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1.
Anal Chem ; 95(19): 7693-7701, 2023 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-37145768

RESUMO

Post-arthroplasty periprosthetic joint infection (PJI) is a serious ailment that can be difficult to diagnose. Herein, we developed a novel integrated microfluidic system (IMS) capable of detecting two common PJI biomarkers, alpha defensin human neutrophil peptide 1 (HNP-1) and C-reactive protein (CRP), from synovial fluid (SF). A magnetic bead-based one-aptamer-one-antibody assay was carried out automatically within 45 min on a single chip for simultaneous detection of both biomarkers at concentration ranges of 0.01-50 (HNP-1) and 1-100 (CRP) mg/L. It is the first report for utilizing these two biomarkers as targets to establish the new one-aptamer-one-antibody assay to detect PJI on-chip, and the aptamers demonstrated high specificity to their SF targets. As 20 clinical samples were correctly diagnosed with our IMS (verified by a common gold standard kit), it could serve as a promising tool for PJI diagnostics.


Assuntos
Artrite Infecciosa , Infecções Relacionadas à Prótese , Humanos , Líquido Sinovial/química , Infecções Relacionadas à Prótese/diagnóstico , Microfluídica , Sensibilidade e Especificidade , Biomarcadores/metabolismo , Proteína C-Reativa/análise , Artrite Infecciosa/diagnóstico , Artrite Infecciosa/metabolismo
2.
Int J Mol Sci ; 22(12)2021 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-34200896

RESUMO

The goals of this study are to develop a high purity patented silk fibroin (SF) film and test its suitability to be used as a slow-release delivery for insulin-like growth factor-1 (IGF-1). The release rate of the SF film delivering IGF-1 followed zero-order kinetics as determined via the Ritger and Peppas equation. The release rate constant was identified as 0.11, 0.23, and 0.09% h-1 at 37 °C for SF films loaded with 0.65, 6.5, and 65 pmol IGF-1, respectively. More importantly, the IGF-1 activity was preserved for more than 30 days when complexed with the SF film. We show that the IGF-1-loaded SF films significantly accelerated wound healing in vitro (BALB/3T3) and in vivo (diabetic mice), compared with wounds treated with free IGF-1 and an IGF-1-loaded hydrocolloid dressing. This was evidenced by a six-fold increase in the granulation tissue area in the IGF-1-loaded SF film treatment group compared to that of the PBS control group. Western blotting analysis also demonstrated that IGF-1 receptor (IGF1R) phosphorylation in diabetic wounds increased more significantly in the IGF-1-loaded SF films group than in other experimental groups. Our results suggest that IGF-1 sustained release from SF films promotes wound healing through continuously activating the IGF1R pathway, leading to the enhancement of both wound re-epithelialization and granulation tissue formation in diabetic mice. Collectively, these data indicate that SF films have considerable potential to be used as a wound dressing material for long-term IGF-1 delivery for diabetic wound therapy.


Assuntos
Bombyx/química , Diabetes Mellitus Experimental/fisiopatologia , Sistemas de Liberação de Medicamentos , Fibroblastos/efeitos dos fármacos , Fibroínas/química , Fator de Crescimento Insulin-Like I/administração & dosagem , Cicatrização/efeitos dos fármacos , Animais , Bandagens , Preparações de Ação Retardada , Feminino , Fator de Crescimento Insulin-Like I/farmacologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Knockout , Reepitelização , Receptores para Leptina/fisiologia
3.
Int J Mol Sci ; 19(10)2018 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-30322072

RESUMO

The investigation of human disease mechanisms is difficult due to the heterogeneity in gene expression and the physiological state of cells in a given population. In comparison to bulk cell measurements, single-cell measurement technologies can provide a better understanding of the interactions among molecules, organelles, cells, and the microenvironment, which can aid in the development of therapeutics and diagnostic tools. In recent years, single-cell technologies have become increasingly robust and accessible, although limitations exist. In this review, we describe the recent advances in single-cell technologies and their applications in single-cell manipulation, diagnosis, and therapeutics development.


Assuntos
Técnicas Analíticas Microfluídicas/tendências , Análise de Célula Única/métodos , Humanos , Dispositivos Lab-On-A-Chip , Técnicas Analíticas Microfluídicas/instrumentação , Análise de Célula Única/instrumentação , Análise de Célula Única/tendências
4.
J Appl Toxicol ; 35(10): 1211-8, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26099253

RESUMO

Graphene and its functionalized derivatives have recently emerged as interesting nanomaterials with promising applications in biomedicine. In this study, the long-term in vivo biodistribution of intravenously injected nanographene oxide (NGO) functionalized with poly sodium 4-styrenesulfonate (PSS) was systematically examined and the potential toxicity over 6 months of NGO-PSS nanoparticles was investigated. Our results showed that the nanoparticles mainly accumulate in the lung, liver and spleen, where they persist for at least 6 months. These nanoparticles result in acute liver injury and chronic inflammation of the lung, liver and spleen, as evidenced by blood biochemistry results and histological examinations.


Assuntos
Grafite/farmacocinética , Grafite/toxicidade , Nanoestruturas/toxicidade , Animais , Doença Hepática Induzida por Substâncias e Drogas/patologia , Doença Crônica , Inflamação/induzido quimicamente , Inflamação/patologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Polímeros/toxicidade , Ácidos Sulfônicos/toxicidade , Distribuição Tecidual
5.
Analyst ; 139(23): 6249-58, 2014 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-25320952

RESUMO

We introduce a localized single-cell membrane nano-electroporation with controllable sequential molecular delivery by millisecond to nanosecond electrical pulses. An intense electrical field was generated by a pair of transparent indium tin oxide (ITO)-based nano-electrodes, which was confined to a narrow region of the single-cell membrane surface near the nano-electrode edges (approximately 2 µm × 50 nm area), whereas the remaining area of the membrane was unaffected. Moreover, a 250 nm SiO2 passivation layer on top of the nano-electrode reduced not only the thermal effect on the cell membrane surface, but it also avoided the generation of ions during the experiment, resulting in the reduction of cell toxicity and a significant enhancement of cell viability. Our approach precisely delivers dyes, Quantum Dots (QDs) and plasmids, through a localized region of single HeLa cells by considerably enhanced electrophoresis and diffusion effects with different duration of the pulsing process. The smaller molecules took less time to deliver into a single cell with a single pulse, whereas larger biomolecules took longer time even for multiple numbers of long lasting pulses. The system not only generates sequential well-controlled nano-pores allowing for the rapid recovery of cell membranes, but it also provides spatial, temporal and qualitative dosage control to deliver biomolecules into localized single-cell levels, which can be potentially beneficial for single cell studies and therapeutic applications.


Assuntos
Eletroporação/métodos , Nanotecnologia/métodos , Adesão Celular , Células Imobilizadas , Corantes , Eletroforese/métodos , Eletroporação/instrumentação , Células HeLa , Humanos , Microscopia de Fluorescência , Plasmídeos , Pontos Quânticos , Propriedades de Superfície
6.
Carcinogenesis ; 34(6): 1304-14, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23385061

RESUMO

Tylophorine, a phenanthroindolizidine alkaloid, is the major medicinal constituent of herb Tylophora indica. Tylophorine treatment increased the accumulation of c-Jun protein, a component of activator protein 1 (AP1), in carcinoma cells. An in vitro kinase assay revealed that the resultant c-Jun phosphorylation was primarily mediated via activated c-Jun N-terminal protein kinase (JNK). Moreover, flow cytometry indicated that ectopically overexpressed c-Jun in conjunction with tylophorine significantly increased the number of carcinoma cells that were arrested at the G1 phase. The tylophorine-mediated downregulation of cyclin A2 protein levels is known to be involved in the primary G1 arrest. Chromatin immunoprecipitation and reporter assays revealed that tylophorine enhanced the c-Jun downregulation of the cyclin A2 promoter activity upon increased binding of c-Jun to the deregulation AP1 site and decreased binding to the upregulation activating transcription factor (ATF) site in the cyclin A2 promoter, thereby reducing cyclin A2 expression. Further, biochemical studies using pharmacological inhibitors and RNA silencing approaches demonstrated that tylophorine-mediated elevation of the c-Jun protein level occurs primarily via two discrete prolonged signaling pathways: (i) the NF-κB/PKCδ_(MKK4)_JNK cascade, which phosphorylates c-Jun and increases its stability by slowing its ubiquitination, and (ii) the PI3K_PDK1_PP2A_eEF2 cascade, which sustains eukaryotic elongation factor 2 (eEF2) activity and thus c-Jun protein translation. To the best of our knowledge, this report is the first to demonstrate the involvement of c-Jun in the anticancer activity of tylophorine and the release of c-Jun translation from a global translational blockade via the PI3K_PDK1_eEF2 signaling cascade.


Assuntos
Alcaloides/farmacologia , Antineoplásicos Fitogênicos/farmacologia , Carcinoma/tratamento farmacológico , Indolizinas/farmacologia , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Fenantrenos/farmacologia , Proteínas Proto-Oncogênicas c-jun/metabolismo , Fator 1 Ativador da Transcrição/metabolismo , Linhagem Celular Tumoral , Ciclina A2/biossíntese , Ciclina A2/genética , Regulação para Baixo , Quinase do Fator 2 de Elongação/genética , Quinase do Fator 2 de Elongação/metabolismo , Fatores de Iniciação em Eucariotos/genética , Fatores de Iniciação em Eucariotos/metabolismo , Pontos de Checagem da Fase G1 do Ciclo Celular , Células Hep G2 , Humanos , Proteínas Quinases JNK Ativadas por Mitógeno/biossíntese , Sistema de Sinalização das MAP Quinases , NF-kappa B/metabolismo , Fenantrolinas , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação/efeitos dos fármacos , Regiões Promotoras Genéticas/efeitos dos fármacos , Proteína Quinase C-delta/metabolismo , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Proto-Oncogênicas c-jun/genética , Piruvato Desidrogenase Quinase de Transferência de Acetil , Interferência de RNA , RNA Interferente Pequeno , Fator de Transcrição AP-1/metabolismo , Tylophora
7.
J Biol Chem ; 287(3): 1903-14, 2012 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-22128156

RESUMO

The histidine-containing phosphotransfer protein-B (HptB; PA3345) is an intermediate protein involved in transferring a phosphoryl group from multiple sensor kinases to the response regulator PA3346 in Pseudomonas aeruginosa PAO1. The objective of this study was to elucidate the biological significance of the HptB-PA3346 interaction and the regulatory mechanisms thereafter. The transcription profiling analysis of an hptB knock-out mutant showed that the expression of a number of motility-related genes was altered consistent with the non-swarming phenotype observed for the mutant. Domain analysis indicated that the PA3346 C-terminal region (PA3346C) exhibits ∼30% identity with the anti-σ factor SpoIIAB of Bacillus subtilis. The presence of Ser/Thr protein kinase activity targeting an anti-σ antagonist, PA3347, at Ser-56 was confirmed in PA3346C using an in vitro phosphorelay assay. Furthermore, PA3346C and the anti-σ(28) factor FlgM were found to interact with PA3347 individually both in vivo and in vitro. FlgM displaced PA3346C in binding of PA3347 and was then competitively displaced by σ(28) from the PA3347-FlgM complex, forming a phosphorylation-dependent partner-switching system. The significance of PA3347 phosphorylation in linking the partner-switching system and swarming motility was established by analyzing the swarming phenotype of the PA3347 knock-out mutant and its complement strains.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Transporte/metabolismo , Complexos Multiproteicos/metabolismo , Pseudomonas aeruginosa/metabolismo , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Proteínas de Bactérias/genética , Proteínas de Transporte/genética , Deleção de Genes , Complexos Multiproteicos/genética , Estrutura Terciária de Proteína , Pseudomonas aeruginosa/genética
8.
Biomed Mater ; 18(5)2023 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-37567188

RESUMO

An optimal wound-healing hydrogel requires effective antibacterial properties and a favorable cell adhesion and proliferation environment. AlthoughBombyx morisilk fibroin (SF) possesses inherent wound-healing properties, it lacks these essential qualities. This study aimed to fabricate a novel photo-polymerizable hydrogel by utilizing SF's wound-healing efficiency and the epsilon-poly-L-lysine (EPL) antimicrobial activity. The SF was modified with three different concentrations of glycidyl methacrylate (GMA) to obtain SF-GMA(L), SF-GMA(M), and SF-GMA(H). A methacrylated EPL (EPL-GMA) was also produced. Then, SF-GMA was mixed with EPL-GMA to produce photo-crosslinkable SF-GMA-EPL hydrogels. The SF-GMA(L)-EPL, SF-GMA(M)-EPL, and SF-GMA(H)-EPL hydrogels, fabricated with 20% EPL-GMA, demonstrated maximum antimicrobial activity and mammalian cell adhesion ability. The hydroxyl radical (•OH) scavenging efficiency of the hydrogels was tested and shown to be between 69% and 74%. These hydrogels also exhibited 60% efficiency in removing bacterial lipopolysaccharides. The water absorption ability of the hydrogels was consistent with the size of their internal pores. The hydrogels exhibited a slow degradation fashion, and their degradation products appeared cytocompatible. Finally, the elastomeric properties of the hydrogels were determined, and a storage modulus (G') of 300-600 Pa was demonstrated. In conclusion, the hydrogels created in this study possess excellent biological and physical properties to support wound healing.


Assuntos
Anti-Infecciosos , Fibroínas , Animais , Polilisina , Hidrogéis , Cicatrização , Seda , Mamíferos
9.
Langmuir ; 28(19): 7428-35, 2012 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-22524463

RESUMO

The Klebsiella pneumoniae type 3 fimbriae are mainly composed of MrkA pilins that assemble into a helixlike filament. This study determined the biomechanical properties of the fimbriae and analyzed 11 site-directed MrkA mutants to identify domains that are critical for the properties. Escherichia coli strains expressing type 3 fimbriae with an Ala substitution at either F34, V45, C87, G189, T196, or Y197 resulted in a significant reduction in biofilm formation. The E. coli strain expressing MrkAG189A remained capable of producing a normal number of fimbriae. Although F34A, V45A, T196A, and Y197A substitutions expressed on E. coli strains produced sparse quantities of fimbriae, no fimbriae were observed on the cells expressing MrkAC87A. Further investigations of the mechanical properties of the MrkAG189A fimbriae with optical tweezers revealed that, unlike the wild-type fimbriae, the uncoiling force for MrkAG189A fimbriae was not constant. The MrkAG189A fimbriae also exhibited a lower enthalpy in the differential scanning calorimetry analysis. Together, these findings indicate that the mutant fimbriae are less stable than the wild-type. This study has demonstrated that the C-terminal ß strands of MrkA are required for the assembly and structural stability of fimbriae.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Fímbrias/metabolismo , Klebsiella pneumoniae/metabolismo , Proteínas de Bactérias/química , Biofilmes , Proteínas de Fímbrias/química , Estrutura Terciária de Proteína
10.
J Immunol ; 184(4): 1748-56, 2010 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-20083663

RESUMO

Membrane-bound IgE (mIgE) is part of the IgE-BCR and is essential for generating isotype-specific IgE responses. On mIgE(+) B cells, the membrane-bound epsilon-chain (mepsilon) exists predominantly in the long isoform, mepsilon(L), containing an extra 52 aa CepsilonmX domain between CH4 and the C-terminal membrane-anchoring segment; the short isoform of mepsilon, mepsilon(S), exists in minor proportions. CepsilonmX thus provides an attractive site for immunologic targeting of mIgE(+) B cells. In this study, we show that nine newly prepared CepsilonmX-specific mAbs, as well as the previously reported a20, bound to mIgE.Fc(L)-expressing CHO cells, while only 4B12 and 26H2 bound to mIgE.Fc(L)-expressing B cell line Ramos cells. The mAb 4B12 bound to the N-terminal part, 26H2 the middle part, and all others the C-terminal part of CepsilonmX. Expression of Igalpha and Igbeta on the mIgE.Fc(L)-CHO cells reduces the binding of a20 to CepsilonmX as compared with that of 4B12 and 26H2. The chimeric mAbs c4B12 and c26H2, when cross-linked by secondary antibodies, lysed mIgE.Fc(L)-Ramos cells by apoptosis through a BCR-dependent caspase pathway. Using PBMCs as the source of effector cells, c4B12 and c26H2 demonstrated Ab-dependent cellular cytotoxicity toward mIgE.Fc(L)-Ramos cells in a dose-dependent fashion. In cultures of PBMCs from atopic dermatitis patients, c4B12 and c26H2 inhibited the synthesis of IgE driven by anti-CD40 and IL-4. These results suggest that 4B12 and 26H2 and an immunogen using the peptide segments recognized by these mAbs are potentially useful for targeting mIgE(+) B cells to control IgE production.


Assuntos
Subpopulações de Linfócitos B/imunologia , Subpopulações de Linfócitos B/metabolismo , Epitopos de Linfócito B/genética , Epitopos de Linfócito B/metabolismo , Marcação de Genes , Imunoglobulina E/biossíntese , Cadeias épsilon de Imunoglobulina/biossíntese , Receptores de Antígenos de Linfócitos B/metabolismo , Sequência de Aminoácidos , Animais , Citotoxicidade Celular Dependente de Anticorpos/genética , Apoptose/genética , Apoptose/imunologia , Sítios de Ligação de Anticorpos/genética , Células CHO , Linhagem Celular , Linhagem Celular Tumoral , Células Clonais , Cricetinae , Cricetulus , Humanos , Imunoglobulina E/genética , Imunoglobulina E/metabolismo , Cadeias épsilon de Imunoglobulina/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Isoformas de Proteínas/biossíntese , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo
11.
J Antibiot (Tokyo) ; 75(6): 354-359, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35459856

RESUMO

Epsilon-poly-L-lysine (EPL) is an antimicrobial peptide with low mammalian toxicity; thus, it is commonly used as food preservative. Here, the capacity of EPL to improve the efficacy of the antibiotics ampicillin (AMP), gentamycin (GEN), tetracycline (TCN), and methicillin (MET) against four bacterial pathogens, namely Pseudomonas aeruginosa PAO1, Klebsiella pneumoniae CG43, MET-sensitive Staphylococcus aureus ATCC 25923 (MSSA), and MET-resistant S. aureus ATCC 33591 (MRSA), was investigated. Some antibiotic-EPL combinations, i.e., AMP-EPL, GEN-EPL, and TCN-EPL, were particularly active against the pathogens through synergy, partial synergy, or additive effects. Additionally, MET-EPL displayed a partial synergistic effect against MRSA. GEN-EPL had the most powerful antimicrobial effect against MSSA: it eradicated the bacterium within an hour. Conversely, AMP-EPL and MET-EPL were the least potent combinations against MRSA, and TCN-EPL was least potent against K. pneumoniae; for these combinations, bactericidal activities occurred >10 h after initial treatments. All antibiotic-EPL treatments showed inhibitory activities against P. aeruginosa biofilm formation and enhanced preformed biofilm disruption in vitro. Similarly, the inhibition of biofilm formation on a porcine skin model was observed. Moreover, no significant cytotoxicity was detected for any antibiotic-EPL treatment in tests using Balb/3t3 fibroblasts. Given the rise in antibiotic-resistant bacteria, combining antibiotics with EPL may enhance antibiotic effectiveness, as shown in this study, while helping to avoid antimicrobial resistance.


Assuntos
Antibacterianos , Staphylococcus aureus Resistente à Meticilina , Animais , Ampicilina/farmacologia , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Bactérias , Gentamicinas/farmacologia , Mamíferos , Meticilina/farmacologia , Testes de Sensibilidade Microbiana , Polilisina/farmacologia , Pseudomonas aeruginosa , Suínos
12.
J Microbiol Immunol Infect ; 55(4): 620-633, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35367140

RESUMO

BACKGROUND/PURPOSE: Two urease operons were identified in Klebsiella pneumoniae CG43, ure-1 and ure-2. This study investigates whether a differential regulation of the expression of ure-1 and ure-2 exists and how urease activity influences the acid stress response and expression of type 1 and type 3 fimbriae. METHODS: The ureA1 and ureA2 gene specific deletion mutants were constructed. Promoter activity was assessed using a LacZ reporter system. The sensitivity to acid stress was determined by assessing the survival after pH 2.5 treatment. The influence on type 1 and type 3 fimbriae expression was assessed using western blotting and mannose-sensitive yeast agglutination and biofilm formation assay, respectively. RESULTS: Bacterial growth analysis in mM9-U or modified Stuart broth revealed that ure-1 was the principal urease system, and ure-2 had a negative effect on ure-1 activity. Deletion of the fur or nac gene had no apparent effect on the activity of Pure1, Pure2-1, and Pure2-2. The Pure2-2 activity was enhanced by deletion of the hns gene. ureA1 deletion increased acid stress sensitivity, whereas the deleting effect of ureA2 was notable without hns. Deletion of ureA1 or ureA2 significantly induced the expression of type 1 fimbriae but decreased MrkA production and biofilm formation. CONCLUSION: ure-1 is the primary expression system in K. pneumoniae CG43, while ure-2 is active in the absence of hns. Impairment of urease activity increases the sensitivity to acid stress, and the accumulation of urea induces the expression of type 1 fimbriae but represses type 3 fimbriae expression.


Assuntos
Klebsiella pneumoniae , Urease , Proteínas de Bactérias , Fímbrias Bacterianas , Regulação Bacteriana da Expressão Gênica
13.
Biosens Bioelectron ; 197: 113740, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34785491

RESUMO

This study demonstrates a novel multi-functional microfluidic system, designated three dimensional Alternative Current Electrokinetic/Surface Enhanced Raman Scattering (3D-ACEK/SERS), which can concentrate bacteria from whole blood, identify bacterial species, and determine antibiotic susceptibilities of the bacteria rapidly. The system consists of a hybrid electrokinetic mechanism, integrating AC-electroosmosis (AC-EO) and dielectrophoresis (DEP) that allows thousand-fold concentration of bacteria, including S. aureus, Escherichia coli, and Chryseobacterium indologenes, in the center of an electrode with a wide range of working distance (hundreds to thousands of µm), while exclusion of blood cells through negative DEP forces. This microchip employs SERS assay to determine the identity of the concentrated bacteria in approximately 2 min with a limit of detection of 3 CFU/ml, 5 orders of magnitude lower than that using standard centrifugation-purification process. Finally, label-free antibiotic susceptibility testing has been successfully demonstrated on the platform using both antibiotic-sensitive and multidrug-resistant bacterial strains illustrating a potential utility of the system to clinical applications.


Assuntos
Técnicas Biossensoriais , Staphylococcus aureus , Antibacterianos/farmacologia , Bactérias , Análise Espectral Raman
14.
J Bacteriol ; 193(7): 1710-7, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21296962

RESUMO

Klebsiella pneumoniae is a Gram-negative bacterium of the family Enterobacteriaceae that possesses diverse metabolic capabilities: many strains are leading causes of hospital-acquired infections that are often refractory to multiple antibiotics, yet other strains are metabolically engineered and used for production of commercially valuable chemicals. To study its metabolism, we constructed a genome-scale metabolic model (iYL1228) for strain MGH 78578, experimentally determined its biomass composition, experimentally determined its ability to grow on a broad range of carbon, nitrogen, phosphorus and sulfur sources, and assessed the ability of the model to accurately simulate growth versus no growth on these substrates. The model contains 1,228 genes encoding 1,188 enzymes that catalyze 1,970 reactions and accurately simulates growth on 84% of the substrates tested. Furthermore, quantitative comparison of growth rates between the model and experimental data for nine of the substrates also showed good agreement. The genome-scale metabolic reconstruction for K. pneumoniae presented here thus provides an experimentally validated in silico platform for further studies of this important industrial and biomedical organism.


Assuntos
Proteínas de Bactérias/metabolismo , Regulação Bacteriana da Expressão Gênica/fisiologia , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/metabolismo , Proteínas de Bactérias/genética , Evolução Biológica , Biomarcadores , Biomassa , Meios de Cultura , Metabolismo Energético/genética , Metabolismo Energético/fisiologia , Genoma Bacteriano
15.
J Bacteriol ; 193(7): 1718-25, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-21239584

RESUMO

This study investigated the structural and mechanical properties of Klebsiella pneumoniae type 3 fimbriae, which constitute a known virulence factor for the bacterium. Transmission electron microscopy and optical tweezers were used to understand the ability of the bacterium to survive flushes. An individual K. pneumoniae type 3 fimbria exhibited a helix-like structure with a pitch of 4.1 nm and a three-phase force-extension curve. The fimbria was first nonlinearly stretched with increasing force. Then, it started to uncoil and extended several micrometers at a fixed force of 66 ± 4 pN (n = 22). Finally, the extension of the fimbria shifted to the third phase, with a characteristic force of 102 ± 9 pN (n = 14) at the inflection point. Compared with the P fimbriae and type 1 fimbriae of uropathogenic Escherichia coli, K. pneumoniae type 3 fimbriae have a larger pitch in the helix-like structure and stronger uncoiling and characteristic forces.


Assuntos
Proteínas de Fímbrias/metabolismo , Fímbrias Bacterianas/metabolismo , Regulação Bacteriana da Expressão Gênica/fisiologia , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/metabolismo , Proteínas de Fímbrias/química , Proteínas de Fímbrias/genética , Fímbrias Bacterianas/química , Fímbrias Bacterianas/genética , Mecânica , Microscopia Eletrônica de Varredura , Conformação Proteica , Escherichia coli Uropatogênica/metabolismo , Fatores de Virulência
16.
J Cell Physiol ; 226(7): 1750-62, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-21506107

RESUMO

Many tumor cells are capable of migrating through endothelial cell (EC) junctions and disintegrating sub-endothelial extracellular matrix to achieve extravasation. We demonstrate in this study that certain solid tumor cells can induce EC apoptosis to facilitate their escape from the circulation. The EC apoptosis is triggered by elevated intracellular reactive oxygen species (ROS) levels and direct contacts with tumor cells are required. Treating ECs with antioxidants, such as ascorbate and N-acetyl-L-cysteine (NAC), and a glutathione precursor can rescue the ECs from tumor-induced apoptosis and reduce the number of tumor cells migrating across endothelial barriers. NAD(P)H oxidase was identified as the major ROS producer in the event since inhibitors and small interference RNA specific to the enzyme could abrogate the tumor-induced ROS production and hence EC death. This study also provides evidence showing that the interaction between tumor and EC increases intracellular Ca(2+) concentration and activates protein kinase C (PKC) activity, which leads to NAD(P)H oxidase activation through the serine-phosphorylation of p47(phox) subunit. These findings suggest that blocking the tumor-induced EC apoptosis is a potential way to prevent tumor metastasis.


Assuntos
Apoptose , Comunicação Celular , Movimento Celular , Células Endoteliais/enzimologia , NADPH Oxidases/metabolismo , Neoplasias/metabolismo , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Animais , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Cálcio/metabolismo , Comunicação Celular/efeitos dos fármacos , Movimento Celular/efeitos dos fármacos , Técnicas de Cocultura , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/patologia , Ativação Enzimática , Inibidores Enzimáticos/farmacologia , Células HeLa , Células Hep G2 , Humanos , NADPH Oxidases/antagonistas & inibidores , NADPH Oxidases/genética , Invasividade Neoplásica , Neoplasias/patologia , Estresse Oxidativo/efeitos dos fármacos , Fosforilação , Proteína Quinase C/metabolismo , Interferência de RNA , Ratos , Serina , Fatores de Tempo , Transfecção
17.
Anal Biochem ; 418(1): 19-23, 2011 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-21810404

RESUMO

Bacteria monitoring is essential for many industrial manufacturing processes, particularly those involving in food, biopharmaceuticals, and semiconductor production. Firefly luciferase ATP luminescence assay is a rapid and simple bacteria detection method. However, the detection limit of this assay for Escherichia coli is approximately 10(4) colony-forming units (CFU), which is insufficient for many applications. This study aims to improve the assay sensitivity by simultaneous conversion of PP(i) and AMP, two products of the luciferase reaction, back to ATP to form two chain-reaction loops. Because each consumed ATP continuously produces two new ATP molecules, this approach can achieve exponential amplification of ATP. Two consecutive enzyme reactions were employed to regenerate AMP into ATP: adenylate kinase converting AMP into ADP using UTP as the energy source, and acetate kinase catalyzing acetyl phosphate and ADP into ATP. The PP(i)-recycling loop was completed using ATP sulfurylase and adenosine 5' phosphosulfate. The modification maintains good quantification linearity in the ATP luminescence assay and greatly increases its bacteria detection sensitivity. This improved method can detect bacteria concentrations of fewer than 10 CFU. This exponential ATP amplification assay will benefit bacteria monitoring in public health and manufacturing processes that require high-quality water.


Assuntos
Monofosfato de Adenosina/metabolismo , Trifosfato de Adenosina/metabolismo , Bactérias/isolamento & purificação , Difosfatos/metabolismo , Monofosfato de Adenosina/química , Adenosina Fosfossulfato/química , Adenosina Fosfossulfato/metabolismo , Trifosfato de Adenosina/química , Bacillus cereus/metabolismo , Contagem de Colônia Microbiana , Difosfatos/química , Luminescência , Medições Luminescentes/métodos , Pseudomonas aeruginosa/metabolismo , Sensibilidade e Especificidade , Sulfato Adenililtransferase/química , Sulfato Adenililtransferase/metabolismo
18.
Artigo em Inglês | MEDLINE | ID: mdl-21821900

RESUMO

The regulatory domain (PA3346RS), comprising the receiver and stalk domains, of the response regulator PA3346 requires phosphorylation for activation with magnesium ions as cofactors in order to modulate the downstream protein phosphatase activity for the regulation of swarming motility in Pseudomonas aeruginosa PAO1. Fusion-tagged recombinant PA3346RS of total molecular mass 25.3 kDa has been overexpressed in Escherichia coli, purified using Ni(2+)-NTA and Q-Sepharose ion-exchange columns and crystallized using the hanging-drop vapour-diffusion method. X-ray diffraction data were collected from PA3346RS crystals to 2.0 Šresolution. The crystal belonged to space group P4(1) or P4(3), with unit-cell parameters a = 82.38, c = 73.34 Å. Preliminary analysis indicated the presence of a dimer of PA3346RS in the asymmetric unit, with a solvent content of 48.6%.


Assuntos
Proteínas de Bactérias/química , Pseudomonas aeruginosa/química , Proteínas de Bactérias/isolamento & purificação , Cristalização , Cristalografia por Raios X
19.
Exp Cell Res ; 316(17): 2893-902, 2010 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-20691680

RESUMO

UDP-glucose dehydrogenase (UGDH) catalyzes oxidation of UDP-glucose to yield UDP-glucuronic acid, a precursor of hyaluronic acid (HA) and other glycosaminoglycans (GAGs) in extracellular matrix. Although association of extracellular matrix with cell proliferation and migration has been well documented, the importance of UGDH in these behaviors is not clear. Using UGDH-specific small interference RNA to treat HCT-8 colorectal carcinoma cells, a decrease in both mRNA and protein levels of UGDH, as well as the cellular UDP-glucuronic acid and GAG production was observed. Treatment of HCT-8 cells with either UGDH-specific siRNA or HA synthesis inhibitor 4-methylumbelliferone effectively delayed cell aggregation into multicellular spheroids and impaired cell motility in both three-dimensional collagen gel and transwell migration assays. The reduction in cell aggregation and migration rates could be restored by addition of exogenous HA. These results indicate that UGDH can regulate cell motility through the production of GAG. The enzyme may be a potential target for therapeutic intervention of colorectal cancers.


Assuntos
Movimento Celular , Neoplasias Colorretais/metabolismo , Glicosaminoglicanos/biossíntese , Uridina Difosfato Glucose Desidrogenase/genética , Adesão Celular , Linhagem Celular Tumoral , Regulação para Baixo/genética , Matriz Extracelular/metabolismo , Humanos , Ácido Hialurônico/farmacologia
20.
Planta Med ; 77(17): 1932-8, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21728149

RESUMO

An investigation of alkaloids present in the leaves and stems of Tylophora ovata led to the isolation of two new septicine alkaloids and one new phenanthroindolizidine alkaloid, tylophovatines A, B, C (1, 2, and 5), respectively, together with two known septicine and six known phenanthroindolizidine alkaloids. The structures of the new alkaloids 1, 2, and 5 were established by means of spectroscopic analyses. These eleven alkaloids show in vitro anti-inflammatory activities with IC50 values ranging from 84 nM to 20.6 µM through their suppression of nitric oxide production in RAW264.7 cells stimulated by lipopolysaccharide and interferon-γ. Moreover, these substances display growth inhibition in HONE-1, NUGC-3, HepG2, SF-268, MCF-7, and NCI-H460 cancer cell lines, with GI50 values ranging from 4 nM to 24.2 µM. In addition, tylophovatine C (5) and 13a(S)-(+)-tylophorine (7) were found to exhibit potent in vivo anti-inflammation activities in a rat paw edema model. Finally, structure­activity relationships were probed by using the isolated phenanthroindolizidines and septicines. Phenanthroindolizidines are suggested to be divided into cytotoxic agents (e.g., 10 and 11) and anti-inflammation based anticancer agents (e.g., 5­9).


Assuntos
Alcaloides/farmacologia , Indolizinas/farmacologia , Fenantrolinas/farmacologia , Extratos Vegetais/farmacologia , Tylophora/química , Alcaloides/química , Alcaloides/isolamento & purificação , Animais , Anti-Inflamatórios/farmacologia , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Linhagem Celular Tumoral , Humanos , Indolizinas/química , Indolizinas/isolamento & purificação , Interferon gama/farmacologia , Lipopolissacarídeos/farmacologia , Medicina Tradicional Chinesa , Estrutura Molecular , Óxido Nítrico/metabolismo , Fenantrolinas/química , Fenantrolinas/isolamento & purificação , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Folhas de Planta/química , Caules de Planta/química , Plantas Medicinais/química , Ratos , Relação Estrutura-Atividade , Taiwan
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