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1.
Pediatr Infect Dis J ; 2019 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-31738328

RESUMO

BACKGROUND: Mycoplasma pneumoniae pneumonia is generally a self-limiting disease, but it can develop into severe Mycoplasma pneumoniae pneumonia (SMPP). Immunologic mechanisms are thought to play an important role in the pathogenesis of SMPP. Therefore, the use of systemic glucocorticoids may have beneficial effects. However, to date, the use of glucocorticoid therapy in SMPP is limited to small case series, and the glucocorticoid dosage for children with SMPP has not been established. METHODS: Here, we used a meta-analysis method to collect data from randomized control trials of different doses of methylprednisolone in SMPP to assess the safety and efficacy of treatment with low- versus high-dose methylprednisolone in children with SMPP. RESULTS: We included 13 Chinese randomized control trials that included 1049 children. The high- and low-dose groups were comprised of 524 and 525 children, respectively. The high-dose group was significantly more effective than the low-dose group in clinical efficacy [risk ratio = 1.30, 95% confidence interval (CI) (1.23, 1.38), P < 0.05]. In addition, compared with low-dose methylprednisolone, high-dose methylprednisolone significantly shortened hospital stays and antipyretic therapy, pulmonary rales disappearance, cough disappearance and pulmonary shadow absorption times. There was no significant difference in adverse events between the high- and low-dose groups: risk ratio= 0.85, 95% CI (0.53, 1.36), P > 0.05. CONCLUSIONS: We conclude that high-dose methylprednisolone is effective in the treatment of SMPP without increasing the incidence of adverse reactions.

2.
Org Lett ; 2019 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-31424222

RESUMO

A general protocol for the preparation of enantioenriched α-tetrasubstituted α-trifluoromethyl homoallylic amines is disclosed. Despite the significant challenge in stereoselectivity control, Ir-catalyzed asymmetric cascade umpolung allylation/2-aza-Cope rearrangement of trifluoromethylated fluorenone imines with allylic carbonates was realized with excellent efficiency and remarkable stereoselectivity. These were enabled by the suitable protective imino moiety and an unexpectedly exclusive E-geometrical imine of the allylation intermediate. This methodology is also applicable to facile access to chiral α-trisubstituted α-trifluoromethyl homoallylic amines in similarly high yield and stereoselectivity.

3.
Clin Lab ; 65(8)2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31414767

RESUMO

BACKGROUND: The C-reactive protein to albumin ratio (CAR) is a novel inflammation index that has recently been used as a marker for poor prognosis or mortality in various patient groups. This study aimed to evaluate the association between the CAR and 30-day mortality in patients with hepatitis B virus-related decompensated cirrhosis (HBV-DeCi). METHODS: This was a retrospective cohort study of 113 patients who had been diagnosed with HBV-DeCi. Univariate and multivariate regression models were used to determine risk factors for mortality. RESULTS: The CAR was observed to be significantly higher in the non-surviving patients compared to the surviving patients. Moreover, the CAR was positively correlated with the model for end-stage liver disease (MELD) score and Child-Pugh score. In multivariate analysis, the CAR and the MELD score were independent prognostic factors for HBV-DeCi patients. CONCLUSIONS: A high CAR value at admission can serve as an independent predictor of 1-month mortality in patients with HBV-DeCi.

4.
Org Lett ; 21(12): 4842-4848, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31145631

RESUMO

An unprecedented Ir-catalyzed asymmetric cascade umpolung allylation/2-aza-Cope rearrangement of trifluoroethylisatin ketimines has been realized. The current method provides a facile access to biologically important α-trifluoromethyl-containing homoallylic amines in high yields with excellent enantioselectivity. Notably, umpolung reactivity of trifluoroethylisatin ketimine was discovered for the first time. Mechanism studies revealed the key intermediates in the initial umpolung allylation and the stereospecific chirality transfer in the subsequent 2-aza-Cope rearrangement.

5.
Chemistry ; 25(37): 8681-8685, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31054197

RESUMO

An unprecedented asymmetric allenylic alkylation of readily available imine esters, which was enabled by a synergistic Cu/Pd catalysis, has been developed. This dual catalytic system possesses good substrate compatibility, delivering a diverse array of nonproteinogenic α-allenylic α-mono- or α,α-disubstituted α-amino acids (α-AAs) with high yields and generally excellent enantioselectivities. Furthermore, the scalability and practicability of the current synthetic protocol were proven by performing gram-scale reactions and by the first catalytic asymmetric synthesis of naturally occurring (S)-γ-allenic α-amino acid, respectively.

6.
Chem Commun (Camb) ; 55(47): 6672-6684, 2019 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-31134230

RESUMO

Chiral multi-nitrogen-containing heterocycles, such as pyrazole, imidazole and pyridazine, are widely found in naturally occurring organic compounds and pharmaceuticals, and hence, their stereoselective and efficient synthesis is an important issue in organic synthesis. Out of the variety of methods that have been developed over the past century, the catalytic asymmetric cyclization and cycloaddition reactions are recognized as the most synthetically useful strategies due to their step-, atom- and redox-economic nature. In particular, the recently developed annulation reactions using azoalkenes as key intermediates show their great ability to construct diverse types of multi-nitrogen-containing heterocycles. In this feature article, we critically analyse the strategic development and the efficient transformation of azoalkenes to chiral heterocycles and α-functionalized ketone derivatives since 2010. The plausible mechanism for each reaction model is also discussed.

7.
Nat Commun ; 10(1): 1594, 2019 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-30962429

RESUMO

The efficient construction of enantiomerically enriched molecules from simple starting materials via catalytic asymmetric synthesis strategies is a key challenge in synthetic chemistry. Metallated azomethine ylides are commonly-used synthons for the preparation of N-heterocycles and α-amino acids. Remarkably, to date, the utilization of azomethine ylides for the facile access to chiral amines has proven elusive. Here, we report that a synergistic Cu/Ir-catalytic system combined with careful tuning of the steric congestion can be used to convert aldimine esters to a variety of chiral homoallylic amines via a cascade allylation/2-aza-Cope rearrangement. The elucidation of the distinct effects of each stereogenic center of the allylation intermediates on the stereochemical outcome and chirality transfer in the rearrangement further guided the selection of catalysts combination.

8.
Org Lett ; 21(4): 1191-1196, 2019 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-30707591

RESUMO

The first example of highly efficient kinetic resolution of exo-3-oxodicyclopentadienes and endo-3-oxodicyclopentadiene has been developed by means of Cu(I)-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylide. Compared with the existing methodologies for those synthetically important optically active convex molecules, the current protocol provides an alternative but more practical approach from the readily available racemic starting materials, which is free from the repetitive reduction/oxidation steps in the enzymatic resolution or the indispensable stoichiometric amount of chirality-induction reagents.

9.
J Org Chem ; 83(19): 11814-11824, 2018 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-30149707

RESUMO

The mechanism of the Cu(I)/( S, Rp)-PPFOMe-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with fluorinated aldimines has been studied using labeling experiments, control experiments, and linear effect experiments, which clearly ruled out the 1,3-DC/epimerization pathways and explained the unusal exo'-selective stereochemistry. This protocol allows for the preparation of a series of highly functionalized fluorinated imidazolidines in good yields with excellent stereoselectivities. Moreover, the current methods have been successfully extended to synthesize more challenging imidazolidines bearing a CF3-containing quaternary stereogenic center via the endo-selective 1,3-DC of azomethine ylides with trifluorinated ketimine under identical reaction conditions.

10.
Org Lett ; 20(12): 3482-3486, 2018 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-29846076

RESUMO

An efficient kinetic resolution of readily available racemic cyclopentene-1,3-diones has been developed via a Ag(I)-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides. This methodology shows good functional-group tolerance, delivering an array of synthetically valuable cyclopentene-1,3-diones with excellent stereoselectivity and generally high resolution efficiency ( s = 48-226) accompanied by the biologically important fused pyrrolidine derivatives. Notably, this strategy allows facile access to the key intermediates for the synthesis of (+)-madindolines A and B.

11.
Org Biomol Chem ; 16(15): 2591-2601, 2018 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-29560980

RESUMO

Spirocyclic pyrrolidines are structural motifs frequently found in a wide variety of natural products, pharmaceuticals and biologically significant compounds. In the past few years, catalytic asymmetric 1,3-dipolar cycloaddition reactions of azomethine ylides have shown to be one of the most straightforward methods for the stereoselective preparation of diverse biologically important spiropyrrolidine heterocycles in high yields with excellent enantioselectivities under mild reaction conditions. In this review, we will discuss the recent major developments in the catalytic enantioselective synthesis of chiral spiropyrrolidine derivatives since 2009.

12.
Chem Commun (Camb) ; 54(20): 2506-2509, 2018 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-29459924

RESUMO

An unprecedented copper(i)-catalyzed asymmetric inverse electron demand Diels-Alder reaction of azoalkenes with fulvenes is reported. This methodology offers a directed entry to synthesize bicyclic tetrapyridazine derivatives in good yield with exclusive regioselectivity and excellent stereoselectivity.

13.
J Am Chem Soc ; 140(4): 1508-1513, 2018 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-29303578

RESUMO

Cu/Ir dual catalysis has been developed for the stereodivergent α-allylation of aldimine esters. The method enables the preparation of a series of nonproteinogenic α-amino acids (α-AAs) bearing two contiguous stereogenic centers in high yield with excellent stereoselectivity. All four product stereoisomers could be obtained from the same set of starting materials via pairwise combination of two chiral catalysts. Notably, one-pot protocol could be successfully applied for the preparation of the bimetallic Cu/Ir complexes to simplify the manipulation of Cu/Ir dual catalysis. This method could be further utilized for the construction of the key intermediate of a bioactive pyrrolidine derivative and the concise synthesis of a plant growth regulator (2S,3S)-2-amino-3-cyclopropylbutanoic acid.


Assuntos
Aminoácidos/síntese química , Cobre/química , Irídio/química , Aminoácidos/química , Catálise , Estrutura Molecular , Estereoisomerismo
14.
J Cancer ; 9(2): 321-330, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29344279

RESUMO

Purpose: SET and MYND domain-containing protein2 (SMYD2), a histone lysine methyltransferases, is a candidate human oncogene in multiple tumors. However, the expression dynamics of SMYD2 in hepatocellular carcinoma (HCC) and its clinical/prognostic significance are unclear. Methods: The SMYD2 expression profile was examined by quantitative real-time polymerase chain reaction (qRT-PCR), and immunohistochemistry (IHC) in HCC tissues and matched adjacent non-tumorous tissues. SMYD2 was silenced in HCC cell lines to determine its role in tumor proliferation and cell cycle progression, and the possible mechanism. Spearman's rank correlation, Kaplan-Meier plots and Cox proportional hazards regression model were used to analyze the data. Results: The SMYD2 expression in HCC tissues were significantly up-regulated at both mRNA and protein levels as compared with the matched adjacent non-tumorous tissues. By IHC, positive expression of SMYD2 was examined in 122/163 (74.85%) of HCC and in 10/59 (16.95%) of tumor-adjacent tissues. Positive expression of SMYD2 was correlated with tumor size, vascular invasion, differentiation and TNM stage (P < 0.05). In univariate survival analysis, a significant association between positive expression of SMYD2 and shortened patients' survival was found (P < 0.05). Importantly, SMYD2 expression together with vascular invasion (P < 0.05) provided significant independent prognostic parameters in multivariate analysis. Functionally, SMYD2 silenced markedly inhibited cell proliferation and cell cycle progression in SMMC-7721 cell. Conclusions: Our findings provide evidences that positive expression of SMYD2 in HCC may be important in the acquisition of an aggressive phenotype, and it is an independent biomarker for poor prognosis of patients with HCC.

15.
Acta Pharmacol Sin ; 39(1): 59-73, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28770830

RESUMO

Recent evidence shows that resveratrol (RSV) may ameliorate high-glucose-induced cardiac oxidative stress, mitochondrial dysfunction and myocardial fibrosis in diabetes. However, the mechanisms by which RSV regulates mitochondrial function in diabetic cardiomyopathy have not been fully elucidated. Mitochondrial dysfunction contributes to cardiac dysfunction in diabetic patients, which is associated with dysregulation of peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α). In this study we examined whether resveratrol alleviated cardiac dysfunction in diabetes by improving mitochondrial function via SIRT1-mediated PGC-1α deacetylation. T2DM was induced in rats by a high-fat diet combined with STZ injection. Diabetic rats were orally administered RSV (50 mg·kg-1·d-1) for 16 weeks. RSV administration significantly attenuated diabetes-induced cardiac dysfunction and hypertrophy evidenced by increasing ejection fraction (EF%), fraction shortening (FS%), ratio of early diastolic peak velocity (E velocity) and late diastolic peak velocity (A velocity) of the LV inflow (E/A ratio) and reducing expression levels of pro-hypertrophic markers ANP, BNP and ß-MHC. Furthermore, manganese superoxide dismutase (SOD) activity, ATP content, mitochondrial DNA copy number, mitochondrial membrane potential and the expression of nuclear respiration factor (NRF) were all significantly increased in diabetic hearts by RSV administration, whereas the levels of malondialdehvde (MDA) and uncoupling protein 2 (UCP2) were significantly decreased. Moreover, RSV administration significantly activated SIRT1 expression and increased PGC-1α deacetylation. H9c2 cells cultured in a high glucose (HG, 30 mmol/L) condition were used for further analyzing the role of SIRT1/PGC-1α pathway in RSV regulation of mitochondrial function. RSV (20 µmol/L) caused similar beneficial effects in HG-treated H9c2 cells in vitro as in diabetic rats, but these protective effects were abolished by addition of a SIRT1 inhibitor sirtinol (25 µmol/L) or by SIRT1 siRNA transfection. In H9c2 cells, RSV-induced PGC-1α deacetylation was dependent on SIRT1, which was also abolished by a SIRT1 inhibitor and SIRT1 siRNA transfection. Our results demonstrate that resveratrol attenuates cardiac injury in diabetic rats through regulation of mitochondrial function, which is mediated partly through SIRT1 activation and increased PGC-1α deacetylation.


Assuntos
Cardiotônicos/uso terapêutico , Cardiomiopatias Diabéticas/tratamento farmacológico , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Sirtuína 1/metabolismo , Estilbenos/uso terapêutico , Acetilação/efeitos dos fármacos , Animais , Antioxidantes/administração & dosagem , Antioxidantes/uso terapêutico , Cardiomegalia/tratamento farmacológico , Cardiotônicos/administração & dosagem , Linhagem Celular , Masculino , Mitocôndrias/metabolismo , Biogênese de Organelas , Estresse Oxidativo/efeitos dos fármacos , Ratos Sprague-Dawley , Resveratrol , Estilbenos/administração & dosagem , Proteína Desacopladora 2/metabolismo , Função Ventricular Esquerda/efeitos dos fármacos
16.
iScience ; 11: 146-159, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30612034

RESUMO

Development of a general catalytic and highly efficient method utilizing readily available precursors for the regio- and stereoselective construction of bioactive natural-product-inspired spiro architectures remains a formidable challenge in chemical research. Transition metal-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides produces numerous N-heterocycles, but reaction control with the regioselectivity opposite to the conventional fashion has rarely been demonstrated. Herein, we report a unique ligand-controlled Cu(I)-catalyzed umpolung-type 1,3-dipolar cycloaddition of azomethine ylide to realize efficient kinetic resolution of racemic alkylidene norcamphors with the concomitant construction of previously inaccessible spiro N-heterocycles with high levels of regio- and stereoselectivity. The success of this methodology relies on the strategy of kinetic resolution, and the serendipitous discovery of a unique ligand-enabled regiospecific cycloaddition, which not only provides evidence for the existence of the minor zwitterionic resonance form in metallated azomethine ylide but also diversifies the existing chemistry of azomethine ylide-involved 1,3-dipolar cycloadditions with rare polarity inversion.

17.
Biomed Res Int ; 2017: 1945631, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28929107

RESUMO

BACKGROUND AND AIM: Aberrant activation of the TGF-ß1/Smad pathway contributes to the activation of hepatic stellate cells (HSCs). MicroRNA-195 has been shown to regulate the activation of HSCs. The aim of this study was to investigate the role of miRNA-195 in HSCs activation. METHODS: A liver fibrotic rat model induced by diethylnitrosamine was established. Dual luciferase reporter assays were performed to verify that Smad7 was the target of miRNA-195. The expression levels of miR-195, Smad7, and α-SMA in HSC-T6 transfected, respectively, with miR-195 mimic, inhibitor, or control were measured by qRT-PCR. The protein expression of Smad7 was detected by Western blot analysis. RESULTS: Enhanced miR-195 and decreased Smad7 were observed in diethylnitrosamine-induced liver fibrotic rats (P < 0.05). Dual luciferase reporter assays showed that the miR-195 mimic significantly suppressed the luciferase activity of a reporter plasmid carrying the binding site of miR-195 on the 3'UTR of Smad7 (P < 0.05). The miR-195 mimics activated HSCs, further elevated miR-195 and α-SMA (P < 0.01), and reduced the Smad7 level (P < 0.05). The miR-195 inhibitors blocked the activation of HSCs, reduced the expression of miR-195 and α-SMA (P < 0.01), and upregulated the expression of Smad7 (P < 0.05). CONCLUSION: Collectively, we demonstrated that miRNA-195 activated HSCs by targeting Smad7.


Assuntos
Regulação da Expressão Gênica , Cirrose Hepática/genética , MicroRNAs/metabolismo , Proteína Smad7/metabolismo , Regiões 3' não Traduzidas/genética , Animais , Dietilnitrosamina/efeitos adversos , Modelos Animais de Doenças , Genes Reporter , Células Estreladas do Fígado/metabolismo , Cirrose Hepática/induzido quimicamente , Masculino , MicroRNAs/genética , Ratos , Ratos Sprague-Dawley , Proteína Smad7/genética , Fator de Crescimento Transformador beta1/genética , Fator de Crescimento Transformador beta1/metabolismo , Regulação para Cima
18.
Org Lett ; 19(17): 4532-4535, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28812364

RESUMO

An unprecedented asymmetric Diels-Alder reaction of 3-hydroxy-2-pyrones with prochiral cyclopentene-1,3-diones via desymmetrization was efficiently realized with high stereoselective control with the aid of fine-tunable cinchona alkaloid derived bifunctional amine-thiourea catalysts bearing multiple hydrogen-bonding donors. This protocol provides an expedient access to the multifunctional-bridged tricyclic lactones featuring four contiguous stereogenic centers and one remote quaternary stereogenic center with a broad substrate scope. The cycloadduct can be readily elaborated into enantioenriched cyclopentane-1,3-diones via ring opening/aromatization.

19.
Angew Chem Int Ed Engl ; 56(40): 12312-12316, 2017 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-28741842

RESUMO

An unprecedented enantioselective allylic alkylation of readily available aldimine esters has been developed, and is catalyzed by a synergistic Cu/Pd catalyst system. This strategy provides facile access to nonproteinogenic α,α-disubstituted α-amino acids in high yield with excellent enantioselectivity. The more challenging double allylic alkylation of glycinate-derived imine esters was also realized. Furthermore, this methodology was applied for the construction of the key intermediate of PLG peptidomimetics.

20.
Chemistry ; 23(21): 4995-4999, 2017 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-28261883

RESUMO

An unprecedented copper(I)-catalyzed asymmetric desymmetrization of 5-silylcyclopentadienes with in situ formed azoalkene was realized through an inverse-electron-demand aza-Diels-Alder reaction (IEDDA) pathway, in which 5-silylcyclopentadienes served as efficient enophiles. This new protocol provides a facile access to the biologically important heterocyclic tetrahydropyridazines containing a unique α-chiral silane motif and three adjoining stereogenic centers in generally good yield (up to 92 %) with exclusive regioselectivity, high diastereoselectivity (>20:1 diastereomeric ratio), and excellent enantioselectivity (up to 98 % enantiomeric excess). DFT calculations and control experiments further confirmed the proposed reaction mechanism.

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