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1.
J Am Chem Soc ; 146(29): 20116-20121, 2024 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-39007298

RESUMO

Adiabatic demagnetization refrigeration (ADR) is a promising cooling technology with high efficiency and exceptional stability in achieving ultralow temperatures, playing an indispensable role at the forefront of fundamental and applied science. However, a significant challenge for ADR is that existing magnetic refrigerants struggle to concurrently achieve low magnetic ordering temperatures (T0) and substantial magnetic entropy changes (-ΔSm) at ultralow temperatures. In this work, we propose the combination of Gd3+ and Yb3+ to effectively regulate both -ΔSm and T0 in ultralow temperatures. Notably, the -ΔSm values for Gd0.1Yb0.9F3 (1) and Gd0.3Yb0.7F3 (2) in the 0.4-1.0 K range exceed those of all previously reported magnetic refrigerants within this temperature interval, positioning them as the most efficient magnetic refrigerants for the third stage to date. Although the -ΔSm values for Gd0.5Yb0.5F3 (3) in 1-4 K are less than those of the leading magnetic refrigerant Gd(OH)F2, the -ΔSm values for Gd0.7Yb0.3F3 (4) in 1-4 K at 2 T surpass those of all magnetic refrigerants previously documented within the same temperature range, making it the superior magnetic refrigerant for the fourth stage identified thus far.

2.
J Am Chem Soc ; 146(32): 22134-22139, 2024 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-39083626

RESUMO

Open hollow dodecahedral cage clusters have long been a coveted target in synthetic chemistry, yet their creation poses immense challenges. Here we report two open hollow dodecahedral lanthanide-aluminum (Ln-Al) heterometallic cage clusters, namely, [Ln210Al140(µ2-OH)210(µ3-OH)540(OAc)180(H2O)156](ClO4)120·(MeCN)x·(H2O)y, (Ln = Dy and x = 27, y = 300 for 1; Ln = Y and x = 28, y = 420 for 2). Remarkably, the 350 metal atoms in 1 and 2 display a Keplerate-type four-shell structure of truncated icosidodecahedron@dodecahedron@dodecahedron@icosidodecahedron. The diameter of the cationic cluster in 1 is approximately 5.0 nm, with an inner cavity diameter of about 2.8 nm and a window diameter of roughly 0.66 nm. The cluster in 1 boasts an accessible inner void volume of up to 15,000 Å3. Notably, these cage clusters maintain stability in water, and the truncated icosidodecahedrons in 1 and 2 are the first of their kind synthesized to date. Given that the open hollow dodecahedral Ln-Al cage cluster has never been reported before, this work represents a member in the family of hollow open dodecahedral cages.

3.
Inorg Chem ; 63(28): 12880-12885, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-38935512

RESUMO

Keggin-Fe13 clusters are considered foundational building blocks or prenucleation precursors of ferrihydrite. Understanding the factors that influence the rotational configuration of these clusters, and their transformations in water, is vital for comprehending the formation mechanism of ferrihydrite. Here, we report syntheses and crystal structures of four lanthanide-iron-oxo clusters, namely, [Dy6Fe13(Gly)12(µ2-OH)6(µ3-OH)18(µ4-O)4(H2O)17]·13ClO4·19H2O (1), [Dy6Fe13(Gly)12(µ3-OH)24(µ4-O)4(H2O)18]·13ClO4·14H2O (2), [Pr8Fe34(Gly)24(µ3-OH)28(µ3-O)30(µ4-O)4(H2O)30]·6ClO4·20H2O (3), and [Pr6Fe13(Gly)12(µ3-OH)24(µ4-O)4(H2O)18]·13ClO4·22H2O (4, Gly = glycine). Single-crystal analyses reveal that 1 has a ß-Keggin-Fe13 cluster, marking the first documented instance of such a cluster to date. Conversely, both 2 and 4 contain an α-Keggin-Fe13 cluster, while 3 is characterized by four hexavacant ε-Keggin-Fe13 clusters. Magnetic property investigations of 1 and 2 show that 2 exhibits ferromagnetic interactions, while 1 exhibits antiferromagnetic interactions. An exploration of the synthetic conditions for 1 and 2 indicates that a higher pH promotes the formation of α-Keggin-Fe13 clusters, while a lower pH favors ß-Keggin-Fe13 clusters. A detailed analysis of the transition from 3 to 4 emphasizes that lacunary Keggin-Fe13 clusters can morph into Keggin-Fe13 clusters with a decrease in pH, accompanied by a significant change in their rotational configuration.

4.
ACS Appl Mater Interfaces ; 16(25): 32394-32401, 2024 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-38875495

RESUMO

Adiabatic demagnetization refrigeration is known to be the only cryogenic refrigeration technology that can achieve ultralow temperatures (≪1 K) at gravity-free conditions. The key indexes to evaluate the performance of magnetic refrigerants are their magnetic entropy changes (-ΔSm) and magnetic ordering temperature (T0). Although, based on the factors affecting the -ΔSm of magnetic refrigerants, one has been able to judge if a magnetic refrigerant has a large -ΔSm, how to accurately predict their T0 remains a huge challenge due to the fact that the T0 of magnetic refrigerants is related to not only magnetic exchange but also single-ion anisotropy and magnetic dipole interaction. Here, we, taking GdCO3F (1), Gd(HCOO)F2, Gd2(SO4)3·8H2O, GdF3, Gd(HCOO)3 and Gd(OH)3 as examples, demonstrate that the T0 of magnetic refrigerants with very weak magnetic interactions and small anisotropy can be accurately predicted by integrating mean-field approximation with quantum Monte Carlo simulations, providing an effective method for predicting the T0 of ultralow-temperature magnetic refrigerants. Thus, the present work lays a solid foundation for the rational design and preparation of ultralow-temperature magnetic refrigerants in the future.

5.
BMC Plant Biol ; 24(1): 511, 2024 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-38844870

RESUMO

The invasion of Mikania micrantha by climbing and covering trees has rapidly caused the death of many shrubs and trees, seriously endangering forest biodiversity. In this study, M. micrantha seedlings were planted together with local tree species (Cryptocarya concinna) to simulate the process of M. micrantha climbing under the forest. We found that the upper part of the M. micrantha stem lost its support after climbing to the top of the tree, grew in a turning and creeping manner, and then grew branches rapidly to cover the tree canopy. Then, we simulated the branching process through turning treatment. We found that a large number of branches had been formed near the turning part of the M. micrantha stem (TP). Compared with the upper part of the main stem (UP), the contents of plant hormones (auxin, cytokinin, gibberellin), soluble sugars (sucrose, glucose, fructose) and trehalose-6-phosphate (T6P) were significantly accumulated at TP. Further combining the transcriptome data of different parts of the main stem under erect or turning treatment, a hypothetical regulation model to illustrate how M. micrantha can quickly cover trees was proposed based on the regulation of sugars and hormones on plant branching; that is, the lack of support after ascending the top of the tree led to turning growth of the main stem, and the enhancement of sugars and T6P levels in the TP may first drive the release of nearby dormant buds. Plant hormone accumulation may regulate the entrance of buds into sustained growth and maintain the elongation of branches together with sugars to successfully covering trees.


Assuntos
Espécies Introduzidas , Mikania , Árvores , Mikania/crescimento & desenvolvimento , Árvores/crescimento & desenvolvimento , Reguladores de Crescimento de Plantas/metabolismo
6.
Inorg Chem ; 63(18): 8003-8007, 2024 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-38647013

RESUMO

A series of chiral heterometallic Ln-Co clusters, denoted as Co2Ln and Co3Ln2 (Ln = Dy and Er), were synthesized by reacting the chiral chelating ligand (R/S)-2-(1-hydroxyethyl)pyridine (Hmpm), CoAc2·4H2O, and Ln(NO3)3·6H2O. Co2Ln and Co3Ln2 exhibit perfect mirror images in circular dichroism within the 320-700 nm range. Notably, the Co2Er and Co3Er2 clusters display pronounced magnetic circular dichroism (MCD) responses of the hypersensitive f-f transitions 4I15/2-4G11/2 at 375 nm and 4I15/2-2H11/2 at 520 nm of ErIII ions. This study highlights the strong magneto-optical activity associated with hypersensitive f-f transitions in chiral 3d-4f magnetic clusters.

7.
J Glob Health ; 14: 04090, 2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38577809

RESUMO

Background: This study aims to assess the global incidence, mortality, and disability-adjusted life years (DALYs) of thyroid cancer between 1990 and 2030. Methods: Our study analysed Global Burden of Disease (GBD) 2019 data from 204 countries, spanning 1990-2019. It focused on age-standardised thyroid cancer incidence, mortality, and disability-adjusted life years (DALYs), using the sociodemographic index (SDI) for assessing socioeconomic levels. Generalised additive models (GAMs) projected thyroid cancer trends for 2020-2030. Results: The global burden of thyroid cancer is predicted to increase significantly from 1990 to 2030. The number of thyroid cancer incidence cases is projected to rise from 233 846.64 in 2019 to 305 078.08 by 2030, representing an approximate 30.46% increase. The ASIR (age-standardised incidence rate) is expected to continue its upward trend (estimated annual percentage change (EAPC) = 0.83). The age-standardised death rate (ASDR) for thyroid cancer is projected to decline in both genders, more notably in women (EAPC = -0.34) compared to men (EAPC = -0.17). The burden of disease escalates with advancing age, with significant regional disparities. Regions with lower SDI, particularly in South Asia, are anticipated to witness substantial increases in thyroid cancer incidence from 2020 to 2030. The overall disease burden is expected to rise, especially in countries with low to middle SDI, reflecting broader socio-economic and health care shifts. Conclusions: This study highlights significant regional and gender-specific variations in thyroid cancer, with notable increases in incidence rates, particularly in areas like South Asia. These trends suggest improvements in diagnostic capabilities and the influence of socio-economic factors. Additionally, the observed decline in mortality rates across various regions reflects advancements in thyroid cancer management. The findings underline the critical importance of regionally tailored prevention strategies, robust cancer registries, and public health initiatives to address the evolving landscape of thyroid cancer and mitigate health disparities globally.


Assuntos
Morte Perinatal , Neoplasias da Glândula Tireoide , Humanos , Masculino , Feminino , Carga Global da Doença , Anos de Vida Ajustados por Qualidade de Vida , Efeitos Psicossociais da Doença , Incidência , Neoplasias da Glândula Tireoide/epidemiologia , Saúde Global
8.
BMC Geriatr ; 24(1): 125, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38302872

RESUMO

BACKGROUND: Falls pose a severe threat to the health of older adults worldwide. Determining gait and kinematic parameters that are related to an increased risk of falls is essential for developing effective intervention and fall prevention strategies. This study aimed to investigate the discriminatory parameter, which lay an important basis for developing effective clinical screening tools for identifying high-fall-risk older adults. METHODS: Forty-one individuals aged 65 years and above living in the community participated in this study. The older adults were classified as high-fall-risk and low-fall-risk individuals based on their BBS scores. The participants wore an inertial measurement unit (IMU) while conducting the Timed Up and Go (TUG) test. Simultaneously, a depth camera acquired images of the participants' movements during the experiment. After segmenting the data according to subtasks, 142 parameters were extracted from the sensor-based data. A t-test or Mann-Whitney U test was performed on the parameters for distinguishing older adults at high risk of falling. The logistic regression was used to further quantify the role of different parameters in identifying high-fall-risk individuals. Furthermore, we conducted an ablation experiment to explore the complementary information offered by the two sensors. RESULTS: Fifteen participants were defined as high-fall-risk individuals, while twenty-six were defined as low-fall-risk individuals. 17 parameters were tested for significance with p-values less than 0.05. Some of these parameters, such as the usage of walking assistance, maximum angular velocity around the yaw axis during turn-to-sit, and step length, exhibit the greatest discriminatory abilities in identifying high-fall-risk individuals. Additionally, combining features from both devices for fall risk assessment resulted in a higher AUC of 0.882 compared to using each device separately. CONCLUSIONS: Utilizing different types of sensors can offer more comprehensive information. Interpreting parameters to physiology provides deeper insights into the identification of high-fall-risk individuals. High-fall-risk individuals typically exhibited a cautious gait, such as larger step width and shorter step length during walking. Besides, we identified some abnormal gait patterns of high-fall-risk individuals compared to low-fall-risk individuals, such as less knee flexion and a tendency to tilt the pelvis forward during turning.


Assuntos
Vida Independente , Equilíbrio Postural , Humanos , Idoso , Equilíbrio Postural/fisiologia , Marcha/fisiologia , Caminhada , Medição de Risco/métodos , Acidentes por Quedas/prevenção & controle
9.
Dalton Trans ; 53(7): 3097-3103, 2024 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-38235965

RESUMO

Five decanuclear lanthanide-iron clusters, formulated as [Ln2Fe8(hmp)10(µ2-OH)4(µ3-OH)2(µ4-O)4(H2O)6]·6ClO4·xH2O (x ≈ 8, Ln = Y for 1; x ≈ 6, Ln = Dy for 2; x ≈ 6, Ln = Ho for 3; x ≈ 7, Ln = Tb for 4; x ≈ 7, Ln = Gd for 5, Hhmp = 2-(hydroxymethyl)pyridine), have been synthesized and structurally characterized. Single-crystal structural analysis reveals that the cluster consists of six face-sharing defective cubane units. Dynamic magnetic investigations indicated that cluster 2 exhibits single-molecule magnet behavior under a zero dc field eliciting an effective energy barrier of Ueff = 17.76 K and a pre-exponential factor of τ0 = 7.93 × 10-8 s. Investigation of the performance of a series of FeIII-DyIII SMMs indicates that the relatively low energy barrier in 2 is associated with the weak ferromagnetic coupling between FeIII and DyIII ions, while the strength of ferromagnetic interaction in these clusters is mainly related to the bond distances between DyIII and O atoms coordinated to FeIII ions. Clusters 3 and 4 exhibit similar dual relaxation pathways under their respective optimal external applied dc field, where the direct relaxation process occurs in the low-frequency area, which impedes the extraction of the Ueff, while the secondary relaxation process appears at a higher frequency, which is probably a connection with intermolecularly driven relaxation. Our findings offer a magneto-structural correlation model for further investigating the single-molecule magnet behavior in lanthanide-iron systems.

10.
Microb Biotechnol ; 16(10): 1971-1984, 2023 10.
Artigo em Inglês | MEDLINE | ID: mdl-37606280

RESUMO

To identify the potential role of the 3-hydroxyl group of the pyridine ring in nosiheptide (NOS) for its antibacterial activity against Gram-positive pathogens, enzymatic glycosylation was utilized to regio-selectively create a monoglycosyl NOS derivative, NOS-G. For this purpose, we selected OleD, a UDP glycosyltransferase from Streptomyces antibioticus that has a low productivity for NOS-G. Activity of the enzyme was increased by swapping domains derived from OleI, both single and in combination. Activity enhancement was best in mutant OleD-10 that contained four OleI domains. This chimer was engineered by site-directed mutagenesis (single and in combination) to increase its activity further, whereby variants were screened using a newly-established colorimetric assay. OleD-10 with I117F and T118G substitutions (FG) had an increased NOS-G productivity of 56%, approximately 70 times higher than that of wild-type OleD. The reason for improved activity of FG towards NOS was structurally attributed to a closer distance (<3 Å) between NOS/sugar donor and the catalytic amino acid H25. The engineered enzyme allowed sufficient activity to demonstrate that the produced NOS-G had enhanced stability and aqueous solubility compared to NOS. Using a murine MRSA infection model, it was established that NOS-G resulted in partial protection within 20 h of administration and delayed the death of infected mice. We conclude that 3-hydroxypyridine is a promising site for structural modification of NOS, which may pave the way for producing nosiheptide derivatives as a potential antibiotic for application in clinical treatment.


Assuntos
Antibacterianos , Glicosiltransferases , Animais , Camundongos , Glicosiltransferases/genética , Glicosiltransferases/metabolismo , Sequência de Aminoácidos , Antibacterianos/metabolismo , Piridinas
11.
Inorg Chem ; 62(5): 1781-1785, 2023 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-35608919

RESUMO

Two Keggin Fe13-oxo clusters, [Pr12Fe33(NO3)6(L-van)4(D-van)5(TEOA)12(µ3-OH)12(µ4-OH)12(µ4-O)28(H2O)4]·(ClO4)3·(NO3)·10H2O (1) and [Dy12Fe33(NO3)2(L-van)3(D-van)3(TEOA)12(µ3-OH)18(µ4-OH)6(µ4-O)28(H2O)9]·(ClO4)5·(NO3)6·15H2O (2), where L-van = l-valine, D-van = d-valine, and TEOA = triethanolamine, were prepared by using Ln3+ as a stabilizer. Cluster 1 crystallizes in a chiral space group of C2, while cluster 2 crystallizes in a centrosymmetric space group of Pnma. Dynamic magnetic measurements of 2 under a zero direct-current field reveal that 2 exhibits single-molecule-magnet characteristics with an energy barrier of 18.79 K. Significantly, the formation of the chiral cluster 1 is closely related to the larger radius of the Pr3+ ion.

12.
Sensors (Basel) ; 22(18)2022 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-36146103

RESUMO

Falls have been recognized as the major cause of accidental death and injury in people aged 65 and above. The timely prediction of fall risks can help identify older adults prone to falls and implement preventive interventions. Recent advancements in wearable sensor-based technologies and big data analysis have spurred the development of accurate, affordable, and easy-to-use approaches to fall risk assessment. The objective of this study was to systematically assess the current state of wearable sensor-based technologies for fall risk assessment among community-dwelling older adults. Twenty-five of 614 identified research articles were included in this review. A comprehensive comparison was conducted to evaluate these approaches from several perspectives. In general, these approaches provide an accurate and effective surrogate for fall risk assessment. The accuracy of fall risk prediction can be influenced by various factors such as sensor location, sensor type, features utilized, and data processing and modeling techniques. Features constructed from the raw signals are essential for predictive model development. However, more investigations are needed to identify distinct, clinically interpretable features and develop a general framework for fall risk assessment based on the integration of sensor technologies and data modeling.


Assuntos
Vida Independente , Dispositivos Eletrônicos Vestíveis , Idoso , Humanos , Medição de Risco/métodos
13.
Chemosphere ; 280: 130756, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33971405

RESUMO

In this study, the strengthening effect of bio-carrier inoculation in the process of aerobic granulation and its influence on the microbial secretion of extracellular polymeric substances (EPS) has been systematically explored, to further understand and perfect the rapid granulation mechanism. Complete granulation was achieved within 15 days, and the granule morphology realized in a reactor inoculated with the bio-carrier (R1) was better than that in the control group (R2), in which complete granulation was not achieved during the entire operation period. However, AGS gradually disintegrated after the 20th day because of the strong shearing force, the crushed AGS enhanced granulation, however did not ensure stability. The average EPS content in R1 20 mg﹒gVSS-1 higher than that in R2, and the protein (PN) content changes around 41.23-82.56 mg﹒gVSS-1 during the granulation process. This indicates that the bio-carrier stimulates microorganisms to secrete more EPS, and PN may have a greater effect on the aggregation of microorganisms. The results showed that the addition of the bio-carrier shortened the AGS granulation time, and increased the EPS content, and the broken AGS played an auxiliary role as the nucleus for floc attachment.


Assuntos
Matriz Extracelular de Substâncias Poliméricas , Esgotos , Aerobiose , Reatores Biológicos , Eliminação de Resíduos Líquidos
14.
Inorg Chem ; 60(10): 6981-6985, 2021 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-33913721

RESUMO

Four pairs of chiral 3D coordination polymers (CPs), [Zn2(BDC)(lac)(DMF)]·guest (2) (H2BDC = benzene dicarboxylic acid; H2lac = lactic acid; guest = 1.5DMF + i-PrOH), [Co2(BDC)(lac)(DMF)]·guest (3) (guest = DMF + 2H2O), [Fe4(BDC)3(lac)2(DMF)2](CO3)·guest (4) (guest = DMF + 2H2O), and {Zn11(BPDC)6(lac)6[NH2(CH3)2]2}·guest (H2BPDC = 3,3'-biphenyldicarboxylic acid; guest = 6DMF + 18H2O) (5), are prepared through the reactions of racemic lactic acid (rac-H2lac) with different metal ions and auxiliary ligands. Structural analyses and DFT calculations reveal that forming more and stronger coordination bonds between the auxiliary ligand and metal ions is more conducive to the spontaneous resolution of enantiomers in 3D CPs than simply increasing the entropy of the auxiliary ligand itself.

15.
Chemistry ; 26(52): 11985-11988, 2020 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-32614459

RESUMO

The formation mechanism of ferrihydrite is the key to understand its treatment of pollutants in waste water and purification of surface water and groundwater. Although emerging evidence suggests that formation of the ferrihydrite occurs through the aggregation of prenucleation clusters, rather than classical atom-by-atom growth, its formation mechanism remains unclear. Herein, an iron-oxo anionic cluster of [Fe22 (µ4 -O)8 (µ3 -OH)20 (µ2 -OH)18 (CH3 COO)16 (H2 O)2 ]4- viewed as a dimer of bivacant ß-Keggin-Fe13 clusters was for the first time obtained by using lanthanide ions as stabilizers. Upon dissolution in a mixed solution of isopropanol and water, the lacunary ß-Keggin-Fe13 cluster can transform into an α-Keggin-Fe13 cluster, distinctly demonstrating that the Keggin-Fe13 cluster rotational isomerization can be realized through the vacant Keggin-Fe13 cluster.

16.
Demography ; 57(3): 1035-1062, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32572789

RESUMO

Children with many siblings have lower average educational attainment compared with children raised in smaller families, and this disadvantage by sibship size has been observed across many countries. We still know remarkably little, however, about how sibship size disadvantage has changed within countries and how such trends vary across countries. Using comparative data from 111 surveys from 26 low-fertility countries, we find an overall trend of growing sibship size disadvantage across cohorts in the majority of countries: between the 1931-1940 birth cohort and the 1971-1980 birth cohort, 16 of 26 countries showed a statistically significant increase in sibship size disadvantage in education, while only two countries showed a significant reduction in sibship size disadvantage. The disadvantage in years of education associated with having an additional sibling increased remarkably in post-socialist (0.3) and East Asian countries (0.34) and, to a lesser extent, Western European countries (0.2). In contrast, this disadvantage showed little change in Nordic countries (0.05) and even decreased in Anglo-Saxon countries (-0.11). We discuss explanations and implications of our comparative evidence in the context of the intergenerational transmission of education.


Assuntos
Sucesso Acadêmico , Coeficiente de Natalidade/tendências , Características da Família , Irmãos , Capitalismo , Humanos , Seguridade Social/estatística & dados numéricos , Fatores Socioeconômicos
17.
Crit Rev Eukaryot Gene Expr ; 29(1): 37-45, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31002593

RESUMO

Toll-like receptors (TLRs) are a family of highly conserved pattern recognition receptors that can recognize both pathogen-associated molecular patterns and danger-associated molecular patterns. These receptors are important in the activation of the innate immune system and play a role in shaping the adaptive immune system. For years, the expression of TLRs in the brain has been proposed to contribute to the immunological protection of the central nervous system. However, emerging studies have provided increasing evidence of non-immune functions of TLRs and suggest that these receptors may participate in more complex processes that extend beyond the regulation of the innate immune response. In this review, we highlight the expression of TLRs in non-immune cells and epitomize TLR non-immune functions. We aim to reveal the novel roles of TLRs that are distinct from their traditional functions in immunity. Negative regulatory approaches used to study TLR signaling pathways are also discussed, providing potential directions for further studies.


Assuntos
Receptores Toll-Like/metabolismo , Animais , Diferenciação Celular , Proliferação de Células , Reparo do DNA , Humanos , Transdução de Sinais
18.
Brain Res ; 1690: 96-104, 2018 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-29551652

RESUMO

To investigate the neuroprotective effect of edaravone was dependent on 5-lipoxygenase (5-LOX) signalling pathway or not. Middle cerebral artery occlusion (MCAO) and oxygen glucose deprivation (OGD) were established in SD rats and PC12 cells to mimic ischemic injury. In vivo, edaravone can significantly reduce neurological deficit scores, infarct volume, ROS level and expression of 5-LOX. For in vitro experiment, reduced viability, cell death which occurred via necrosis and apoptosis were shown after OGD and even severer in OGD-reperfusion (OGD-R). Interestingly, edaravone (0.01, 0.1, 1 µmol/L) and caffeic acid (5-LOX inhibitor) can dramatically attenuate OGD/OGD-R injuries. Profoundly, mitochondrial transmembrane potential was ameliorated and cristae membranes (detected by electron microscope) were swollen in OGD/OGD-R cells; however, edaravone preserved the normal ultrastructure of mitochondria and reduced ROS. Astonishingly, immunohistochemistry analyses showed that 5-LOX was first located in the cytosol, dendrites and nuclei of control cells and then translocated to the nuclear membrane after OGD/OGD-R, which indicated the activation of 5-LOX pathway. Edaravone and caffeic acid can inhibit 5-LOX translocation to the nuclear membrane after OGD/OGD-R and reduce cysteinyl leukotrienes (CysLTs), which are metabolites of 5-LOX. Our results are the first to indicate that the protective action of edaravone may function, at least in part, by inhibiting 5-LOX activation, maintaining the ultrastructure and integrated function of mitochondria, thus protecting neuronal cells from ischemia. Furthermore, the instability of mitochondria may be another critical factor in 5-LOX activation.


Assuntos
Isquemia Encefálica/tratamento farmacológico , Edaravone/farmacologia , Sequestradores de Radicais Livres/farmacologia , Mitocôndrias/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Fármacos Neuroprotetores/farmacologia , Animais , Araquidonato 5-Lipoxigenase/metabolismo , Ácido Araquidônico/metabolismo , Isquemia Encefálica/metabolismo , Isquemia Encefálica/patologia , Ácidos Cafeicos/farmacologia , Morte Celular/efeitos dos fármacos , Morte Celular/fisiologia , Hipóxia Celular/efeitos dos fármacos , Hipóxia Celular/fisiologia , Relação Dose-Resposta a Droga , Glucose/deficiência , Masculino , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Neurônios/metabolismo , Neurônios/patologia , Células PC12 , Ratos , Traumatismo por Reperfusão/tratamento farmacológico , Traumatismo por Reperfusão/metabolismo , Traumatismo por Reperfusão/patologia , Transdução de Sinais/efeitos dos fármacos
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