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1.
Alzheimers Dement ; 19(11): 5074-5085, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37186161

RESUMO

INTRODUCTION: The prevalence and risk factors for subjective cognitive decline (SCD) and its correlation with objective cognition decline (OCD) among community-dwelling older adults is inconsistent. METHODS: Older adults underwent neuropsychological and clinical evaluations to reach a consensus on diagnoses. RESULTS: This study included 7486 adults without mild cognitive impairment and dementia (mean age: 71.35 years [standard deviation = 5.40]). The sex-, age-, and residence-adjusted SCD prevalence was 58.33% overall (95% confidence interval: 58.29% to 58.37%), with higher rates of 61.25% and 59.87% in rural and female subgroups, respectively. SCD global and OCD language, SCD memory and OCD global, SCD and OCD memory, and SCD and OCD language were negatively correlated in fully adjusted models. Seven health and lifestyle factors were associated with an increased risk for SCD. DISCUSSION: SCD affected 58.33% of older adults and may indicate concurrent OCD, which should prompt the initiation of preventative intervention for dementia. HIGHLIGHTS: SCD affects 58.33% of older adults in China. SCD may indicate concurrent objective cognitive decline. Difficulty finding words and memory impairments may indicate a risk for AD. The presence of SCD may prompt preventative treatment initiation of MCI or dementia. Social network factors may be initial targets for the early prevention of SCD.


Assuntos
Disfunção Cognitiva , Demência , Humanos , Feminino , Idoso , Estudos de Coortes , Prevalência , Vida Independente , Disfunção Cognitiva/psicologia , Cognição , Envelhecimento , Fatores de Risco , Demência/etiologia , Testes Neuropsicológicos
2.
Bioorg Chem ; 112: 104863, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33823405

RESUMO

The chemoenzymatic remodeled monoclonal antidodies with well-defined glycan structure at the Fc domain display improved biological activities, such as ADCC and ADCP, and are more likely to yield a better safety profile by eliminating the non-human glycans derived from CHO cell culture. We covalently immobilize wild type endoglycosidase S (EndoS), fucosidase, and EndoS2 mutant on magnetic beads through a linker to efficiently generate homogeneous antibody glycoforms without additional purification step to remove endoglycosidase and fucosidase. We also used the biotinylated wild type EndoS2 and EndoS2 mutant in combination with covalently immobilized fucosidase on magnetic beads to allow the sequential removal of endoglycosidases and fucosidase for efficient glyco-engineering and isolation of antibodies without purifying deglycosylated antibody intermediate. Notably, the relatively expensive fucosidase can be recovered to reduce the cost, and the strong affinity of streptavidin to biotin would complete the isolation of biotinylated enzymes. We used Trastuzumab as a model to demonstrate both approaches were reliable for the large-scale production and isolation of antibodies without the residual contamination of endoglycosidase to avoid deglycosylation over storage time.


Assuntos
Antibacterianos/metabolismo , Desenvolvimento de Medicamentos , Glicosídeo Hidrolases/metabolismo , Trastuzumab/metabolismo , alfa-L-Fucosidase/metabolismo , Antibacterianos/química , Antibacterianos/isolamento & purificação , Biotinilação , Relação Dose-Resposta a Droga , Enzimas Imobilizadas/genética , Enzimas Imobilizadas/metabolismo , Glicosídeo Hidrolases/genética , Fenômenos Magnéticos , Estrutura Molecular , Mutação , Relação Estrutura-Atividade , Trastuzumab/química , Trastuzumab/isolamento & purificação , alfa-L-Fucosidase/genética
3.
Mol Ther ; 28(4): 1016-1032, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32105604

RESUMO

Display of short peptides on the surface of adeno-associated viruses (AAVs) is a powerful technology for the generation of gene therapy vectors with altered cell specificities and/or transduction efficiencies. Following its extensive prior use in the best characterized AAV serotype 2 (AAV2), recent reports also indicate the potential of other AAV isolates as scaffolds for peptide display. In this study, we systematically explored the respective capacities of 13 different AAV capsid variants to tolerate 27 peptides inserted on the surface followed by production of reporter-encoding vectors. Single-round screening in pre-arrayed 96-well plates permitted rapid and simple identification of superior vectors in >90 cell types, including T cells and primary cells. Notably, vector performance depended not only on the combination of capsid, peptide, and cell type, but also on the position of the inserted peptide and the nature of flanking residues. For optimal data availability and accessibility, all results were assembled in a searchable online database offering multiple output styles. Finally, we established a reverse-transduction pipeline based on vector pre-spotting in 96- or 384-well plates that facilitates high-throughput library panning. Our comprehensive illustration of the vast potential of alternative AAV capsids for peptide display should accelerate their in vivo screening and application as unique gene therapy vectors.


Assuntos
Dependovirus/genética , Peptídeos/metabolismo , Análise Serial de Tecidos/métodos , Terapia Genética , Vetores Genéticos , Humanos , Biblioteca de Peptídeos , Peptídeos/genética , Transdução Genética , Proteínas Virais/genética , Proteínas Virais/metabolismo
4.
Molecules ; 24(18)2019 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-31487951

RESUMO

To obtain highly selective toxic derivatives of fipronil, a series of Schiff bases with an alkynyl group (3a-3k) were designed and synthesized from 4-ethynylbenzaldehyde (2) and 4-substituted 5-amino-N-arylpyrazole (1a-1k) via a nucleophilic addition elimination reaction in ionic liquids. Utilization of ionic liquids was demonstrated to endow the yield of each compound beyond 50%, which was enhanced over 1.5 times of the synthetic productive rates comparing the conventional method by which longer reactive time was consumed. The derivatives were characterized via nuclear magnetic resonance hydrogen spectroscopy (1H-NMR), carbon-13 nuclear magnetic resonance spectroscopy (13C-NMR), and electrospray ionization high resolution mass spectrometry (ESI-HRMS). The cytotoxicity of these derivatives on Trichoplusia ni (Hi-5) cell and Spodoptera litura cell (SL cell) was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) bioassays. The results indicated that several compounds had potential cytotoxicity on Hi-5 cell, especially a 4-ethyl substituted alkynyl Schiff base derivative (3f) that was demonstrated to possess high selective toxicity to the Hi-5 cell than the SL cell. In addition, 3f exhibited comparable toxic activity to commercial fipronil on a Hi-5 cell while a little toxic effect on the SL cell, which satisfied the expectation for selective toxicity screening.


Assuntos
Líquidos Iônicos/química , Pirazóis/síntese química , Pirazóis/farmacologia , Bases de Schiff/química , Antineoplásicos/química , Antineoplásicos/farmacologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Técnicas de Química Sintética , Humanos , Estrutura Molecular , Bases de Schiff/síntese química
5.
Biochemistry ; 56(40): 5417-5427, 2017 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-28872301

RESUMO

Bacteria cell walls contain many repeating glycan structures, such as peptidoglycans, lipopolysaccharides, teichoic acids, and capsular polysaccharides. Their synthesis starts in the cytosol, and they are constructed from a glycan lipid carrier, undecaprenyl phosphate (C55P), which is essential for cell growth and survival. The lipid derivative undecaprenol (C55OH) is predominant in many Gram-positive bacteria but has not been detected in Gram-negative bacteria; its origin and role have thus remained unknown. Recently, a homologue of diacylglycerol kinase (DgkA) in Escherichia coli (E. coli) was demonstrated to be an undecaprenol kinase (UK) in the Gram-positive bacterium Streptococcus mutans (S. mutans). In this study, we found that S. mutans UK was not only an undecaprenol kinase but also a Mg-ADP-dependent undecaprenyl phosphate phosphatase (UpP), catalyzing the hydrolysis of C55P to C55OH and a free inorganic phosphate. Furthermore, the naturally undetectable C55OH was observed in E. coli cells expressing S. mutans dgkA, supporting the phosphatase activity of UK/UpP in vivo. These two activities were indispensable to each other and utilized identical essential residues binding to their substrates, suggesting that both activities share the same active site and might involve a direct phosphoryl transfer mechanism. This study revealed a unique membrane enzyme displaying bifunctional activities determined by substrate binding and C55OH production. The reciprocal conversion of C55P and the undecaprenol pool efficiently regulate cell wall synthesis, especially in Gram-positive bacteria.


Assuntos
Metabolismo dos Lipídeos , Monoéster Fosfórico Hidrolases/metabolismo , Fosfotransferases (Aceptor do Grupo Álcool)/metabolismo , Fosfatos de Poli-Isoprenil/metabolismo , Streptococcus mutans/enzimologia , Difosfato de Adenosina/metabolismo , Modelos Moleculares , Monoéster Fosfórico Hidrolases/química , Fosforilação , Estrutura Secundária de Proteína , Especificidade por Substrato
6.
J Virol ; 90(11): 5219-5230, 2016 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-26962225

RESUMO

UNLABELLED: The adeno-associated viruses (AAVs), which are being developed as gene delivery vectors, display differential cell surface glycan binding and subsequent tissue tropisms. For AAV serotype 1 (AAV1), the first viral vector approved as a gene therapy treatment, and its closely related AAV6, sialic acid (SIA) serves as their primary cellular surface receptor. Toward characterizing the SIA binding site(s), the structure of the AAV1-SIA complex was determined by X-ray crystallography to 3.0 Å. Density consistent with SIA was observed in a pocket located at the base of capsid protrusions surrounding icosahedral 3-fold axes. Site-directed mutagenesis substitution of the amino acids forming this pocket with structurally equivalent residues from AAV2, a heparan sulfate binding serotype, followed by cell binding and transduction assays, further mapped the critical residues conferring SIA binding to AAV1 and AAV6. For both viruses five of the six binding pocket residues mutated (N447S, V473D, N500E, T502S, and W503A) abolished SIA binding, whereas S472R increased binding. All six mutations abolished or decreased transduction by at least 50% in AAV1. Surprisingly, the T502S substitution did not affect transduction efficiency of wild-type AAV6. Furthermore, three of the AAV1 SIA binding site mutants-S472R, V473D, and N500E-escaped recognition by the anti-AAV1 capsid antibody ADK1a. These observations demonstrate that common key capsid surface residues dictate both virus binding and entry processes, as well as antigenic reactivity. This study identifies an important functional capsid surface "hot spot" dictating receptor attachment, transduction efficiency, and antigenicity which could prove useful for vector engineering. IMPORTANCE: The adeno-associated virus (AAV) vector gene delivery system has shown promise in several clinical trials and an AAV1-based vector has been approved as the first gene therapy treatment. However, limitations still exist with respect to transduction efficiency and the detrimental effects of preexisting host antibodies. This study aimed to identify key capsid regions which can be engineered to overcome these limitations. A sialic glycan receptor recognition pocket was identified in AAV1 and its closely related AAV6, using X-ray crystallography. The site was confirmed by mutagenesis followed by cell binding and transduction assays. Significantly, residues controlling gene expression efficiency, as well as antibody escape variants, were also identified. This study thus provides, at the amino acid level, information for rational structural engineering of AAV vectors with improved therapeutic efficacy.


Assuntos
Proteínas do Capsídeo/química , Capsídeo/química , Dependovirus/química , Ácido N-Acetilneuramínico/metabolismo , Receptores Virais/metabolismo , Ligação Viral , Substituição de Aminoácidos/genética , Sítios de Ligação , Capsídeo/metabolismo , Proteínas do Capsídeo/genética , Proteínas do Capsídeo/metabolismo , Linhagem Celular , Cristalografia por Raios X , Dependovirus/genética , Vetores Genéticos , Modelos Moleculares , Mutagênese Sítio-Dirigida , Mutação , Ácido N-Acetilneuramínico/química , Ligação Proteica , Receptores Virais/química , Transdução Genética
7.
J Org Chem ; 79(18): 8629-37, 2014 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-25137529

RESUMO

We herein describe the first synthesis of iminosugar C-glycosides of α-D-GlcNAc-1-phosphate in 10 steps starting from unprotected D-GlcNAc. A diastereoselective intramolecular iodoamination-cyclization as the key step was employed to construct the central piperidine ring of the iminosugar and the C-glycosidic structure of α-D-GlcNAc. Finally, the iminosugar phosphonate and its elongated phosphate analogue were accessed. These phosphorus-containing iminosugars were coupled efficiently with lipophilic monophosphates to give lipid-linked pyrophosphate derivatives, which are lipid II mimetics endowed with potent inhibitory properties toward bacterial transglycosylases (TGase).


Assuntos
Acetilglucosamina/análogos & derivados , Proteínas de Bactérias/antagonistas & inibidores , Glicosídeos/química , Glicosiltransferases/antagonistas & inibidores , Glicosiltransferases/química , Imino Açúcares/síntese química , Acetilglucosamina/química , Proteínas de Bactérias/química , Glicosídeo Hidrolases/química , Imino Açúcares/química , Estrutura Molecular , Estereoisomerismo
8.
Angew Chem Int Ed Engl ; 53(31): 8060-5, 2014 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-24990652

RESUMO

The emergence of antibiotic resistance has prompted active research in the development of antibiotics with new modes of action. Among all essential bacterial proteins, transglycosylase polymerizes lipid II into peptidoglycan and is one of the most favorable targets because of its vital role in peptidoglycan synthesis. Described in this study is a practical enzymatic method for the synthesis of lipid II, coupled with cofactor regeneration, to give the product in a 50-70% yield. This development depends on two key steps: the overexpression of MraY for the synthesis of lipid I and the use of undecaprenol kinase for the preparation of polyprenol phosphates. This method was further applied to the synthesis of lipid II analogues. It was found that MraY and undecaprenol kinase can accept a wide range of lipids containing various lengths and configurations. The activity of lipid II analogues for bacterial transglycolase was also evaluated.


Assuntos
Enzimas/química , Uridina Difosfato Ácido N-Acetilmurâmico/análogos & derivados , Uridina Difosfato Ácido N-Acetilmurâmico/síntese química
9.
J Alzheimers Dis ; 98(3): 941-955, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38489185

RESUMO

Background: As a prodromal stage of dementia, significant emphasis has been placed on the identification of modifiable risks of mild cognitive impairment (MCI). Research has indicated a correlation between exposure to air pollution and cognitive function in older adults. However, few studies have examined such an association among the MCI population inChina. Objective: We aimed to explore the association between air pollution exposure and MCI risk from the Hubei Memory and Aging Cohort Study. Methods: We measured four pollutants from 2015 to 2018, 3 years before the cognitive assessment of the participants. Logistic regression models were employed to calculate odds ratios (ORs) to assess the relationship between air pollutants and MCI risk. Results: Among 4,205 older participants, the adjusted ORs of MCI risk for the highest quartile of PM2.5, PM10, O3, and SO2 were 1.90 (1.39, 2.62), 1.77 (1.28, 2.47), 0.56 (0.42, 0.75), and 1.18 (0.87, 1.61) respectively, compared with the lowest quartile. Stratified analyses indicated that such associations were found in both males and females, but were more significant in older participants. Conclusions: Our findings are consistent with the growing evidence suggesting that air pollution increases the risk of mild cognitive decline, which has considerable guiding significance for early intervention of dementia in the older population. Further studies in other populations and broader geographical areas are warranted to validate these findings.


Assuntos
Poluentes Atmosféricos , Poluição do Ar , Disfunção Cognitiva , Demência , Masculino , Feminino , Humanos , Idoso , Estudos de Coortes , Estudos de Casos e Controles , Exposição Ambiental/efeitos adversos , Exposição Ambiental/análise , Poluição do Ar/efeitos adversos , Poluição do Ar/análise , Poluentes Atmosféricos/efeitos adversos , Poluentes Atmosféricos/análise , Disfunção Cognitiva/epidemiologia , China/epidemiologia , Material Particulado/efeitos adversos , Material Particulado/análise
10.
J Am Chem Soc ; 135(45): 17078-89, 2013 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-24131464

RESUMO

The emergence of antibiotic resistance has prompted scientists to search for new antibiotics. Transglycosylase (TGase) is an attractive target for new antibiotic discovery due to its location on the outer membrane of bacteria and its essential role in peptidoglycan synthesis. Though there have been a few molecules identified as TGase inhibitors in the past thirty years, none of them have been developed into antibiotics for humans. The slow pace of development is perhaps due to the lack of continuous, quantitative, and high-throughput assay available for the enzyme. Herein, we report a new continuous fluorescent assay based on Förster resonance energy transfer, using lipid II analogues with a dimethylamino-azobenzenesulfonyl quencher in the lipid chain and a coumarin fluorophore in the peptide chain. During the process of transglycosylation, the quencher-appended polyprenol is released and the fluorescence of coumarin can be detected. Using this system, the substrate specificity and affinity of lipid II analogues bearing various numbers and configurations of isoprene units were investigated. Moreover, the inhibition constants of moenomycin and two previously identified small molecules were also determined. In addition, a high-throughput screening using the new assay was conducted to identify potent TGase inhibitors from a 120,000 compound library. This new continuous fluorescent assay not only provides an efficient and convenient way to study TGase activities, but also enables the high-throughput screening of potential TGase inhibitors for antibiotic discovery.


Assuntos
Bactérias/enzimologia , Transferência Ressonante de Energia de Fluorescência/métodos , Peptidoglicano Glicosiltransferase/metabolismo , Cumarínicos/química , Cumarínicos/metabolismo , Ensaios Enzimáticos/métodos , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Peptidoglicano Glicosiltransferase/antagonistas & inibidores , Uridina Difosfato Ácido N-Acetilmurâmico/análogos & derivados , Uridina Difosfato Ácido N-Acetilmurâmico/química , Uridina Difosfato Ácido N-Acetilmurâmico/metabolismo
11.
Life Sci ; 329: 121835, 2023 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-37295712

RESUMO

Fluorene was previously reported to have anticancer activity against human cancer cells. In this study, we examined the in vitro function of 9-methanesulfonylmethylene-2, 3-dimethoxy-9 H -fluorene (MSDF), a novel fluorene derivative, its anticancer potential in human hepatocellular carcinoma (HCC) cells and its underlying molecular mechanism. The disruption of cellular homeostasis caused by MSDF was found to promote reactive oxygen species (ROS) generation, leading to the activation of cellular apoptosis. As a survival strategy, cells undergo autophagy during oxidative stress. MSDF-induced apoptosis occurred through both receptor-mediated extrinsic and mitochondrial-mediated intrinsic routes. The development of acidic vesicular organelles and the accumulation of LC3-II protein suggest an increase in the autophagic process. Apoptosis was detected by double staining. The MAPK/ERK and PI3K/Akt signaling pathways were indeed suppressed during treatment. Along with elevated ROS generation and apoptosis, MSDF also caused anoikis and cell death by causing cells to lose contact with their extracellular matrix. ROS production was induced by MSDF and sustained by an NAC scavenger. MSDF-induced apoptosis led to increased autophagy, as shown by the suppression of apoptosis by Z-VAD-FMK. However, inhibition of autophagy by inhibitor 3-MA increased MSDF-induced apoptosis. More evidence shows that MSDF downregulated the expression of immune checkpoint proteins, suggesting that MSDF could be used in the future as an adjuvant to improve the effectiveness of HCC immunotherapy. Altogether, our results highlight the potential of MSDF as a multitarget drug for the treatment of HCC.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Humanos , Carcinoma Hepatocelular/patologia , Espécies Reativas de Oxigênio/metabolismo , Anoikis , Fosfatidilinositol 3-Quinases/metabolismo , Neoplasias Hepáticas/patologia , Linhagem Celular Tumoral , Apoptose , Autofagia/fisiologia , Fluorenos/farmacologia
12.
Microsyst Nanoeng ; 8: 38, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35450325

RESUMO

A micromachined resonator immersed in liquid provides valuable resonance parameters for determining the fluidic parameters. However, the liquid operating environment poses a challenge to maintaining a fine sensing performance, particularly through electrical characterization. This paper presents a piezoelectric micromachined cantilever with a stepped shape for liquid monitoring purposes. Multiple modes of the proposed cantilever are available with full electrical characterization for realizing self-actuated and self-sensing capabilities. The focus is on higher flexural resonances, which nonconventionally feature two-dimensional vibration modes. Modal analyses are conducted for the developed cantilever under flexural vibrations at different orders. Modeling explains not only the basic length-dominant mode but also higher modes that simultaneously depend on the length and width of the cantilever. This study determines that the analytical predictions for resonant frequency in liquid media exhibit good agreement with the experimental results. Furthermore, the experiments on cantilever resonators are performed in various test liquids, demonstrating that higher-order flexural modes allow for the decoupled measurements of density and viscosity. The measurement differences achieve 0.39% in density and 3.50% in viscosity, and the frequency instability is below 0.05‰. On the basis of these results, design guidelines for piezoelectric higher-mode resonators are proposed for liquid sensing.

13.
Eur Cell Mater ; 20: 415-30, 2010 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-21154247

RESUMO

Manipulating an incorporated scaffold to direct cell behaviors play a key role in tissue engineering. In this study, we developed novel nano-topographic oxidized silicon nanosponges capable of being modified with various chemicals of a few nm in thickness to gain further insight into the fundamental biology of cell-environment interactions in vitro. A wet etching technique was applied to fabricate the silicon nanosponges in a high-throughput manner and was followed by vapor deposition of various organo-silane chemicals to enable self-assembly on the surfaces of the silicon nanosponges. When Chinese hamster ovary cells were cultured on these chemically modified nano-topographic structures, they displayed distinct morphogenesis, adherent responses, and biochemical properties in comparison with those of their planar oxidized silicon counterparts. There were predominant nano-actin punches and slender protrusions formed while cells were cultured on the nano-topographic structures, indicating that cell behaviors can be influenced by the physical characteristic derived from nano-topography, in addition to the hydrophobicity of contact surfaces. This study demonstrates potential applications of these nano-topographic biomaterials for controlling cell development in tissue engineering as well as in basic cell biology research.


Assuntos
Materiais Biomiméticos/química , Adesão Celular , Técnicas de Cultura de Células/métodos , Nanoestruturas , Compostos de Organossilício/química , Dióxido de Silício/química , Animais , Materiais Biomiméticos/síntese química , Células CHO , Proliferação de Células , Sobrevivência Celular , Cricetinae , Cricetulus , Citoesqueleto/ultraestrutura , Proteína-Tirosina Quinases de Adesão Focal/biossíntese , Interações Hidrofóbicas e Hidrofílicas , Compostos de Organossilício/síntese química , Propriedades de Superfície
14.
Bioorg Med Chem ; 18(24): 8512-29, 2010 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-21075637

RESUMO

To identify new transglycosylase inhibitors with potent anti-methicillin-resistant Staphylococcus aureus (MRSA) activities, a high-throughput screening against Staphylococcus aureus was conducted to look for antibacterial cores in our 2M compound library that consists of natural products, proprietary collection, and synthetic molecules. About 3600 hits were identified from the primary screening and the subsequent confirmation resulted in a total of 252 compounds in 84 clusters which showed anti-MRSA activities with MIC values as low as 0.1 µg/ml. Subsequent screening targeting bacterial transglycosylase identified a salicylanilide-based core that inhibited the lipid II polymerization and the moenomycin-binding activities of transglycosylase. Among the collected analogues, potent inhibitors with the IC(50) values below 10 µM against transglycosylase were identified. The non-carbonhydrate scaffold reported in this study suggests a new direction for development of bacterial transglycosylase inhibitors.


Assuntos
Antibacterianos/química , Glicosiltransferases/efeitos dos fármacos , Ensaios de Triagem em Larga Escala , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Antibacterianos/farmacologia , Concentração Inibidora 50 , Staphylococcus aureus Resistente à Meticilina/enzimologia , Testes de Sensibilidade Microbiana , Bibliotecas de Moléculas Pequenas , Infecções Estafilocócicas/tratamento farmacológico , Relação Estrutura-Atividade
15.
Front Chem ; 8: 826, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33195036

RESUMO

In this study, pretilachlor was encapsulated into polyurea microcapsules prepared by water-initiated polymerization of polyaryl polymethylene isocyanate and eventually made into pretilachlor microcapsules suspension (PMS). We used response surface methodology (RSM) combined with the Box-Behnken design (BBD) model to optimize the formulation of PMS. The encapsulation efficiency (EE) of PMS was investigated with respect to three independent variables including wall material dosage (X1), emulsifier dosage (X2), and polymerization stirring speed (X3). The results showed that the regression equation model had a satisfactory accuracy in predicting the EE of PMS. To achieve an optimal condition for PMS preparation, the dose of wall material was set to 5%, the dose of emulsifier was set to 3.5% and the polymerization stirring speed was set to 200 rpm. The EE of PMS was up to 95.68% under the optimized condition, and the spherical shape with smooth surface morphology was observed. PMS was also proven to have delayed release capability and in vivo herbicidal activity against barnyard grass [Echinochloa crusgalli (L.) Beauv.] with an LC50 value of 274 mg/L. Furthermore, PMS had efficient weed management compared to commercially available 30% pretilachlor emulsifier (PE), showing a promising potential application for weeding paddy fields.

16.
Rev Sci Instrum ; 89(12): 125001, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30599598

RESUMO

In order to improve the measuring accuracy of micro-electromechanical system (MEMS) resonant sensor with micro-cantilever structure to measure fluid density, a temperature compensation method is presented. The elastic modulus of the micro-cantilever is calculated considering its temperature coefficient so that the working equation to measure fluid density is obtained with decreasing temperature disturbance on the measuring accuracy. The simulations and experimental measurements of several fluids with different densities were carried out by the MEMS micro-cantilever resonant sensor under different temperatures. The simulation analyses showed that the fluid densities measured by using the proposed resonant density sensor with temperature compensation were more fitted with the reference density values than those without temperature compensation. The experimental results showed that both the measuring accuracy and stability of the MEMS micro-cantilever resonant sensor in fluid density measurement were increased more than twice based on the temperature compensation method. Therefore, the proposed temperature compensation method is important to improve the measuring precision and stability of the MEMS micro-cantilever resonant sensor in fluid density detection fields.

17.
Chem Commun (Camb) ; 54(56): 7858, 2018 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-29966030

RESUMO

Correction for 'Development of glycosynthases with broad glycan specificity for the efficient glyco-remodeling of antibodies' by Sachin S. Shivatare et al., Chem. Commun., 2018, 54, 6161-6164.

18.
Chem Commun (Camb) ; 54(48): 6161-6164, 2018 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-29809215

RESUMO

The first systematic investigation of the effect of high mannose, hybrid, and bi- and tri-antennary complex type glycans on the effector functions of antibodies was achieved by the discovery of novel Endo-S2 mutants generated by site-directed mutagenesis as glycosynthases with broad substrate specificity.


Assuntos
Anticorpos/química , Glicosiltransferases/química , Polissacarídeos/química , Anticorpos/metabolismo , Glicosídeo Hidrolases/genética , Glicosilação , Glicosiltransferases/genética , Mutagênese Sítio-Dirigida , Engenharia de Proteínas , Receptores de IgG/metabolismo , Streptococcus pyogenes/enzimologia , Relação Estrutura-Atividade , Especificidade por Substrato
20.
Sci Rep ; 6: 31579, 2016 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-27531195

RESUMO

Systematic structural modifications of the muramic acid, peptide, and nucleotide moieties of Park's nucleotide were performed to investigate the substrate specificity of B. subtilis MraY (MraYBS). It was found that the simplest analogue of Park's nucleotide only bearing the first two amino acids, l-alanine-iso-d-glutamic acid, could function as a MraYBS substrate. Also, the acid group attached to the Cα of iso-d-glutamic acid was found to play an important role for substrate activity. Epimerization of the C4-hydroxyl group of muramic acid and modification at the 5-position of the uracil in Park's nucleotide were both found to dramatically impair their substrate activity. Unexpectedly, structural modifications on the uracil moiety changed the parent molecule from a substrate to an inhibitor, blocking the MraYBS translocation. One unoptimized inhibitor was found to have a Ki value of 4 ± 1 µM against MraYBS, more potent than tunicamycins.


Assuntos
Proteínas de Bactérias/metabolismo , Nucleotídeos/metabolismo , Transferases/metabolismo , Antibacterianos/farmacologia , Bacillus subtilis/efeitos dos fármacos , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/química , Testes de Sensibilidade Microbiana , Conformação de Ácido Nucleico , Nucleotídeos/química , Staphylococcus aureus/efeitos dos fármacos , Especificidade por Substrato , Transferases/antagonistas & inibidores , Transferases/química , Transferases (Outros Grupos de Fosfato Substituídos)
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