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1.
Brief Bioinform ; 25(1)2023 11 22.
Artigo em Inglês | MEDLINE | ID: mdl-38197310

RESUMO

Network pharmacology (NP) provides a new methodological perspective for understanding traditional medicine from a holistic perspective, giving rise to frontiers such as traditional Chinese medicine network pharmacology (TCM-NP). With the development of artificial intelligence (AI) technology, it is key for NP to develop network-based AI methods to reveal the treatment mechanism of complex diseases from massive omics data. In this review, focusing on the TCM-NP, we summarize involved AI methods into three categories: network relationship mining, network target positioning and network target navigating, and present the typical application of TCM-NP in uncovering biological basis and clinical value of Cold/Hot syndromes. Collectively, our review provides researchers with an innovative overview of the methodological progress of NP and its application in TCM from the AI perspective.


Assuntos
Inteligência Artificial , Medicina Tradicional Chinesa , Humanos , Farmacologia em Rede , Pesquisadores
2.
Nano Lett ; 24(28): 8702-8708, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-38953472

RESUMO

Quasi-2D perovskites based blue light-emitting diodes (LEDs) suffer from its poor electroluminescence performance, mainly caused by the nonradiative recombination in in defect-rich low-n phases and the unbalanced hole-electron injection in the device. Here, we developed a highly efficient quasi-2D perovskite based sky-blue LEDs behaving recorded external quantum efficiency (EQE) of 21.07% by employing carbon dots (CDs) as additives in the hole transport layer (HTL). We ascribe the high EQE to the effective engineering of CDs: (1) The CDs at the interface of HTLs can suppress the formation of low-efficient n = 1 phase, resulting a high luminescence quantum yield and energy transfer efficiency of the mixed n-phase quasi-2D perovskites. (2) The CDs additives can reduce the conductivity of HTL, partially blocking the hole injection, and thus making more balanced hole-electron injection. The CDs-treated devices have excellent Spectral stability and enhanced operational stability and could be a new alternative additive in the perovskite optoelectronic devices.

3.
Nano Lett ; 24(9): 2904-2911, 2024 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-38385631

RESUMO

Carbon dots (CDs) are promising luminescent emission layer materials for next generation electroluminescent light emitting diodes (EL-LEDs) due to their many advantages, such as environmental friendliness, low cost, and high stability. However, limited by the spin-forbidden properties of the triplet transition, it is difficult to improve the external quantum efficiency (EQE) of fluorescent CDs-based EL-LEDs. Meanwhile, traditional thermally activated delayed fluorescent (TADF) CDs prepared using coating strategies are difficult to utilize in EL-LEDs due to the nonconductivity of the coating agent. Herein, we successfully developed matrix-free TADF CDs with yellow emission and achieved a device EQE of 5.68%, which is the highest value reported in CDs-based EL-LEDs. In addition, we also developed white EL-LEDs with an EQE of 1.70%. This study highlights the importance of interactions between precursors in modulating the electroluminescence properties of TADF emitters and provides an effective design principle for matrix-free TADF CDs.

4.
J Sep Sci ; 47(1): e2300664, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38010472

RESUMO

Chicory, renowned for its multifaceted benefits, houses two vital coumarins, esculetin and esculin, both instrumental in reducing uric acid. This study emphasizes the metabolic pathways of esculetin and esculin under both standard and hyperuricemia conditions. Hyperuricemia was induced in Sprague-Dawley rats using oxonic acid potassium salt (300 mg·kg-1 ) and a 10% fructose water regimen over 21 days. Leveraging the ultra-high-performance liquid chromatography-Q Exactive hybrid quadrupole-orbitrap high resolution mass spectrometry, we analyzed the fragmentation behaviors of esculetin and esculin in rat bio-samples. Post oral-intake of esculetin or esculin, a notable dip in serum uric acid levels was observed in hyperuricemia rats. The investigation unveiled 24 esculetin metabolites and 14 for esculin. The metabolic pathways of both compounds were hydrolysis, hydroxylation, hydrogenation, dehydroxylation, glucuronidation, sulfation, and methylation. Interestingly, certain metabolites presented variations between standard and hyperuricemia rats, indicating that elevated levels of uric acid may affect enzyme activity linked to these metabolic reactions. This is the first systematic study on comparison of metabolic profiles of esculetin and esculin in both normal and hyperuricemia states, which was helpful to enrich our understanding of the complicated structure-activity relationships between esculin and esculetin and shed light to their action mechanism.


Assuntos
Cichorium intybus , Hiperuricemia , Umbeliferonas , Ratos , Animais , Esculina/análise , Esculina/química , Esculina/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Ratos Sprague-Dawley , Ácido Úrico , Espectrometria de Massas/métodos
5.
Nano Lett ; 23(18): 8794-8800, 2023 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-37487142

RESUMO

Carbon dots (CDs) are promising nanomaterials for next-generation lighting and displays due to their tunable bandgap, high photoluminescence quantum yield (PLQY), and high stability. However, the exciton utilization efficiency (EUE) of CD-based films can only reach 25%, fundamentally limiting their application in electroluminescent light-emitting diodes (LEDs). Improving the EUE is therefore of great significance. Herein, we developed composite films containing CDs and poly(9-vinylcarbazole) (PVK). The films were then used to construct a series of high-performance electroluminescent LEDs with tunable emission colors covering the blue to green regions as the concentration of CDs in the films increased, delivering a maximum external quantum efficiency and current efficiency of 2.62% and 5.11 cd/A, respectively. Theoretical calculations and experiments established that the excellent performance at low film PLQY was due to a hot exciton effect in the CDs, achieving nearly 100% EUE. This work provides new design strategies toward high-performance CD-based electroluminescent LEDs.

6.
Plant Cell Rep ; 43(1): 23, 2023 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-38150101

RESUMO

KEY MESSAGE: Imbalanced chromosomes and cell cycle arrest, along with down-regulated genes in DNA damage repair and sperm cell differentiation, caused pollen abortion in synthetic allodiploid Brassica juncea hybrids. Interspecific hybridization is considered to be a major pathway for species formation and evolution in angiosperms, but the occurrence of pollen abortion in the hybrids is common, prompting us to recheck male gamete development in allodiploid hybrids after the initial combination of different genomes. Here, we investigated the several key meiotic and mitotic events during pollen development using the newly synthesised allodiploid B. juncea hybrids (AB, 2n = 2× = 18) as a model system. Our results demonstrated the partial synapsis and pairing of non-homologous chromosomes concurrent with chaotic spindle assembly, affected chromosome assortment and distribution during meiosis, which finally caused difference in genetic constitution amongst the final tetrads. The mitotic cell cycle arrest during microspore development resulted in the production of anucleate pollen cells. Transcription analysis showed that sets of key genes regulating cyclin (CYCA1;2 and CYCA2;3), DNA damage repair (DMC1, NBS1 and MMD1), and ubiquitin-proteasome pathway (SINAT4 and UBC) were largely downregulated at the early pollen meiosis stages, and those genes involved in sperm cell differentiation (DUO1, PIRL1, PIRL9 and LBD27) and pollen wall synthesis (PME48, VGDH11 and COBL10) were mostly repressed at the late pollen mitosis stages in the synthetic allodiploid B. juncea hybrids (AB). In conclusion, this study elucidated the related mechanisms affecting pollen fertility during male gametophyte development at the cytological and transcriptomic levels in the synthetic allodiploid B. juncea hybrids.


Assuntos
Mostardeira , Sementes , Feminino , Gravidez , Humanos , Mostardeira/genética , Fertilidade/genética , Perfilação da Expressão Gênica , Transcriptoma/genética
7.
BMC Med Educ ; 23(1): 881, 2023 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-37978369

RESUMO

BACKGROUND: Flipped classroom, blended with online and offline learning, was regarded as an effective learning approach in pharmacy education. This meta-analysis was to comprehensively compare the effectiveness of flipped classroom and traditional lecture-based approaches, attempting to generate a unified and firm conclusion of the effectiveness of flipped classroom in pharmacy education. METHODS: Data were collected from 7 databases, involving Cochrane Library, PubMed, Embase, ScienceDirect, Web of Science, China National Knowledge Infrastructure (CNKI), and Chinese Biomedical Literature Service System (SinoMed). The studies were included if they included objective evaluation of students' performance between groups of flipped classroom and traditional approaches. The standardized mean difference (SMD) with a corresponding 95% confidence interval (95% CI) was used as the outcomes for data pooling. RESULTS: A total of 22 studies (28 comparing groups) with 4379 participants were included in the meta-analysis. The risk of bias was relatively high. Results of the analysis revealed that flipped classroom presented significant advantages over traditional approaches in student performance improvement, with no evidence of publication bias. Through subgroup analysis, it showed better outcomes for flipped classrooms over traditional lectures for the other subgroups, including different performance, degree programs. CONCLUSIONS: Current evidence reveals that the flipped classroom approach in pharmacy education yields a statistical improvement in student learning compared with traditional methods. In the future, instructors should introduce more online technology into classroom and construct an interactive learning environment.


Assuntos
Educação em Farmácia , Treinamento por Simulação , Humanos , Aprendizagem , Avaliação Educacional , Estudantes , Educação em Farmácia/métodos , Aprendizagem Baseada em Problemas/métodos , Currículo
8.
Sensors (Basel) ; 23(8)2023 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-37112204

RESUMO

It is important to obtain information on an instantaneous target. A high-speed camera can capture a picture of an immediate scene, but spectral information about the object cannot be retrieved. Spectrographic analysis is a key tool for identifying chemicals. Detecting dangerous gas quickly can help ensure personal safety. In this paper, a temporally and spatially modulated long-wave infrared (LWIR)-imaging Fourier transform spectrometer was used to realize hyperspectral imaging. The spectral range was 700~1450 cm-1 (7~14.5 µm). The frame rate of infrared imaging was 200 Hz. The muzzle-flash area of guns with calibers of 5.56 mm, 7.62 mm, and 14.5 mm were detected. LWIR images of muzzle flash were obtained. Spectral information on muzzle flash was obtained using instantaneous interferograms. The main peak of the spectrum of the muzzle flash appeared at 970 cm-1 (10.31 µm). Two secondary peaks near 930 cm-1 (10.75 µm) and 1030 cm-1 (9.71 µm) were observed. Radiance and brightness temperature were also measured. The spatiotemporal modulation of the LWIR-imaging Fourier transform spectrometer provides a new method for rapid spectral detection. The high-speed identification of hazardous gas leakage can ensure personal safety.

9.
Int J Mol Sci ; 24(2)2023 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-36674804

RESUMO

The nuclear receptors-liver X receptors (LXR α and ß) are potential therapeutic targets in cardiovascular and neurodegenerative diseases because of their key role in the regulation of lipid homeostasis and inflammatory processes. Specific oxy(phyto)sterols differentially modulate the transcriptional activity of LXRs providing opportunities to develop compounds with improved therapeutic characteristics. We isolated oxyphytosterols from Sargassum fusiforme and synthesized sidechain oxidized sterol derivatives. Five 24-oxidized sterols demonstrated a high potency for LXRα/ß activation in luciferase reporter assays and induction of LXR-target genes APOE, ABCA1 and ABCG1 involved in cellular cholesterol turnover in cultured cells: methyl 3ß-hydroxychol-5-en-24-oate (S1), methyl (3ß)-3-aldehydeoxychol-5-en-24-oate (S2), 24-ketocholesterol (S6), (3ß,22E)-3-hydroxycholesta-5,22-dien-24-one (N10) and fucosterol-24,28 epoxide (N12). These compounds induced SREBF1 but not SREBP1c-mediated lipogenic genes such as SCD1, ACACA and FASN in HepG2 cells or astrocytoma cells. Moreover, S2 and S6 enhanced cholesterol efflux from HepG2 cells. All five oxysterols induced production of the endogenous LXR agonists 24(S)-hydroxycholesterol by upregulating the CYP46A1, encoding the enzyme converting cholesterol into 24(S)-hydroxycholesterol; S1 and S6 may also act via the upregulation of desmosterol production. Thus, we identified five novel LXR-activating 24-oxidized sterols with a potential for therapeutic applications in neurodegenerative and cardiovascular diseases.


Assuntos
Doenças Neurodegenerativas , Fitosteróis , Humanos , Receptores X do Fígado , Esteróis/farmacologia , Receptores Nucleares Órfãos/genética , Hidroxicolesteróis , Doenças Neurodegenerativas/tratamento farmacológico , Colesterol
10.
Zhongguo Zhong Yao Za Zhi ; 48(22): 5965-5976, 2023 Nov.
Artigo em Zh | MEDLINE | ID: mdl-38114202

RESUMO

Network targets theory and technology have transcended the limitations of the "single gene, single target" model, aiming to decipher the mechanisms of traditional Chinese medicine(TCM) based on biological network from the perspective of informatics and system. As the core of TCM network pharmacology, with the development of computer science and high-throughput experimental techniques, the network target theory and technology are beginning to exhibit a trend of organic integration with artificial intelligence technology and high-throughput multi-modal multi-omics experimental techniques. Taking the network target analysis of TCM like Yinqiao Qingre Tablets as a typical case, network target theory and technology have achieved the systematic construction, in-depth analysis, and high-throughput multi-modal multi-omics validation of multi-level biological networks spanning from traditional Chinese and Western phenotypes to tissues, cells, molecules, and traditional Chinese and Western medicines. This development helps to address critical issues in the analysis of mechanisms of TCM, including the discovery of key targets, identification of functional components, discovery of synergistic effects among compound ingredients, and elucidation of the regulatory mechanisms of formulae. It provides powerful theoretical and technological support for advancing clinical precision diagnosis and treatment, precise positioning of TCM, and precise research and development of TCM. Thus, a new paradigm of TCM research gradually emerges, combining big data and artificial intelligence(AI) with the integration of human experience and scientific evidence.


Assuntos
Medicamentos de Ervas Chinesas , Medicina Tradicional Chinesa , Humanos , Inteligência Artificial , Medicamentos de Ervas Chinesas/farmacologia , Tecnologia , Projetos de Pesquisa
11.
Angew Chem Int Ed Engl ; 61(33): e202207817, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35731186

RESUMO

This work reports the successful preparation of a new type of crystalline luminescent organic nanodot (<3.5 nm) by kinetically trapped self-assembly, which is then used as a simplified π-packing model to simulate the structure of CDs. The precise structure and J-aggregation-induced photoluminescence (PL) of the nanodots are revealed by investigating the structural relationship between the nanodots and the corresponding single crystals and their properties. Compared with the single crystals, crystalline organic nanodots show longer PL lifetime, higher PL quantum yield, and narrower PL peak, indicating that they are potential organic quantum nanodots. In addition, the efficient π-stacking environment in the corresponding single crystals can promote π-aggregation-induced PL anisotropy. This work indicates crystalline organic nanodots with precise structures to be potentially useful for understanding the structures of CDs and to be attractive potential luminescent materials.

12.
Mar Drugs ; 19(9)2021 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-34564147

RESUMO

Dysregulation of cholesterol homeostasis is a major risk factor of atherosclerosis, which can lead to serious health problems, including heart attack and stroke. Liver X receptor (LXR) α and ß are transcription factors belonging to the nuclear receptor superfamily, which play important roles in cholesterol homeostasis. Selectively activating LXRß provides a promising strategy for the treatment of atherosclerosis. Here, we employed atherosclerotic apoE-knockout mice to evaluate the effects of saringosterol, a phytosterol with potent and selective action for LXRß, which we identified previously in edible marine seaweed Sargassum fusiforme. We found that saringosterol treatment reduced the atherosclerotic plaque burden without having undesirable adverse hepatic effects in apoE-deficient mice fed an atherogenic diet. Meanwhile, reduced serum levels of cholesterol, accompanied by altered expression of LXR-regulated genes involved in cholesterol absorption, transport, efflux, excretion, and elimination, were observed in apoE-knockout mice after saringosterol treatment. Together, our study not only establishes saringosterol as an effective cholesterol-lowering and anti-atherogenic phytosterol but also provides insights into the underlying mechanism.


Assuntos
Aterosclerose/tratamento farmacológico , Colesterol/metabolismo , Hipolipemiantes/uso terapêutico , Sargassum , Estigmasterol/análogos & derivados , Animais , Aterosclerose/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Dieta Hiperlipídica , Hipolipemiantes/farmacologia , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Proteínas de Membrana Transportadoras/genética , Camundongos Knockout para ApoE , Estigmasterol/farmacologia , Estigmasterol/uso terapêutico
13.
Angew Chem Int Ed Engl ; 60(48): 25514-25521, 2021 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-34549866

RESUMO

Miniaturized solid-state lasers with a single longitudinal mode are vital for various photonic applications. Here we prepare red-emissive carbon dots (CDs) with a photoluminescence quantum yield (PLQY) of 65.5 % by combining graphitic nitrogen doping and surface modification. High-concentration doping alters the CDs' emission from blue to red, while the electron-donating groups and polymer coating on their surfaces improve the PLQY and photostability. The CDs exhibit excellent stimulated emission characteristics, with a low threshold of amplified spontaneous emission (ASE) and long gain lifetime. A planar microcavity with only one resonant mode, which fitted with the CDs' ASE peak, was constructed. Combining the CDs and microcavity produced a solid-state laser with a single longitudinal mode, a linewidth of 0.14 nm and a signal-to-noise ratio of 14.8 dB (Q∼4600). Our results will aid the development of colorful solid-state micro/nano lasers with potential use in practical photonics.

14.
J Environ Sci (China) ; 88: 90-102, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31862083

RESUMO

Sulfide-modified nanoscale zero-valent iron (S-nZVI) is a promising material for removal of organic pollutants from water, but S-nZVI nanoparticles (NPs) easily agglomerate and have poor contact with organic contaminants. Herein, we propose a new S-nZVI/graphene aerogel (S-nZVI/GA) composite which exhibits superior removal capability for trichloroethylene (TCE) from water. Three-dimensional porous graphene aerogel (GA) can improve the efficiency of electron transport, enhance the adsorption of organic pollutants and restrain the agglomeration of the core-shell S-nZVI NPs. The TCE removal rates of FeS, nZVI, GA and S-nZVI were 27.8%, 42%, 63% and 75% in 2 hr, respectively. Furthermore, TCE was completely removed within 50 min by S-nZVI/GA. The TCE removal rate increased with increasing pH and temperature, and TCE removal followed the pseudo-first-order kinetic model. The results demonstrate the great potential of S-nZVI/GA composite as a low-cost, easily separated and superior monolithic adsorbent for removal of organic pollutants.


Assuntos
Grafite , Água Subterrânea , Tricloroetileno , Poluentes Químicos da Água , Purificação da Água/métodos , Adsorção , Ferro , Sulfetos , Água
15.
Zhongguo Zhong Yao Za Zhi ; 45(2): 367-373, 2020 Jan.
Artigo em Zh | MEDLINE | ID: mdl-32237320

RESUMO

To identify and verify the active ingredients from Astragalus membranaceus on hypertensive cardiac remodeling based on network pharmacology and heart RNA-sequencing data. The monomers of A. membranaceus and their intervention target database were established by using network pharmacology. The genes associated to cardiac remodeling were then screened by analyzing cardiac RNA-sequencing data. An overlap between genes related to cardiac remodeling and targets of ingredients form A. membranaceus was collected to obtain monomers with protective effect on hypertensive cardiac remodeling. Angiotensin Ⅱ(AngⅡ)-induced mouse cardiac remodeling model was used to validate the protective effect of active ingredients from A. membranaceus on hypertensive cardiac remodeling. Finally, a total of 81 monomers and 1 197 targets were enrolled in our database. Mouse RNA-sequencing data showed that 983 genes were significantly up-regulated and 465 genes were down-regulation in myocardial tissues of the cardiac remodeling mice as compared with blank group mice, respectively. Ninety-two genes were found via overlapping between genes related to cardiac remodeling and targets, involving 59 monomers from A. membranaceus. Further research found that vanillic acid(VA) could intervene 27 genes associated with hypertensive cardiac remodeling, ranking top 1. Meanwhile, VA could significantly inhibit AngⅡ-induced increase in ratio of heart weight to body weight and heart weight to tibial length, ANP and BNP mRNA levels in myocardial tissues, myocardial tissue damage, cardiac fibrosis level and cardiac hypertrophy level in vivo. Those results showed that network pharmacology screen-based VA has protective effect on AngⅡ-induced cardiac remodeling.


Assuntos
Astragalus propinquus/química , Hipertensão/genética , Ácido Vanílico/farmacologia , Remodelação Ventricular/efeitos dos fármacos , Angiotensina II , Animais , Coração , Camundongos , Substâncias Protetoras/farmacologia , Remodelação Ventricular/genética
16.
Opt Lett ; 44(14): 3490-3493, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31305555

RESUMO

We demonstrate all-optical carrier recovery exploring optical parametric amplification (OPA) in a monolithic high-finesse silicon nitride microring cavity. Compared to a nonresonant OPA process in nonlinear waveguides, cavity-based OPA allows a much narrower gain bandwidth by manipulating the intracavity light interactions with a controllable parametric gain, thus facilitating high-resolution carrier extraction without needing a large guard band between the carrier tone and data spectrum. Here, we achieve narrowband OPA with a 22.0 dB peak gain and a bandwidth as low as 15.2 MHz in a 100 µm radius microring cavity, which is applied to implement carrier recovery of a 16QAM optical orthogonal-frequency-division-multiplexing data signal. A highly coherent phase is conserved between the recovered carrier tone and the original data, enabling self-homodyne detection with high data quality and minimized electrical compensation. Our study holds potential to constitute energy-friendly coherent receivers.

17.
Opt Lett ; 43(21): 5359-5362, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30383007

RESUMO

We propose and experimentally demonstrate a broadband chaos generation scheme by introducing self-phase modulation (SPM) in the feedback loop of an external-cavity semiconductor laser and propagating the chaos through a microsphere resonator (MR). Four chaos generation cases-conventional optical feedback (COF), COF+MR, individual SPM optical feedback (SPMOF), and the proposed SPMOF+MR-are experimentally discussed. The experimental results demonstrate that with respect to the other three cases, in the proposed scheme with the joint effects of SPMOF and MR, the relaxation oscillation effect in chaos can be eliminated and a flat RF spectrum with much more significant bandwidth enhancement can be achieved. Simultaneously, the time delay signature (TDS) in the chaos can be perfectly suppressed at a very low level close to 0 in a wide operation range of feedback. This work shows a novel scheme to generate broadband chaos with flat spectrum and perfect TDS suppression.

18.
Chemistry ; 22(42): 15075-15084, 2016 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-27601275

RESUMO

The threading of biomolecules through pores or channels in membranes is important to validate the physiological activities of cells. To aid understanding of the controlling factors required for the translocation in space with confined size and distorted conformation, it is desirable to identify experimental systems with minimized complexity. We demonstrate the mechanism of a linear guest L1 threading into a tris(crown ether) host TC with a combinational distorted cavity to form a triply interlocked [2]pseudorotaxane 3in-[L1⊂TC]. An inchworm-motion mechanism is proposed for the process. For the forward-threading steps that lead to the formation of higher-order interlocked species, guest L1 must adopt a bent conformation to find the next crown ether cavity. Two simplified models are applied to investigate the self-assembly dynamic of 3in-[L1⊂TC]. Kinetic NMR spectroscopic and molecular dynamics (MD) studies show that formation of the singly penetrated species is fast, whereas formation of the doubly and triply threaded species is several orders of magnitude slower. During threading the freedom of both the guest L1 and host TC gradually decrease due to their interactions. This results in a significant entropy effect for the threading dynamic, which is also observed for the threading of a biomolecular chain through a channel.

19.
Neurobiol Dis ; 82: 580-592, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26303888

RESUMO

Ischemic strokes cause excessive release of glutamate, leading to overactivation of N-methyl-d-aspartate receptors (NMDARs) and excitotoxicity-induced neuronal death. For this reason, inhibition of NMDARs has been a central focus in identifying mechanisms to avert this extensive neuronal damage. N-acetyl-aspartyl-glutamate (NAAG), the most abundant neuropeptide in the brain, is neuroprotective in ischemic conditions in vivo. Despite this evidence, the exact mechanism underlying its neuroprotection, and more specifically its effect on NMDARs, is currently unknown due to conflicting results in the literature. Here, we uncover a pH-dependent subunit-specific action of NAAG on NMDARs. Using whole-cell electrophysiological recordings on acute hippocampal slices from adult mice and on HEK293 cells, we found that NAAG increases synaptic GluN2A-containing NMDAR EPSCs, while effectively decreasing extrasynaptic GluN2B-containing NMDAR EPSCs in physiological pH. Intriguingly, the results of our study further show that in low pH, which is a physiological occurrence during ischemia, NAAG depresses GluN2A-containing NMDAR EPSCs and amplifies its inhibitory effect on GluN2B-containing NMDAR EPSCs, as well as upregulates the surface expression of the GluN2A subunit. Altogether, our data demonstrate that NAAG has differential effects on NMDAR function based on subunit composition and pH. These findings suggest that the role of NAAG as a neuroprotective agent during an ischemic stroke is likely mediated by its ability to reduce NMDAR excitation. The inhibitory effect of NAAG on NMDARs and its enhanced function in acidic conditions make NAAG a prime therapeutic agent for the treatment of ischemic events.


Assuntos
Região CA1 Hipocampal/fisiologia , Dipeptídeos/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Sinapses/fisiologia , Animais , Região CA1 Hipocampal/efeitos dos fármacos , Dipeptídeos/administração & dosagem , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Células HEK293 , Humanos , Concentração de Íons de Hidrogênio , Camundongos , Técnicas de Patch-Clamp , Prótons , Sinapses/efeitos dos fármacos , Técnicas de Cultura de Tecidos
20.
J Chem Phys ; 140(10): 104702, 2014 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-24628191

RESUMO

By combining molecule dynamics (MD) simulation and quantum chemistry computation, we calculate the surface sum-frequency vibrational spectroscopy (SFVS) of R-limonene molecules at the gas-liquid interface for SSP, PPP, and SPS polarization combinations. The distributions of the Euler angles are obtained using MD simulation, the ψ-distribution is between isotropic and Gaussian. Instead of the MD distributions, different analytical distributions such as the δ-function, Gaussian and isotropic distributions are applied to simulate surface SFVS. We find that different distributions significantly affect the absolute SFVS intensity and also influence on relative SFVS intensity, and the δ-function distribution should be used with caution when the orientation distribution is broad. Furthermore, the reason that the SPS signal is weak in reflected arrangement is discussed.


Assuntos
Cicloexenos/química , Simulação de Dinâmica Molecular , Análise Espectral , Terpenos/química , Algoritmos , Gases/química , Limoneno , Propriedades de Superfície , Vibração
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