RESUMO
BACKGROUND: As probiotics protect host cells, they are used to treat bacterial infections. It has been indicated that probiotics may prevent or reduce the attachment of pathogens to host cells. In this study, Streptococcus strain D19T was isolated from the oropharynx of a healthy child, and its adhesion performance and Staphylococcus aureus adhesion inhibition effect were analysed using human bronchial epithelial (16-HBE) cells, as an in vitro cell model. We evaluated the probiotic properties of the D19T strain based on its acid-base, bile salt, and lysozyme tolerance; antibacterial activity; cytotoxicity; antibiotic sensitivity; in vitro adhesion to 16-HBE cells; and competitive, exclusion, and displacement effects against S. aureus. RESULTS: Streptococcus strain D19T showed tolerance to a PH range of 2-5 and 0.5-1% bile. However, it was more tolerant to 0.5% bile than to 1% bile. The strain also demonstrated an ability to adapt to maladaptive oropharyngeal conditions (i.e., tolerating 200 µg/mL lysozyme). It was resistant to 0.8 mM H2O2. The results also demonstrated that D19T exhibited inhibitory activities against various common pathogenic bacteria. Furthermore, D19T was not toxic to 16-HBE cells at different multiplicities of infection and was sensitive to most antibiotics tested. The adhesion rate of D19T cells to 16-HBE cells was 47% ± 1.2%, which was significantly higher than that of S. aureus to 16-HBE cells. The competition, exclusion, and displacement assay results showed that D19T has good inhibitory effect against S. aureus adhesion. CONCLUSIONS: The present study revealed that Streptococcus strain D19T has the potential to be developed as a respiratory microbiota preparations.
Assuntos
Probióticos , Staphylococcus aureus , Criança , Humanos , Muramidase , Saúde Bucal , Peróxido de Hidrogênio/farmacologia , Streptococcus , Antibacterianos/farmacologia , Probióticos/farmacologiaRESUMO
In the microbiome, probiotics modulate oral diseases. In this study, Streptococcus strain C17T was isolated from the oropharynx of a 5-year-old healthy child, and its potential probiotic properties were analysed using human bronchial epithelial cells (16-HBE) used as an in vitro oropharyngeal mucosal model. The results demonstrated that the C17T strain showed tolerance to moderate pH ranges of 4-5 and 0·5-1% bile. However, it was more tolerant to 0·5% bile than 1% bile. It also demonstrated an ability to accommodate maladaptive oropharyngeal conditions (i.e. tolerating lysozyme at 200 µg ml-1 ). It was also resistant to hydrogen peroxide at 0·8 mM. In addition, we found out that the strain possesses inhibitory activities against various common pathogenic bacteria. Furthermore, C17T was not cytotoxic to 16-HBE cells at different multiplicities of infection. Scanning electron microscopy disclosed that C17T adhesion to 16-HBE cells. Competition, exclusion and displacement assays showed that it had good anti-adhesive effect against S. aureus. The present study revealed that Streptococcus strain C17T is a potentially efficacious oropharyngeal probiotic.
Assuntos
Saúde Bucal , Probióticos , Streptococcus , Aderência Bacteriana , Pré-Escolar , Humanos , Probióticos/farmacologia , Staphylococcus aureus/efeitos dos fármacos , Streptococcus/efeitos dos fármacos , Streptococcus/genéticaRESUMO
Several series of novel non-thiourea-containing aminopyrazine derivatives were designed based on the MK-2 inhibitors 1-(2-aminopyrazin-3-yl)methyl-2-thioureas. These compounds were synthesized and evaluated for their inhibitory activity against MK-2 enzyme in vitro. Compounds with low micromolar to sub-micromolar IC50 values were identified, and several compounds were also found to be active in suppressing the lipopolysaccharide (LPS)-stimulated TNFα production in THP-1 cells with minimum shift compared to their enzyme activity.
Assuntos
Desenho de Fármacos , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Pirazinas/síntese química , Pirazinas/farmacologia , Linhagem Celular , Ativação Enzimática/efeitos dos fármacos , Humanos , Concentração Inibidora 50 , Estrutura Molecular , Pirazinas/químicaRESUMO
OBJECTIVE: To study the effect of 1,4-naphthoquinone aged black carbon (BC/1,4-NQ) on reactive oxygen species and DNA strand breaks in human bronchial epithelial cells (16HBE). METHODS: In the study, 16HBE cells were exposed to BC/1,4-NQ, BC and 1,4-NQ at the concentrations of BC/1,4-NQ (10.0/0.2, 20.0/0.4, 40.0/0.8, 80.0/1.6, 160.0/3.2 mg/L), BC (10.0, 20.0, 40.0, 80.0, 160.0 mg/L), 1,4-NQ (0.2, 0.4, 0.8, 1.6, 3.2 mg/L) for 24, 48, and 72 h, respectively. Cytotoxicity was detected by cell count kit 8 (CCK-8) at the end point. Then the 16HBE cells were exposed to BC/1,4-NQ (20.0/0.4, 40.0/0.8, 80.0/1.6 mg/L), BC (20.0, 40.0, 80.0 mg/L), 1,4-NQ (0.4, 0.8, 1.6 mg/L) for 24 h. The reactive oxygen species (ROS) generation was determined via flow cytometry with DCFH-DA probe. Single cell gel electrophoresis (SCGE) assay was performed to evaluate genotoxicity by Olive tail moment (OTM) value. RESULTS: Except for the concentration of 10.0/0.2 mg/L within the exposure time 24 h, the cell viabilities of BC/1,4-NQ were significantly lower than the control (P<0.05) within the exposure time 24-72 h, showing a dose-dependent cytotoxicity. Especially, BC/1,4-NQ showed greater cytotoxicity than BC single exposure, lower than 1,4-NQ at the concentration of BC/1,4-NQ≥80.0/1.6 mg/L. BC/1,4-NQ also showed greater ROS generation and OTM value than the control within the exposure time 24 h at each concentration (P<0.05). Especially, the ROS generation and OTM value of BC/1,4-NQ were greater than BC single exposure, lower than 1,4-NQ at the concentration of 80.0/1.6 mg/L (P<0.05). CONCLUSION: BC/1,4-NQ can induce intracellular ROS generation, cytotoxicity and genotoxicity in 16HBE cells. And at high concentration, the intracellular ROS level, cytotoxicity and genotoxicity induced by BC/1,4-NQ were greater than those by BC single exposure, but lower than those by 1,4-NQ.
Assuntos
Dano ao DNA , Células Epiteliais/efeitos dos fármacos , Naftoquinonas/química , Espécies Reativas de Oxigênio/metabolismo , Fuligem/química , Linhagem Celular , Sobrevivência Celular , HumanosRESUMO
OBJECTIVE: To make an assessment on the genotoxicity caused by black carbon (BC) and ozonized black carbon (O3-BC). METHODS: In this study, 74 healthy male ICR mice [weighed (28 ± 1.5) g] were randomly divided into 7 groups, including one phosphate buffer solution (PBS) control group and six particles exposed groups by intratracheal instillation with either BC or O3-BC at the doses of 50, 100, 200 µg/mouse, respectively. There were 12 mice in the groups of 200 µg/mouse and 10 mice in others. The mice were sacrificed 24 h after four intratrachealinstillations. The activities of catalase (CAT) in serum and the levels of malondialdehyde (MDA) in lung tissue homogenate were measured. As the DNA damage mark, 8-hydroxyguanosine (8-OHdG) in urine and serum were quantified with ELISA method. Micronucleus test was used for potential genotoxicity of BC and O3-BC. Hematoxylin and eosin staining was used to stain lung paraffin section. RESULTS: The mice were in good condition during instillation, and the liver coefficient of the test groups was significantly lower than that of the control group (P<0.05). The activities of CAT in serum significantly increased in the 100 µg/mouse and 200 µg/mouse groups after being exposed to these two kinds of particles. The micronucleus rate in allthe BC and O3-BC exposed groups increased (P<0.05), but there was no statistically significant difference among the groups in the levels of 8-OHdG in serum and urine and MDA in lung tissue homogenate. Inflammatory response was found in the lung tissue under the microscope after exposure to BC and O3-BC. CONCLUSION: Intratracheal instillation of BC and O3-BC induced increasing of oxidative stress and genetic damage in mice. But there was no significant difference between these two particles in toxicity. Whether the genotoxicity of O3-BC is higher than that of BC or not is uncertain. Further research is needed.
Assuntos
Dano ao DNA , Ozônio , Fuligem/toxicidade , Animais , Catalase/sangue , Fígado , Pulmão , Masculino , Malondialdeído/metabolismo , Camundongos , Camundongos Endogâmicos ICR , Oxirredução , Estresse OxidativoRESUMO
OBJECTIVE: To investigate the protective effect of polyenylphosphatidyl choline (PPC) on liver in rat with sepsis. METHODS: A total of 50 healthy male SD rats were randomly divided into four groups according to random number table: normal control group (NS group, n=10), sepsis model group (LPS group, n=15), PPC control group (PPC group, n=10) and PPC protection group (P+L group, n=15). A single dose of lipopolysaccharide (LPS) 6 mg/kg was injected to the peritoneal cavity to reproduce the sepsis model, while in NS group and PPC group, same volume of normal saline was used. PPC 10 ml/kg (232.5 mg/kg) was injected 24 hours and 6 hours before LPS via the tail vein in PPC group and P+L group, while in NS group and LPS group 5% glucose solution in the same volume was given. Behavioral changes and mortality rate of rats were recorded, and all survived rats were sacrificed 24 hours after LPS injection. Venous blood was taken for alanine aminotransferase (ALT) and aspartate aminotransferase (AST) determination. Ratios of liver weight/body weight (L/Wb) and wet weight/dry weight of liver (W/D) were calculated. Histopathology changes in liver tissue were observed with hematoxylin eosin (HE) stain, and intercellular adhesion molecule-1 (ICAM-1) expression with instant two-step immunohistochemistry. RESULTS: Twenty-four hours after LPS injection (LPS group), the rats became lethargic, with less activity and drinking, while rats in P+L group, showed much better mental status, water intake and activity than LPS group. The mortality rate of P+L group was significantly lower than that of LPS group [6.7% (1/15) vs. 46.7% (7/15),P<0.05]. Compared with LPS group, rats in P+L group had lower levels of plasma ALT and AST, L/Wb, W/D , and liver ICAM-1 positive expression ratio [ALT (U/L): 157.71 ± 32.63 vs. 225.63 ± 43.47; AST (U/L): 53.21 ± 13.85 vs. 85.25 ± 18.91; L/Wb: (4.09 ± 0.28)% vs. (4.50 ± 0.25)%; W/D : 3.52 ± 0.27 vs. 3.84 ± 0.18; ICAM-1 positive expression ratio: 35.7% (5/14) vs. 87.5 (7/8),P<0.05 or P <0.01]. All parameters were normal in NS group and PPC group, and no statistical significance was observed between them (all P >0.05). LPS-injection led to severe inflammatory reaction in hepatic tissue , including obvious edema of hepatic parenchymal cells, exudation and aggregation of inflammatory cells, while in P+L group, these morphological changes were milder than that in LPS group but more obvious than that of NS group. CONCLUSION: Pre-treatment of rats with PPC alleviates progressive inflammatory disturbances of hepatic tissue caused by endotoxin injection, and it attenuates liver edema and ICAM-1 expression, protects liver function and decreases mortality rate in rats with sepsis.
Assuntos
Fígado/efeitos dos fármacos , Fígado/patologia , Fosfatidilcolinas/farmacologia , Sepse/metabolismo , Sepse/patologia , Animais , Molécula 1 de Adesão Intercelular/metabolismo , Fígado/metabolismo , Masculino , Ratos , Ratos Sprague-DawleyRESUMO
Novel 1-(2-aminopyrazin-3-yl)methyl-2-thioureas are described as inhibitors of mitogen-activated protein kinase-activated protein kinase 2 (MK-2). These compounds demonstrate potent in vitro activity against the enzyme with IC(50) values as low as 15 nM, and suppress expression of TNFalpha in THP-1 cells and in vivo in an acute inflammation model in mice. The synthesis, structure-activity relationship (SAR), and biological evaluation of these compounds are discussed.
Assuntos
Peptídeos e Proteínas de Sinalização Intracelular/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Tioureia/química , Animais , Linhagem Celular Tumoral , Avaliação Pré-Clínica de Medicamentos , Humanos , Inflamação/tratamento farmacológico , Concentração Inibidora 50 , Camundongos , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Relação Estrutura-Atividade , Tioureia/farmacologia , Tioureia/uso terapêutico , Fator de Necrose Tumoral alfa/efeitos dos fármacosRESUMO
Non-adherence with medication remains a major correctable cause for poor outcome in schizophrenia. We describe a surgically implantable preparation of haloperidol with the aim that patients will have superior outcomes with improved medication adherence from implants. In contrast to depot formulations, implantable pellets could last many months, providing symptomatic improvement for periods of time never before possible. Additionally, in the event of unacceptable side effects, implants could be removed, offering a degree of reversibility not available with depot formulations. A surgically-implantable formulation of haloperidol has been created using biodegradable polymers. Implants have been characterized for in-vitro kinetics, as well as in-vivo bioactivity in rodents. Haloperidol implants demonstrate steady release of drug for 5 months. Animals treated with haloperidol implants display increased striatal D2 receptor expression as well as increased apomorphine stimulated locomotion. Surgically-implantable formulations are a viable approach to provide long-term delivery of antipsychotic medications to patients with psychotic disorders.
Assuntos
Antipsicóticos/administração & dosagem , Cateteres de Demora , Sistemas de Liberação de Medicamentos/métodos , Esquizofrenia/tratamento farmacológico , Animais , Cateteres de Demora/estatística & dados numéricos , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Preparações de Ação Retardada/administração & dosagem , Sistemas de Liberação de Medicamentos/estatística & dados numéricos , Haloperidol/administração & dosagem , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Polietilenoglicóis/administração & dosagem , Poliglactina 910/administração & dosagem , Ratos , Ratos Sprague-Dawley , Receptores de Dopamina D2/biossínteseRESUMO
OBJECTIVE: To assess the effects of perioperative comprehensive supportive care interventions on outcome of Chinese esophageal cancer patients in a prospective study. METHODS: 60 patients with primary esophageal carcinoma were randomized into an intervention group (IG, n=31) and a control group (CG, n=29). The Chinese version of symptom checklist-90 (SCL-90) was adopted to assess their psychological status. The interventions, including health education, psychological support, stress management, coping strategies and behavior training, were carried out in 3 phases (preoperative, postoperative I and postoperative II), and psychological effects were thereafter evaluated accordingly before surgery, and 1 week, 4 weeks and 24 weeks post-surgery. Medical costs were estimated at discharge. Survival of patients was estimated each year post-surgery. General health status and satisfaction-with-hospital were surveyed by a follow-up questionnaire 4 years post-surgery. RESULTS: All the subjects demonstrated higher scores in the preoperative phase than the normal range of Chinese population concerning 7 psychological domains including somatization, obsessive-compulsive, depression, anxiety, hostility, phobic anxiety and paranoid ideation. Although no significant difference was observed between the two groups at admission, the scores of IG, which tended to decrease at a faster rate, were generally lower than those of CG at weeks 1, 4 and 24 post-surgery. The length of hospital stay and medical costs of IG were significantly less than those of CG and satisfaction-with-hospital was better. However, there was no significant difference in 4-year survival or health status between two groups. CONCLUSIONS: Appropriate perioperative comprehensive supportive care interventions help to improve the psychological state of Chinese patients with esophageal carcinoma, to reduce health care costs and to promote satisfaction of patients and their families with hospital.
Assuntos
Adaptação Psicológica , Ansiedade/prevenção & controle , Depressão/prevenção & controle , Neoplasias Esofágicas/psicologia , Estresse Psicológico/prevenção & controle , Adolescente , Adulto , Idoso , Ansiedade/psicologia , Estudos de Casos e Controles , China , Aconselhamento , Depressão/psicologia , Neoplasias Esofágicas/reabilitação , Neoplasias Esofágicas/cirurgia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Cuidados Paliativos , Assistência Perioperatória , Prognóstico , Estudos Prospectivos , Inquéritos e Questionários , Adulto JovemRESUMO
BACKGROUND: Whether Tai Chi benefits patients with osteoarthritis remains controversial. We performed a meta-analysis to assess the effectiveness of Tai Chi exercise for pain, stiffness, and physical function in patients with osteoarthritis. METHODS: A computerized search of PubMed and Embase (up to Sept 2012) was performed to identify relevant studies. The outcome measures were pain, stiffness, and physical function. Two investigators identified eligible studies and extracted data independently. The quality of the included studies was assessed by the Jadad score. Standard mean differences (SMDs) and 95% confidence intervals (CIs) were calculated and pooled using a random effects model. The change in outcomes from baseline was compared to the minimum clinically important difference. RESULTS: A total of seven randomized controlled trials involving 348 patients with osteoarthritis met the inclusion criteria. The mean Jadad score was 3.6. The pooled SMD was -0.45 (95% CI -0.70--0.20, Pâ=â0.0005) for pain, -0.31 (95% CI -0.60--0.02, Pâ=â0.04) for stiffness, and -0.61 (95% CI -0.85--0.37, P<0.00001) for physical function. A change of 32.2-36.4% in the outcomes was greater than the minimum clinically important difference. CONCLUSIONS: Twelve-week Tai Chi is beneficial for improving arthritic symptoms and physical function in patients with osteoarthritis and should be included in rehabilitation programs. However, the evidence may be limited by potential biases; thus, larger scale randomized controlled trials are needed to confirm the current findings and investigate the long-term effects of Tai Chi.
Assuntos
Osteoartrite/fisiopatologia , Osteoartrite/terapia , Dor/fisiopatologia , Tai Chi Chuan , Estudos de Casos e Controles , Humanos , Osteoartrite/complicações , Avaliação de Resultados em Cuidados de Saúde , Dor/complicações , Ensaios Clínicos Controlados Aleatórios como Assunto , Resultado do TratamentoRESUMO
BACKGROUND: Although unsupported upper extremity exercise (UUEE) is recommended in the guidelines for pulmonary rehabilitation (PR), it is controversial whether UUEE improves dyspnea in patients with COPD. The present study conducted a meta-analysis of randomized controlled trials to clarify whether UUEE could improve dyspnea in COPD patients. METHODS: A computerized search through PubMed and Embase (up to Mar 2012) was performed to obtain sample studies. Methodological quality was assessed using the PEDro scale. Weighted mean differences (WMDs), and 95% confidence intervals (CIs) were calculated and heterogeneity was assessed with the I(2) test. The overall effect sizes were compared with the minimum clinically important difference (MCID). RESULTS: 240 patients from 7 studies were included in this meta-analysis. The mean PEDro score was 7.0 (SD = 1.7). The results indicated UUEE relieved dyspnea and arm fatigue during activities of daily living (ADL) (WMD = -0.58, -0.55 scores; 95% CI = -1.13 to -0.02, -1.08 to -0.01), however, the overall treatment effects were lower than the MCID of 1 unit for the Borg scale. There was no statistical significance for dyspnea and arm fatigue during intervention (WMD = -0.34, 0.24 scores; 95% CI = -0.78 to 0.09, -0.33 to 0.81). CONCLUSIONS: UUEE can relieve dyspnea and arm fatigue in patients with COPD during ADL and should be included in the PR program, however, there is currently a lack of clinical evidence to support UUEE relieving dyspnea and arm fatigue. Further study is urgent to investigate these effects of UUEE.
Assuntos
Dispneia/terapia , Terapia por Exercício/métodos , Doença Pulmonar Obstrutiva Crônica/reabilitação , Atividades Cotidianas , Braço , Fadiga/prevenção & controle , Humanos , Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
Previous work has shown that the α-tocopherol transfer protein (α-TTP) can bind to vesicular or immobilized phospholipid membranes. Revealing the molecular mechanisms by which α-TTP associates with membranes is thought to be critical to understanding its function and role in the secretion of tocopherol from hepatocytes into the circulation. Calculations presented in the Orientations of Proteins in Membranes database have provided a testable model for the spatial arrangement of α-TTP and other CRAL-TRIO family proteins with respect to the lipid bilayer. These calculations predicted that a hydrophobic surface mediates the interaction of α-TTP with lipid membranes. To test the validity of these predictions, we used site-directed mutagenesis and examined the substituted mutants with regard to intermembrane ligand transfer, association with lipid layers and biological activity in cultured hepatocytes. Substitution of residues in helices A8 (F165A and F169A) and A10 (I202A, V206A and M209A) decreased the rate of intermembrane ligand transfer as well as protein adsorption to phospholipid bilayers. The largest impairment was observed upon mutation of residues that are predicted to be fully immersed in the lipid bilayer in both apo (open) and holo (closed) conformations such as Phe165 and Phe169. Mutation F169A, and especially F169D, significantly impaired α-TTP-assisted secretion of α-tocopherol outside cultured hepatocytes. Mutation of selected basic residues (R192H, K211A, and K217A) had little effect on transfer rates, indicating no significant involvement of nonspecific electrostatic interactions with membranes.
Assuntos
Proteínas de Transporte/química , Proteínas de Transporte/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Sequência de Bases , Sítios de Ligação/genética , Proteínas de Transporte/genética , Primers do DNA/genética , Células Hep G2 , Hepatócitos/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Técnicas In Vitro , Ligantes , Bicamadas Lipídicas/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Proteínas Mutantes/química , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Conformação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homologia de Sequência de Aminoácidos , Eletricidade Estática , Termodinâmica , alfa-Tocoferol/metabolismoRESUMO
We report here our preliminary investigations on the mechanism of alpha-TTP-mediated ligand transfer as assessed using fluorescence resonance energy transfer (FRET) assays. These assays monitor the movement of the model alpha-tocopherol fluorescent derivative ((R)-2,5,7,8-tetramethyl-chroman-2-[9-(7-nitro-benzo[1,2,5]oxadiazol-4-yl amino)-nonyl]-chroman-6-ol; NBD-Toc) from protein to acceptor vesicles containing the fluorescence quencher TRITC-PE. We have found that alpha-TTP utilizes a collisional mechanism of ligand transfer requiring direct protein-membrane contact, that rates of ligand transfer are greater to more highly curved lipid vesicles, and that such rates are insensitive to the presence of anionic phospholipids in the acceptor membrane. These results point to hydrophobic features of alpha-TTP dominating the binding energy between protein and membrane.
Assuntos
Proteínas de Transporte/metabolismo , Bicamadas Lipídicas/química , Fluidez de Membrana/efeitos dos fármacos , Fosfolipídeos/farmacologia , alfa-Tocoferol/metabolismo , Transporte Biológico Ativo/efeitos dos fármacos , Proteínas de Transporte/fisiologia , Metabolismo Energético , Humanos , Interações Hidrofóbicas e Hidrofílicas , Ligantes , Lipossomos/química , Lipossomos/metabolismo , Fosfolipídeos/química , alfa-Tocoferol/farmacocinéticaRESUMO
Quinolinones and naphthyridinones with C7 N-t-butyl piperidine substituents were found to be potent p38 MAP kinase inhibitors. These compounds significantly suppress TNF-alpha release in both cellular and LPS-stimulated whole blood assays. They also displayed excellent PK profiles across three animal species. Quinolinone at 10 mpk showed comparable oral efficacy to that of dexamethasone at 1 mpk in a murine collagen-induced arthritis model.
Assuntos
Inibidores Enzimáticos/farmacologia , Naftiridinas/química , Piperidinas/química , Quinolonas/química , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores , Animais , Artrite Experimental , Colágeno/química , Dexametasona/química , Cães , Haplorrinos , Humanos , Concentração Inibidora 50 , Lipopolissacarídeos/metabolismo , Camundongos , Modelos Químicos , Ratos , Fatores de Tempo , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Fator de Necrose Tumoral alfa/química , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
We have developed assays for the binding of nucleotide and protein substrates to p38alpha protein kinase based on time-resolved Forster resonance energy transfer. p38alpha was biotinylated by addition of a sequence that targets biotin to a single lysine when coexpressed with biotin ligase in Escherichia coli, allowing formation of a complex between a streptavidin "LANCE" europium chelate conjugate and p38alpha. When this reagent was combined with M39AF, a p38 inhibitor containing a fluorescent moiety whose excitation wavelengths match the emission wavelengths of the europium chelate, a change in ratio of light emitted at 665 nm/615 nm is detected. Less than 100pM complex was detected with a signal/background ratio of >30-fold. The complex exhibits slow, tight binding kinetics where the apparent K(d) decreases with a relaxation time of 21 min at 125 pM biotin-p38alpha. Preincubating inhibitors or ATP with biotin-p38alpha and adding M39AF as a competitor yielded IC(50)s consistent with those measured by enzyme assay for the activated form of biotin-p38alpha. The same technique was also used to measure affinity of inhibitors for the unphosphorylated and catalytically inactive form of biotin-p38alpha. To measure affinity of p38alpha for its protein substrate MK2, we incubated biotin-p38alpha with a glutathione S-transferase MK2 fusion protein. Detection of the complex after incubation with streptavidin-allophycocyanin and a LANCE-conjugated anti-GST allowed measurement of affinity of MK2 for biotin-p38alpha and detection of 0.5 nM p38alpha.MK2 complex with signal/background ratio >5-fold. Competition with unbiotinylated p38alpha yielded an IC(50) value of 5 nM. Activation of either p38alpha or MK2 had no effect on the measured K(d). M39AF was found to bind in a ternary complex with p38alpha.MK2 with lower affinity than that observed in the binary complex with p38alpha alone.