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While the existence and functional role of class C G-protein-coupled receptors (GPCR) dimers is well established, there is still a lack of consensus regarding class A and B GPCR multimerization. This lack of consensus is largely due to the inherent challenges of demonstrating the presence of multimeric receptor complexes in a physiologically relevant cellular context. The C-X-C motif chemokine receptor 4 (CXCR4) is a class A GPCR that is a promising target of anticancer therapy. Here, we investigated the potential of CXCR4 to form multimeric complexes with other GPCRs and characterized the relative size of the complexes in a live-cell environment. Using a bimolecular fluorescence complementation (BiFC) assay, we identified the ß2 adrenergic receptor (ß2AR) as an interaction partner. To investigate the molecular scale details of CXCR4-ß2AR interactions, we used a time-resolved fluorescence spectroscopy method called pulsed-interleaved excitation fluorescence cross-correlation spectroscopy (PIE-FCCS). PIE-FCCS can resolve membrane protein density, diffusion, and multimerization state in live cells at physiological expression levels. We probed CXCR4 and ß2AR homo- and heteromultimerization in model cell lines and found that CXCR4 assembles into multimeric complexes larger than dimers in MDA-MB-231 human breast cancer cells and in HCC4006 human lung cancer cells. We also found that ß2AR associates with CXCR4 multimers in MDA-MB-231 and HCC4006 cells to a higher degree than in COS-7 and CHO cells and in a ligand-dependent manner. These results suggest that CXCR4-ß2AR heteromers are present in human cancer cells and that GPCR multimerization is significantly affected by the plasma membrane environment.
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Neoplasias , Receptores Adrenérgicos beta 2 , Receptores CXCR4 , Transducción de Señal , Animales , Cricetinae , Humanos , Células CHO , Cricetulus , Proteínas de la Membrana/metabolismo , Neoplasias/metabolismo , Receptores CXCR4/metabolismo , Receptores Adrenérgicos beta 2/metabolismo , Multimerización de ProteínaRESUMEN
Efforts to stabilize the global climate change while also continuing human development depend upon "decoupling" economic growth from fossil fuel CO2 emissions. However, evaluations of such decoupling have typically relied on production-based emissions, which do not account for emissions embodied in international trade. Yet international trade can greatly change emissions accounting and reshape the decoupling between emissions and economic growth. Here, we evaluate decoupling of economic growth from different accounts of emissions in each of the 159 countries and analyze the drivers of decoupling. We find that between 1995 and 2015, although 29 countries exhibited strong decoupling of territorial emissions (growing economies and decreasing emissions), only 19 countries achieved economic growth while their consumption-based emissions decreased. Most developed countries have achieved decoupling of emissions related to domestic goods and services, but have not achieved decoupling of emissions related to imported goods and services. The U-test confirms that the domestic component of consumption-based emissions exhibits a stronger decoupling trend from gross domestic product (GDP) growth than consumption-based emissions, and emissions from imports continue to rise with GDP per capita without a corresponding decline, providing a statistical validation of the decoupling analysis. Moreover, in the countries where economic growth and consumption-based emissions are most decoupled, a key driver is decreasing emissions intensity due to technological progressâand especially reductions in the intensity of imported goods and services. Our results reveal the importance of assessing decoupling using consumption-based emissions; successful decoupling may require international cooperation and coordinated mitigation efforts of trading partners.
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The cilia of the outer hair cells (OHCs) are the key microstructures involved in cochlear acoustic function, and their interactions with lymph in the cochlea involve complex, highly nonlinear, coupled motion and energy conversions, including macroscopic fluid-solid coupling. Recent optical measurements have shown that the frequency selectivity of the cochlea at high sound levels is entirely mechanical and is determined by the interactions of the hair bundles with the surrounding fluid. In this paper, an analytical mathematical model of the spiral cochlea containing macro- and micromeasurements was developed to investigate how the phonosensitive function of OHCs' motions is influenced by the macrostructural and microstructural fluid-solid coupling in the spiral cochlea. The results showed that the macrostructural and microstructural fluid-solid coupling exerted the radial forces of OHCs through the flow field, deflecting the cilia and generating frequency-selective properties of the microstructures. This finding showed that microstructural frequency selectivity arises from the radial motions of stereocilia hair bundles and enhances the hearing of sound signals at specific frequencies. It also implied that the macrostructural and microstructural fluid-solid couplings influence the OHCs' radial forces and that this is a key factor in the excitation of ion channels that enables their activity in helping the brain to detect sound.
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Cóclea , Audición , Células Ciliadas Auditivas Externas , Movimiento (Física) , Modelos TeóricosRESUMEN
Vasorin (VASN), a transmembrane protein heavily expressed in endothelial cells, has garnered recent interest due to its key role in vascular development and pathology. The oligomeric state of VASN is a crucial piece of knowledge given that receptor clustering is a frequent regulatory mechanism in downstream signaling activation and amplification. However, documentation of VASN oligomerization is currently absent. In this brief report, we describe the measurement of VASN oligomerization in its native membranous environment, leveraging a class of fluorescence fluctuation spectroscopy. Our investigation revealed that the majority of VASN resides in a monomeric state, while a minority of VASN forms homodimers in the cellular membrane. This result raises the intriguing possibility that ligand-independent clustering of VASN may play a role in transforming growth factor signaling.
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Células Endoteliales , Proteínas de la Membrana , Membrana Celular , Transducción de Señal , Espectrometría de FluorescenciaRESUMEN
Agriculture is one of humankind's most significant sources of biomass; it also places tremendous pressure on ecosystems through its increasing demand for agricultural products. However, few studies have assessed human pressures on ecosystems from agricultural production and consumption based on a whole-supply-chain perspective. Based on the concept of human appropriation of net primary productivity (HANPP), we evaluate trends of agricultural HANPP embodied in consumption from a global perspective and trace the pressure from agriculture production that is exerted on the environment using an environmentally extended multiregional input-output (MRIO) model. The results show that agricultural HANPP embodied in consumption accounted for over two-thirds of total HANPP but brought about less than 7% of global value added. India, Brazil, and China were found to have the highest level of agricultural HANPP embodied in consumption. Agricultural net exporters were found to usually be low- and lower-income countries, while net importers are found to be high-income countries. According to the driving factor analysis, high-income and low-income countries should cooperate by adjusting consumption patterns and sharing agricultural technology to alleviate the pressure from agricultural production. Our study highlights the importance of agrarian expertise sharing and the need to develop sustainable and green agricultural production.
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Agricultura , Ecosistema , Humanos , Biomasa , Tecnología , ChinaRESUMEN
Soils are important carbon (C) reservoirs and play a critical role in regulating the global C cycle. Soil water potential (SWP) measures the energy with which water is retained in the soil and is one of the most vital factors that constrain the decomposition of soil organic C (SOC). The measurements for soil water retention curve (SWRC), on which the estimation of SWP depends, are usually carried out above -1.5 MPa (i.e., the wilting point for many plants). However, the average moisture threshold at which soil microbial activity ceases is usually below -10 MPa in mineral soils. Beyond the measurement range, the SWP estimation has to be derived from extrapolating the SWRC, which violates the statistical principle, resulting in possibly inaccurate SWP estimations. To date, it is unclear to what extent the extrapolated SWP estimation deviates from the "true value" and how it impacts the modeling of SOC decomposition. This study combined SWRC measurements down to -43.7 MPa, a 72-day soil incubation experiment with four moisture levels, and an SOC decomposition model. In addition to the complete SWRC (SWRCall ), we fitted two more SWRCs by using measurements above -0.5 MPa (SWRC0.5 ) and -1.7 MPa (SWRC1.7 ), respectively, to quantify the deviations of extrapolated SWPs from the complete SWRC. Results showed that extrapolating the SWRC beyond its measurement range significantly underestimated the SWP. Incorporating the extrapolated SWP in the model significantly underestimated the SOC decomposition under relatively dry conditions. With the extrapolated SWP, the model predicted no SOC decomposition in the driest treatment, while the experiment observed a significant CO2 emission. The results emphasize that accurate SWP estimations beyond the wilting point are critically needed to improve the modeling of SOC decomposition.
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Suelo , Agua , Carbono , PlantasRESUMEN
Soil respiration, the major pathway for ecosystem carbon (C) loss, has the potential to enter a positive feedback loop with the atmospheric CO2 due to climate warming. For reliable projections of climate-carbon feedbacks, accurate quantification of soil respiration and identification of mechanisms that control its variability are essential. Process-based models simulate soil respiration as functions of belowground C input, organic matter quality, and sensitivity to environmental conditions. However, evaluation and calibration of process-based models against the long-term in situ measurements are rare. Here, we evaluate the performance of the Terrestrial ECOsystem (TECO) model in simulating total and heterotrophic soil respiration measured during a 16-year warming experiment in a mixed-grass prairie; calibrate model parameters against these and other measurements collected during the experiment; and explore whether the mechanisms of C dynamics have changed over the years. Calibrating model parameters against observations of individual years substantially improved model performance in comparison to pre-calibration simulations, explaining 79-86% of variability in observed soil respiration. Interannual variation of the calibrated model parameters indicated increasing recalcitrance of soil C and changing environmental sensitivity of microbes. Overall, we found that (1) soil organic C became more recalcitrant in intact soil compared to root-free soil; (2) warming offset the effects of increasing C recalcitrance in intact soil and changed microbial sensitivity to moisture conditions. These findings indicate that soil respiration may decrease in the future due to C quality, but this decrease may be offset by warming-induced changes in C cycling mechanisms and their responses to moisture conditions.
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Carbono , Suelo , Cambio Climático , Ecosistema , Pradera , Poaceae , Microbiología del SueloRESUMEN
BACKGROUND Previous research suggests that formative assessment (FA) enhances learning outcomes, but few studies have evaluated its impact on clinical skills training in China. We conducted this study in a clinical skills integral curriculum to further explore the educational value of FA. MATERIAL AND METHODS Sixty undergraduates from the Second Clinical Medical School of the Southern Medical University in 2016 were selected as the experimental group (consecutive FA), and 50 undergraduates in 2015 were selected as the control term (only final summative assessment, SA). Undergraduates in the FA group completed the after-class questionnaire at each lesson. Teachers, teaching content, assessment objectives, and topics are the same in both groups. RESULTS The results of single-factor covariance (ANCOVA) analysis and Cochran-Mantel-Haenszel (CMH) analysis demonstrated that students of the FA group obtained better performance and higher success rates in summative examination than in the SA group. The students with relatively poor grades benefited more from FA, while the performance of students with higher grades was similar between the FA group and SA group. According to the results of questionnaire for students, the satisfaction of students with the course increased gradually, from 84.4% to 93.0%. CONCLUSIONS Proper use of FA is associated with better learning outcomes for students, especially for those with poorer grades. Our results, together with previous research, indicated that the use of FA may be of great benefit to students' academic performance and satisfaction with the clinical skills training curriculum.
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Rendimiento Académico/estadística & datos numéricos , Competencia Clínica/estadística & datos numéricos , Educación de Pregrado en Medicina/métodos , Evaluación Educacional/métodos , Estudiantes de Medicina/estadística & datos numéricos , China , Curriculum , Humanos , Encuestas y CuestionariosRESUMEN
In this study, a novel monolithic capillary column based on a NH2-MIL-53(Al) metal-organic framework (MOF) incorporated in poly (3-acrylamidophenylboronic acid/methacrylic acid-co-ethylene glycol dimethacrylate) (poly (AAPBA/MAA-co-EGDMA)) was prepared using an in situ polymerization method. The characteristics of the MOF-polymer monolithic column were investigated by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffractometry, Brunauer-Emmett-Teller analysis, and thermogravimetric analysis. The prepared MOF-polymer monolithic column showed good permeability, high extraction efficiency, chemical stability, and good reproducibility. The MOF-polymer monolithic column was used for in-tube solid-phase microextraction (SPME) to efficiently adsorb trace sulfonamides from food samples. A novel method combining MOF-polymer-monolithic-column-based SPME with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was successfully developed. The linear range was from 0.015 to 25.0 µg/L, with low limits of detection of 1.3-4.7 ng/L and relative standard deviations (RSDs) of < 6.1%. Eight trace sulfonamides in fish and chicken samples were determined, with recoveries of the eight analytes ranging from 85.7% to 113% and acceptable RSDs of < 7.3%. These results demonstrate that the novel MOF-polymer-monolithic-column-based SPME coupled with UHPLC-MS/MS is a highly sensitive, practical, and convenient method for monitoring trace sulfonamides in food samples previously extracted with an adequate solvent.
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Análisis de los Alimentos , Polímeros/química , Microextracción en Fase Sólida , Sulfonamidas/análisis , Espectrometría de Masas en Tándem , Adsorción , Animales , Calibración , Pollos , Cromatografía Líquida de Alta Presión , Peces , Concentración de Iones de Hidrógeno , Estructuras Metalorgánicas , Reología , Espectroscopía Infrarroja por Transformada de Fourier , Temperatura , Difracción de Rayos XRESUMEN
This protocol provides a novel, environmentally friendly and simple method for the synthesis of (Z)-tetrahydrothiophene derivatives using the nucleophilic thiyl radical intramolecular cycloaddition cascade process to construct C-S bonds under transition-metal-free conditions. This transformation process offers a broad substrate scope, good functional group tolerance, and excellent stereoselectivity (Z/E ratios up to 99/1). Moreover, the process uses odourless, stable and cheap EtOCS2K as the sulfur source.
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Climate warming can result in both abiotic (e.g., permafrost thaw) and biotic (e.g., microbial functional genes) changes in Arctic tundra. Recent research has incorporated dynamic permafrost thaw in Earth system models (ESMs) and indicates that Arctic tundra could be a significant future carbon (C) source due to the enhanced decomposition of thawed deep soil C. However, warming-induced biotic changes may influence biologically related parameters and the consequent projections in ESMs. How model parameters associated with biotic responses will change under warming and to what extent these changes affect projected C budgets have not been carefully examined. In this study, we synthesized six data sets over 5 years from a soil warming experiment at the Eight Mile Lake, Alaska, into the Terrestrial ECOsystem (TECO) model with a probabilistic inversion approach. The TECO model used multiple soil layers to track dynamics of thawed soil under different treatments. Our results show that warming increased light use efficiency of vegetation photosynthesis but decreased baseline (i.e., environment-corrected) turnover rates of SOC in both the fast and slow pools in comparison with those under control. Moreover, the parameter changes generally amplified over time, suggesting processes of gradual physiological acclimation and functional gene shifts of both plants and microbes. The TECO model predicted that field warming from 2009 to 2013 resulted in cumulative C losses of 224 or 87 g/m2 , respectively, without or with changes in those parameters. Thus, warming-induced parameter changes reduced predicted soil C loss by 61%. Our study suggests that it is critical to incorporate biotic changes in ESMs to improve the model performance in predicting C dynamics in permafrost regions.
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Carbono/análisis , Cambio Climático , Suelo/química , Tundra , Alaska , Carbono/metabolismo , Modelos Teóricos , Hielos Perennes/química , Hielos Perennes/microbiología , Fotosíntesis , Plantas/metabolismo , Microbiología del SueloRESUMEN
Quantifying soil organic carbon (SOC) decomposition under warming is critical to predict carbon-climate feedbacks. According to the substrate regulating principle, SOC decomposition would decrease as labile SOC declines under field warming, but observations of SOC decomposition under warming do not always support this prediction. This discrepancy could result from varying changes in SOC components and soil microbial communities under warming. This study aimed to determine the decomposition of SOC components with different turnover times after subjected to long-term field warming and/or root exclusion to limit C input, and to test whether SOC decomposition is driven by substrate lability under warming. Taking advantage of a 12-year field warming experiment in a prairie, we assessed the decomposition of SOC components by incubating soils from control and warmed plots, with and without root exclusion for 3 years. We assayed SOC decomposition from these incubations by combining inverse modeling and microbial functional genes during decomposition with a metagenomic technique (GeoChip). The decomposition of SOC components with turnover times of years and decades, which contributed to 95% of total cumulative CO2 respiration, was greater in soils from warmed plots. But the decomposition of labile SOC was similar in warmed plots compared to the control. The diversity of C-degradation microbial genes generally declined with time during the incubation in all treatments, suggesting shifts of microbial functional groups as substrate composition was changing. Compared to the control, soils from warmed plots showed significant increase in the signal intensities of microbial genes involved in degrading complex organic compounds, implying enhanced potential abilities of microbial catabolism. These are likely responsible for accelerated decomposition of SOC components with slow turnover rates. Overall, the shifted microbial community induced by long-term warming accelerates the decomposition of SOC components with slow turnover rates and thus amplify the positive feedback to climate change.
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Carbono/metabolismo , Cambio Climático , Microbiología del Suelo , Suelo/química , OklahomaRESUMEN
Climatic changes are altering Earth's hydrological cycle, resulting in altered precipitation amounts, increased interannual variability of precipitation, and more frequent extreme precipitation events. These trends will likely continue into the future, having substantial impacts on net primary productivity (NPP) and associated ecosystem services such as food production and carbon sequestration. Frequently, experimental manipulations of precipitation have linked altered precipitation regimes to changes in NPP. Yet, findings have been diverse and substantial uncertainty still surrounds generalities describing patterns of ecosystem sensitivity to altered precipitation. Additionally, we do not know whether previously observed correlations between NPP and precipitation remain accurate when precipitation changes become extreme. We synthesized results from 83 case studies of experimental precipitation manipulations in grasslands worldwide. We used meta-analytical techniques to search for generalities and asymmetries of aboveground NPP (ANPP) and belowground NPP (BNPP) responses to both the direction and magnitude of precipitation change. Sensitivity (i.e., productivity response standardized by the amount of precipitation change) of BNPP was similar under precipitation additions and reductions, but ANPP was more sensitive to precipitation additions than reductions; this was especially evident in drier ecosystems. Additionally, overall relationships between the magnitude of productivity responses and the magnitude of precipitation change were saturating in form. The saturating form of this relationship was likely driven by ANPP responses to very extreme precipitation increases, although there were limited studies imposing extreme precipitation change, and there was considerable variation among experiments. This highlights the importance of incorporating gradients of manipulations, ranging from extreme drought to extreme precipitation increases into future climate change experiments. Additionally, policy and land management decisions related to global change scenarios should consider how ANPP and BNPP responses may differ, and that ecosystem responses to extreme events might not be predicted from relationships found under moderate environmental changes.
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Cambio Climático , Ecosistema , Pradera , Poaceae , LluviaRESUMEN
Tissue culture seedlings of Bletilla striata were treated with MeJA, SA and two kinds of endophytic fungi in order to study the effects of those treatments on the physiology and total phenols content. The method of tissue culture was used to culture seeds into seedlings, and then different treatments were applied on them to observe and measure the changes of physiology and total phenols content. We find that the growth of seedlings treated with SA was poor, which treated with 40 µmolâ¢L⻹ MeJA, 50 mLâ¢L⻹ Hypocrea koningii and 10 mLâ¢L⻹ Trichoderma koningiopsis showed better. The activity of SOD, POD and CAT was at a high level under SA treatment of each concentration. The activity of SOD and POD increased as the rise of MeJA concentration, while CAT was highest at 80 µmolâ¢L⻹. The activity of SOD and POD increased with the increasing of the concentration of H. koningii treatment, while CAT reached the highest at 1 mLâ¢L⻹. The activity of SOD, POD and CAT increased first and then declined with the concentration of T. koningiopsis increasing, and the highest activity was at 10 mLâ¢L⻹. The contents of MDA, soluble protein and proline were increased more or less under the four treatments. The content of polysaccharide was at a high level under 60 µmolâ¢L⻹ of MeJA. The total phenols content was at a high level under 40 µmolâ¢L⻹ of MeJA, 60 µmolâ¢L⻹ of SA, 1 mLâ¢L⻹ of H. koningii and 10 mLâ¢L⻹ of T. koningiopsis. The results indicated that the addition of exogenous MeJA, SA and endophytic fungi under certain concentrations could improve the resistance of B. striata and increase the content of total phenols at some degree and the trearment of MeJA, H. koningii and T. koningiopsis could promote the growth of seedlings under certain concentrations.
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Acetatos/farmacología , Ciclopentanos/farmacología , Hongos , Orchidaceae/química , Oxilipinas/farmacología , Fenoles/análisis , Plantones/química , Catalasa , Endófitos , Orchidaceae/microbiología , Peroxidasa , Semillas , Superóxido DismutasaRESUMEN
Copper ranks among the most important metal ions in living organism, owing to its key catalytic effect in a range of biochemical processes. Dysregulation of in vivo copper(I) metabolism is extremely toxic and would cause serious diseases in human, such as Wilson's and Menkes. Thus, it would be highly valuable to have a proper approach to monitor the dynamics of copper(I) in vivo, as it is directly related to the onset of human copper(I)-related diseases. Under these circumstance, developing fluorescent protein based copper(I) sensors is highly demanded. However, these established sensors are mostly based on green or yellow FPs. Fluorescent copper(I) sensors with a spectra in the red range are more desirable due to lower phototoxicity, less auto-fluorescent noise and better penetration of red light. In the present work, we grafted a special red FP into three different location of a copper(I) binding protein, and generate a series of red fluorescent copper(I) sensors. Despite their limited in vivo sensitivity toward copper(I), these sensors are viable for cellular copper(I) imaging. Furthermore, these red fluorescent copper(I) sensors are a good starting point to develop superior copper(I) biosensors capable of imaging copper(I) fluctuations within a truly biologically relevant concentration, and further effort to realize this endeavor is under way.
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Técnicas Biosensibles , Células/metabolismo , Cobre/análisis , Técnicas Genéticas , Proteínas Luminiscentes/genética , Imagen Molecular/métodos , Células HEK293 , Humanos , Proteína Fluorescente RojaRESUMEN
Due to ethical issues and the very fine and complex structure of the cochlea, it is difficult to directly perform experimental measurement on the human cochlea. Therefore, the finite element method has become an effective and replaceable new research means. Accurate numerical analysis on human ear using finite element method can provide better understanding of sound transmission and can be used to assess the influence of diseases on hearing and to treat hearing loss. In this research, a three-dimensional (3D) finite element model (FEM) of the human ear of cochlea was presented to investigate the destruction of basilar membrane (BM), round window (RW) sclerosis and perilymph fistula, the key structures of the cochlea, and analyze the effects of these abnormal pathological states in the cochlea on cochlear hearing, resulting in the changes in cochlear sense structure biomechanical behavior and quantitative prediction of the degree and harm of the disorder to the decline of human hearing. Therefore, this paper can deepen reader's understanding of the cochlear biomechanical mechanism and provide a theoretical foundation for clinical otology.
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Cóclea , Pérdida Auditiva , Humanos , Audición , Ventana Redonda , Membrana BasilarRESUMEN
So far, explaining the mechanism on active phonosensitive amplification in the cochlea is a major and difficult medical question. Among them, one of the key problems is that the motion pattern of the organ of Corti (OC) is still unknown. To this end, a multi-scale cochlear model including a three-dimensional spiral OC was established based on CT data and light source imaging experimental data, which complete combined the macroscopic and microscopic structure. On the basis of verifying the reliability of the model, acoustic-solid coupling calculation and modal analysis were performed on the model, and the vibration modes of basilar membrane (BM) and structures of the OC at different characteristic frequencies were discussed. The results show that tectorial membrane (TM) exhibits completely different vibration modes from BM at low frequencies, while the two movements gradually synchronize as the frequency increases. The amplitude position of OC's motion moves laterally with increasing frequency from Deiters' cells to Hensen's cells and then back to Deiters' cells. The OC exhibits longitudinal vibrations following BM when BM's displacement is large, while it manifests more as lateral movement of Deiters' cells when BM's displacement is small. This model can well simulate the motion process of BM and OC in the lymphatic fluid, which provides theoretical support and a numerical simulation computational platform to explore the interaction between macroscopic and microscopic tissue structures of the overall cochlea.
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BACKGROUND: The gut microbiome is composed of various microorganisms such as bacteria, fungi, and protozoa, and constitutes an important part of the human gut. Its composition is closely related to human health and disease. Alzheimer's disease (AD) is a neurodegenerative disease whose underlying mechanism has not been fully elucidated. Recent research has shown that there are significant differences in the gut microbiota between AD patients and healthy individuals. Changes in the composition of gut microbiota may lead to the development of harmful factors associated with AD. In addition, the gut microbiota may play a role in the development and progression of AD through the gut-brain axis. However, the exact nature of this relationship has not been fully understood. AIMS: This review will elucidate the types and functions of gut microbiota and their relationship with AD and explore in depth the potential mechanisms of gut microbiota in the occurrence of AD and the prospects for treatment strategies. METHODS: Reviewed literature from PubMed and Web of Science using key terminologies related to AD and the gut microbiome. RESULTS: Research indicates that the gut microbiota can directly or indirectly influence the occurrence and progression of AD through metabolites, endotoxins, and the vagus nerve. DISCUSSION: This review discusses the future challenges and research directions regarding the gut microbiota in AD. CONCLUSION: While many unresolved issues remain regarding the gut microbiota and AD, the feasibility and immense potential of treating AD by modulating the gut microbiota are evident.
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Enfermedad de Alzheimer , Microbioma Gastrointestinal , Enfermedades Neurodegenerativas , Humanos , Enfermedad de Alzheimer/terapia , Eje Cerebro-Intestino , PubMed , EncéfaloRESUMEN
Grasslands are one of the most important terrestrial biomes, supporting a wide range of ecological functions and services. Grassland degradation due to overgrazing is a severe issue worldwide, especially in developing regions. However, observations from multiple sources have shown that temperate grasslands in China have significantly increased during the past two decades. It remains controversial what factors have driven the vegetation restoration in this region. In this study, we combined remote-sensing images and field survey datasets to quantify the contributions of different factors to vegetation restoration in six temperate grasslands in northern China. Across the six grasslands, the Normalized Difference Vegetation Index (NDVI) increased by 0.003-0.0319 year-1. The average contributions of grazing exclusion and climate change to the NDVI increase were 49.23 % and 50.77 %, respectively. Precipitation change was the primary climate factor driving vegetation restoration, contributing 50.76 % to the NDVI variance. By contrast, climate warming tended to slow vegetation restoration, and atmospheric CO2 concentration change contributed little to the NDVI increase in the temperate grasslands. These results emphasize the significant contributions of both climate change and human management to grassland vegetation restoration.
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Cambio Climático , Pradera , Humanos , Ecosistema , China , Telemetría , TemperaturaRESUMEN
Alzheimer's disease (AD) is a common neurodegenerative disease in the elderly, the exact pathogenesis of which remains incompletely understood, and effective preventive and therapeutic drugs are currently lacking. Cholesterol plays a vital role in cell membrane formation and neurotransmitter synthesis, and its abnormal metabolism is associated with the onset of AD. With the continuous advancement of imaging techniques and molecular biology methods, researchers can more accurately explore the relationship between cholesterol metabolism and AD. Elevated cholesterol levels may lead to vascular dysfunction, thereby affecting neuronal function. Additionally, abnormal cholesterol metabolism may affect the metabolism of ß-amyloid protein, thereby promoting the onset of AD. Brain cholesterol levels are regulated by multiple factors. This review aims to deepen the understanding of the subtle relationship between cholesterol homeostasis and AD, and to introduce the latest advances in cholesterol-regulating AD treatment strategies, thereby inspiring readers to contemplate deeply on this complex relationship. Although there are still many unresolved important issues regarding the risk of brain cholesterol and AD, and some studies may have opposite conclusions, further research is needed to enrich our understanding. However, these findings are expected to deepen our understanding of the pathogenesis of AD and provide important insights for the future development of AD treatment strategies targeting brain cholesterol homeostasis.