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1.
BMC Plant Biol ; 24(1): 819, 2024 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-39215284

RESUMO

BACKGROUND: Salt stress is a major abiotic factor that affects the distribution and growth of plants. Asparagus officinalis is primarily resistant to salt stress and is suitable for cultivation in saline-alkali soil. RESULTS: The study integrated the morphology, physiological indexes, and transcriptome of A. officinalis exposed to different levels of NaCl, with the aim of understanding its biological processes under salt stress. The findings indicated that exposure to salt stress led to decreases in the height and weight of A. officinalis plants. Additionally, the levels of POD and SOD, as well as the amounts of MDA, proline, and soluble sugars, showed an increase, whereas the chlorophyll content decreased. Analysis of the transcriptome revealed that 6,203 genes that showed differential expression at different salt-stress levels. Various TFs, including FAR1, MYB, NAC, and bHLH, exhibited differential expression under salt stress. KEGG analysis showed that the DEGs were primarily associated with the plant hormone signal transduction and lignin biosynthesis pathways. CONCLUSION: These discoveries provide a solid foundation for an in-depth exploration of the pivotal genes, including Aux/IAA, TCH4, COMT, and POD, among others, as well as the pathways involved in asparagus's salt stress responses. Consequently, they have significant implications for the future analysis of the molecular mechanisms underlying asparagus's response to salt stress.


Assuntos
Asparagus , Perfilação da Expressão Gênica , Estresse Salino , Asparagus/genética , Asparagus/efeitos dos fármacos , Estresse Salino/genética , Transcriptoma , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Genes de Plantas
2.
Sensors (Basel) ; 24(11)2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38894239

RESUMO

OBJECTIVE: The aim was to evaluate and optimize the performance of sensor monitors in measuring PM2.5 and PM10 under typical emission scenarios both indoors and outdoors. METHOD: Parallel measurements and comparisons of PM2.5 and PM10 were carried out between sensor monitors and standard instruments in typical indoor (2 months) and outdoor environments (1 year) in Shanghai, respectively. The optimized validation model was determined by comparing six machining learning models, adjusting for meteorological and related factors. The intra- and inter-device variation, measurement accuracy, and stability of sensor monitors were calculated and compared before and after validation. RESULTS: Indoor particles were measured in a range of 0.8-370.7 µg/m3 and 1.9-465.2 µg/m3 for PM2.5 and PM10, respectively, while the outdoor ones were in the ranges of 1.0-211.0 µg/m3 and 0.0-493.0 µg/m3, correspondingly. Compared to machine learning models including multivariate linear model (ML), K-nearest neighbor model (KNN), support vector machine model (SVM), decision tree model (DT), and neural network model (MLP), the random forest (RF) model showed the best validation after adjusting for temperature, relative humidity (RH), PM2.5/PM10 ratios, and measurement time lengths (months) for both PM2.5 and PM10, in indoor (R2: 0.97 and 0.91, root-mean-square error (RMSE) of 1.91 µg/m3 and 4.56 µg/m3, respectively) and outdoor environments (R2: 0.90 and 0.80, RMSE of 5.61 µg/m3 and 17.54 µg/m3, respectively), respectively. CONCLUSIONS: Sensor monitors could provide reliable measurements of PM2.5 and PM10 with high accuracy and acceptable inter and intra-device consistency under typical indoor and outdoor scenarios after validation by RF model. Adjusting for both climate factors and the ratio of PM2.5/PM10 could improve the validation performance.

3.
Plant J ; 110(3): 781-801, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35132706

RESUMO

The efficiency of plant regeneration from explants is influenced by phytohormones and environmental conditions. Light has a particularly marked effect on in vitro shoot regeneration, and some light signaling factors are involved in shoot regeneration, while the underlying molecular mechanism remains elusive. Here, ELONGATED HYPOCOTYL5 (HY5), as the key transcription factor of light signaling, was found to inhibit shoot regeneration under a range of light conditions. The heightened shoot regeneration capacity of the hy5-215 mutant was less marked in the dark than in the light, showing that HY5-mediated inhibition of shoot regeneration is partly light dependent. The co-localization of WUSCHEL (WUS) and CLAVATA3 (CLV3) expressions was found to coincide with the initiation of stem cell niches in root explants during shoot regeneration. HY5 could directly repress CLV3 and WUS expression by binding to their respective promoters. In parallel, HY5 indirectly repressed CLV3 and WUS by binding to the ARABIDOPSIS RESPONSE REGULATOR12 (ARR12) promoter. The resulting dual regulation exerted by HY5 on WUS and CLV3 impeded the initiation of shoot stem cell niches. A HY5-mediated inhibitory pathway was identified that links cytokinin signaling and the pluripotency pathway during shoot regeneration.


Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/genética , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Citocininas/metabolismo , Regulação da Expressão Gênica de Plantas , Proteínas de Homeodomínio/genética , Brotos de Planta/metabolismo , Nicho de Células-Tronco
4.
Allergy ; 2023 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-37458141

RESUMO

BACKGROUND: The urban ambient air quality has been largely improved in the past decade. It is unknown whether childhood asthma prevalence is still increasing in ever top-ranking city of Shanghai, whether the improved air quality is beneficial for children's asthma and what time window of exposure plays critical roles. METHODS: Using a repeat cross-sectional design, we analyzed the association between early life exposure to particles and wheezing/asthma in each individual and combined surveys in 2011 and 2019, respectively, in 11,825 preschool children in Shanghai. RESULTS: A significantly lower prevalence of doctor-diagnosed asthma (DDA) (6.6% vs. 10.5%, p < 0.001) and wheezing (10.5% vs. 23.2%, p < 0.001) was observed in 2019 compared to 2011. Exposure to fine particulate matter (PM2.5 ), coarse particles (PM2.5-10 ) and inhalable particles (PM10 ) was decreased in 2019 by 6.3%, 35.4%, and 44.7% in uterus and 24.3%, 20.2%, and 31.8% in infancy, respectively. Multilevel log-binomial regression analysis showed exposure in infancy had independent association with wheezing/DDA adjusting for exposure in uterus. For each interquartile range (IQR) increase of infancy PM2.5 , PM2.5-10 and PM10 exposure, the odds ratios were 1.39 (95% confidence interval (CI): 1.24-1.56), 1.51 (95% CI:1.15-1.98) and 1.53 (95% CI:1.27-1.85) for DDA, respectively. The distributed lag non-linear model showed the sensitive exposure window (SEW) was 5.5-11 months after birth. Stratified analysis showed the SEWs were at or shortly after weaning, but only in those with <6 months of exclusive breastfeeding. CONCLUSIONS: Improved ambient PM benefits in decreasing childhood asthma prevalence. We firstly reported the finding of SEW to PM at or closely after weaning on childhood asthma.

5.
J Org Chem ; 87(1): 855-865, 2022 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-34905369

RESUMO

A novel aza-Piancatelli rearrangement triggered cascade reaction has been developed by utilizing methyl furylacrylates as a new type of functionalized furanoxonium ion precursor, permitting rapid and flexible construction of diverse cyclopenta[b]pyrrolidinone derivatives. The unprecedented and highly efficient bicyclic γ-lactam product formation is originated from an unusual retro-aza-Piancatelli rearrangement of the major cis-fused multifunctionalized cyclopentenone to the minor trans-fused one followed by a lactamization reaction.


Assuntos
Compostos de Anilina , Pirrolidinonas , Lactamas , Estereoisomerismo
6.
Acta Derm Venereol ; 102: adv00655, 2022 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-35083495

RESUMO

Cryotherapy is one of the most common treatments for warts; however, pain during treatment and relatively high recurrence rates limit its use. Local hyperthermia has also been used successfully in the treatment of plantar warts. The aim of this study was to compare the clinical effectiveness of local hyperthermia vs cryotherapy for the treatment of plantar warts. This multi- centre, open, 2-arm, non-randomized concurrent controlled trial included 1,027 patients, who received either cryotherapy or local hyperthermia treatment. Three months after treatment, local hyperthermia and cryotherapy achieved complete clearance rates of 50.9% and 54.3%, respectively. Recurrence rates were 0.8% and 12%, respectively. Pain scores during local hyperthermia were significantly lower than for cryotherapy. Both local hyperthermia and cryotherapy demonstrated similar efficacy for clearance of plantar warts; while local hyperthermia had a lower recurrence rate and lower pain sensation during treatment.


Assuntos
Hipertermia Induzida , Verrugas , Crioterapia/efeitos adversos , Humanos , Hipertermia Induzida/efeitos adversos , Estudos Prospectivos , Resultado do Tratamento , Verrugas/tratamento farmacológico
7.
Zhongguo Yi Liao Qi Xie Za Zhi ; 46(3): 342-345, 2022 May 30.
Artigo em Zh | MEDLINE | ID: mdl-35678449

RESUMO

OBJECTIVE: To solve the ESB bus performance and safety problems caused by the explosive growth of the hospital's business, and to ensure the stable interaction of the hospital's business system. METHODS: Taking the construction of our hospital's information system as an example, we used AlwaysOn, load balancing and other technologies to optimize the ESB bus architecture to achieve high availability and scalability of the hospital's ESB bus. RESULTS: The ESB bus high-availability architecture effectively eliminates multiple points of failure. Compared with the traditional dual-machine Cluster solution, the security is significantly improved. The nodes based on load balancing can be scaled horizontally according to the growth of the hospital's business volume. CONCLUSIONS: The construction of the ESB bus high-availability architecture effectively solves the performance and security issues caused by business growth, and provides practical experience for medical information colleagues. It has certain guiding significance for the development of regional medical information.


Assuntos
Sistemas de Informação Hospitalar , Sistemas de Informação
8.
Beilstein J Org Chem ; 17: 1171-1180, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34093882

RESUMO

A visible light-mediated heterogeneous photocatalytic cyanomethylarylation of alkenes with acetonitrile has been established using K-modified carbon nitride (CN-K) as a recyclable semiconductor photocatalyst. This protocol, employing readily accessible alkyl N-hydroxyphthalimide (NHPI) ester as a radical initiator, allows the efficient construction of a broad array of structural diverse nitrogenous heterocyclic compounds including indolines, oxindoles, isoquinolinones, and isoquinolinediones.

9.
Mikrochim Acta ; 187(8): 449, 2020 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-32676680

RESUMO

Graphitic carbon nitride (g-C3N4) as an outstanding photoresponsive nanomaterial has been widely used in biosensing. Other than the conventional single channel sensing mode, a triple-channel sensing array was developed for high discrimination of proteins based on the photoresponsive g-C3N4. Besides the photoluminescence and Rayleigh light scattering features of g-C3N4, we exploit the new photosensitive colorimetry of g-C3N4 as the third channel optical input. The triple-channel optical behavior of g-C3N4 can be synchronously changed after interaction with the protein, resulting in the distinct response patterns related to each specific protein. Such a triple-channel sensing array is demonstrated for highly discriminative and precise identification of nine proteins (hemoglobin, trypsin, lysozyme, cytochrome c, horseradish peroxidase, transferrin, human serum albumin, pepsin, and myoglobin) at 1 µM concentration levels with 100% accuracy. It also can discriminate proteins being present at different concentration and protein mixtures with different content ratios. The practicability of this sensor array is validated by high accuracy identification of nine proteins in human urine samples. This indicates that the array has a great potential in terms of analyzing biological fluids. Graphic abstract .


Assuntos
Grafite/química , Nanoestruturas/química , Compostos de Nitrogênio/química , Proteínas/análise , Armoracia/enzimologia , Colorimetria/métodos , Grafite/efeitos da radiação , Humanos , Luz , Nanoestruturas/efeitos da radiação , Compostos de Nitrogênio/efeitos da radiação , Urina/química
10.
Sensors (Basel) ; 20(1)2020 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-31948079

RESUMO

Adaptive filtering has the advantages of real-time processing, small computational complexity, and good adaptability and robustness. It has been widely used in communication, navigation, signal processing, optical fiber sensing, and other fields. In this paper, by adding an interferometer with the same parameters as the signal interferometer as the reference channel, the sensing signal of the interferometric fiber-optic hydrophone is denoised by two adaptive filtering schemes based on the least mean square (LMS) algorithm and the normalized least mean square (NLMS) algorithm respectively. The results show that the LMS algorithm is superior to the NLMS algorithm in reducing total harmonic distortion, improving the signal-to-noise ratio and filtering effect.

11.
Int J Mol Sci ; 21(8)2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-32326350

RESUMO

Botrytis cinerea is a pathogenic fungus that causes gray mold disease in a broad range of crops. The high intraspecific variability of B. cinerea makes control of this fungus very difficult. Here, we isolated a variant B05.10M strain from wild-type B05.10. The B05.10M strain showed serious defects in mycelial growth, spore and sclerotia production, and virulence. Using whole-genome resequencing and site-directed mutagenesis, a single nucleotide mutation in the adenylate cyclase (BAC) gene that results in an amino acid residue (from serine to proline, S1407P) was shown to be the cause of various defects in the B05.10M strain. When we further investigated the effect of S1407 on BAC function, the S1407P mutation in bac showed decreased accumulation of intracellular cyclic AMP (cAMP), and the growth defect could be partially restored by exogenous cAMP, indicating that the S1407P mutation reduced the enzyme activity of BAC. Moreover, the S1407P mutation exhibited decreased spore germination rate and infection cushion formation, and increased sensitivity to cell wall stress, which closely related to fungal development and virulence. Taken together, our study indicates that the S1407 site of bac plays an important role in vegetative growth, sclerotial formation, conidiation and virulence in B. cinerea.


Assuntos
Adenilil Ciclases/genética , Botrytis/fisiologia , Micoses/genética , Micoses/microbiologia , Polimorfismo de Nucleotídeo Único , Adenilil Ciclases/metabolismo , Botrytis/patogenicidade , Parede Celular/metabolismo , Ativação Enzimática , Regulação Fúngica da Expressão Gênica , Genoma Fúngico , Genômica/métodos , Mutação , Fenótipo , Esporos Fúngicos , Virulência , Sequenciamento Completo do Genoma
12.
Chemistry ; 25(29): 7177-7184, 2019 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-30861204

RESUMO

A hydrogen atom transfer-directed electrochemical intramolecular C-H amination has been developed in which the N-radical species are generated at the anode, and the base required for the reaction is generated at the cathode. A broad range of valuable pyrrolidines were prepared in good yields and with high chemoselectivity. The reaction was easily scaled up in both batch and continuous flow systems.

13.
Eur Radiol ; 29(2): 725-735, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29992386

RESUMO

OBJECTIVES: To assess the performance of sonoelastography for differential diagnosis between malignant and benign parotid lesions using a meta-analysis. METHODS: An independent literature search of English medical databases, such as PubMed, Embase and Medline ( Embase.com ), Web of Science, Cochrane Library and Ovid was performed. The diagnostic accuracy of sonoelastography was compared with that of histopathology and/or cytology, which was used as reference standard. The pooled sensitivity, specificity, diagnostic odds ratio (DOR) and area under the curve (AUC) were calculated to evaluate the accuracy of sonoelastography. A meta-regression analysis evaluating imaging mechanisms, shear wave elastography techniques, assessment methods and QUADAS scores was performed. RESULTS: Ten eligible studies that included a total sample of 711 patients with 725 parotid lesions were included. Sonoelastography showed a pooled sensitivity of 0.67 (95% CI 0.59-0.74), specificity of 0.64 (95% CI 0.60-0.68), DOR of 8.00 (95% CI 2.96-21.63) and an AUC of 0.77. The results of the meta-regression analysis revealed that no heterogeneity was due to the imaging mechanism (p = 0.119), shear wave elastography technique (p = 0.473) or QUADAS score (p = 0.462). However, the assessment method was a significant factor that affected the study heterogeneity (p = 0.035). According to the subgroup analysis, quantitative and semiquantitative methods performed better than qualitative ones. CONCLUSION: Overall, sonoelastography has a limited value for differential diagnosis between malignant and benign parotid lesions. Quantitative and semiquantitative methods perform better than qualitative ones. KEY POINTS: • Overall, sonoelastography has a limited value for differential diagnosis between malignant and benign parotid lesions. • Quantitative and semiquantitative assessment methods perform better than qualitative ones. • Semiquantitative and quantitative methods are automatically calculated by an ultrasound machine and are thus less operator-dependent.


Assuntos
Técnicas de Imagem por Elasticidade/métodos , Doenças Parotídeas/diagnóstico , Glândula Parótida/diagnóstico por imagem , Diagnóstico Diferencial , Humanos
14.
J Org Chem ; 84(1): 1-13, 2019 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-30339377

RESUMO

Halofunctionalization methods enable the vicinal difunctionalization of alkenes with heteroatom nucleophiles and halogen moieties. As a fundamental transformation in organic synthesis, the catalytic asymmetric variants have only recently been reported. In sharp contrast to the asymmetric halocyclization of simple alkenes which involves a nucleophile-assisted alkene activation process, the asymmetric halofunctionalization of enones developed by our laboratory features an electrophile-assisted 1,4-addition pathway. Our work in this area has resulted in the development of several different types of regio-, diastereo-, and enantioselective processes, including inter- and intramolecular haloaminations, haloetherifications, and haloazidations. The scope, updated mechanism, limitations, and future perspective of these reactions are discussed.

15.
Environ Res ; 179(Pt A): 108749, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31557603

RESUMO

To evaluate the short-term effects of filtered fresh air ventilation system on classroom indoor air and biomarkers in saliva and nasal samples in preschool children, a randomized crossover study was conducted in a kindergarten in Shanghai, China in 2016. Two classrooms at the same grade (n = 43) were selected and fresh air ventilation systems (FAVS) with high efficiency particulate air filter (HEPA) were installed. In the first week, FAVS-HEPA was run in one classroom for 2 continuous school days and the other classroom was remained as usual with no use of FAVS-HEPA. After one week of wash-out, the ventilation modes exchanged between two classrooms and another 2 days of intervention were repeated. Real-time indoor and outdoor air pollution and climate factors (PM2.5, Temp and relative humidity (R.H.)) were measured. Saliva and nasal internal mucosa samples were collected immediately at the end of each intervention scenario. Linear mixed-effect regression model was applied to evaluate the effects of intervention on children's health indicators controlling for age, gender, height, BMI and temperature. The results showed, with FAVS-HEPA, the classroom indoor fine particulate matter (PM2.5)(29.1 ±â€¯17.9 µg/m3) was on average significantly lower than that without FAVS-HEPA (85.7 ±â€¯43.2 µg/m3). By regression analysis, each 10 µg/m3 decrease of indoor PM2.5 during the 8 school hours in the first intervention day was associated with an average of 1.76% (95% confidence interval (CI) 0.43-3.08%) increase in saliva lysozyme. This percentage increased to 2.41% (95%CI 0.52-4.26%) if related to the PM2.5 level in 16 school hours over 2 days of intervention. A total of 19 nasal bacterial taxa were lower in subjects exposed to FAVS-HEPA, compared to that with no use of FAVS-HEPA, despite the general bacteria diversity levels in nasal samples were not statistically different. Among others, Providencia species showed significant effects in mediating the associations between higher PM2.5 and lower lysozyme. In conclusion, using FAVS-HEPA was effective in decreasing the classroom indoor PM2.5. Saliva lysozyme, as a non-specific immune biomarker, was significantly inversely associated with indoor PM2.5. Certain nasal bacteria might play key roles in mediating PM2.5 exposure and children's lysozyme levels.


Assuntos
Poluentes Atmosféricos , Poluição do Ar em Ambientes Fechados/análise , Exposição por Inalação/análise , Ventilação/métodos , Poluição do Ar em Ambientes Fechados/estatística & dados numéricos , Biomarcadores/metabolismo , Pré-Escolar , China , Estudos Cross-Over , Humanos , Exposição por Inalação/estatística & dados numéricos , Material Particulado , Saliva/metabolismo , Instituições Acadêmicas
16.
BMC Complement Altern Med ; 19(1): 178, 2019 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-31324247

RESUMO

BACKGROUND: To evaluate the effectiveness and safety of HuoXueHuaYu (HXHY) therapy in treating nonalcoholic fatty liver disease (NAFLD) through a systematic review and meta-analysis. METHODS: We performed comprehensive searches on Embase, Pubmed, Cochrane Library, CNKI, VIP and Wanfang databases up to June 2017 for randomized controlled trials using HXHY in the treatment of NAFLD compared with conventional treatment. RESULTS: This meta-analysis included 13 studies involving 1429 patients which 775 patients belonged to HXHY group and 654 patients belonged to conventional treatment group. The results of meta-analysis showed that HXHY can significantly improve B ultrasonic level (OR = 2.33; 95% CI:1.60, 3.40; P < 0.00001) of NAFLD compared with conventional treatment. As to lipids, HXHY was tested to be better on reduction of total cholesterol (TC) (MD = -0.38, 95% CI: - 0.48, - 0.29; P < 0.00001) and triglyceride (TG) (MD = -0.31; 95% CI: - 0.37, - 0.24; P < 0.00001) than conventional treatment. HXHY also had a greater beneficial effect on liver function in reducing alanine transaminase (ALT) (MD = -1.69; 95% CI: - 2.24, - 1.14; P < 0.00001) and aspartate transaminase (AST) (MD = -22.53; 95% CI: - 33.16, - 11.90; P < 0.00001) compared with conventional treatment. HXHY can also significantly improve the effective rate (OR = 3.55; 95% CI:2.65, 4.76; P < 0.00001) compared with conventional treatment. No serious adverse reactions were reported. CONCLUSIONS: HXHY seems to be an effective and safe therapy for NAFLD. It is suggested that further study of HXHY in the treatment of NAFLD requires trials with rigorous design, multicenter, large-scale and high-quality worldwide.


Assuntos
Medicamentos de Ervas Chinesas/administração & dosagem , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Adulto , Idoso , Feminino , Humanos , Fígado , Masculino , Pessoa de Meia-Idade , Ensaios Clínicos Controlados Aleatórios como Assunto , Resultado do Tratamento , Triglicerídeos/metabolismo
17.
Angew Chem Int Ed Engl ; 56(15): 4282-4285, 2017 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-28294473

RESUMO

An efficient nickel-catalyzed decarbonylative amination reaction of aryl and heteroaryl esters has been achieved for the first time. The new amination protocol allows the direct interconversion of esters and amides into the corresponding amines and represents a good alternative to classical rearrangements as well as cross coupling reactions.

18.
Angew Chem Int Ed Engl ; 55(45): 14126-14130, 2016 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-27723211

RESUMO

The first catalytic asymmetric Piancatelli reaction is reported. Catalyzed by a chiral Brønsted acid, the rearrangement of a wide range of furylcarbinols with a series of aniline derivatives provides valuable aminocyclopentenones in high yields as well as excellent enantioselectivities and diastereoselectivities. The high value of the aza-Piancatelli rearrangement was demonstrated by the synthesis of a cyclopentane-based hNK1 antagonist analogue.

19.
Chemistry ; 21(17): 6386-9, 2015 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-25760895

RESUMO

An asymmetric synthesis of cyclic sulfamates by catalytic haloaminocyclization of primary sulfamate ester derivatives is described. The remarkable reversal of diastereoselectivity was found to be dependent on the halogen source and the chiral catalyst. By using privileged complexes of N,N'-dioxides with Sc(OTf)3 or Lu(OTf)3 as the catalyst, a variety of enantioenriched syn- and anti-cyclic sulfamates or related trans-aziridines could be obtained in 92-99 % ee and up to 97 % yield.

20.
Nat Cell Biol ; 10(9): 1062-8, 2008 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19160486

RESUMO

Cell spreading, adhesion and remodelling of the extracellular matrix (ECM) involve bi-directional signalling and physical linkages between the ECM, integrins and the cell cytoskeleton. The actin-binding proteins talin1 and 2 link ligand-bound integrins to the actin cytoskeleton and increase the affinity of integrin for the ECM. Here we report that depletion of talin2 in talin1-null (talin1(-/-)) cells did not affect the initiation of matrix-activated spreading or Src family kinase (SFK) activation, but abolished the ECM-integrin-cytoskeleton linkage and sustained cell spreading and adhesion. Specifically, focal adhesion assembly, focal adhesion kinase (FAK) signalling and traction force generation on substrates were severely affected. The talin1 head domain restored beta1 integrin activation but only full-length talin1 restored the ECM-cytoskeleton linkage and normal cytoskeleton organization. Our results demonstrate three biochemically distinct steps in fibronectin-activated cell spreading and adhesion: (1) fibronectin-integrin binding and initiation of spreading, (2) fast cell spreading and (3) focal adhesion formation and substrate traction. We suggest that talin is not required for initial cell spreading. However, talin provides the important mechanical linkage between ligand-bound integrins and the actin cytoskeleton required to catalyse focal adhesion-dependent pathways.


Assuntos
Movimento Celular , Fibroblastos/citologia , Integrina beta1/metabolismo , Talina/deficiência , Actomiosina/metabolismo , Animais , Adesão Celular/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Fibroblastos/efeitos dos fármacos , Fibroblastos/enzimologia , Fibronectinas/farmacologia , Quinase 1 de Adesão Focal/metabolismo , Adesões Focais/efeitos dos fármacos , Adesões Focais/enzimologia , Proteínas de Fluorescência Verde/metabolismo , Humanos , Camundongos , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Fosfotirosina/metabolismo , Proteínas Recombinantes de Fusão/metabolismo
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