Apoptosis in leukocytes induced by UVA in the presence of 8-methoxypsoralen,chlorpromazine or 4,6,4'-trimethylangelicin

Although 8-methoxypsoralen (8-MOP) has been successfully used in extracorporeal photochemotherapy (ECP) of several T cell-mediated diseases, the exact mechanism of the drug therapeutic action has not been established. We have studied in vitro apoptotic activity of 8-MOP, and for comparison of 4,6,4'-trimethylangelicin (TMA) and chlorpromazine (CPZ) as alternative photosensitizers for potential use in photopheresis. However, while 8-MOP and CPZ are known for their immune suppressive activity, TMA does not exhibit such an activity in an animal model for ECP. Apoptosis and necrosis were measured in both Jurkat cells and primary rat leukocytes under conditions comparable to those used in the animal model to suppress contact hypersensitivity (CHS). Cells were irradiated with UVA (200 kJ/m(2)) after treatment with 8-MOP, CPZ or TMA (300 ng/ml). Flow cytometric analysis (annexin-V-FLUOS/propidium iodide) and fluorescence microscopy examinations, using acridine orange/propidium iodide, indicated that the number of cells undergoing apoptosis or necrosis increased significantly after 24 h following treatment. Similar results were observed irrespective of the cell type and photosensitizer used. The results of the present study, combined with previous observations with the animal model for ECP, suggest that apoptosis is not likely to be a critical step in the cascade of events leading to immunosuppression.     

Differential-pulse voltammetric determination of molybdenum in nitrate medium in the presence of 8-hydroxyquinoline

The determination of Mo(VI) by differential-pulse voltammetry based on catalytic currents in nitrate medium is described. The existence of catalytic currents in the system Mo(VI)NO₃^? in the presence of 8-hydroxyquinoline was proved by various polarographic techniques. The optimum background electrolyte is 20 ml 0.5 M KNO₃?0.005 M HNO³ with the addition of 1 ml of 1 × 10^?2 M 8-hydroxyquinoline. The detection limit is 7 × 10^?10 M under these conditions. Cr(VI), Cu(II), Cd(II) and Pb(II) interfere when present at higher concentrations then Mo(VI) and W(VI) interferes at an equal concentration to Mo(VI). The method was successfully used in analyses of environmental samples.     

High-performance liquid chromatographic measurement of 8-methoxypsoralen in plasma

Summary A simple high-performance liquid chromatographic method for the measurement of 8-Methoxypsoralen (8-MOP) in human plasma following a single 40mg dose has been described. After addition of phosphate-NaOH buffer, pH 12, and internal standard (trimethylpsoralen), the sample is vortex-mixed with diisopropylether. The resulting extract is analysed on a reverse phase column using phosphoric acid (0.05% v/v): acetonitrile (1:1) as mobile phase, and U.V. detection at 220nm. No interference from endogenous sources has been observed. The limit of sensitivity of the assay is 5ng/ml plasma. The measuring range is between 10–700ng 8-MOP/ml plasma, to be expected from oral doses of 0.6mg 8-MOP/kg body weight, and corresponds to the therapeutic plasma concentration. The relative standard deviation at 50ng/ml level of 8-MOP is 3.6%.     

Photocarcinogenesis in the Tg.AC mouse: lomefloxacin and 8-methoxypsoralen

The Tg.AC mouse is a good predictor of carcinogenic potential when the test article is administered by dorsal painting (Tennant et al. (1995) Environ. Health Perspect. 103, 942). We have used lomefloxacin (LOME) and 8-methoxypsoralen (8-MOP) in combination with UVA to determine whether the Tg.AC transgenic mouse also responds to parenterally administered photocarcinogens. Female Tg.AC mice were given LOME (25 mg/kg intraperitoneal in normal saline) followed by UVA (25 J/cm2) 1-2 h later, five times every 2 weeks on a repetitive schedule. Other groups received LOME, UVA or vehicle alone. After 16 weeks, the mean numbers of papillomas/mouse +/- SD (% responding) were: saline, 0.3 +/- 0.5 (33%); UVA + saline, 1.3 +/- 0.6 (100%); LOME, 1.9 +/- 1.6 (86%) and LOME-UVA, 1.5 +/- 1.9 (64%). Only the 100% incidence of tumors in the UVA group and the maximum tumor yields in the LOME and UVA groups are significant (P < 0.05) when compared with the control. In a second study, Tg.AC mice were administered the classical photocarcinogen 8-MOP (8 mg/kg intragastric in corn oil) followed by 2 J/cm2 UVA 1-2 h later, five times every 2 weeks on a repetitive schedule. The second group received 8-MOP, whereas the third was exposed to UVA alone. Papillomas began to appear at 2 weeks in the 8-MOP-UVA group, and after 17 weeks the mean numbers of papillomas/mouse +/- SD (% responding) were: 8-MOP-UVA, 6.9 +/- 8.6 (93%); UVA + corn oil, 1.1 +/- 1.2 (69%) and 8-MOP, 1.1 +/- 1.6 (50%). The maximum tumor yield in the 8-MOP-UVA group was significantly higher (P < 0.01) than that in the other two groups. Our findings suggest that more studies need to be done before the Tg.AC mouse can be used with confidence to identify parenterally administered photocarcinogens.     

Exciplexes and the fluorescence of Staphylococcus aureus endonuclease

Abstract— The family of fluorescence spectra obtained from the endonuclease of Staphylococcus aureus at temperatures from 140° to 230°K, when superimposed, show a unique intersection point at 336nm. This indicates that only two types of fluorescent species need be considered with this protein, a low-temperature form and a high-temperature form. Since the high-temperature form lacks fine structure and has a large Stokes' shift, the spectral observations are consistent with the notion that high-temperature fluorescence comes from a tryptophan that has formed a complex with a solvent molecule within its excited-state lifetime. The absorption spectrum and both of the fluorescence spectra indicate that the tryptophan, even in the high-temperature state, is in an environment with a low dielectric constant.     

Comprehensive profiling of lysine acetylome in Staphylococcus aureus

The Gram-positive bacterium Staphylococcus aureus(S.aureus)is a wide spread common opportunistic pathogen that causes a wide variety of infectious diseases,from benign skin infections to life-threatening diseases such as the methicillin-resistant Staphylococcus aureus(MRSA)infection.Although emerging evidence suggests that lysine acetylation may play critical roles in bacterial physiology,the atlas of acetylome in S.aureus has not been studied.To comprehensively profile protein lysine acetylation in S.aureus,we used an integrated approach that combined immune affinity peptide enrichment using anti-lysine acetylation antibody,high-pH HPLC fractionation,and HPLC/mass spectrometry analysis.This study led to the identification of 1361 non-redundant acetylation sites on 412 proteins found in a search of S.aureus protein database extracted from the Swiss-Prot database.We further performed bioinformatic analysis to characterize this modification,including gene ontology annotation,protein-protein interaction,and domain analysis of the acetylation sites.We found that the acetylated proteins were enriched in multiple biological pathways,such as ribosomal function and energy metabolism.Our data provides a rich source for functional studies of lysine acetylation in S.aureus.     

The role of oxygen in the visible-light inactivation of Staphylococcus aureus

Exposure to visible-light causes the photoinactivation of certain bacteria by a process that is believed to involve the photo-stimulation of endogenous intracellular porphyrins. Studies with some bacterial species have reported that this process is oxygen-dependent. This study examines the role of oxygen in the visible-light inactivation of Staphylococcus aureus. Suspensions of S. aureus were exposed to broadband visible-light under both oxygen depletion and oxygen enhancement conditions to determine whether these environmental modifications had any effect on the staphylococcal inactivation rate. Oxygen enhancement was achieved by flowing oxygen over the surface of the bacterial sample during light inactivation and results demonstrated an increased rate of staphylococcal inactivation, with approximately 3.5 times less specific dose being required for inactivation compared to that for a non-enhanced control. Oxygen depletion, achieved through the addition of oxygen scavengers to the S. aureus suspension, further demonstrated the essential role of oxygen in the light inactivation process, with significantly reduced staphylococcal inactivation being observed in the presence of oxygen scavengers. The results of the present study demonstrate that the presence of oxygen is important for the visible-light inactivation of S. aureus, thus providing supporting evidence that the nature of the mechanism occurring within the visible-light-exposed staphylococci is photodynamic inactivation through the photo-excitation of intracellular porphyrins.     

133Xe release during post-irradiation annealing of uranium metal in the presence of a constant volume of air

The fractional release of¹³³Xe at different temperatures was studied as a function of time in the presence of an atmosphere of air during post-irradiation annealing of uranium metal. It was found that the relation between the fractional release and t^1/2 is irregular. There is an initial step in the annealing curves (at the temperature range of 400–710°C) which decreases by increasing temperature and totally disappears at the high temperature of 800–1000 °C. The other parts of the release curves are typical for¹³³Xe release from uranium metal. The initial step was found to be due to the surface oxidation of uranium metal.     

超高效液相串联质谱法同时测定中成药中5-甲氧基补骨脂素、8-甲氧基补骨脂素和欧前胡素

建立了同时测定中成药都梁滴丸中5-甲氧基补骨脂素、8-甲氧基补骨脂素和欧前胡素的超高效液相-串联质谱检测方法。都梁滴丸以甲醇超声提取45 min,提取液稀释后经Waters Oasis HLB固相萃取小柱净化,采用WatersACQUITY UPLC BEHC18(50 mm×2.1 mm,1.7μm)色谱柱,以乙腈(A)和水(B)为流动相进行梯度洗脱。采用电喷雾电离正离子模式,多反应监测模式检测,以保留时间和离子比定性,外标法定量。方法的定量限8-甲氧基补骨脂素和5-甲氧基补骨脂素均为0.3 mg/kg;欧前胡素为0.75 mg/kg。3种化合物在25~500μg/L范围内均呈线性,相关系数r0.99。在高,中,低三种添加水平的平均回收率为82.0%~107.4%日内精密度(RSD%)为1.1%~12%。     

Discovery of an Iron-Regulated Citrate Synthase in Staphylococcus aureus

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Highlights? Staphylococcus aureus SbnG is discovered to be an iron-regulated citrate synthase ? SbnG provides citrate for synthesis of the citrate siderophore staphyloferrin B ? Staphyloferrin B can be synthesized in vitro using purified enzymes ? SbnG inhibitors identified     

Aptamer Immobilized Magnetoelastic Sensor for the Determination of Staphylococcus aureus

An aptamer-based magnetoelastic sensor for the determination of Staphylococcus aureus is reported. Aptamers specific to S. aureus were used to ensure specific and selective binding of bacteria on the sensor surface. The sensors were exposed to S. aureus concentrations of 1 × 10¹–1 × 10¹¹ colony forming units per milliliter, and the changes in resonance frequency were monitored. The sensitivity was higher for sensors with smaller physical dimensions. The biosensor with dimensions of 2 × 5 × 0.028 millimeters provided a linear dynamic range of 10¹–10¹¹ colony forming units per milliliter and a detection limit of 5 colony forming units per milliliter. The results also demonstrated that the magnetoelastic sensors determined the targeted pathogenic species with good selectivity. The method was employed to determine S. aureus in water, and the results were comparable to those obtained by plate-counting methods. The high sensitivity, selectivity, and stability of the aptamer provide a promising approach for the determination of pathogenic bacteria.     

Determination of 8-methoxypsoralen in plasma by gas chromatography-mass spectrometry using selected-ion monitoring.

A sensitive and accurate assay was developed for the measurement of 8-methoxypsoralen in plasma using electron-impact positive-ion mass fragmentography. 4,5,8-Trimethylpsoralen was used as an internal standard. Sample preparation consisted of a two-step liquid phase extraction using acetonitrile and methylene chloride. The calibration curve showed a linear relationship between the peak areas of 8-methoxypsoralen and 4,5,8-trimethylpsoralen over a wide range of 8-methoxypsoralen concentrations (1-500 ng/ml). With-in- and between-run precisions, measured at five different drug concentrations, varied from 0.82 to 1.41% and from 0.82 to 1.86%, respectively.     

Investigations of the interaction between cuprous oxide nanoparticles and Staphylococcus aureus

Science China Chemistry - In this study, cuprous oxide nanoparticles of 30–50 nm in size were prepared in the presence of cetyltrimethylammonium bromide (CTAB). By taking Staphylococcus...     

Peppermint oil decreases the production of virulence-associated exoproteins by Staphylococcus aureus

The present study aimed to evaluate the antimicrobial activity of peppermint oil against Staphylococcus aureus, and further investigate the influence of peppermint oil on S. aureus virulence-related exoprotein production. The data show that peppermint oil, which contained high contents of menthone, isomenthone, neomenthol, menthol, and menthyl acetate, was active against S. aureus with minimal inhibitory concentrations (MICs) ranging from 64-256 μg/mL, and the production of S. aureus exotoxins was decreased by subinhibitory concentrations of peppermint oil in a dose-dependent manner. The findings suggest that peppermint oil may potentially be used to aid in the treatment of S. aureus infections.     

Effect of gamma irradiation on the expressed proteins in the foodborne pathogen Staphylococcus aureus

A capillary electrophoresis method with UV detection was developed to analyze protein composition of the foodborne pathogen Staphylococcus aureus. Bacterial samples containing 10⁹ CFU/ml, obtained after two cycles of incubations of 24 h, were gamma irradiated at different doses of 1.2, 3.5 and 2.9 kGy to respectively create damage cells, to kill cells and to provoke viable but non cultivable cells (VBNC). It was observed that an irradiation at a sensitive dose of 1.2 kGy caused a significantly increase in the protein with molecular weight (MW) of 17.7 kDa (from 0.61% to 1.2%). This treatment also caused decreases in the expressed proteins with the MWs of 16.3 kDa (from 6.2% to 5.3%) and of 23.4 kDa (from 4.0% to 2.30%). Irradiation at a VBCN dose of 2.9 kGy caused increases in expressed proteins with the MWs of 17.7 kDa (from 0.61% to 3.43%), 18.7 kDa (from 1.04% to 4.30%), 19.5 kDa (from 0.71% to 2.30%), 21.1 kDa (from 1.20% to 3.80%). Moreover, this treatment (2.9 kGy) also caused significantly decreases (P≤0.05) in the expressed proteins with the MW of 30.7 kDa (from 8.6% to 5.15%), 36.3 kDa (from 3.1% to 2.7%) and 40.5 kDa (from 11.3% to 8.5%). Finally, for the irradiation at a lethal dose of 3.5 kGy, it can be found that the expressed proteins with the MW of 17.7 kDa, 18.7 kDa and 19.5 kDa were increased less than that of expressed proteins at the VCNC dose (2.9 kGy) and these might be the very important proteins which are responsible for the survival of the S. aureus. Further, there were also the decreases in expressed proteins with the MW of 30.7 kDa, 36.3 kDa and 75.1 kDa at this dose of treatment (3.5 kGy) which can be expected that these proteins are seriously affected at high dose of γ-irradiation treatment.