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1.
Glob Chang Biol ; 30(4): e17274, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38605677

RESUMEN

Climate change and other anthropogenic disturbances are increasing liana abundance and biomass in many tropical and subtropical forests. While the effects of living lianas on species diversity, ecosystem carbon, and nutrient dynamics are receiving increasing attention, the role of dead lianas in forest ecosystems has been little studied and is poorly understood. Trees and lianas coexist as the major woody components of forests worldwide, but they have very different ecological strategies, with lianas relying on trees for mechanical support. Consequently, trees and lianas have evolved highly divergent stem, leaf, and root traits. Here we show that this trait divergence is likely to persist after death, into the afterlives of these organs, leading to divergent effects on forest biogeochemistry. We introduce a conceptual framework combining horizontal, vertical, and time dimensions for the effects of liana proliferation and liana tissue decomposition on ecosystem carbon and nutrient cycling. We propose a series of empirical studies comparing traits between lianas and trees to answer questions concerning the influence of trait afterlives on the decomposability of liana and tree organs. Such studies will increase our understanding of the contribution of lianas to terrestrial biogeochemical cycling, and help predict the effects of their increasing abundance.


Asunto(s)
Ecosistema , Clima Tropical , Bosques , Árboles , Carbono
2.
Rev Cardiovasc Med ; 25(6): 215, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-39076319

RESUMEN

Background: Growing evidence suggests that concurrent ischaemic stroke (IS) exacerbates the prognosis of patients with dilated cardiomyopathy (DCM) and that this effect may be further influenced by sex. However, the exact effect of sex remains unclear. This study aimed to explore the effects of the relevant risk factors on the prognosis of patients with DCM and concurrent IS. Considering the sex differences in DCM, this study further investigated the impact of concurrent IS on the prognosis of men and women with DCM. Methods: A total of 632 patients with DCM enrolled between 2016 and 2021 were included in this study. Clinical data were obtained from medical records, and all participants were followed up in the outpatient clinic or by telephone for at least 1 year. A Cox proportional hazards model and Kaplan-Meier curves were used to evaluate the effects of concurrent IS on the prognosis of patients with DCM. Results: Patients with DCM complicated with IS (DCM-IS) had significantly lower cumulative survival rates than patients with DCM without IS (non-IS) (74.6% vs. 84.2%, χ 2 = 6.85, p = 0.009). Additionally, IS was associated with greater risks of death and heart transplantation (HTx) in men (75.8% vs. 85.1%, χ 2 = 5.02, p = 0.025), but not in women (71.0% vs. 81.5%, χ 2 = 1.91, p = 0.167). Conclusions: This large-scale multicentre prospective cohort study demonstrated a poorer prognosis in patients with concurrent DCM and IS, particularly among men. Patients with DCM should not be overlooked in IS screening, emphasis should be placed on the occurrence of IS in patients with DCM. Early and proactive secondary prevention of cerebrovascular diseases might improve the prognosis of DCM patients. More intervention studies focusing on men with DCM complicated with IS should be prioritised.

3.
New Phytol ; 240(6): 2253-2264, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37737019

RESUMEN

Understanding how intra-annual stem growth responds to atmospheric and soil conditions is essential for assessing the effects of climate extremes on forest productivity. In species-poor forests, such understanding can be obtained by studying stem growth of the dominant species. Yet, in species-rich (sub-)tropical forests, it is unclear whether these responses are consistent among species. We monitored intra-annual stem growth with high-resolution dendrometers for 27 trees belonging to 14 species over 5 yr in a montane subtropical forest. We quantified diel and seasonal stem growth patterns, verified to what extent observed growth patterns coincide across species and analysed their main climatic drivers. We found very consistent intra-annual growth patterns across species. Species varied in the rate but little in the timing of growth. Diel growth patterns revealed that - across species - trees mainly grew before dawn when vapour pressure deficit (VPD) was low. Within the year, trees mainly grew between May and August driven by temperature and VPD, but not by soil moisture. Our study reveals highly consistent stem growth patterns and climatic drivers at community level. Further studies are needed to verify whether these results hold across climates and forests, and whether they can be scaled up to estimate forest productivity.


Asunto(s)
Bosques , Árboles , Árboles/fisiología , Estaciones del Año , Temperatura , Suelo , Cambio Climático
4.
Plant Cell Environ ; 46(9): 2747-2762, 2023 09.
Artículo en Inglés | MEDLINE | ID: mdl-37427808

RESUMEN

Tropical forests are experiencing increases in vapour pressure deficit (D), with possible negative impacts on tree growth. Tree-growth reduction due to rising D is commonly attributed to carbon limitation, thus overlooking the potentially important mechanism of D-induced impairment of wood formation due to an increase in turgor limitation. Here we calibrate a mechanistic tree-growth model to simulate turgor limitation of radial stem growth in mature Toona cilitata trees in an Asian tropical forest. Hourly sap flow and dendrometer measurements were collected to simulate turgor-driven growth during the growing season. Simulated seasonal patterns of radial stem growth matched well with growth observations. Growth mainly occurred at night and its pre-dawn build-up appeared to be limited under higher D. Across seasons, the night-time turgor pressure required for growth was negatively related to previous midday D, possibly due to a relatively high canopy conductance at high D, relative to stem rehydration. These findings provide the first evidence that tropical trees grow at night and that turgor pressure limits tree growth. We suggest including turgor limitation of tree stem growth in models also for tropical forest carbon dynamics, in particular, if these models simulate effects of warming and increased frequency of droughts.


Asunto(s)
Bosque Lluvioso , Árboles , Presión de Vapor , Agua , Bosques , Carbono , Clima Tropical
5.
Glob Chang Biol ; 27(23): 6192-6205, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34525229

RESUMEN

Subtropical forests are important ecosystems globally due to their extensive role in carbon sequestration. Extreme climate events are known to introduce disturbances in the ecosystem that cause long-term changes in carbon balance and radiation reflectance. However, how these ecosystem function changes contribute to global warming in terms of radiative forcing (RF), especially in the years following a disturbance, still needs to be investigated. We studied an extreme snow event that occurred in a subtropical evergreen broadleaved forest in south-western China in 2015 and used 9 years (2011-2019) of net ecosystem CO2 exchange (NEE) and surface albedo (α) data to investigate the effect of the event on the ecosystem RF changes. In the year of the disturbance, leaf area index (LAI) declined by 40% and α by 32%. The annual NEE was -718 ±â€…128 g C m-2 as a sink in the pre-disturbance years (2011-2014), but after the event, the sink strength dropped significantly by 76% (2015). Both the vegetation, indicated by LAI, and α recovered to pre-disturbance levels in the fourth post-disturbance year (2018). However, the NEE recovery lagged and occurred a year later in 2019, suggesting a more severe and lasting impact on the ecosystem carbon balance. Overall, the extreme event caused a positive (warming effect) net RF which was predominantly caused by changes in α (90%-93%) rather than those in NEE. This result suggests that, compared to the climate effect caused by forest carbon sequestration changes, the climate effect of α alterations can be more sensitive to vegetation damage induced by natural disturbances. Moreover, this study demonstrates the important role of vegetation recovery in driving canopy reflectance and ecosystem carbon balance during the post-disturbance period, which determines the ecosystem feedbacks to the climate change.


Asunto(s)
Ecosistema , Nieve , Carbono , Dióxido de Carbono , Cambio Climático , Bosques
6.
Glob Chang Biol ; 26(3): 1778-1794, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-31696994

RESUMEN

High-elevation forests are experiencing high rates of warming, in combination with CO2 rise and (sometimes) drying trends. In these montane systems, the effects of environmental changes on tree growth are also modified by elevation itself, thus complicating our ability to predict effects of future climate change. Tree-ring analysis along an elevation gradient allows quantifying effects of gradual and annual environmental changes. Here, we study long-term physiological (ratio of internal to ambient CO2 , i.e., Ci /Ca and intrinsic water-use efficiency, iWUE) and growth responses (tree-ring width) of Himalayan fir (Abies spectabilis) trees in response to warming, drying, and CO2 rise. Our study was conducted along elevational gradients in a dry and a wet region in the central Himalaya. We combined dendrochronology and stable carbon isotopes (δ13 C) to quantify long-term trends in Ci /Ca ratio and iWUE (δ13 C-derived), growth (mixed-effects models), and evaluate climate sensitivity (correlations). We found that iWUE increased over time at all elevations, with stronger increase in the dry region. Climate-growth relations showed growth-limiting effects of spring moisture (dry region) and summer temperature (wet region), and negative effects of temperature (dry region). We found negative growth trends at lower elevations (dry and wet regions), suggesting that continental-scale warming and regional drying reduced tree growth. This interpretation is supported by δ13 C-derived long-term physiological responses, which are consistent with responses to reduced moisture and increased vapor pressure deficit. At high elevations (wet region), we found positive growth trends, suggesting that warming has favored tree growth in regions where temperature most strongly limits growth. At lower elevations (dry and wet regions), the positive effects of CO2 rise did not mitigate the negative effects of warming and drying on tree growth. Our results raise concerns on the productivity of Himalayan fir forests at low and middle (<3,300 m) elevations as climate change progresses.


Asunto(s)
Abies , Dióxido de Carbono , Cambio Climático , Bosques , Árboles
8.
Glob Chang Biol ; 25(3): 938-953, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30552830

RESUMEN

It is critical to accurately estimate carbon (C) turnover time as it dominates the uncertainty in ecosystem C sinks and their response to future climate change. In the absence of direct observations of ecosystem C losses, C turnover times are commonly estimated under the steady state assumption (SSA), which has been applied across a large range of temporal and spatial scales including many at which the validity of the assumption is likely to be violated. However, the errors associated with improperly applying SSA to estimate C turnover time and its covariance with climate as well as ecosystem C sequestrations have yet to be fully quantified. Here, we developed a novel model-data fusion framework and systematically analyzed the SSA-induced biases using time-series data collected from 10 permanent forest plots in the eastern China monsoon region. The results showed that (a) the SSA significantly underestimated mean turnover times (MTTs) by 29%, thereby leading to a 4.83-fold underestimation of the net ecosystem productivity (NEP) in these forest ecosystems, a major C sink globally; (b) the SSA-induced bias in MTT and NEP correlates negatively with forest age, which provides a significant caveat for applying the SSA to young-aged ecosystems; and (c) the sensitivity of MTT to temperature and precipitation was 22% and 42% lower, respectively, under the SSA. Thus, under the expected climate change, spatiotemporal changes in MTT are likely to be underestimated, thereby resulting in large errors in the variability of predicted global NEP. With the development of observation technology and the accumulation of spatiotemporal data, we suggest estimating MTTs at the disequilibrium state via long-term data assimilation, thereby effectively reducing the uncertainty in ecosystem C sequestration estimations and providing a better understanding of regional or global C cycle dynamics and C-climate feedback.


Asunto(s)
Ciclo del Carbono , Secuestro de Carbono , Cambio Climático , Ecosistema , Monitoreo del Ambiente , Carbono/análisis , China , Bosques , Modelos Teóricos , Lluvia , Temperatura
9.
Neurol Sci ; 40(10): 2097-2103, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31147857

RESUMEN

The aim of our study is to determine the pathological changes of white matter microstructure in patients with early post-stroke depression (PSD), and to investigate the association between white matter integrity examined by diffusion kurtosis imaging (DKI) and early PSD. Thirty-eight patients with acute cerebral infarction were selected, including 17 patients with depression (PSD group), and 21 patients without depression (N-PSD group). In addition, 20 normal healthy controls (NORM group) were selected. All were taken DKI scans. The white matter of the frontal lobe, temporal lobe, parietal lobe, occipital lobe, anterior limb of internal capsule, and posterior limb of internal capsule, in addition to the genu of corpus callosum and splenium of corpus callosum was selected as a region of interest (ROI). Selected parameters include fractional anisotropy (FA) and mean kurtosis (MK). Compared with N-PSD group and NORM group, FA value of the left frontal lobe and MK value of the bilateral frontal lobe, bilateral temporal lobe, and genu of corpus callosum in PSD group were decreased (P < 0.05). Our results indicated that the early PSD patients had white matter microstructure abnormalities in the frontal lobe, temporal lobe, and genu of corpus callosum. DKI provides a comprehensive brain imaging reference for detecting early microstructural damage of white matter in PSD patients, which can be used as an imaging biomarker to detect early PSD and its progression potentially.


Asunto(s)
Encéfalo/patología , Depresión/patología , Accidente Cerebrovascular/patología , Accidente Cerebrovascular/psicología , Sustancia Blanca/patología , Anciano , Encéfalo/diagnóstico por imagen , Depresión/etiología , Imagen de Difusión Tensora/métodos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Neuroimagen/métodos , Accidente Cerebrovascular/diagnóstico por imagen , Sustancia Blanca/diagnóstico por imagen
10.
New Phytol ; 209(1): 123-36, 2016 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-26378984

RESUMEN

The evolution of lignified xylem allowed for the efficient transport of water under tension, but also exposed the vascular network to the risk of gas emboli and the spread of gas between xylem conduits, thus impeding sap transport to the leaves. A well-known hypothesis proposes that the safety of xylem (its ability to resist embolism formation and spread) should trade off against xylem efficiency (its capacity to transport water). We tested this safety-efficiency hypothesis in branch xylem across 335 angiosperm and 89 gymnosperm species. Safety was considered at three levels: the xylem water potentials where 12%, 50% and 88% of maximal conductivity are lost. Although correlations between safety and efficiency were weak (r(2)  < 0.086), no species had high efficiency and high safety, supporting the idea for a safety-efficiency tradeoff. However, many species had low efficiency and low safety. Species with low efficiency and low safety were weakly associated (r(2)  < 0.02 in most cases) with higher wood density, lower leaf- to sapwood-area and shorter stature. There appears to be no persuasive explanation for the considerable number of species with both low efficiency and low safety. These species represent a real challenge for understanding the evolution of xylem.


Asunto(s)
Cycadopsida/fisiología , Magnoliopsida/fisiología , Xilema/fisiología , Hojas de la Planta/fisiología , Transpiración de Plantas , Agua/fisiología , Madera
11.
New Phytol ; 205(1): 128-36, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25264136

RESUMEN

Lianas exhibit peak abundance in tropical forests with strong seasonal droughts, the eco-physiological mechanisms associated with lianas coping with water deficits are poorly understood. We examined soil water partitioning, sap flow, and canopy eco-physiological properties for 99 individuals of 15 liana and 34 co-occurring tree species in three tropical forests that differed in soil water availability. In the dry season, lianas used a higher proportion of deep soil water in the karst forest (KF; an area with severe seasonal soil water deficit (SSWD)) and in the tropical seasonal forest (TSF, moderate SSWD), permitting them to maintain a comparable leaf water status than trees in the TSF or a better status than trees in the KF. Lianas exhibited strong stomatal control to maximize carbon fixation while minimizing dry season water loss. During the dry period, lianas significantly decreased water consumption in the TSF and the KF. Additionally, lianas had a much higher maximum photosynthetic rates and sap flux density in the wet season and a lower proportional decline in photosynthesis in the dry season compared with those of trees. Our results indicated that access to deep soil water and strong physiological adjustments in the dry season together with active wet-season photosynthesis may explain the high abundance of lianas in seasonally dry forests.


Asunto(s)
Bosques , Estaciones del Año , Árboles/fisiología , Clima Tropical , Agua/metabolismo , Análisis de Varianza , China , Ritmo Circadiano/fisiología , Fotosíntesis , Suelo , Árboles/crecimiento & desarrollo , Presión de Vapor
12.
Medicine (Baltimore) ; 103(34): e39405, 2024 Aug 23.
Artículo en Inglés | MEDLINE | ID: mdl-39183424

RESUMEN

Neurodegenerative diseases are complex disorders that significantly challenge human health, with their incidence increasing with age. A key pathological feature of these diseases is the accumulation of misfolded proteins. The underlying mechanisms involve an imbalance in calcium homeostasis and disturbances in autophagy, indicating a likely correlation between them. As the most important second messenger, Ca2+ plays a vital role in regulating various cell activities, including autophagy. Different organelles within cells serve as Ca2+ storage chambers and regulate Ca2+ levels under different conditions. Ca2+ in these compartments can affect autophagy via Ca2+ channels or other related signaling proteins. Researchers propose that Ca2+ regulates autophagy through distinct signal transduction mechanisms, under normal or stressful conditions, and thereby contributing to the occurrence and development of neurodegenerative diseases. This review provides a systematic examination of the regulatory mechanisms of Ca2+ in cell membranes and different organelles, as well as its downstream pathways that influence autophagy and its implications for neurodegenerative diseases. This comprehensive analysis may facilitate the development of new drugs and provide more precise treatments for neurodegenerative diseases.


Asunto(s)
Autofagia , Calcio , Enfermedades Neurodegenerativas , Humanos , Autofagia/fisiología , Enfermedades Neurodegenerativas/metabolismo , Calcio/metabolismo , Señalización del Calcio/fisiología , Transducción de Señal
13.
Tree Physiol ; 44(9)2024 Sep 03.
Artículo en Inglés | MEDLINE | ID: mdl-39030688

RESUMEN

Tropical montane evergreen broad-leaved forests cover the majority of forest areas and have high carbon storage in Xishuangbanna, southwest China. However, stem radial growth dynamics and their correlations with climate factors have never been analyzed in this forest type. By combining bi-weekly microcoring and high-resolution dendrometer measurements, we monitored xylogenesis and stem radius variations of the deciduous species Betula alnoides Buch.-Ham. ex D. Don and the evergreen species Schima wallichii (DC.) Korth. We analyzed the relationships between weekly climate variables prior to sampling and the enlarging zone width or wall-thickening zone width, as well as weekly radial increments and climate factors during two consecutive years (2020 to 2021) showing contrasting hydrothermal conditions in the pre-monsoon season. In the year 2020, which was characterized by a warmer and drier pre-monsoon season, the onset of xylogenesis and radial increments of B. alnoides and S. wallichii were delayed by three months and one month, respectively, compared with the year 2021. In 2020, xylem formation and radial increments were significantly reduced for B. alnoides, but not for S. wallichii. The thickness of enlarging zone and wall-thickening zone in S. wallichii were positively correlated with relative humidity, and minimum and mean air temperature, but were negatively correlated with vapor pressure deficit during 2020 to 2021. The radial increments of both species showed significant positive correlations with precipitation and relative humidity, and negative correlations with vapor pressure deficit and maximum air temperature during two years. Our findings reveal that drier pre-monsoon conditions strongly delay growth initiation and reduce stem radial growth, providing deep insights to understand tree growth and carbon sequestration potential in tropical forests under a predicted increase in frequent drought events.


Asunto(s)
Sequías , Bosques , Árboles , China , Árboles/crecimiento & desarrollo , Árboles/fisiología , Clima Tropical , Betula/crecimiento & desarrollo , Betula/fisiología , Xilema/crecimiento & desarrollo , Xilema/fisiología , Estaciones del Año , Tallos de la Planta/crecimiento & desarrollo , Tallos de la Planta/fisiología , Tallos de la Planta/anatomía & histología
14.
Sci Total Environ ; 919: 170726, 2024 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-38331275

RESUMEN

The fraction of photosynthetically assimilated carbon that trees allocate to long-lasting woody biomass pools (biomass production efficiency - BPE), is a key metric of the forest carbon balance. Its apparent simplicity belies the complex interplay between underlying processes of photosynthesis, respiration, litter and fruit production, and tree growth that respond differently to climate variability. Whereas the magnitude of BPE has been routinely quantified in ecological studies, its temporal dynamics and responses to extreme events such as drought remain less well understood. Here, we combine long-term records of aboveground carbon increment (ACI) obtained from tree rings with stand-level gross primary productivity (GPP) from eddy covariance (EC) records to empirically quantify aboveground BPE (= ACI/GPP) and its interannual variability in two European beech forests (Hainich, DE-Hai, Germany; Sorø, DK-Sor, Denmark). We found significant negative correlations between BPE and a daily-resolved drought index at both sites, indicating that woody growth is de-prioritized under water limitation. During identified extreme years, early-season drought reduced same-year BPE by 29 % (Hainich, 2011), 31 % (Sorø, 2006), and 14 % (Sorø, 2013). By contrast, the 2003 late-summer drought resulted in a 17 % reduction of post-drought year BPE at Hainich. Across the entire EC period, the daily-to-seasonal drought response of BPE resembled that of ACI, rather than that of GPP. This indicates that BPE follows sink dynamics more closely than source dynamics, which appear to be decoupled given the distinctive climate response patterns of GPP and ACI. Based on our observations, we caution against estimating the magnitude and variability of the carbon sink in European beech (and likely other temperate forests) based on carbon fluxes alone. We also encourage comparable studies at other long-term EC measurement sites from different ecosystems to further constrain the BPE response to rare climatic events.


Asunto(s)
Ecosistema , Fagus , Biomasa , Fagus/fisiología , Sequías , Bosques , Carbono , Cambio Climático
15.
Sci Rep ; 14(1): 6262, 2024 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-38491084

RESUMEN

CD4+CD25+ regulatory T cells (Tregs) play an important role in maintaining immune homeostasis in multiple sclerosis (MS). Hence, we aimed to explore the therapeutic efficacy and safety of adoptive cell therapy (ACT) utilizing induced antigen-specific Tregs in an animal model of MS, that is, in an experimental autoimmune encephalomyelitis (EAE) model. B cells from EAE model that were activated with soluble CD40L were used as antigen-presenting cells (APCs) to induce the differentiation of antigen-specific Tregs from naïve CD4 precursors, and then, a stepwise isolation of CD4+CD25highCD127low Tregs was performed using a flow sorter. All EAE mice were divided into Treg-treated group (2 × 104 cells in 0.2 mL per mouse, n = 14) and sham-treated group (0.2 mL normal saline (NS), n = 20), which were observed daily for clinical assessment, and for abnormal appearance for 6 weeks. Afterward, histological analysis, immunofluorescence and real-time PCR were performed. Compared to sham-treated mice, Treg-treated mice exhibited a significant decrease in disease severity scores and reduced inflammatory infiltration and demyelination in the spinal cord. Additionally, Tregs-treated mice demonstrated higher CCN3 protein and mRNA levels than sham-treated mice. The results of this preclinical study further support the therapeutic potential of this ACT approach in the treatment of MS.


Asunto(s)
Encefalomielitis Autoinmune Experimental , Esclerosis Múltiple , Ratones , Animales , Linfocitos T Reguladores , Médula Espinal/patología , Células Presentadoras de Antígenos , Ratones Endogámicos C57BL
16.
World J Clin Cases ; 11(4): 719-724, 2023 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-36818629

RESUMEN

Cardioembolic stroke, referred to as cardiogenic stroke, is a clinical syndrome in which emboli from the heart pass through the circulatory system and cause cerebral artery embolism and corresponding brain dysfunction. Compared to other subtypes of ischemic stroke, cardiogenic stroke presents with more etiologies, greater severity, worse prognosis, and a higher recurrence rate. In this minireview, we provide new insights into the etiological classification, diagnostic methods, and interventions of cardiogenic stroke.

17.
Environ Sci Pollut Res Int ; 30(5): 13521-13531, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36138290

RESUMEN

Calcium and manganese are common ions that pollute drinking water and, therefore, ingestion may seriously harm human health. However, despite its importance, few studies into the synergistic removal of calcium and manganese have been reported. Calcium and manganese have similar chemical properties and, consequently, can be removed by co-crystallization, as the exact crystalline phase formed by this process and the process rate depend on the pH, the dissolved oxygen (DO) content, and the concentrations of the component ions. In this work, we experimentally studied the co-crystallization of Mn and Ca using an automatic potentiometric titrator. We found that the concentration of Mn2+ can be reduced from 3.0 to <0.1 mg/L by the co-crystallization of Mn and Ca at pH 10.5 and a DO content of 8.5 mg/L. In addition, the crystallizations of Ca and Mn are mutually inhibitory; the crystallization process of Mn is obviously divided into two stages: crystal nucleation and crystal growth. Increasing the pH, decreasing the DO content, and decreasing the Mn ion concentration increase the rate of CaCO3 crystallization, whereas the opposite changes increase the rate of Mn crystallization. Furthermore, Mn-Ca co-crystallization leads to the formation of various substances, including single crystals (CaCO3/MnCO3), mixed crystals (CaMnCO3), and Mn oxides (MnxOy/Mn(OH)O). Our findings regarding the effects, precipitation rates, and precipitation mechanisms of Mn-Ca co-crystallization serve as an important guide for the optimization and control of Mn-Ca co-crystallization processes.


Asunto(s)
Calcio , Agua Potable , Humanos , Calcio/química , Manganeso/química , Cristalización
18.
Plant Physiol Biochem ; 197: 107655, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36989992

RESUMEN

The pseudobulb is a storage organ for water and nutrients that plays a crucial role in the growth and survival of epiphytic orchids. However, the role of water and metabolites in pseudobulb during adaptation to environmental stress are rarely detected through control experiments. In the present study, water-related physiological traits and metabolite changes in the pseudobulbs at the flowering stage and full leaf expansion stage for Pleione aurita were investigated after drought stress and recovery treatments. We found that the composition of non-structural carbohydrates (starch vs. soluble sugar) varied over the lifetime of pseudobulbs, and older pseudobulbs stored more water, whereas younger pseudobulbs stored more dry matter. When plants were subjected to drought stress and subsequent recovery, multiple metabolites in the pseudobulbs including non-structural carbohydrates, flavonoids, phenolic acids, as well as amino acids and their derivatives responded positively to these water level fluctuations. For those metabolites that differently accumulated in both stress and recovery processes, old pseudobulbs contained a higher number of these key metabolites than did the connected younger pseudobulbs. In addition, young and old pseudobulbs use different metabolic pathways to both respond and recover to drought. These results indicate that orchid pseudobulbs cope with water level fluctuations by mobilizing metabolite reserves and that pseudobulbs of different ages exhibit different physiological and metabolic responses to drought stress. These findings broadens our understanding of the role pseudobulbs play in the survival of orchids growing in epiphytic habitats.


Asunto(s)
Orchidaceae , Orchidaceae/metabolismo , Sequías , Hojas de la Planta/metabolismo , Carbohidratos , Agua/metabolismo , Estrés Fisiológico
19.
Front Cardiovasc Med ; 10: 1128022, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37034338

RESUMEN

Objective: This study aims to identify relevant risk factors, assess the interactions between variables, and establish a predictive model for ischemic stroke (IS) in patients with cardiac myxoma (CM) using the Bayesian network (BN) approach. Methods: Data of patients with CM were collected from three tertiary comprehensive hospitals in Beijing from January 2002 to January 2022. Age, sex, medical history, and information related to CM were extracted from the electronic medical record system. The BN model was constructed using the tabu search algorithm, and the conditional probability of each node was calculated using the maximum likelihood estimation method. The probability of each node of the network and the interrelationship between IS and its related factors were qualitatively and quantitatively analyzed. A receiver operating characteristic (ROC) curve was also plotted. Sensitivity, specificity, and area under the curve (AUC) values were calculated and compared between the BN and logistic regression models to evaluate the efficiency of the predictive model. Results: A total of 416 patients with CM were enrolled in this study, including 61 with and 355 without IS. The BN model found that cardiac symptoms, systemic embolic symptoms, platelet counts, and tumor with high mobility were directly associated with the occurrence of IS in patients with CM. The BN model for predicting CM-IS achieved higher scores on AUC {0.706 [95% confidence interval (CI), 0.639-0.773]} vs. [0.697 (95% CI, 0.629-0.766)] and sensitivity (99.44% vs. 98.87%), but lower scores on accuracies (85.82% vs. 86.06%) and specificity (6.56% vs. 11.48%) than the logistic regression model. Conclusion: Cardiac symptoms, systemic embolic symptoms, platelet counts, and tumor with high mobility are candidate predictors of IS in patients with CM. The BN model was superior or at least non-inferior to the traditional logistic regression model, and hence is potentially useful for early IS detection, diagnosis, and prevention in clinical practice.

20.
Front Cardiovasc Med ; 10: 1294229, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-38259317

RESUMEN

Objective: This study aimed to seek the risk factors and develop a predictive model for ischemic stroke (IS) in patients with infective endocarditis (IE) utilizing a Bayesian network (BN) approach. Methods: Data were obtained from the electronic medical records of all adult patients at three hospitals between 1 January 2018, and 31 December 2022. Two predictive models, logistic regression and BN, were used. Patients were randomly assigned to the training and test sets in a 7:3 ratio. We established a BN model with the training dataset and validated it with the testing dataset. The Bayesian network model was built by using the Tabu search algorithm. The areas under the receiver operating characteristic curve (AUCs), calibration curve, and decision curve were used to evaluate the prediction performance between the BN and logistic models. Results: A total of 542 patients [mean (SD) age, 49.6 (15.3) years; 137 (25.3%) female] were enrolled, including 151 (27.9%) with IS and 391 (72.1%) without IS. Hyperlipidemia, hypertension, age, vegetation size (>10 mm), S. aureus infection, and early prosthetic valve IE were closely correlated with IS. The BN models outperformed the logistic regression in training and testing sets, with accuracies of 76.06% and 74.1%, AUC of 0.744 and 0.703, sensitivities of 25.93% and 20.93%, and specificities of 96.27% and 90.24%, respectively. Conclusion: The BN model is more efficient than the logistic regression model. Therefore, BN models may be suitable for the early diagnosis and prevention of IS in IE patients.

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