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1.
J Affect Disord ; 260: 84-90, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31493644

RESUMO

BACKGROUND: Previous studies have investigated the role of cognitive factors in the relationship between stressful life events and depression; however, few studies comprehensively considered cognitive and personality factors. Therefore, this study investigated the multiple mediating roles of fatalism and core self-evaluations in the relationship between stressful life events and depression. METHODS: A cross-sectional survey was conducted with 537 Chinese university students (Mage = 20.20, SD = 1.38) at two universities in Guizhou and Sichuan provinces. The independent variable was stressful life events; mediating variables were fatalism and core self-evaluations; and the dependent variable was extent of depression. Multiple mediation analysis was performed using the PROCESS macro in SPSS. RESULTS: Significant positive correlations were found among stressful life events, fatalism, and depression, while core self-evaluations were significantly negatively correlated with stressful life events, fatalism, and depression. After adjusting for demographic variables, stressful life events directly and positively influenced depression (ß = 0.370, 95% CI = 0.292-0.448). Fatalism and core self-evaluations played multiple mediating roles in the relationship between stressful life events and depression, with stressful life events influencing depression through three mediation pathways (total mediation effect = 0.199, 95% CI = 0.145-0.254), which accounted for 53.85% of the total effect. LIMITATIONS: The data used in this study were self-reported by university students and measureed via cross-sectional designs. CONCLUSIONS: Stressful life events can influence depression either directly or indirectly by simultaneously increasing fatalism and lowering core self-evaluations (parallel mediation) or decreasing core self-evaluations through increasing the level of fatalism (serial mediation).

2.
Anal Biochem ; 588: 113474, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31614116

RESUMO

With Escherichia coli alkaline phosphatase (ECAP) as the tag fused to the N-terminus of Pseudomonas Aeruginosa arylsulfatase (PAAS) and its mutants via a flexible linker, the comparison of the activity ratios of an applicable enzyme and its mutants to a suitable enzyme tag in cell lysates of their fused forms was tested for high-throughput (HTP) screening of mutants. After both the induced expression of a fused form and alkaline lysis of the transformed cells in microplate wells, HTP assay of the activities of ECAP and PAAS/mutant was realized via spectrophotometric-dual-enzyme-simultaneous-assay to derive their activity ratio. The successful induced expression of fused forms required ECAP activities higher than 5.3 U/L in cell lysates. Of three representative fused PAAS/mutants in cell lysates, there were similar proteolytic fragments and the comparison of their activity ratios greatly enhanced the recognition of weakly positive mutants. After saturation mutagenesis at M72 of the fused PAAS, the activity ratios of PAAS/mutants to ECAP in cell lysates of their fused forms were proportional to specific activities of their non-fused counterparts in cell lysates by an immunoturbidimetric assay. Therefore, the proposed strategy was absorbing for both HTP screening of mutants and HTP elucidation of sequence-activity relationship of applicable enzymes.

3.
J Nanosci Nanotechnol ; 20(4): 2584-2591, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31492280

RESUMO

Magnetic iron oxide (Fe3O4) nanoparticles (NPs) have attracted extensive attentions in biomedical fields such as magnetic resonance imaging (MRI). However, the instability and unfavorable dispersity of bare Fe3O4 NPs is a challenge for biomedical applications. Herein, we proposed a strategy using hollow carbon sphere (HCS) as a shell structure to endow Fe3O4 NPs better stability, dispersity, as well as biocompatibility. To verify intracellular behaviors and biosafety of HCSdecorated Fe3O4 nanoparticles (Fe3O4@HCS NPs), the assessment of cellular effects of these NPs based on synchrotron radiation-based techniques were done to explore detailed interaction between Fe3O4@HCS NPs and liver cells, HepG2. We found that a large number of NPs were internalized by cells in a time-dependent manner determined by inductively coupled plasma mass spectrometry (ICP-MS), which was further supported by intracellular accumulation of iron via X-ray fluorescence (XRF) imaging. Moreover, confocal imaging showed that these NPs mainly located in the lysosomes where they remained stable and undissolved within 72 hours, which was verified by chemical form characterization of iron via Fe K-edge X-ray adsorption near edge structure (XANES). With the coating shell of HCS, the release of iron ions was prevented even in acidic lysosome and the integrity of lysosomal membrane remained unchanged during the storage of NPs. As a result, Fe3O4@HCS NPs exhibited low level of oxidative stress and induced negligible cytotoxicity towards HepG2 cells. Based on the powerful techniques, we demonstrated that the carbon outer layer provides a physical barrier that helps remain excellent properties of magnetic Fe3O4 NPs and good dispersity, chemical stability, as well as biocompatibility for potential applications in biomedical fields.

4.
Mater Sci Eng C Mater Biol Appl ; 107: 110311, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31761197

RESUMO

In this study, a small-diameter, double-layered eggshell membrane/thermoplastic polyurethane (ESM/TPU) vascular graft with a wavy structure was developed. The avian eggshell membrane, a fibrous structure similar to the extracellular matrix (ECM), has the potential to yield rapid endothelialization in vitro. The dopamine and heparin modification of the ESM surface not only promoted human umbilical vein endothelial cell (HUVEC) proliferation via cytocompatibility assessment, but also improved its anticoagulation properties as verified in platelet adhesion tests. The biomimetic mechanical properties of the vascular graft were provided by the elastic TPU fibers via electrospinning using a wavy cross-section rotating collector. The advantage of combining these two materials is to make use of the bioactivity of ESM as the internal membrane and the tunable mechanical properties of TPU as the external layer. The circumferentially wavy structure of the vascular graft produced a toe region in the non-linear section of the stress-strain curve similar to that of natural blood vessels. The ESM/TPU graft's circumferential ultimate strength was 2.57 MPa, its strain was 339% mm/mm, and its toe region was found to be around 20% mm/mm. Cyclical tension tests showed that the vascular graft could maintain good mechanical properties and showed no structural damage under repeated extension tests.

5.
Opt Express ; 27(20): 27936-27945, 2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31684555

RESUMO

We investigate the mutual interaction of two spatially-separated Airy beams in the nonlinear Schrödinger equation with the fractional Laplacian. Depending on the beam separation (d), relative phase and Lévy index (α), we observed an anomalous attraction or repulsion between the Airy beams. Anomalous attraction leads to a single breather soliton with a period that grows exponentially as α increases. In this region of the parameter space, we identify a crossover between two asymmetric regimes: as the Lévy index exceeds a critical value α c, the period of breather soliton for d>0 is orders of magnitude larger than for d<0, while the opposite occurs as α<α c. Our results reveal a novel scenario for Airy beams interaction in the framework of fractional nonlinear Schrödinger equation and provide an alternative mechanism to control breather soliton generation.

6.
Molecules ; 24(21)2019 Nov 05.
Artigo em Inglês | MEDLINE | ID: mdl-31694145

RESUMO

Carbon fiber mesh reinforced cement-based composites (CMCCs) have received extensive attention in the field of engineering repair and structural reinforcement due to their outstanding properties such as two-way force, rust prevention, high specific strength, and low base surface requirements. However, the development of this material has been slowed down to some extent due to the poor interfacial bonding between the carbon fiber mesh and the cement matrix. In this paper, a novel fabrication strategy was proposed in which the carbon fiber mesh was modified with epoxy resin and silane coupling agent (SCA) to increase its surface chemical activity. Meanwhile, the hydroxymethyl cellulose (HMC) was also filled into the concrete matrix to improve the mechanical strength of the matrix as well as the load transfer behaviors between the mortar and carbon fiber (CF) mesh. The potential to employ SCA and HMC was evaluated for the making of CMCCs via the above methods. The results showed that the longitudinal shear strength of composites with SCA and SCA&HMC increased by 26.6% and 56.1% compared to those of CF with epoxy resin (EP) reinforced composites, respectively. The flexural strength of composite with SCA&HMC increases by 147.6% compared to I-(F) without CF. The novel II-HCM&CF/EP-SCA composites with excellent performance are promised to be applied in practical uses.

7.
Pest Manag Sci ; 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31696614

RESUMO

BACKGROUND: Pydiflumetofen is a new generation succinate dehydrogenase inhibitor currently in the registration process in China for the control of Fusarium head blight in wheat. Resistance risk assessment of Fusarium graminearum to pydiflumetofen was investigated in this study. RESULTS: A total of 75 pydiflumetofen-resistant mutants were generated through spontaneous selection and displayed high resistance with average RF value of 78. Four mutants were generated through UV mutagenesis and displayed very high resistance with RF value > 1000. The sequence analysis results for Sdh genes and fitness studies revealed the existence of four types of mutations. In particular, 32 spontaneous selection mutants (SP-mutants) had an arginine (R) to histidine (H) transition at position 86 in FGSdhC, resulting in seriously reduced fitness. Seven SP-mutants had an R to cysteine (C) transition at position 86 in FGSdhC, resulting in reduced fitness. Thirty-six SP-mutants had an alanine (A) to valine (V) transition at position 83 in FGSdhC and had no fitness penalties. The efficacy of pydiflumetofen to mutant carrying A83V in FGSdhC in vivo was significantly decreased with efficacy of 42.71%. Four UV-mutants had no mutations on all Sdh genes and no fitness penalties. Cross-resistance among pydiflumetofen and boscalid, fluopyram was observed. CONCLUSION: Sdhc mutations were found and other target site resistance may be present in laboratory PR mutants of F. graminearum. An overall moderate risk of resistance development in F. graminearum was recommended for pydiflumetofen. This article is protected by copyright. All rights reserved.

8.
Mediators Inflamm ; 2019: 3592620, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31686981

RESUMO

Objective: This study is aimed at evaluating the diagnostic value of blood lipid indicators (BLIs) for insulin resistance (IR) among major ethnic groups in Xinjiang, China, to identify the most valuable indicators and appropriate cut-off points for each ethnic group and to lay the foundation for the early detection, diagnosis, and treatment of metabolic diseases in remote rural areas. Methods: Overall, 418 Uygurs, 331 Kazakhs, and 220 Hans were randomly included in our study. The homeostasis model assessment was the gold standard for identifying IR. The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value, and the nomogram was utilized to analyze the predictive value. The size of the area under the curve (AUC) reflected the accuracy of screening and prediction. Results: Differences in races were observed in terms of IR and BLIs, and the Kazakhs had the highest IR level at 5.27 mmol/L. The correlation between IR and BLIs differed among the three races. For the Kazakhs and Hans, all BLIs, except total cholesterol (TC), were correlated to IR. However, for the Uygurs, only the triglyceride (TG) level, TG/high-density lipoprotein cholesterol (HDL-C) ratio, and TC/HDL-C ratio were associated with IR. After further adjustment of confounding factors, these indicators were still correlated to IR. BLIs that independently correlated to IR in the three nationalities had a certain diagnostic value for IR. In terms of the AUC size, the TG level was the highest in Uygurs, the TG/HDL-C ratio was the highest for Kazakhs and Hans, and the corresponding best cut-off points for IR were 1.515, 1.230, and 1.495 mmol/L, respectively. In addition, for each race, when the indicators with a certain diagnostic value were combined, the diagnostic value for IR was higher. Conclusion: BLIs had a certain diagnostic value for IR and could be used as a screening tool for IR among Uygurs, Kazakhs, and Hans in Xinjiang. These findings are extremely important for the prevention and treatment of IR and metabolic diseases in remote rural areas.

9.
J Sep Sci ; 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31670445

RESUMO

High-performance liquid chromatography coupled with photodiode array detection has been extensively applied in many fields and the peaks among the analyzed samples can be shifted due to the variations of instrumental and experimental conditions. In multivariate analysis, retention time alignment is an important pretreatment step. Hence, the shifted peaks in high-performance liquid chromatography coupled with photodiode array detection three-dimensional spectra should be aligned for further analysis. Being motivated by this purpose, the interval correlated shifting method combined with the proposed data arrangement methods are recommended and employed on high-performance liquid chromatography coupled with photodiode array detection data as a demonstration. We validate the alignment performance of the proposed method through comparison the consistency of the retention time before and after alignment. The obtained results demonstrated that the proposed method is capable of successful aligning the employed data. Additionally, the interval correlated shifting method combined with the data arrangement modes is implemented in an easy-to-use graphical user interface environment and so can be operated easily by users not familiar with programming languages.

10.
Neuroscience ; 419: 72-82, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31682827

RESUMO

Previous studies reported that long-term nociceptive stimulation could result in neurovascular coupling (NVC) dysfunction in brain, but these studies were based mainly on unimodal imaging biomarkers, thus could not comprehensively reflect NVC dysfunction. We investigated the potential NVC dysfunction in chronic migraine by exploring the relationship between neuronal activity and cerebral perfusion maps. The Pearson correlation coefficients between these 2 maps were defined as the NVC biomarkers. NVC biomarkers in migraineurs were significantly lower in left inferior parietal gyrus (IPG), left superior marginal gyrus (SMG) and left angular gyrus (AG), but significantly higher in right superior occipital gyrus (SOG), right superior parietal gyrus (SPG), and precuneus. These brain regions were located mainly in parietal or occipital lobes and were related to visual or sensory information processing. ALFF-CBF in right SPG was positively correlated with disease history and that in right precuneus was negatively correlated with migraine persisting time. fALFF-CBF in left SMG and AG were negatively related to headache frequency and positively related to health condition and disease history. In conclusion, multi-modal MRI could be used to detect NVC dysfunction in chronic migraine patients, which is a new method to assess the impact of chronic pain on the brain.

11.
Biomed Pharmacother ; 121: 109611, 2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31731196

RESUMO

BACKGROUND: Our previous studies have showed that p-Hydroxylcinnamaldehyde (CMSP) could induce the differentiation of ESCC cells via the cAMP-RhoA-MAPK signalling pathway, which suggests a new potential strategy for ESCC treatment. Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is a potent inducer of apoptosis in several tumour cells by binding to the death receptors DR4 and DR5. However, TRAIL has little effect on oesophageal squamous cell carcinoma (ESCC) cells due to the loss of the receptors. The present study determined the effect of CMSP, the firstly found chemical constituent of Cochinchinamomordica seed (CMS), on TRAIL-induced apoptosis and its mechanism in ESCC cells. METHODS: MTS assays were performed to examine the CMSP- and TRAIL-mediated inhibition of ESCC cell growth. Flow cytometry and Hoechst 33258 staining assays were used to detect apoptosis in ESCC cells treated with CMSP combined with TRAIL. Western blotting was used to determine the effect of CMSP on the expression of p38, p-p38, DR4, DR5, Bid and caspase-3/8 in ESCC cells treated with CMSP combined with TRAIL. Additionally, immunodeficient Balb-c/null mouse model was used to determine the chemotherapeutic efficacy of CMSP and TRAIL against ESCC tumour xenograft growth in vivo. RESULTS: We found that the combination of CMSP and TRAIL had a greater inhibitory effect on ESCC cell viability in vitro than CMSP or TRAIL alone. CMSP enhanced the TRAIL-induced apoptosis in ESCC cells by upregulating the expression of DR4 and DR5 via the p38 MAPK signalling pathway. Furthermore, the increased expression of DR4 and DR5 upon TRAIL-induced apoptosis in ESCC cells was mediated at least in part by subsequent caspase-3 and caspase-8 activation. Moreover, the in vivo model showed that tumour growth was significantly slower in CMSP and TRAIL combination-treated mice than in mice treated with CMSP or TRAIL alone. CONCLUSION: Taken together, our findings indicate that CMSP as an extract from TCM, might be as a potential sensitizer of TRAIL and thus provide a novel strategy for the clinical treatment of ESCC.

12.
Mol Med Rep ; 20(5): 4706-4712, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31702041

RESUMO

The effect of leptin on ulcerative colitis (UC) has been controversial. The present study aimed to investigate the role of leptin and its receptor ob­R in UC and the underlying mechanism of this role. The level of serum leptin and the protein expression of the leptin receptor ob­R in the colonic mucosa were determined in patients with UC. Experimental colitis was induced through intrarectal administration of 2,4,6­trinitrobenzene sulfonic acid (TNBS) in leptin receptor­deficient Zucker rats (LR­D). The body weight, disease activity index, colon length, and macroscopic and histopathological appearance were evaluated. Furthermore, the myeloperoxidase (MPO) enzyme activity and cytokine levels in colon tissues were also determined. The expression of the signal transducer and activator of transcription 3 (STAT3), phosphorylated STAT3 (p­STAT3), nuclear factor (NF)­κB­p65, and Ras homolog gene family member A (RhoA) proteins in colon tissues was assessed. The results revealed that the expression of the leptin receptor ob­R was increased in the colonic mucosa but the serum leptin level was not altered in patients with UC compared with healthy volunteers. The severity of experimental colitis, represented by body weight loss, disease activity index, colon length, and macroscopic and histological changes, was ameliorated in LR­D rats compared with the wild­type (WT) rats. Moreover, the MPO activity; levels of cytokines including interleukin (IL)­1ß, IL­6, and tumor necrosis factor­α; and expression of p­STAT3, NF­κB, and RhoA proteins were reduced in colon tissues of LR­D rats compared with WT rats. In conclusion, activation of the leptin receptor ob­R is an important pathogenic mechanism of UC, and leptin receptor deficiency may provide resistance against TNBS­induced colitis by inhibiting the NF­κB and RhoA signaling pathways.

13.
J Am Chem Soc ; 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31707779

RESUMO

Rubriflordilactone B (1) is a schinortriterpenoid isolated by Sun and colleagues, which possesses a tetrasubstituted benzene moiety and eight stereocenters. The previous synthesis of 1 by Li and co-workers uncovered the existence of its naturally occurring stereoisomer "pseudorubriflordilactone B". Here we report a collaborative study by the two groups that elucidates the structure of pseudorubriflordilactone B to be 16,17-bis-epi-rubriflordilactone B (26). Chemical synthesis served as an important tool in the structure determination. Taking advantage of a modular synthetic route, we systematically "mutated" the configurations of C-23, C-22, C-20, and C-16/C-17 located at the right-hand domain of 1, and thus prepared its fifteen stereoisomers for spectrum comparison. The 1H NMR spectra of synthetic 26 in deuterated chloroform and pyridine were identical to those of authentic pseudorubriflordilactone B, respectively. This synthetic sample displayed anti-HIV activity (EC50 = 0.288 µM) in vitro.

14.
iScience ; 21: 308-327, 2019 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-31678913

RESUMO

Plant exosomes protect plants against infection; however, whether edible plant exosomes can protect mammalian hosts against infection is not known. In this study, we show that ginger exosome-like nanoparticles (GELNs) are selectively taken up by the periodontal pathogen Porphyromonas gingivalis in a GELN phosphatidic acid (PA) dependent manner via interactions with hemin-binding protein 35 (HBP35) on the surface of P. gingivalis. Compared with PA (34:2), PA (34:1) did not interact with HBP35, indicating that the degree of unsaturation of PA plays a critical role in GELN-mediated interaction with HBP35. On binding to HBP35, pathogenic mechanisms of P. gingivalis were significantly reduced following interaction with GELN cargo molecules, including PA and miRs. These cargo molecules interacted with multiple pathogenic factors in the recipient bacteria simultaneously. Using edible plant exosome-like nanoparticles as a potential therapeutic agent to prevent/treat chronic periodontitis was further demonstrated in a mouse model.

15.
J Environ Manage ; 254: 109810, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31698300

RESUMO

In order to predict the effects of climate change on the global carbon cycle, it is crucial to understand the environmental factors that affect soil carbon storage in grasslands. In the present study, we attempted to explain the relationships between the distribution of soil carbon storage with climate, soil types, soil properties and topographical factors across different types of grasslands with different grazing regimes. We measured soil organic carbon in 92 locations at different soil depth increments, from 0 to 100 cm in southwestern China. Among soil types, brown earth soils (Luvisols) had the highest carbon storage with 19.5 ±â€¯2.5 kg m-2, while chernozem soils had the lowest with 6.8 ±â€¯1.2 kg m-2. Mean annual temperature and precipitation, exerted a significant, but, contrasting effects on soil carbon storage. Soil carbon storage increased as mean annual temperature decreased and as mean annual precipitation increased. Across different grassland types, the mean carbon storage for the top 100 cm varied from 7.6 ±â€¯1.3 kg m-2 for temperate desert to 17.3 ±â€¯2.9 kg m-2 for alpine meadow. Grazing/cutting regimes significantly affected soil carbon storage with lowest value (7.9 ±â€¯1.5 kg m-2) recorded for cutting grass, while seasonal (11.4 ±â€¯1.3 kg m-2) and year-long (12.2 ±â€¯1.9 kg m-2) grazing increased carbon storage. The highest carbon storage was found in the completely ungrazed areas (16.7 ±â€¯2.9 kg m-2). Climatic factors, along with soil types and topographical factors, controlled soil carbon density along a soil depth in grasslands. Environmental factors alone explained about 60% of the total variation in soil carbon storage. The actual depth-wise distribution of soil carbon contents was significantly influenced by the grazing intensity and topographical factors. Overall, policy-makers should focus on reducing the grazing intensity and land conversion for the sustainable management of grasslands and C sequestration.

16.
Lab Invest ; 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31748682

RESUMO

Tumor-associated macrophages (TAMs) constitute a large population of glioblastoma and facilitate tumor growth and invasion of tumor cells, but the underlying mechanism remains undefined. In this study, we demonstrate that chemokine (C-C motif) ligand 8 (CCL8) is highly expressed by TAMs and contributes to pseudopodia formation by GBM cells. The presence of CCL8 in the glioma microenvironment promotes progression of tumor cells. Moreover, CCL8 induces invasion and stem-like traits of GBM cells, and CCR1 and CCR5 are the main receptors that mediate CCL8-induced biological behavior. Finally, CCL8 dramatically activates ERK1/2 phosphorylation in GBM cells, and blocking TAM-secreted CCL8 by neutralized antibody significantly decreases invasion of glioma cells. Taken together, our data reveal that CCL8 is a TAM-associated factor to mediate invasion and stemness of GBM, and targeting CCL8 may provide an insight strategy for GBM treatment.

17.
Viruses ; 11(11)2019 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-31766138

RESUMO

Traditional pathogenesis studies of alphaviruses involves monitoring survival, viremia, and pathogen dissemination via serial necropsies; however, molecular imaging shifts this paradigm and provides a dynamic assessment of pathogen infection. Positron emission tomography (PET) with PET tracers targeted to study neuroinflammation (N,N-diethyl-2-[4-phenyl]-5,7-dimethylpyrazolo[1,5-a]pyrimidine-3-acetamide, [18F]DPA-714), apoptosis (caspase-3 substrate, [18F]CP-18), hypoxia (fluormisonidazole, [18F]FMISO), blood-brain barrier (BBB) integrity ([18F]albumin), and metabolism (fluorodeoxyglucose, [18F]FDG) was performed on C3H/HeN mice infected intranasally with 7000 plaque-forming units (PFU) of Venezuelan equine encephalitis virus (VEEV) TC-83. The main findings are as follows: (1) whole-brain [18F]DPA-714 and [18F]CP-18 uptake increased three-fold demonstrating, neuroinflammation and apoptosis, respectively; (2) [18F]albumin uptake increased by 25% across the brain demonstrating an altered BBB; (3) [18F]FMISO uptake increased by 50% across the whole brain indicating hypoxic regions; (4) whole-brain [18F]FDG uptake was unaffected; (5) [18F]DPA-714 uptake in (a) cortex, thalamus, striatum, hypothalamus, and hippocampus increased through day seven and decreased by day 10 post exposure, (b) olfactory bulb increased at day three, peaked day seven, and decreased day 10, and (c) brain stem and cerebellum increased through day 10. In conclusion, intranasal exposure of C3H/HeN mice to VEEV TC-83 results in both time-dependent and regional increases in brain inflammation, apoptosis, and hypoxia, as well as modest decreases in BBB integrity; however, it has no effect on brain glucose metabolism.

18.
Chemistry ; 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31747078

RESUMO

The electrochemical reduction of CO2 presents a promising strategy to mitigate the greenhouse effect and reduce the excess carbon dioxide emission to realize a carbon-neutral energy cycle, but it suffers from the lack of high-performance electrocatalysts. In this work, we precisely anchor catalytic active cobalt porphyrin [TCPP(Co) = (5,10,15,20)-tetrakis(4-carboxyphenyl)porphyrin-Co(II)] onto the water-stable 2-D MOF nanosheets (Zr-BTB) to obtain ultra-thin 2-D MOF nanosheets [TCPP(Co)/Zr-BTB] with accessible catalytic sites for CO2 reduction reaction. Compared with molecular cobalt porphyrin, the TCPP(Co)/Zr-BTB exhibits ultrahigh turnover frequency (TOF = 4768 hr-1 at -0.919 V vs. RHE) due to high active-site utilization. Besides, we obtained three post-modified 2-D MOF nanosheets [TCPP(Co)/Zr-BTB-PABA, TCPP(Co)/Zr-BTB-PSBA, TCPP(Co)/Zr-BTB-PSABA], with the modifiers of p-(aminomethyl)benzoic acid (PABA), p-sulfobenzoic acid potassium (PSBA) and p-sulfamidobenzoic acid (PSABA), respectively, to change the micro-environments around TCPP(Co) through the tuning of steric effect. Among them, the TCPP(Co)/Zr-BTB-PSABA exhibited the best performance with Faradaic efficiency (FECO) of 85.1%, TOF of 5315 hr-1 and jtotal of 6 mA/cm2 at -0.769 V (vs. RHE). In addition, long-term durability of electrocatalysts is evaluated and the role of pH buffer is revealed.

20.
Artigo em Inglês | MEDLINE | ID: mdl-31721397

RESUMO

Fluorinated ketones are widely prevalent in numerous biologically interesting molecules, and the development of novel transformations to access these structures is an important task in organic synthesis. As an emerging powerful strategy, the concurrent installation of fluorine and ketone moieties into target molecules from simple, variable, and abundant feedstocks remains synthetically challenging and underdeveloped. Here, we report a multicomponent radical acylfluoroalkylation of olefins in the presence of various commercially available aromatic aldehydes and fluoroalkyl reagents through N -heterocyclic carbene organocatalysis. Notably, a broad spectrum of olefin substrates, including styrenes, cyclic internal alkenes, indoles, vinyl ethers, vinyl esters, and the unactivated simple alkenes, could be compatible in this organocatalytic system. With this protocol, over 120 examples of functionalized ketones with diverse fluorine substituents have been facilely synthesized in up to 99% yield with complete regioselectivity. The generality of this catalytic strategy was further highlighted by its successful application in the late-stage functionalization of pharmaceutical skeletons. Interestingly, excellent diastereoselectivity could be achieved in the reactions forging multiple stereocenters. In addition, preliminary results have been achieved on the catalytic asymmetric variant of the olefin difunctionalization process. The reaction mechanism involves a single-electron reduction of fluoroalkyl reagents by deprotonated Breslow intermediates, radical addition to alkenes, and the radical-radical recombination.

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