Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 59
Filtrar
1.
J Am Chem Soc ; 146(23): 16194-16202, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38832699

RESUMO

Although progress has been made in enantioselective hydroboration of di- and trisubstituted alkenes over the past decades, enantioselective hydroboration of tetrasubstituted alkenes with high diastereo- and enantioselectivities continues as an unmet challenge since the 1950s due to its extremely low reactivity and the difficulties to simultaneously control the regio- and stereoselectivity of a tetrasubstituted alkene. Here, we report highly regio-, diastereo-, and enantioselective catalytic hydroboration of diverse acyclic tetrasubstituted alkenes. The delicate interplay of an electron-rich rhodium complex and coordination-assistance forms a highly adaptive catalyst that effectively overcomes the low reactivity and controls the stereoselectivity. The generality of the catalyst system is exemplified by its efficacy across various tetrasubstituted alkenes with diverse steric and electronic properties.

2.
Sci Total Environ ; 915: 170153, 2024 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-38232821

RESUMO

Precipitation is a vital component of the global atmospheric and hydrological cycles and influencing the distribution of water resources. Even subtle changes in precipitation can significantly impact ecosystems, energy cycles, agricultural production, and food security. Therefore, understanding the changes in the precipitation structure under climate change is essential. The Qinghai-Tibet Plateau (QTP) is a region sensitive to global climate change and profoundly impacts the atmospheric water cycle in Asia and even globally, rendering it a hot topic in climate change research in recent years. Few studies have examined on the sub-daily scale precipitation structure over the QTP. In this paper, the characteristics of sub-daily precipitation on the QTP were systematically investigated from multiple perspectives, including the concentration index, skewness (the third standardized moment of a distribution), and kurtosis (the fourth standardized moment of a distribution). The results indicated that the frequency of moderate-intensity nighttime precipitation on the QTP generally increased, and the analysis of both the concentration index and kurtosis (skewness) suggested that extreme precipitation was more frequent in the southwestern foothills of the QTP. Furthermore, potential high-risk areas for natural disasters were identified on the QTP, and found that the southeastern part of the plateau constituted a potential hotspot area for flood disasters. Given the complexity of climate change, a comprehensive analysis of the spatiotemporal characteristics of diurnal and nighttime precipitation changes on the QTP could help reveal the regularity of precipitation changes. This has significant implications for forecasting, warning, disaster preparedness, and mitigation efforts on the QTP.

3.
Zhongguo Gu Shang ; 36(11): 1058-64, 2023 Nov 25.
Artigo em Chinês | MEDLINE | ID: mdl-38012875

RESUMO

OBJECTIVE: To evaluate the feasibility of S2 alar iliac screw insertion in Chinese children using computerized three-dimension reconstruction and simulated screw placement technique, and to optimize the measurement of screw parameters. METHODS: A total of 83 pelvic CT data of children who underwent pelvic CT scan December 2018 to December 2020 were retrospectively analyzed, excluding fractures, deformities, and tumors. There were 44 boys and 39 girls, with an average age of (10.66±3.52) years, and were divided into 4 groups based on age (group A:5 to 7 years old;group B:8 to 10 years old;group C:11-13 years old;group D:14 to 16 years old). The original CT data obtained were imported into Mimics software, and the bony structure of the pelvis was reconstructed, and the maximum and minimum cranial angles of the screws were simulated in the three-dimensional view with the placement of 6.5 mm diameter S2 alar iliac screws. Subsequently, the coronal angle, sagittal angle, transverse angle, total length of the screw, length of the screw in the sacrum, width of the iliac, and distance of the entry point from the skin were measured in 3-Matic software at the maximum and minimum head tilt angles, respectively. The differences among the screw parameters of S2 alar iliac screws in children of different ages and the differences between gender and side were compared and analyzed. RESULTS: In all 83 children, 6.5 mm diameter S2 iliac screws could be placed. There was no significant difference between the side of each screw placement parameter. The 5 to 7 years old children had a significantly smaller screw coronal angle than other age groups, but in the screw sagittal angle, the difference was more mixed. The 5 to 7 years old children could obtain a larger angle at the maximum head tilt angle of the screw, but at the minimum cranial angle, the larger angle was obtained in the age group of 11 to 13 years old. There were no significant differences among the age groups. The coronal angle and sagittal angle under maximum cephalic angle and minimum cranial angle of 5 to 7 years old male were (40.91±2.91)° and (51.85±3.75)° respectively, which were significantly greater than in female. The coronal angle under minimum cranial angle was significantly greater in girls aged 8-10 years old than in boys. For the remaining screw placement angle parameters, there were no significant differences between gender. The differences in the minimum iliac width, the screw length, and the length of the sacral screws showed an increasing trend with age in all age groups. The distance from the screw entry point to the skin in boys were significantly smaller than that of girls. The minimum width of the iliac in boys at 14 to 16 years of age were significantly wider than that in girls at the same stage. In contrast, in girls aged 5 to 7 years and 11 to 13 years, the screw length was significantly longer than that of boys at the same stage. CONCLUSION: The pelvis of children aged 5 to 16 years can safely accommodate the placement of 6.5 mm diameter S2 alar iliac screws, but the bony structures of the pelvis are developing and growing in children, precise assessment is needed to plan a reasonable screw trajectory and select the appropriate screw length.


Assuntos
Ílio , Fusão Vertebral , Humanos , Masculino , Feminino , Criança , Adolescente , Pré-Escolar , Ílio/cirurgia , Estudos Retrospectivos , Estudos de Viabilidade , Parafusos Ósseos , Pelve , Sacro/cirurgia , Fusão Vertebral/métodos
4.
J Contam Hydrol ; 258: 104234, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37659246

RESUMO

Owing to the limitations of the spatial arrangement of monitoring stations and time acquisition of satellite remote sensing images, the water quality monitoring of rivers, especially small- and medium-sized rivers, cannot be satisfied in terms of time and space continuity. In this study, we propose a standardization method for the camera images derived at different locations on different time considering the influences of light, shadows, reflections, ripples, leaves and so on. After this algorithm is established, an estimation algorithm based on the comprehensive appearance of water body is proposed, which has the potential of realising real-time, mobile, and continuous monitoring of water quality with low costs. The test results showed that the accuracy of the model was quite high compared to the results of the hydrological monitoring stations. Compared with the single-point detection of water quality monitoring stations, this method has advantages in terms of dynamic detection and small- andmedium-sized water body detection, which can serve as a supplement to traditional detection.


Assuntos
Monitoramento Ambiental , Qualidade da Água , Monitoramento Ambiental/métodos , Rios , Algoritmos
5.
Acc Chem Res ; 56(3): 308-321, 2023 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-36628651

RESUMO

ConspectusAlkenes are versatile compounds that are readily available on a large scale from industry or through organic synthesis. The widespread occurrence of alkenes provides the continuous impetus for the development of catalytic asymmetric alkene hydrofunctionalizations, which enables expeditious construction of complex chiral molecules from readily available starting materials. Catalytic asymmetric hydrofunctionalization of internal alkenes presents a notable challenge, due to their low reactivity, many potential side reactions, and the simultaneous control of the regio-, diastereo-, and enantioselectivities.Dehydroamino acids and enamides are among the first substrates that provide notable enantioselectivities in catalytic asymmetric hydrogenation. The crucial importance of an amide coordinating group is established by a series of classical mechanistic studies. This initial success greatly stimulated further development for catalytic hydrogenation and hydrofunctionalization. Building on these pioneering works in asymmetric hydrogenation as well as related hydrofunctionalizations, we have adopted coordination assistance as a powerful tool to address the challenges associated with the asymmetric hydrofunctionalization of internal alkenes. Using a functional group on the alkene substrate as a native coordinating group, a two-point binding mode of the substrate to the metal center effectively enhances the reactivity and facilitates the control of regio-, diastereo- and enantioselectivities. Through this strategy, we have developed a number of alkene hydrofunctionalization methods with excellent regio-, diastereo-, and enantiocontrols.In this Account, we summarize the recent advance in our lab using coordination assistance as a key element to achieve regio- and enantioselective hydroalkynylation of internal alkenes. First, we describe our early work aimed at controlling the regio- and enantioselectivity of hydroalkynylation using disubstituted enamide as the substrate. Both α- and ß-alkynylation were achieved by channeling the reaction pathway into a Chalk-Harrod or modified Chalk-Harrod mechanism. Next, we discuss the further development of catalysts to achieve regiodivergent and enantioselective hydroalkynylation of trisubstituted enamide to access vicinal stereocenters and quaternary carbon stereocenters. We also discuss the hydroalkynylation of α,ß-unsaturated amides to achieve unconventional site-selectivity through a combination of alkene isomerization and regioselective hydroalkynylation. This provides the basis for the construction of a remote quaternary carbon stereocenter through catalytic hydroalkynylation of trisubstituted ß,γ-unsaturated amides. We further show that this controlling principle is applicable to terminal alkene with a coordinating group as well. A ligand-controlled mechanism shift is discussed for the enantioselective alkynylation at the terminal and internal position of 1,1,-disubstituted alkenes. Finally, we briefly mention the application of coordination assistance to other hydrofunctionalizations such as hydroboration and hydrosilylation, where previously inaccessible reactivity and selectivity were achieved. Collectively, these catalytic methods demonstrate the power of coordination assistance for enantioselective hydrofunctionalizations. We anticipate that this strategy will create a platform to enable diverse enantioselective alkene transformations.

6.
International Eye Science ; (12): 1080-1086, 2023.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-976474

RESUMO

AIM:To observe the toxic effects of zinc oxide nanoparticles(ZnO NPs)on cornea by constructing intoxicated model in vivo and in vitro.METHODS:Human corneal epithelial cells(HCEpiC)were cultured in vitro and exposed to different concentrations(0.5, 5, 12.5, 25, 50, 100, 250 μg/mL)of ZnO NPs for 24h. The cell culture medium without nano-solution was used as the blank control group. The viability of the cells was assessed by MTT assay. Three different concentrations(25, 50 and 100 μg/mL)of ZnONPs dispersions were exposed to the conjunctival sac of anesthetized mice three times a day for 7d consecutively. The phosphate buffered saline(PBS)eye group was the PBS control group. Corneal morphology was observed on 1, 3, 5 and 7d, and the eyes were removed on 8d for various laboratory examinations, including corneal pathological changes and expression levels of inflammatory factors(TNF-α, IL-6).RESULTS:After treatment of HCEpiC cells with different concentrations of ZnO NPs for 24h, the MTT results showed that Zno NPs cause damage to cells at 0.5 μg/mL, and the cell survival rate was about 80%(P<0.05). Half of the cells were killed at a dose of 5 μg/mL, the damaging effect on cells in the concentration range of 5~250 μg/mL was concentration-dependent(P<0.0001). After 7d of conjunctival capsule spotting in mice, dot-like staining of fluorescein was seen in the 25 μg/mL ZnO NPs and 50 μg/mL ZnO NPs groups. Localized circular fluorescein stained areas were seen in the corneas of the 100 μg/mL ZnO NPs group. HE staining showed that the corneal epithelial layer, stromal layer thickness and stromal layer immune cell number did not change significantly in the 25 μg/mL and 50 μg/mL ZnO NPs groups(all P>0.05), while the corneal epithelial layer thinned, the corneal stromal layer thickened and the stromal layer immune cells increased significantly in the 100 μg/mL ZnO NPs group(all P<0.05). Immunohistochemical staining showed that the number of corneal stromal immune cells producing TNF-α and IL-6 and the mean integral optical density(IOD)values of TNF-α and IL-6 were significantly higher in the 100 μg/mL ZnO NPs group than in the PBS control group(P<0.05), and the degree of inflammation response was concentration-dependent. Compared with the PBS control group, no significant increase in immune cell count and IOD values in the 25 μg/mL ZnO NPs and 50 μg/mL ZnO NPs groups(P>0.05).CONCLUSION:The toxic damaging effect of ZnO NPs on the cornea was confirmed from both in vitro and in vivo, which provided a theoretical basis for the ocular safety evaluation of ZnO NPs.

7.
Nature ; 612(7939): 232-235, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36477130

RESUMO

It is generally believed that long-duration gamma-ray bursts (GRBs) are associated with massive star core collapse1, whereas short-duration GRBs are associated with mergers of compact star binaries2. However, growing observations3-6 have suggested that oddball GRBs do exist, and several criteria (prompt emission properties, supernova/kilonova associations and host galaxy properties) rather than burst duration only are needed to classify GRBs physically7. A previously reported long-duration burst, GRB 060614 (ref. 3), could be viewed as a short GRB with extended emission if it were observed at a larger distance8 and was associated with a kilonova-like feature9. As a result, it belongs to the type I (compact star merger) GRB category and is probably of binary neutron star (NS) merger origin. Here we report a peculiar long-duration burst, GRB 211211A, whose prompt emission properties in many aspects differ from all known type I GRBs, yet its multiband observations suggest a non-massive-star origin. In particular, substantial excess emission in both optical and near-infrared wavelengths has been discovered (see also ref. 10), which resembles kilonova emission, as observed in some type I GRBs. These observations point towards a new progenitor type of GRBs. A scenario invoking a white dwarf (WD)-NS merger with a post-merger magnetar engine provides a self-consistent interpretation for all the observations, including prompt gamma rays, early X-ray afterglow, as well as the engine-fed11,12 kilonova emission.


Assuntos
Raios gama
8.
Sci Total Environ ; 838(Pt 2): 155844, 2022 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-35561909

RESUMO

Compared with other factors influencing vegetation patterns, such as light and temperature, precipitation has relatively large variability, especially on the Qinghai-Tibet Plateau (QTP), where the natural environment is extremely fragile and sensitive. However, the impact of precipitation regimes, rather than precipitation amount, on vegetation has seldom been revealed. This study characterised the precipitation regimes by both the amount and temporal distribution of precipitation and zoned the QTP as different precipitation regimes accordingly. The response of vegetation to such precipitation regimes was then investigated. The results indicate that the vegetation patterns are quite consistent with zoning, that is, there is a certain type or a few dominant types of vegetation in each sub-region divided by the precipitation regimes. The areas where the precipitation became more uniform within a year were concentrated in grassland and bare land, which benefits the restoration and improvement of the ecological environment of the plateau. The increase in precipitation variability in the south-eastern part of the plateau may lead to natural disasters such as floods and mudslides. This study provides a novel perspective to understand the distribution of vegetation patterns.


Assuntos
Planejamento de Cidades , Mudança Climática , Meio Ambiente , Temperatura , Tibet
9.
Clinical Medicine of China ; (12): 199-204, 2022.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-932169

RESUMO

Objective:To investigate the predictive effect of postoperative blood lipid metabolism and C-reactive protein/albumin ratio (CAR) on anastomotic fistula after radical resection of esophageal cancer.Methods:A retrospective case-control study was conducted on 256 patients with esophageal squamous cell carcinoma (all aged >50 years) who underwent radical esophagectomy in the thoracic surgery of the Second Affiliated Hospital of Zhengzhou University from January 2017 to December 2020. Total cholesterol, triglyceride, high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C), ratio of C-reactive protein to albumin (CAR) and hemoglobin test index were collected. According to whether there was anastomotic fistula after operation, the patients were divided into anastomotic fistula group and non-anastomotic fistula group. The measurement data of normal distribution were compared by t-test, the measurement data of non-normal distribution were expressed by M( Q 1, Q 3), the comparison between groups was expressed by Mann-Whitney U test, and the counting data were expressed by (case(%)).The comparison between groups was performed by χ 2 test. Logistic regression model was used for multivariate analysis. ROC curve and Kappa value were used to evaluate the predictive value of total cholesterol and CAR in postoperative anastomotic fistula. Results:The preoperative body mass index (BMI) ((18.71±1.90) kg/m 2) in anastomotic fistula group was higher than that in non-anastomotic fistula group ((20.59±2.88) kg/m 2), and the difference was statistically significant ( t=3.48, P=0.001). The postoperative total cholesterol ((5.44±1.09) mmol/L), LDL-C ((3.82±1.15) mmol/L) and CAR(0.64(0.41, 0.95)) in anastomotic fistula group were higher than those in non-anastomotic fistula group ((4.54±0.94) mmol/L, (2.92±0.76) mmol/L, 0.27(0.13,0.45)). There were significant differences between the two groups (the statistical values were t=4.84, t=5.69, Z=5.16, all P<0.001)). The hemoglobin concentration of 103.20 (84.94,110.48) g/L was lower than that of non anastomotic fistula group (107.68 (99.20,125.20) g/L), the difference was statistically significant ( Z=2.82, P=0.005). Lower BMI( OR=0.652,95% CI 0.482-0.882), higher total cholesterol( OR=3.240,95% CI 1.430-7.340), lower hemoglobin ( OR=0.837,95% CI 0.777-0.902) and higher CAR( OR=2.161,95% CI 1.597-2.925) were the risk factors of anastomotic fistula in esophageal squamous cell carcinoma( P values were 0.006, 0.005, <0.001 and <0.001,respectively). ROC curve analysis showed that the areas under the curve of total cholesterol and CAR were 0.742 (95% CI:0.643-0.841, P<0.001) and 0.790 (95% CI:0.690-0.890, P<0.001) respectively. The cutoff values were 4.915 mmol/L and 0.605, the sensitivity were 80.0% and 80.0%, the specificity were 82.3% and 92.5%, respectively, and the Kappa values were 0.418 and 0.625 respectively (all P<0.001). Conclusion:Total cholesterol and CAR after radical resection of esophageal cancer have a certain predictive value for postoperative anastomotic fistula in patients with esophageal squamous cell carcinoma. The predictive result of CAR is better than that of total cholesterol.

10.
Nat Commun ; 12(1): 3776, 2021 06 18.
Artigo em Inglês | MEDLINE | ID: mdl-34145273

RESUMO

Chiral tertiary boronic esters are important precursors to bioactive compounds and versatile synthetic intermediates to molecules containing quaternary stereocenters. The development of conjugate boryl addition to α,ß-unsaturated amide has been hampered by the intrinsic low electrophilicity of the amide group. Here we show the catalytic asymmetric synthesis of enantioenriched tertiary boronic esters through hydroboration of ß,ß-disubstituted α,ß-unsaturated amides. The Rh-catalyzed hydroboration occurs with previously unattainable selectivity to provide tertiary boronic esters in high enantioselectivity. This strategy opens a door for the hydroboration of inert Michael acceptors with high stereocontrol and may provide future applications in the synthesis of biologically active molecules.

11.
PLoS One ; 16(2): e0246474, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33556136

RESUMO

BACKGROUND: Sex and gender differences in acute coronary syndrome (ACS) have been well studied in the western population. However, limited studies have examined the trends of these differences in a multi-ethnic Asian population. OBJECTIVES: To study the trends in sex and gender differences in ACS using the Malaysian NCVD-ACS Registry. METHODS: Data from 24 hospitals involving 35,232 ACS patients (79.44% men and 20.56% women) from 1st. Jan 2012 to 31st. Dec 2016 were analysed. Data were collected on demographic characteristics, coronary risk factors, anthropometrics, treatments and outcomes. Analyses were done for ACS as a whole and separately for ST-segment elevation myocardial infarction (STEMI), Non-STEMI and unstable angina. These were then compared to published data from March 2006 to February 2010 which included 13,591 ACS patients (75.8% men and 24.2% women). RESULTS: Women were older and more likely to have diabetes mellitus, hypertension, dyslipidemia, previous heart failure and renal failure than men. Women remained less likely to receive aspirin, beta-blocker, angiotensin-converting enzyme inhibitor (ACE-I) and statin. Women were less likely to undergo angiography and percutaneous coronary intervention (PCI) despite an overall increase. In the STEMI cohort, despite a marked increase in presentation with Killip class IV, women were less likely to received primary PCI or fibrinolysis and had longer median door-to-needle and door-to-balloon time compared to men, although these had improved. Women had higher unadjusted in-hospital, 30-Day and 1-year mortality rates compared to men for the STEMI and NSTEMI cohorts. After multivariate adjustments, 1-year mortality remained significantly higher for women with STEMI (adjusted OR: 1.31 (1.09-1.57), p<0.003) but were no longer significant for NSTEMI cohort. CONCLUSION: Women continued to have longer system delays, receive less aggressive pharmacotherapies and invasive treatments with poorer outcome. There is an urgent need for increased effort from all stakeholders if we are to narrow this gap.


Assuntos
Síndrome Coronariana Aguda/epidemiologia , Doenças Cardiovasculares/epidemiologia , Síndrome Coronariana Aguda/tratamento farmacológico , Síndrome Coronariana Aguda/terapia , Inibidores da Enzima Conversora de Angiotensina/uso terapêutico , Povo Asiático , Aspirina/uso terapêutico , Doenças Cardiovasculares/tratamento farmacológico , Doenças Cardiovasculares/terapia , Gerenciamento de Dados , Bases de Dados Factuais , Feminino , Fibrinólise , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Masculino , Estudos Prospectivos , Sistema de Registros/estatística & dados numéricos , Fatores Sexuais , Resultado do Tratamento
12.
Acta Pharmaceutica Sinica B ; (6): 373-393, 2021.
Artigo em Inglês | WPRIM (Pacífico Ocidental) | ID: wpr-881142

RESUMO

The 18 kDa translocator protein (TSPO), previously known as the peripheral benzodiazepine receptor, is predominately localized to the outer mitochondrial membrane in steroidogenic cells. Brain TSPO expression is relatively low under physiological conditions, but is upregulated in response to glial cell activation. As the primary index of neuroinflammation, TSPO is implicated in the pathogenesis and progression of numerous neuropsychiatric disorders and neurodegenerative diseases, including Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), multiple sclerosis (MS), major depressive disorder (MDD) and obsessive compulsive disorder (OCD). In this context, numerous TSPO-targeted positron emission tomography (PET) tracers have been developed. Among them, several radioligands have advanced to clinical research studies. In this review, we will overview the recent development of TSPO PET tracers, focusing on the radioligand design, radioisotope labeling, pharmacokinetics, and PET imaging evaluation. Additionally, we will consider current limitations, as well as translational potential for future application of TSPO radiopharmaceuticals. This review aims to not only present the challenges in current TSPO PET imaging, but to also provide a new perspective on TSPO targeted PET tracer discovery efforts. Addressing these challenges will facilitate the translation of TSPO in clinical studies of neuroinflammation associated with central nervous system diseases.

13.
Nat Commun ; 11(1): 6432, 2020 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-33353940

RESUMO

2,3-Dihydrobenzofurans and indolines are common substructures in medicines and natural products. Herein, we describe a method that enables direct access to these core structures from non-conjugated alkenyl amides and ortho-iodoanilines/phenols. Under palladium(II) catalysis this [3 + 2] heteroannulation proceeds in an anti-selective fashion and tolerates a wide variety of functional groups. N-Acetyl, -tosyl, and -alkyl substituted ortho-iodoanilines, as well as free -NH2 variants, are all effective. Preliminary results with carbon-based coupling partners also demonstrate the viability of forming indane core structures using this approach. Experimental and computational studies on reactions with phenols support a mechanism involving turnover-limiting, endergonic directed oxypalladation, followed by intramolecular oxidative addition and reductive elimination.


Assuntos
Alcenos/química , Paládio/química , Compostos de Anilina/química , Simulação por Computador , Fenóis/química , Termodinâmica
14.
Angew Chem Int Ed Engl ; 58(47): 17068-17073, 2019 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-31538388

RESUMO

We report the development of palladium(0)-catalyzed syn-selective 1,2-carboboration and -silylation reactions of alkenes containing cleavable directing groups. With B2 pin2 or PhMe2 Si-Bpin as nucleophiles and aryl/alkenyl triflates as electrophiles, a broad range of mono-, di-, tri- and tetrasubstituted alkenes are compatible in these transformations. We further describe a directed dearomative 1,2-carboboration of electron-rich heteroarenes by employing this approach. Through use of a removable chiral directing group, we demonstrate the viability of achieving stereoinduction in Heck-type alkene 1,2-difunctionalization. This work introduces new avenues to access highly functionalized boronates and silanes with precise regio- and stereocontrol.


Assuntos
Alcenos/química , Compostos Heterocíclicos/química , Paládio/química , Silanos/química , Catálise , Ciclização , Estrutura Molecular
15.
J Am Chem Soc ; 141(11): 4670-4677, 2019 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-30807127

RESUMO

The control of chemo-, regio-, diastereo-, and enantioselectivity is a central theme in organic synthesis. The capability to obtain the full set of stereoisomers of a molecule would significantly enhance the efficiency for the synthesis of natural product analogues and creation of chiral compound libraries for drug discovery. Despite the tremendous progress achieved in the field of asymmetric synthesis in the past decades, the precise control of both relative and absolute configurations in catalyst-controlled reactions that create multiple stereocenters remains a significant synthetic challenge. We report here the development of a catalyst-controlled hydroboration with hitherto unattainable selectivity. The Rh-catalyzed hydroboration of α, ß-unsaturated carbonyl compounds with pinacolborane proceeds with high levels of regio-, diastereo-, and enantioselectivities to provide a hydroboration product with two vicinal stereocenters. Through the appropriate choice of substrate geometry ( E or Z) and ligand enantiomer ( S or R), all the possible diastereoisomers are readily accessible. The boron-containing products underwent many stereospecific transformations, thus providing a strategy for collective stereodivergent synthesis of diverse valuable chiral building blocks.

16.
Cells Tissues Organs ; 208(1-2): 13-24, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-32045921

RESUMO

OBJECTIVE: The aim of this work was to determine the effect of miR-375 on chondrocyte metabolism and oxidative stress in osteoarthritis (OA) mouse models through the JAK2/STAT3 signaling pathway. METHODS: Chondrocytes were divided into control, IL-1ß, IL-1ß + miR-375 mimic, IL-1ß + miR-375 inhibitor, IL-1ß + miR-NC (negative control), and IL-1ß + miR-375 inhibitor + siJAK2 groups. The chondrocyte proliferation was determined by MTT assay, the superoxide dismutase (SOD) and malondialdehyde (MDA) levels by corresponding kits, and the chondrocyte apoptosis by TUNEL staining. Furthermore, OA mouse models were divided into Sham, OA + miR-NC, and OA + miRNA-375 antagomir groups. The pathological changes were observed, and the expressions of miR-375 and the JAK2/STAT3 pathway were determined by qRT-PCR and Western blotting, respectively. RESULTS: IL-1ß-induced chondrocytes had significant increases in miR-375 and MDA, with decreased proliferation and SOD levels, as compared to the control group. Meanwhile, they also exhibited elevated apoptosis, with upregulations of ADAMTS-5 and MMP-13 and downregulations of COL2A1 and ACAN, as well as decreased p-JAK2/JAK2, p-STAT3/STAT3, and Bcl-2/Bax. However, these changes were significantly improved after transfection with miR-375 inhibitor, but transfection with miR-375 mimic resulted in severer exacerbation. Notably, the improvement of miR-375 inhibitor could be abolished by transfection with siJAK2. Furthermore, miR-375 antagomir significantly alleviated OA progression in OA mice in vivo. CONCLUSION: MiR-375 suppression enhanced the ability of chondrocyte to antagonize the oxidative stress and maintained the homeostasis of extracellular matrix metabolism to protect chondrocytes from OA via activation of the JAK2/STAT3 pathway, indicating that miR-375 is a potential molecular target for OA treatment.


Assuntos
Condrócitos/patologia , MicroRNAs/metabolismo , Osteoartrite , Animais , Apoptose , Modelos Animais de Doenças , Desenvolvimento de Medicamentos , Interleucina-1beta/metabolismo , Janus Quinase 2/metabolismo , Camundongos , Osteoartrite/tratamento farmacológico , Osteoartrite/metabolismo , Estresse Oxidativo , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais
17.
Artigo em Inglês | WPRIM (Pacífico Ocidental) | ID: wpr-776627

RESUMO

OBJECTIVE@#To explore the action mechanisms of Huangqi Decoction Granules (, HQDG) on hepatitis B cirrhosis.@*METHODS@#A total of 85 patients with hepatitis B cirrhosis were randomly divided into HQDG group (42 cases) and control group (43 cases) by a random number table and were treated with HQDG or placebo for 48 weeks (6 g per times and orally for 3 times a day), respectively. After RNA-sequencing of serum samples extracted from the patients, the differentially expressed genes (DEGs) in HQDG and control groups before and after treatment were separately screened. The DEGs were then performed pathway enrichment analysis and proteinprotein interaction (PPI) network analysis. The expression levels of key genes were detected by quantitative realtime polymerase chain reaction (qRT-PCR).@*RESULTS@#After the investigation, 4 and 3 cases were respectively excluded from HQD and control groups because of the incomplete data. Additionally, 3 and 5 cases were lost to follow up in HQD and control groups respectively. Finally, a total of 70 cases with good compliance were included for further DEGs analysis. A total of 1,070 DEGs (including 455 up-regulated genes and 615 down-regulated genes) in HQDG group and 227 DEGs (including 164 up-regulated genes and 63 down-regulated genes) in the control group were identified after treatment. Compared with the control group, 1,043 DEGs were specific in HQDG group. Besides, 1 up-regulated transcription factor (TF, such as GLI family zinc finger 1, GLI1) and 25 down-regulated TFs (such as drosophila mothers against decapentaplegic proteinfamily member 2, SMAD2) were identified. Pathway enrichment analysis showed that down-regulated Ras homolog gene family member A (RHOA) was enriched in pathogenic Escherichia coli infection. In the PPI network, up-regulated epidermal growth factor receptor (EGFR), and down-regulated cell division cycle 42 (CDC42) as well as v-akt murine thymoma viral oncogene homolog 1 (AKT1) had higher degrees. Moreover, long non-coding RNAs (lncRNA) growth arrest-specific 5 (GAS5) was involved in the lncRNA-target regulatory network. Furthermore, qRT-PCR revealed that expression levels of CDC42 and GLI1 had significant differences in HQDG group before and after treatment (P<0.05).@*CONCLUSIONS@#CDC42 and GLI1 may be the targets of HQDG in patients with hepatitis B cirrhosis. Additionally, SMAD2, EGFR, AKT1, RHOA and GAS5 might be associated with the curative effect of HQDG on hepatitis B cirrhosis patients.

18.
Am J Case Rep ; 19: 314-319, 2018 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-29551765

RESUMO

BACKGROUND Melioidosis is a rare tropical bacterial infection caused by the Gram-negative soil saprophyte, Burkholderia pseudomallei. Melioidosis can mimic a variety of diseases due to its varied presentation, and unless it is treated rapidly, it can be fatal.  A rare case of melioidosis, with pericarditis and pericardial effusion, is described, which demonstrates the value of early diagnosis with echocardiography and pericardiocentesis. CASE REPORT A 38-year-old native (Iban) East Malaysian man presented with shortness of breath and tachycardia. Transthoracic echocardiography (TTE) showed cardiac tamponade. Urgent pericardiocentesis drained a large amount of purulent pericardial fluid that grew Burkholderia pseudomallei. Despite appropriate dose and duration of intravenous treatment with ceftazidime followed by meropenem, the patient developed recurrent pericardial effusion and right heart failure due to constrictive pericarditis. The diagnosis of constrictive pericarditis was confirmed by computed tomography (CT) and surgical exploration. Following pericardiectomy, his symptoms resolved, but patient follow-up was recommended for possible sequelae of constrictive pericarditis. CONCLUSIONS After the onset of melioidosis pericarditis, the authors recommend follow-up and surveillance for possible complication of constrictive pericarditis.


Assuntos
Melioidose/complicações , Pericardiectomia/métodos , Pericardite Constritiva/etiologia , Adulto , Burkholderia pseudomallei/isolamento & purificação , Progressão da Doença , Ecocardiografia , Humanos , Masculino , Melioidose/diagnóstico , Melioidose/microbiologia , Pericardite Constritiva/microbiologia , Pericardite Constritiva/cirurgia , Tomografia Computadorizada por Raios X
19.
Chinese Pharmaceutical Journal ; (24): 646-651, 2018.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-858369

RESUMO

OBJECTIVE: To evaluate the effectiveness of pharmacist-participated warfarin anticoagulation management by patient education and medication consultation on patients with pulmonary embolism(PE). METHODS: A total of 204 PE patients were hospitalized in respiratory wards from March 2015 to April 2017 enrolled eventually. Evaluation endpoints including the percentage of INRs within the therapeutic range(TTR), the percentage of INRs within the expanded range(TER), INR recall intervals, bleeding events, emergency department visits and hospitalizations related to anticoagulation therapy. RESULTS: TTR and TER of intervention group were(70.89 ± 26.02)% and (87.71 ± 20.01)% respectively, which were both significantly higher than (47.79 ± 22.31)% and (71.23 ± 21.47)% in control group(P = 0.000). INR recall intervals were(27.48 ± 12.81) d versus(43.35 ± 13.65) d (P = 0.000). There were no significant differences between two groups in total bleeding events(41.96% vs 29.35%, P = 0.062), minor bleeding events(38.39% vs 27.17%, P = 0.091) and major bleeding events(3.57% vs 2.17%, P = 0.864). And a significantly decreased in emergency department visits of intervention group(9.82% vs 1.09%, P = 0.008), whereas no difference was observed in hospitalizations(8.04% vs 2.17%, P = 0.125). CONCLUSION: Clinical pharmacists participated in anticoagulation management of pulmonary embolism patients, which helped patients to monitor INRs more regularly, INR controlling better and decrease frequency of emergency department visits.

20.
J Geriatr Cardiol ; 13(9): 749-759, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27899939

RESUMO

OBJECTIVE: To investigate the risk factors of symptomatic bradyarrhythmias in relation to ß-blockers use. METHODS: A hospital-based case-control study [228 patients: 108 with symptomatic bradyarrhythmias (cases) and 120 controls] was conducted in Sultanah Aminah Hospital, Malaysia between January 2011 and January 2014. RESULTS: The mean age was 61.1 ± 13.3 years with a majority of men (68.9%). Cases were likely than control to be older, hypertensive, lower body mass index and concomitant use of rate-controlling drugs (such as digoxin, verapamil, diltiazem, ivabradine or amiodarone). Significantly higher level of serum potassium, urea, creatinine and lower level of estimated glomerular filtration rate (eGFR) were observed among cases as compared to controls. On univariate analysis among patients on ß-blockers, older age (crude OR: 1.07; 95% CI: 1.03-1.11, P = 0.000), hypertension (crude OR: 5.6; 95% CI: 1.51-20.72, P = 0.010), lower sodium (crude OR: 0.04; 95% CI: 0.81-0.99, P = 0.036), higher potassium (crude OR: 2.36; 95% CI: 1.31-4.26, P = 0.004) and higher urea (crude OR: 1.23; 95% CI: 1.11-1.38, P = 0.000) were associated with increased risk of symptomatic bradyarrhythmias; eGFR was inversely and significantly associated with symptomatic bradyarrhythmias in both 'ß-blockers' (crude OR: 0.97; 95% CI: 0.96-0.98, P = 0.000) and 'non-ß-blockers' (crude OR: 0.99; 95% CI: 0.97-0.99, P = 0.023) arms. However, eGFR was not significantly associated with symptomatic bradyarrhythmias in the final model of both 'ß-blockers' (adjusted OR: 0.98; 95% CI: 0.96-0.98, P = 0.103) and 'non-ß-blockers' (adjusted OR: 0.99; 95% CI: 0.97-1.01, P = 0.328) arms. Importantly, older age was a significant predictor of symptomatic bradyarrhythmias in the 'ß-blockers' as compared to the 'non-ß-blockers' arms (adjusted OR: 1.09; 95% CI: 1.03-1.15, P = 0.003 vs. adjusted OR: 1.03; 95% CI: 0.98-1.09, P = 0.232, respectively). CONCLUSION: Older age was a significant predictor of symptomatic bradyarrhythmias in patients on ß-blockers than those without ß-blockers.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...