Methods: Catalase activity was evaluated by the permanganatometric and calorimetric assays.
Results: This inhibition is not the result of chemical transformations of these compounds to a single inhibitor, as well as it is not the result of NO release from these substances (as NO traps have no effect on the extent of inhibition). It was found that chloride and bromide in concentration above 80 mM and thiocyanate in concentration above 20 μM enhance catalase inhibition by nitrite and the nitroso compounds more than 100 times. The inhibition degree in this case is comparable with that induced by azide.
Discussion: We propose that the direct catalase inhibitor is a positively charged NO-group. This group acquires a positive charge in the active center of enzyme by interaction of nitrite or nitroso compounds with some enzyme groups. Halides and thiocyanate protect the NO+ group from hydration and thus increase its inhibition effect. It is probable that a comparatively low chloride concentration in many cells is the main factor to protect catalase from inhibition by nitrite and nitroso compounds. 相似文献
Objective: Measure polar volatile organic compounds (PVOCs) excreted in urine to document endogenous metabolites and exogenous compounds from environmental exposures.
Methods: Use headspace collection and sorbent tube thermal desorption coupled with bench-top gas chromatography-mass spectrometry (GC-MS) for targeted and non-targeted approaches. Identify and categorize PVOCs that may distinguish among healthy and affected individuals.
Results: Method is successfully demonstrated to tabulate a series of 28 PVOCs detected in human urine across 120 samples from 28 human subjects. Median concentrations range from below detect to 165?ng/mL. Certain PVOCs have potential health implications.
Conclusions: Headspace collection with sorbent tubes is an effective method for documenting PVOCs in urine that are otherwise difficult to measure. This methodology can provide probative information regarding biochemical processes and adverse outcome pathways (AOPs) for toxicity testing. 相似文献
The samples were dried with sodium sulphate and Soxhlet extracted for 16 hours with dichloromethane. Then this solvent was replaced by hexane and the resulting solution was concentrated in a rotary evaporator. The clean-up process consisted of elution through a mixed silica column followed by a treatment with activated copper turnings to remove the sulphur. The sample was then concentrated down to 2 mL by nitrogen stream. The internal standard, 1,4-dibromobenzene, was added to the sample prior to the extraction, whereas the injection standard, 1,3,5-tribromobenzene, was added right before the sample was injected through the chromatographic system.
The limits of quantification ranged from 71 to 500 pg g?1 (dry weight). The reproducibility in the peak areas within a day was better for the compounds with increasing number of chlorines, whereas the reproducibility over time studies provided no significant differences in the peak areas in consecutive days.
The method was successfully applied to the determination of polychlorobenzenes in a certified sediment and, finally, it was applied to the determination of these compounds in several sections of a sediment core from Esthwaite Water Lake (United Kingdom). 相似文献
Objective: Identify circulating microRNAs (miRs) as novel biomarkers for early detection of MDI exposure and prevention of MDI-OA.
Materials and methods: Female BALB/c mice were exposed to one of three exposure regimens: dermal exposure to 1% MDI in acetone; nose-only exposure to 4580?±?1497?μg/m3 MDI-aerosol for 60?minutes; or MDI dermal exposure/sensitization followed by MDI-aerosol inhalation challenge. Blood was collected and miRCURY? miRs qPCR Profiling Service was used to profile circulate miRs from dermally exposed mice. Candidate miRs were identified and verified from mice exposed to three MDI-exposure regimens by TaqMan® miR assays.
Results: Up/down-regulation patterns of circulating mmu-miRs-183-5p, -206-3p and -381-3p were identified and verified. Circulating mmu-miR-183-5p was upregulated whereas mmu-miRs-206-3p and -381-3p were downregulated in mice exposed via all three MDI exposure regimens.
Discussion and conclusion: Upregulation of circulating miR-183-5p along with downregulation of circulating miRs-206-3p and -381-3p may serve as putative biomarkers of MDI exposure and may be considered as potential candidates for validation in exposed human worker populations. 相似文献
Materials and methods: A comprehensive study of conventional water treatment technologies was carried out and their shortcomings were pointed out. Research findings from the leading groups working on enzyme grafted membrane based water purification were summarized. This review also comprehends the patent documents pertinent to the technology of enzyme grafted membranes for water purification.
Results: Immobilization of an enzyme on a membrane improves the performance of membrane filtration, and processes for the treatment of polluted water. Research has started exploring the potential for laccase enzymes because it can catalyze the oxidation of a wide range of substrates, structurally comparable to EDCs, by a radical-catalyzed reaction mechanism, with corresponding reduction of oxygen to water in an electron transfer process. Further, in the presence of certain mediators, the substrate range of laccases can be further enhanced to non-aromatic substrates.
Conclusions: Removal of EDCs by laccase cross-linked enzyme aggregates in fixed-bed reactors or fluidized-bed reactors and laccase immobilized ultrafiltration (LIUF) membranes are proving their worth in water purification technology. The major operational issues with the use of LIUF membranes are enzyme instability in real wastewater and membrane fouling. In view of the above-stated characteristics, laccases are considered as the most promising enzyme for a greener and less expensive water purification technology. 相似文献
Objective: We compared the release of cardiac troponin T (cTnT) after endurance running in training-experience, biological-age and maturity-matched young male and female runners.
Materials and methods: Nineteen male (training history: 2.3?±?1.0?years; mean age: 16.1?±?1.2?years; Tanner stage: 3.7?±?0.6) and 19 female (training history: 2.2?±?1.0?years; mean age: 15.9?±?1.4?years; Tanner stage: 4.0?±?0.4) runners performed a 21?km run with “all-out” effort. Serum cTnT levels were assessed at pre-exercise (Pre-ex) and at 4?h post-exercise (Post-ex).
Results: At Pre-ex, cTnT concentrations were below the 99th percentile value (10?ng.l?1) in 32/38 runners. Post-ex cTnT increased in all subjects but the response was substantially higher (p?<?0.05) in males [median (range): 210 (20–1360) ng.l?1] than females [median (range): 80 (10–550) ng.l?1]. At Post-ex, 95% (95% confidence interval: 75–99%) of males and 63% (95% confidence interval: 41–81%) of females (p?<?0.05) had cTnT concentrations above the cut-off for acute myocardial infarction.
Conclusions: The present data suggest that post-exercise cTnT elevation occurs in all runners but is augmented in young male compared to female athletes. 相似文献
Methods. On the western slope, the bryophyte and lichen layer was collected from 600?cm2 plots on six substrate types with four replications at eight elevations along a gradient from 1900 to 3300?m a.s.l. We recorded the thickness, water-holding capacity and biomass of all samples, as well as environmental parameters.
Key results. At lower elevations substrates had a similar biomass and water-holding capacity per area, but with increasing elevation terricolous substrates showed the strongest increase (highest values at 3100?m). These patterns are associated with climatic variation along the gradient. At the highest elevations, the forest was of low stature and more light reached the forest floor. Also at these high elevations fog provides a daily wetting of the bryophytes and lichens. At lower elevations the water supply is increasingly in the form of rain, which is less frequent than the fog.
Conclusions. The apparent strong coupling of biomass variations to precipitation regimes implies a high sensitivity of the bryophytes and lichens to climatic warming and changes in the cloud base elevation. Furthermore our data suggest that the importance of bryophytes and lichens for regulating ecosystem water fluxes increases with elevation, which underlines the necessity to conserve intact montane forests. 相似文献
Objective: To compare the reliability of urine lactate between controlled hydration and no hydration after maximal exercise.
Material and methods: Athletes performed swimming exercise four times: two followed by consumption of 1?L of water and two followed by no water intake. Blood and urine lactate was measured.
Results: The reliability of urine lactate was good and similar to that in blood only after controlled hydration. Blood and urine lactate were correlated under both hydration conditions.
Discussion and conclusion: Controlled hydration after exercise provides satisfactory reliability of urine lactate. 相似文献
Objective: The aim of this paper is the discovery of new non-invasive biomarker for the monitoring of VHLD patients.
Materials and methods: We compared the urinary proteome of VHLD patients, ccRCC patients and healthy volunteers.
Results: Among all differentially expressed proteins, alpha-1-antitrypsin (A1AT) and APOH (beta-2-glycoprotein-1) are strongly over-abundant only in the urine of VHLD patients with a history of ccRCC.
Discussion and conclusion: A1AT and APOH could be promising non-invasive biomarkers. 相似文献
Objective/Aim: In this work, we investigated the possible effect of lipid composition on the incorporation of trastuzumab-PEG-PE micelles into nanoliposomes and on their subsequent specific cellular targeting.
Materials and methods: Trastuzumab (anti-HER2 monoclonal antibody) was monothiolated and conjugated to maleimide-PEG-PE micelles. Liposomes of different lipid compositions were prepared by the thin layer hydration. Trastuzumab-PEG-PE micelles were incorporated into the liposomes by the post-insertion method. The percentage of lipid mixing was determined based on fluorescence resonance energy transfer. Cellular binding and uptake of rhodamine-labeled immunoliposomes were studied in SKBR-3 (HER2+++) and MCF-7 (HER2+) cells. Also, antitumor cell activity of the immunoliposomes was compared to free trastuzumab and the liposomes.
Results: The lipid mixing of trastuzumab-PEG-PE micelles depended on the liposome composition. The immunoliposomes containing DPPC, cholesterol and PEG-PE showed prominent lipid mixing. The lipid mixing was consistent with the cell binding results which showed an efficient and specific binding of the immunoliposomes to SKBR-3 cells. Antitumor cell activity of the immunoliposomes in SKBR-3, unlike MCF-7 cells, depended on the content of trastuzumab.
Discussion: Cholesterol and PEG-PE in the liposome composition are prerequisites for a successful lipid mixing due to their ability to facilitate fusion. The higher lipid mixing results in higher antibody incorporation and consequently higher targeted cell binding.
Conclusions: The lipid mixing depends on the liposome composition, which reflects targeted cell binding of the immunoliposomes. 相似文献
To analyze the functional role of PrPC in the signal pathway mediated by EGF/EGF-R, a siRNA PrP was applied to ablate PrPC and its function. The treatment with siRNA PrP significantly prevented Akt and ERK1/2 phosphorylation induced by EGF.
Moreover, siRNA PrP treatment significantly prevented neuronal-specific antigens expression induced by EGF/bFGF, indicating that cellular prion protein is essential for EGF/bFGF-induced hDPSCs differentiation.
These results suggest that PrPC interact with EGF-R within lipid rafts, playing a role in the multimolecular signaling complexes involved in hDPSCs neuronal differentiation. 相似文献
Aims: To investigate the habitat selection patterns of tree-nesting Golden Eagles, and identify how potential conflicts with wind farm development could be minimized.
Methods: The study is based on GPS tracking data from 22 adult eagles. We estimated home range sizes using a biased random bridge approach and habitat selection patterns using resource selection functions following a use-availability design.
Results: Core home range size among adults was variable during the breeding season (5–30?km2). Individual movement extents were variable, but sexes did not significantly differ in their scale of movement. At the landscape scale, individuals selected for clear-cuts and coniferous forest with ground lichens, whereas wetland, water bodies and mixed forest were avoided. Steeper and south facing slopes were selected for, whereas, north facing slopes were avoided.
Conclusions: Potential conflicts between eagles and wind energy establishment can be reduced if wind farms are placed away from steep slopes, minimizing areas that are clear-cut during construction, and locating turbines within dense, young and other less favoured forest habitats. 相似文献
Objective: Ascertain the utility of measurements of single-strand breaks (SSB) in DNA for assessment of breast cancer risk.
Methods: Fine-needle aspirates of the breast, SSB by nick translation, percent breast density (PBD), Gail model risk, cumulative methylation index (CMI), enzymes of DNA repair and tissue antioxidants.
Results: DNA repair enzymes and 4-hydroxyestradiol were negatively associated with SSB; CMI and PBD were positively associated.
Conclusions: Quantitative measurement of SSBs by this procedure indicates the relative number of SSBs and is related to promoter methylation, antioxidant availability and percent breast density. 相似文献
The annual removal of the soil activity with the biomass was less than 0.1%. The addition of citric acid (25 mmol kg-1) 1 week before the harvest increased U uptake up to 500-fold. With a ryegrass and mustard yield of 15000 kg ha-1 and 10000 kg ha-1, respectively, up to 3.5% and 4.6% of the soil activity could annually be removed with the biomass.
With a desired activity reduction level of 1.5 and 5 for the bicarbonate washed and control soil, respectively, it would take 10 to 50 years to attain the release limit.
A linear relationship between the plant 238U concentration and the 238U concentration in the soil solution of the control, bicarbonate-washed, or citric acid-treated soil points to the importance of the soil solution activity concentration in determining U uptake and hence to the importance of solubilising agents to increase plant uptake.
However, citric acid addition resulted in a decreased dry weight production (all plants tested) and crop regrowth (in case of ryegrass). 相似文献
Objective: To examine the association between the concentration in house dust of five OPs used commonly in pome fruit orchards and the concentration in urine of dialkylphosphate metabolites (DAP), in a cohort of Hispanic FW and NFW and their children.
Methods: Parents and children participated in three data collection periods over the course of one year. Urine samples were evaluated for the DAPs characteristic of OP exposure, and dust from homes and vehicles was evaluated for intact OP residues.
Results: Geometric mean (GM) concentrations of OPs in house and vehicle dust were higher in FW households than NFW households in all agricultural seasons. GM concentration of urinary DAPs was higher for children in FW households than NFW households.
Discussion: Regression analysis found a positive association between OP residues in house dust and the children’s urinary DAPs.
Conclusions: To our knowledge, this study is the first to report an association between pesticides in house dust and their biological metabolites in urine. 相似文献
Objective: In this context, we decided to investigate the kinetic and mechanistic aspects of Vancomycin (Vanco) photosensitized degradation in the presence of the natural pigment Riboflavin (Vitamin B2, Rf) and the artificial dye Rose Bengal (RB) for comparative purposes.
Methods: The study have been done by using Stationary photolysis, Laser flash photolysis, Time-resolved phosphorence detection of O2(1Δg) experiments and Bactericidal activity evaluation. The experiments were carried out in aqueous solution at different pH values in order to establish relationships between the structure of the compound and its susceptibility to ROS-mediated photooxidation.
Results: Experimental evidence indicates that in the presence of Rf there is considerable contribution of the radical-mediated mechanism, while in the presence of RB the photooxidation process occurs exclusively through O2(1Δg) and the reactivity to this excited species increases with increasing pH of the environment.
Discussion: The results obtained, have been shown that Rf can raise the photodegradation of Vanco by both the radical pathway and the O2(1Δg) mediated. Furthermore, the antibiotic is able to interact with the excited electronic states of Rf as well as O2(1Δg) generated by energy transfer between the excited triplet state of the photosensitizer and the oxygen ground state. The predominant mechanism for photodegradation of Vanco in the presence of the Rf is the radical via because of the considerable interaction with the excited triplet state of the photosensitizer demonstrated by laser flash photolysis experiments.
Microbiological test on Staphylococcus aureus ATCC25923 showed that the bactericidal activity of the antibiotic on the strain studied was affected by the sensitized photodegradation process, suggesting that photoproducts generated eventually do not retain the bactericidal properties of the original antibiotic. 相似文献
Methods: Renal mitochondrial oxidative stress and Sirt3 activity, using Zucker diabetic fatty rats (ZDFRs) and cultured proximal tubular cells under high-glucose condition were evaluated.
Results: At 28 weeks of age, ZDFRs exhibited the increased urinary albumin/liver-type fatty acid-binding protein (L-FABP)/8-hydroxy-2'-deoxyguanosine (8-OHdG) excretion, histological tubular cell damage, compared to non-diabetic Zucker Lean rats. In renal mitochondria, acetylated isocitrate dehydrogenase2 (IDH2) and superoxide dismutase2 (SOD2), accompanied with mitochondrial oxidative stress and mitochondrial morphologic alterations, were increased in ZDFRs, indicating inactivation of Sirt3. Additionally, expression of the NAD-degrading enzyme, CD38, was increased, and the NAD+/NADH (reduced NAD) ratio was reduced in the renal cortex of ZDFRs. High-glucose stimulation in cultured proximal tubular cells also resulted in an increase in acetylated IDH2/SOD2, CD38 overexpression and a reduction in the NAD+/NADH ratio.
Conclusions: Enhancement of mitochondrial oxidative stress in the diabetic kidney was mediated by the reduction of Sirt3 activity. CD38 overexpression may be related to a reduction in the NAD+/NADH ratio in the diabetic kidney. 相似文献