid chromatography (LC) is a promising approach to also obtain chemical information (such as polarity and molecular size) about NOM molecules. However, due to changing solvent composition during gradient elution in LC-FT-ICR-MS, ionization conditions also change throughout the chromatographic separation process. In this study, we applied a post-LC column counter gradient (CG) to ensure stable solvent conditions for transient ESI-MS signals. Suwanee River Fulvic Acid (SRFA) standard and a peat pore water were used as representative dissolved NOM samples for method development and validation. Our results show that in polar NOM fractions (which elute with <50% methanol) the TIC intensity and number of assigned molecular formulas were increased by 48% and 20%, as compared to the standard gradient (SG) method. Further application of a Q-isolation and selective ion accumulation for low abundance fractions revealed over 3 times more molecular formulas (especially for CHNO, CHOS, CHNOS formula classes) than in full scan mode. The number of detected highly polar NOM compounds (with elemental ratios H/C < 1, O/C > 0.6) were more than 20 times larger for CG-LC mode as compared to direct infusion (DI) (5715 vs 266 MF). We conclude that the application of a postcolumn counter gradient in LC-FT-ICR-MS analyses of NOM offers novel insight into the most polar fractions of NOM which are inaccessible in conventional DI measurements.

17.
Photosynth Res ; 149(1-2): 41-55, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32902777

RESUMEN

Increasing amounts of experimental evidence show that anthocyanins provide physiological protection to plants under stress. However, the difference in photoprotection mediated by anthocyanins and other photoprotective substances in different seasons is still uncertain. To determine the relationship between anthocyanin accumulation and the photoprotective effects in different seasons, Castanopsis chinensis and Acmena acuminatissima, whose anthocyanin accumulation patterns differ in different seasons, were used as materials to explain how plants adapt to different seasons; as such, their physiological and biochemical responses were analyzed. Young leaves of C. chinensis and A. acuminatissima presented different colors in the different seasons. In summer, the young leaves of C. chinensis were purplish red, while those of A. acuminatissima were light green. In winter, the young leaves of C. chinensis were light green, while those of A. acuminatissima were red. Compared with the young red leaves, the young light green leaves that did not accumulate anthocyanins had higher flavonoid and phenolics contents, total antioxidant capacity, non-photochemical quenching (NPQ), and relative membrane leakage, and a slower recovery rate in the maximum photochemical efficiency (Fv/Fm) after high-light treatment. In addition, the net photosynthesis rate (Pn), transpiration rate (Tr), stomatal conductance (gs), and the effective quantum yield of PSII (ΦPSII) of the young leaves in winter were significantly lower than those in summer, while the activities of catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1.7), and superoxide dismutase (SOD, EC 1.15.1.1) were significantly higher than those in summer. These data indicate that to adapt to seasonal changes anthocyanins, other antioxidative substances and antioxidative enzymes, as well as components involved in the safe dissipation of excitation energy as heat need to cooperate with one another.


Asunto(s)
Adaptación Ocular/fisiología , Antocianinas/metabolismo , Fagaceae/metabolismo , Myrtaceae/metabolismo , Pigmentación/fisiología , Hojas de la Planta/metabolismo , Estaciones del Año , Luz Solar/efectos adversos , Antioxidantes/metabolismo , China , Fenotipo , Fotosíntesis/fisiología
18.
Photosynth Res ; 149(1-2): 25-40, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32462454

RESUMEN

Anthocyanins are water-soluble pigments in plants known for their photoprotective role against photoinhibitory and photooxidative damage under high light (HL). However, it remains unclear whether light-shielding or antioxidant activity plays a major role in the photoprotection exerted by anthocyanins under HL stress. To shed light on this question, we analyzed the physiological and biochemical responses to HL of three Arabidopsis thaliana lines (Col, chi, ans) with different light absorption and antioxidant characteristics. Under HL, ans had the highest antioxidant capacity, followed by Col, and finally chi; Col had the strongest light attenuation capacity, followed by chi, and finally ans. The line ans had weaker physiological activity of chloroplasts and more severe oxidative damage than chi after HL treatment. Col with highest photoprotection of light absorption capacity had highest resistance to HL among the three lines. The line ans with high antioxidant capacity could not compensate for its disadvantages in HL caused by the absence of the light-shielding function of anthocyanins. In addition, the expression level of the Anthocyanin Synthase (ANS) gene was most upregulated after HL treatment, suggesting that the conversion of colorless into colored anthocyanin precursors was necessary under HL. The contribution of anthocyanins to flavonoids, phenols, and antioxidant capacity increased in the late period of HL, suggesting that plants prefer to synthesize red anthocyanins (a group of colored antioxidants) over other colorless antioxidants to cope with HL. These experimental observations indicate that the light attenuation role of anthocyanins is more important than their antioxidant role in photoprotection.


Asunto(s)
Adaptación Ocular/fisiología , Antocianinas/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Hojas de la Planta/metabolismo , Protección Radiológica , Luz Solar/efectos adversos , Regulación de la Expresión Génica de las Plantas , Genes de Plantas , Variación Genética , Genotipo , Mutación , Estrés Oxidativo/fisiología , Fenotipo , Fotosíntesis/fisiología
19.
Photosynth Res ; 149(1-2): 121-134, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-32297101

RESUMEN

Biological invasion is a hot topic in ecological research. Most studies on the physiological mechanisms of plants focus on leaves, but few studies focus on stems. To study the tolerance of invasive plant (Sphagneticola trilobata L.) to low temperature, relevant physiological indicators (including anthocyanin and chlorophyll) in different organs (leaves and stems) were analyzed, using a native species (Sphagneticola calendulacea L.) as the control. The results showed that, upon exposure to low temperature for 15 days, the stems of two Sphagneticola species were markedly reddened, their anthocyanin content increased, chlorophyll and chlorophyll fluorescence parameters decreased, and the accumulation of reactive oxygen species in the stem increased. The percentage increases of antioxidants and total antioxidant capacities in stems were significantly higher in S. trilobata than in S. calendulacea. This showed that S. trilobata had higher cold tolerance in stems while leaves were opposite. To further verify the higher cold tolerance of the stem of S. trilobata, a defoliation experiment was designed. We found that the defoliated stem of S. trilobata reduced anthocyanin accumulation and increased chlorophyll content, while alleviating membrane lipid damage and electrical conductivity, and the defoliated stem still showed an increase in stem diameter and biomass under low temperature. The discovery of the physiological and adaptive mechanisms of the stem of S. trilobata to low temperature will provide a theoretical basis for explaining how S. trilobata maintains its annual growth in South China. This is of great significance for predicting the future spread of cloned and propagated invasive plants.


Asunto(s)
Adaptación Fisiológica , Asteraceae/fisiología , Frío/efectos adversos , Fotosíntesis/fisiología , Hojas de la Planta/fisiología , Tallos de la Planta/fisiología , Malezas/fisiología , China , Especies Introducidas
20.
Rev Cardiovasc Med ; 22(1): 231-238, 2021 Mar 30.
Artículo en Inglés | MEDLINE | ID: mdl-33792267

RESUMEN

Trimethylamine N-oxide (TMAO) is reported to accelerate atherosclerosis and the development of adverse cardiac outcomes. Relationship between coronary atherosclerotic burden and TMAO has been examined in stable coronary artery disease and ST-segment elevation myocardial infarction, but not in non-ST-segment elevation myocardial infarction (NSTEMI). We examined the association between TMAO and coronary atherosclerotic burden in NSTEMI. In this prospective cohort study, two groups including NSTEMI (n = 73) and age-sex matched Healthy (n = 35) individuals were enrolled between 2019 and 2020. Coronary atherosclerotic burden was stratified based on the number of diseased coronary vessels and clinical risk scores including SYNTAX and GENSINI. Fasting plasma TMAO was measured by isotope dilution high-performance liquid chromatography. The median plasma TMAO levels were significantly higher in the NSTEMI group than in the Healthy group, respectively (0.59 µM; interquartile range [IQR]: 0.43-0.78 versus 0.42 µM; IQR: 0.33-0.64; P = 0.006). Within the NSTEMI group, higher TMAO levels were observed in the multivessel disease (MVD) versus single vessel disease (P = 0.002), and intermediate-high risk (score ≥ 23) versus low risk (score < 23) of SYNTAX (P = 0.003) and GENSINI (P = 0.005). TMAO level remained an independent predictor of MVD (odds ratio [OR]: 5.94, P = 0.005), intermediate-high risk SYNTAX (OR: 3.61, P = 0.013) and GENSINI scores (OR: 4.60, P = 0.008) following adjustment for traditional risk factors. Receiver operating characteristic curve (AUC) analysis for TMAO predicted MVD (AUC: 0.73, 95% confidence interval [Cl]: 0.60-0.86, P = 0.002), intermediate-high SYNTAX score (AUC: 0.70, 95% Cl: 0.58-0.82, P = 0.003) and GENSINI score (AUC: 0.70, 95% Cl: 0.57-0.83, P = 0.005). In all, TMAO levels are independently associated with high coronary atherosclerotic burden in NSTEMI.


Asunto(s)
Aterosclerosis , Infarto del Miocardio sin Elevación del ST , Humanos , Metilaminas , Infarto del Miocardio sin Elevación del ST/diagnóstico por imagen , Infarto del Miocardio sin Elevación del ST/terapia , Estudios Prospectivos
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