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1.
The object of present study is to investigate the effects of 50 GHz microwave frequency electromagnetic fields on reproductive
system of male rats. Male rats of Wistar strain were used in the study. Animals 60 days old were divided into two groups—group
I sham exposed and group II experimental (microwave exposed). During exposure, rats were confined in Plexiglas cages with
drilled ventilation holes for 2 h a day for 45 days continuously at a specified specific absorption rate of 8.0 × 10−4 W/kg. After the last exposure, the rats were sacrificed immediately and sperms were collected. Antioxidant enzyme (superoxide
dismutase (SOD), glutathione peroxidase (GPx), and catalase), histone kinase, apoptosis, and cell cycle were analyzed in sperm
cells. Result shows a significant decrease in the level of sperm GPx and SOD activity (p ≤ 0.05), whereas catalase shows significant increase in exposed group of sperm samples as compared with control (p < 0.02). We observed a statistically significant decrease in mean activity of histone kinase as compared to the control (p < 0.016). The percentage of cells dividing in a spermatogenesis was estimated by analyzing DNA per cell by flow cytometry.
The percentage of apoptosis in electromagnetic field exposed group shows increased ratio as compared to sham exposed (p < 0.004). There were no significant differences in the G0/G1 phase; however, a significant decrease (p < 0.026) in S phase was obtained. Results also indicate a decrease in percentage of G2/M transition phase of cell cycle in exposed group as compared to sham exposed (p < 0.019). We conclude that these radiations may have a significant effect on reproductive system of male rats, which may
be an indication of male infertility. 相似文献
2.
The object of this study is to investigate the effects of 50-GHz microwave radiation on the brain of Wistar rats. Male rats
of the Wistar strain were used in the study. Animals of 60-day age were divided into two groups—group 1, sham-exposed, and
group 2, experimental (microwave-exposed). The rats were housed in a temperature-controlled room (25 °C) with constant humidity
(40–50%) and received food and water ad libitum. During exposure, rats were placed in Plexiglas cages with drilled ventilation
holes and kept in an anechoic chamber. The animals were exposed for 2 h a day for 45 days continuously at a power level of
0.86 μW/cm2 with nominal specific absorption rate 8.0 × 10−4 w/kg. After the exposure period, the rats were killed and homogenized, and protein kinase C (PKC), DNA double-strand break,
and antioxidant enzyme activity [superoxides dismutase (SOD), catalase, and glutathione peroxidase (GPx)] were estimated in
the whole brain. Result shows that the chronic exposure to these radiations causes DNA double-strand break (head and tail
length, intensity and tail migration) and a significant decrease in GPx and SOD activity (p = <0.05) in brain cells, whereas catalase activity shows significant increase in the exposed group of brain samples as compared
with control (p = <0.001). In addition to these, PKC decreased significantly in whole brain and hippocampus (p < 0.05). All data are expressed as mean ± standard deviation. We conclude that these radiations can have a significant effect
on the whole brain. 相似文献
3.
The present study investigates the effect of free radical formation due to mobile phone exposure and effect on fertility pattern
in 70-day-old male Wistar rats (sham exposed and exposed). Exposure took place in Plexiglas cages for 2 h a day for 35 days
to mobile phone frequency. The specific absorption rate was estimated to be 0.9 W/kg. An analysis of antioxidant enzymes glutathione
peroxidase (P < 0.001) and superoxide dismutase (P < 0.007) showed a decrease, while an increase in catalase (P < 0.005) was observed. Malondialdehyde (P < 0.003) showed an increase and histone kinase (P = 0.006) showed a significant decrease in the exposed group. Micronuclei also show a significant decrease (P < 0.002) in the exposed group. A significant change in sperm cell cycle of G0–G1 (P = 0.042) and G2/M (P = 0.022) were recorded. Generation of free radicals was recorded to be significantly increased (P = 0.035). Our findings on antioxidant, malondialdehyde, histone kinase, micronuclei, and sperm cell cycle are clear indications
of an infertility pattern, initiated due to an overproduction of reactive oxygen species. It is concluded that radiofrequency
electromagnetic wave from commercially available cell phones might affect the fertilizing potential of spermatozoa. 相似文献
4.
《Bioelectrochemistry and bioenergetics (Lausanne, Switzerland)》1996,39(2):167-173
Synchronized Chinese hamster ovary (CHO) cells were exposed to continuous wave (CH) 2.45 GHz microwave radiation (MWR) or CW 27 MHz radiofrequency radiation (RFR) under isothermal conditions (37±0.2°) to test the following hypotheses: (1) high frequency electromagnetic radiation exposure directly affects the mammalian cell cycle in the absence of radiation-induced heating; and (2) the magnitude of the cell cycle alteration is frequency dependent. CHO cells in either G0/G1-, S−, or G2/M-phase of the cell cycle were simultaneously exposed to CW 27 MHz RFR or CW 2.45 GHz MWR at specific absorption rates (SARs) of 5 or 25 W kg−1, or sham exposed, at 37±0.2°C. Cell cycle alterations were determined by flow cytofluorometry over a 4 d period after exposure. The DNA distributions of RFR, MWR, and sham exposed cells were compared to detect qualitative effects on the cell cycle. Quantitative measures of the effects of isothermal radiation exposure were determined from differences in the number of exposed and sham exposed cells in various cell cycle phases as well as comparison of the mean DNA content of exposed and sham exposed cell samples. Flow cytofluorometric assay precision and accuracy were determined by comparison of DNA distributions of replicate CHO control cell samples and by the use of internal DNA standards.Exposure to 27 MHz RFR or 2.45 GHz MWR altered the CHO cell cycle for periods of up to 4 d following exposure at SARs of 5 or 25 W kg−1. There were significant differences in temporal responses, cell cycle phase sensitivity, and overall degree of cell cycle alteration for 27 MHz compared with 2.45 GHz radiation exposure. In contrast to the effect of 27 MHz RFR, which did not affect G2/M-phase CHO cells, 2.45 GHz MWR altered all cell cycle phases to varying degrees. Exposure to 2.45 GHz MWR at 5 or 25 W kg−1 was twice as effective as 27 MHz RFR in inducing cell cycle alterations as determined by differences in the number of exposed versus sham-exposed cells in various cell cycle phases. 相似文献
5.
A. Lapresta-Fernández R. Huertas M. Melgosa L. F. Capitán-Vallvey 《Analytical and bioanalytical chemistry》2009,393(4):1361-1366
Spectroradiometric measurements of reflectance and CIELAB hue-angle, were tested for K(I) determination using disposable optical
sensors based on ion exchange mechanism. The linearisation of the sigmoidal response function, using a logistic regression,
increases the linear range noticeably to 7.65 × 10−8–1.5 M and 1.22 × 10−7–1.5 M for CIELAB hue-angle and reflectance, respectively. The trueness of both procedures was demonstrated comparing it with
results obtained by a DAD spectrophotometer used as a reference measurement procedure. The usefulness of the procedure was
checked by analysing K(I) in different types of waters and beverages. Additionally, we studied the possible visual discrimination for the whole potassium
range tested, obtaining the possibility of discriminating twelve groups of concentrations. 相似文献
6.
A fast and sensitive liquid chromatography–mass spectrometry method was developed for the determination of ursolic acid (UA)
in rat plasma and tissues. Glycyrrhetinic acid was used as the internal standard (IS). Chromatographic separation was performed
on a 3.5 μm Zorbax SB-C18 column (30 mm × 2.1 mm) with a mobile phase consisting of methanol and aqueous 10 mM ammonium acetate
using gradient elution. Quantification was performed by selected ion monitoring with (m/z)− 455 for UA and (m/z)− 469 for the IS. The method was validated in the concentration range of 2.5 − 1470 ng mL−1 for plasma samples and 20 − 11760 ng g−1 for tissue homogenates. The intra- and inter-day assay of precision in plasma and tissues ranged from 1.6% to 7.1% and 3.7%
to 9.0%, respectively, and the intra- and inter-day assay accuracy was 84.2 − 106.9% and 82.1 − 108.1%, respectively. Recoveries
in plasma and tissues ranged from 83.2% to 106.2%. The limits of detections were 0.5 ng mL−1 or 4.0 ng g−1. The recoveries for all samples were >90%, except for liver, which indicated that ursolic acid may metabolize in liver. The
main pharmacokinetic parameters obtained were T
max = 0.42 ± 0.11 h, C
max = 1.10 ± 0.31 μg mL−1, AUC = 1.45 ± 0.21 μg h mL−1 and K
a = 5.64 ± 1.89 h−1. The concentrations of UA in rat lung, spleen, liver, heart, and cerebellum were studied for the first time. This method
is validated and could be applicable to the investigation of the pharmacokinetics and tissue distribution of UA in rats. 相似文献
7.
Daniella Morgos Ivan Geroy Richard G. Sevier Molly M. Gribb Kevin P. Ryan Herbert H. Hill 《International Journal for Ion Mobility Spectrometry》2010,13(1):1-7
An ion mobility spectrometer (IMS) probe system for real-time, subsurface soil-gas sampling applications is presented. The
system includes an IMS and supporting electronics encased in a 51 mm diameter stainless steel probe housing. The IMS was challenged
in the laboratory with 2,6-di-tert-butylpyridine (DtBP) and tetrachloroethylene (PCE) in zero air yielding reduced ion mobility
constants (Ko) values of 1.42 cm2/Vs (n = 3) and 1.79 ± 0.01 cm2/Vs (n = 3), respectively. A resolving power of 38 and 31 was obtained for DtBP and PCE, respectively. The system was deployed at
a PCE-contaminated site to demonstrate its performance under field conditions. PCE was detected in the vapor samples as evidenced
by peaks with a Ko value of 1.80 ± 0.01 cm2/Vs for two measurements that were taken 6 min apart. The presence of PCE at the contaminated site was confirmed by GC-MS
analysis of a gas sample at an EPA-certified laboratory, suggesting that this IMS system can be used to detect PCE under field
conditions. 相似文献
8.
Harris GA Falcone CE Fernández FM 《Journal of the American Society for Mass Spectrometry》2012,23(1):153-161
Presented here are findings describing the spatial-dependence of sensitivity and ion suppression effects observed with direct
analysis in real time (DART). Continuous liquid infusion of dimethyl methyl phosphonate (DMMP) revealed that ion yield “hot
spots” did not always correspond with the highest temperature regions within the ionization space. For instance, at lower
concentrations (50 and 100 μM), the highest sensitivities were in the middle of the ionization region at 200 °C where there
was a shorter ion transport distance, and the heat available to thermally desorb neutrals was moderate. Conversely, at higher
DMMP concentrations (500 μM), the highest ion yield was directly in front of the DART source at 200 °C where it was exposed
to the highest temperature for thermal desorption. In matching experiments, differential analyte volatility was observed to
play a smaller role in relative ion suppression than differences in proton affinity and the relative sampling positions of
analytes. At equimolar concentrations sampled at the same position, suppression was as high as 26× between isoquinoline (proton
affinity 952 kJ mol–1, boiling point 242 °C) and p-anisidine (proton affinity 900 kJ mol–1, boiling point 243 °C). This effect was exacerbated when sampling positions of the two analytes differed, reaching levels
of relative suppression as high as 4543.0× ± 1406.0. To mitigate this level of relative ion suppression, sampling positions
and molar ratios of the analytes were modified to create conditions in which ion suppression was negligible. 相似文献
9.
Li Y Dong F Liu X Xu J Li J Lu C Wang Y Zheng Y 《Analytical and bioanalytical chemistry》2011,400(9):3097-3107
A rapid and simple miniaturized liquid–liquid extraction method has been developed for the determination of topramezone in
soil, corn, wheat, and water samples using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-electrospray
ionization (ESI)/MS/MS). The established method for the extraction and purification procedure was based on liquid–liquid partitioning
into an aqueous solution at a low pH (pH ≈ 2.5), followed by back-partitioning into water at pH > 9. Two precursor, product
ion transitions for topramezone were measured and evaluated to provide the maximum degree of confidence in the results. Under
negative ESI conditions, quantitation was achieved by monitoring the fragment at m/z = 334 and the qualitative fragment at m/z = 318, whereas also collecting the corresponding parent ion at m/z = 362. Chromatographic separation was achieved using gradient elution with a mobile phase consisting of methanol and a 0.01%
aqueous ammonium hydroxide solution. Recovery studies for soil, corn, wheat, and water were conducted at four different topramezone
concentrations (5 or 10, 50, 100, and 1,000 μg kg−1); the overall average recoveries ranged from 79.9% to 98.4% with intra-day relative standard deviations (RSD) of 3.1~8.7%
and inter-day RSD of 4.3~7.5%. Quantitative results were determined from calibration curves of topramezone standards containing
1–500 μg L−1 with an R
2 ≥ 0.9994. Method sensitivities expressed as limits of quantitation were typically 6, 8, 9, and 1 μg kg−1 in soil, corn, wheat, and water, respectively. The results of the method validation confirmed that this proposed method was
convenient and reliable for the determination of topramezone residues in soil, corn, wheat, and water. 相似文献
10.
Zhang C Rodriguez C Circu ML Aw TY Feng J 《Analytical and bioanalytical chemistry》2011,401(7):2165-2175
S-glutathionylation (Pr–SSG) is a specific post-translational modification of cysteine residues by the addition of glutathione.
S-Glutathionylated proteins induced by oxidative or nitrosative stress play an essential role in understanding the pathogenesis
of the aging and age-related disorder, such as Alzheimer’s disease (AD). The purpose of this research is to develop a novel
and ultrasensitive method to accurately and rapidly quantify the Pr–SSG by using capillary gel electrophoresis with laser-induced
fluorescence detection (CGE-LIF). The derivatization method is based on the specific reduction of protein-bound S-glutathionylation with glutaredoxin (Grx) and labeling with thiol-reactive fluorescent dye (Dylight 488 maleimide). The experiments
were performed by coupling the derivatization method with CGE-LIF to study electrophoretic profiling in in vitro oxidative
stress model–S-glutathionylated bovine serum albumin (BSA-SSG), oxidant-induced human colon adenocarcinoma (HT-29) cells, brain tissues,
and whole blood samples from an AD transgenic (Tg) mouse model. The results showed almost an eightfold increase in S-glutathionyl abundance when subjecting HT-29 cells in an oxidant environment, resulting in Pr–SSG at 232 ± 10.64 (average
±SD; n = 3) nmol/mg. In the AD–Tg mouse model, an initial quantitative measurement demonstrated the extent of protein S-glutathionylation in three brain regions (hippocampus, cerebellum, and cerebrum), ranging from 1 to 10 nmol/mg. Additionally,
we described our developed method to potentially serve as a highly desirable diagnostic tool for monitoring S-glutathionylated protein profile in minuscule amount of whole blood. The whole blood samples for S-glutathionyl expression of 5-month-old AD–Tg mice are quantified as 16.3 μmol/L (=7.2 nmol/mg protein). Altogether, this
is a fast, easy, and accurate method, reaching the lowest limit of Pr–SSG detection at 1.8 attomole (amol) level, reported
to date. 相似文献
11.
Minakata K Nozawa H Gonmori K Yamagishi I Suzuki M Hasegawa K Watanabe K Suzuki O 《Analytical and bioanalytical chemistry》2011,400(7):1945-1951
An electrospray ionization tandem mass spectrometric (ESI-MS-MS) method has been developed for the determination of cyanide
(CN–) in blood. Five microliters of blood was hemolyzed with 50 μL of water, then 5 μL of 1 M tetramethylammonium hydroxide solution
was added to raise the pH of the hemolysate and to liberate CN– from methemoglobin. CN– was then reacted with NaAuCl4 to produce dicyanogold, Au(CN)2–, that was extracted with 75 μL of methyl isobutyl ketone. Ten microliters of the extract was injected directly into an ESI-MS-MS
instrument and quantification of CN– was performed by selected reaction monitoring of the product ion CN– at m/z 26, derived from the precursor ion Au(CN)2– at m/z 249. CN– could be measured in the quantification range of 2.60 to 260 μg/L with the limit of detection at 0.56 μg/L in blood. This
method was applied to the analysis of clinical samples and the concentrations of CN– in the blood were as follows: 7.13 ± 2.41 μg/L for six healthy non-smokers, 3.08 ± 1.12 μg/L for six CO gas victims, 730 ± 867 μg
for 21 house fire victims, and 3,030 ± 97 μg/L for a victim who ingested NaCN. The increase of CN– in the blood of a victim who ingested NaN3 was confirmed using MS-MS for the first time, and the concentrations of CN– in the blood, gastric content and urine were 78.5 ± 5.5, 11.8 ± 0.5, and 11.4 ± 0.8 μg/L, respectively. 相似文献
12.
13.
M. López-Sánchez M. J. Ayora-Cañada A. Molina-Díaz M. Siam W. Huber G. Quintás S. Armenta B. Lendl 《Analytical and bioanalytical chemistry》2009,394(8):2137-2144
A mid-infrared enzymatic assay for label-free monitoring of the enzymatic reaction of fructose-1,6-bisphosphatase with fructose
1,6-bisphosphate has been proposed. The whole procedure was done in an automated way operating in the stopped flow mode by
incorporating a temperature-controlled flow cell in a sequential injection manifold. Fourier transform infrared difference
spectra were evaluated for kinetic parameters, like the Michaelis–Menten constant (K
M) of the enzyme and V
max of the reaction. The obtained K
M of the reaction was 14 ± 3 g L−1 (41 μM). Furthermore, inhibition by adenosine 5′-monophosphate (AMP) was evaluated, and the K
MApp value was determined to be 12 ± 2 g L−1 (35 μM) for 7.5 and 15 μM AMP, respectively, with V
max decreasing from 0.1 ± 0.03 to 0.05 ± 0.01 g L−1 min−1. Therefore, AMP exerted a non-competitive inhibition. 相似文献
14.
The mobilities of electrosprayed proteins and protein multimers with molecular weights ranging from 12.4 kDa (cytochrome C
monomers) to 154 kDa (nonspecific concanavalin A hexamers) were measured in dry air by a planar differential mobility analyzer
(DMA) coupled to a time-of-flight mass spectrometer (TOF-MS). The DMA determines true mobility at atmospheric pressure, without
perturbing ion structure from that delivered by the electrospray. A nondenaturing aqueous 20 mM triethylammonium formate buffer
yields compact ions with low charge states, moderating polarization effects on ion mobility. Conversion of mobilities into
cross-sections involves a reduction factor ξ for the actual mobility relative to that associated with elastic specular collisions with smooth surfaces. ξ is known to be 1.36 in air from Millikan’s oil drop experiments. A similar enhancement effect ascribed to atomic-scale surface
roughness has been found in numerical simulations. Adopting Millikan’s value ξ = 1.36 and assuming a spherical geometry yields a gas-phase protein density ρ
p = 0.949 ± 0.053 g cm−3 for all our protein data. This is substantially higher than the 0.67 g cm−3 found in recent low-resolution DMA measurements of singly charged proteins. DMA-MS can distinguish nonspecific protein aggregates
formed during the electrospray process from those formed preferentially in solution. The observed charge versus diameter relation
is compatible with a protein charge reduction mechanism based on the evaporation of triethylammonium ions from electrosprayed
drops. 相似文献
15.
Ilona Šperlingová Ludmila Dabrowská Vladimír Stránský Šárka Dušková Jan Kučera Monika Tvrdíková Milon Tichy 《Analytical and bioanalytical chemistry》2010,397(2):433-438
Ethylene glycol monobutyl ether (EGBE), an industrial solvent, is absorbed by the body not only by inhalation but also by
dermal absorption (liquid or vapour). EGBE is metabolized to butoxyacetic acid (BAA). Pooled freeze-dried urine candidate
reference material (RM) was prepared from urine obtained from persons occupationally exposed to EGBE. This material has the
advantage of containing butoxyacetic acid in both the free and conjugated (glutamine and glycine) forms, as found in native
urine. In all GC method modifications used, acid hydrolysis was used to release BAA from its conjugated form. The amount of
butoxyacetic acid in homogeneity and stability testing was measured by GC after derivatisation with N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide. Detection was by MS in EI mode, in the authors’ laboratory. For interlaboratory comparison of the
reference material GC methods with MS, FID, and ECD were used. Different extraction solvents (dichloromethane–isopropanol
2:1, ethyl acetate, or dichloromethane) and derivatisation reagents (trimethylsilyldiazomethane, N-tert-butyldimethylsilyl-N-methyltrifluoroacetamide) were used. Using ANOVA (at the statistical level α = 0.05) no changes were found in the concentration of butoxyacetic acid during fifteen month isochronous stability testing,
or in homogeneity testing. The uncertainty contributions were u
h = 8.8 mg L−1 and u
s = 6.5 mg L−1. The concentration of butoxyacetic acid in freeze-dried urine RM was evaluated from the results of eight laboratory data
sets within an interlaboratory comparison by use of the interactive statistical software IPECA. The contribution to total
uncertainty derived from interlaboratory comparison was u
i = 12.7 mg L−1. The reference value (c = 273 ± 33 mg L−1) is an unweighted arithmetic average of accepted results. The value is traceable to the pure butoxyacetic acid (98% w/w; Acros Organic #257760010) used as calibrant. The uncertainty given is combined expanded uncertainty derived from the results
from interlaboratory comparison, and from homogeneity and stability tests (k = 2). The reference material will be used to verify method performance in the biological monitoring of occupational exposure
to EGBE. 相似文献
16.
Hornuss C Wiepcke D Praun S Dolch ME Apfel CC Schelling G 《Analytical and bioanalytical chemistry》2012,403(2):555-561
Propofol in exhaled breath can be detected and monitored in real time by ion molecule reaction mass spectrometry (IMR-MS).
In addition, propofol concentration in exhaled breath is tightly correlated with propofol concentration in plasma. Therefore,
real-time monitoring of expiratory propofol could be useful for titrating intravenous anesthesia, but only if concentration
changes in plasma can be determined in exhaled breath without significant delay. To evaluate the utility of IMR-MS during
non-steady-state conditions, we measured the time course of both expiratory propofol concentration and the processed electroencephalography
(EEG) as a surrogate outcome for propofol effect after an IV bolus induction of propofol. Twenty-one patients scheduled for
routine surgery were observed after a bolus of 2.5 mg kg−1 propofol for induction of anesthesia. Expiratory propofol was measured using IMR-MS and the cerebral propofol effect was
estimated using the bispectral index (BIS). Primary endpoints were time to detection of expiratory propofol and time to onset
of propofol’s effect on BIS, and the secondary endpoint was time to peak effect (highest expiratory propofol or lowest BIS).
Expiratory propofol and changes in BIS were first detected at 43 ± 21 and 49 ± 11 s after bolus injection, respectively (P = 0.29). Peak propofol concentrations (9.2 ± 2.4 parts-per-billion) and lowest BIS values (23 ± 4) were reached after 208 ± 57
and 219 ± 62 s, respectively (P = 0.57). Expiratory propofol concentrations measured by IMR-MS have similar times to detection and peak concentrations compared
with propofol effect as measured by the processed EEG (BIS). This suggests that expiratory propofol concentrations may be
useful for titrating intravenous anesthesia. 相似文献
17.
Bagheri H Aghakhani A Akbari M Ayazi Z 《Analytical and bioanalytical chemistry》2011,400(10):3607-3613
A micro-solid phase extraction technique was developed using a novel polypyrrole-polyamide nanofiber sheet, fabricated by
electrospinning method. The applicability of the new nanofiber sheet was examined as an extracting medium to isolate malathion
as a model pesticide from aqueous samples. Solvent desorption was subsequently performed in a microvial, and an aliquot of
extractant was injected into gas chromatography–mass spectrometry. Various parameters affecting the electrospinning process
including monomer concentration, polyamide content, applied voltage, and electrospinning time were examined. After fabricating
the most suitable preparation conditions, influential parameters on the extraction and desorption processes were optimized.
The developed method proved to be rather convenient and offers sufficient sensitivity and good reproducibility. The limit
of detection (S/N = 3) and limit of quantification (S/N = 10) of the method under optimized conditions were 50 and 100 ng L−1, respectively. The relative standard deviation at concentration level of 1 ng mL−1 was 2% (n = 3). The calibration curve of analyte showed linearity in the range of 0.1–1 ng mL−1 (R
2 = 0.9975). The developed method was successfully applied to tap and Zayanderood river water samples, while the relative recovery
percentages of 98% and 96% were obtained, respectively. The whole procedure showed to be conveniently applicable and quite
easy to be manipulated. 相似文献
18.
Wanwisa Moon-ai Ploypat Niyomploy Ruethairat Boonsombat Polkit Sangvanich Aphichart Karnchanatat 《Applied biochemistry and biotechnology》2012,166(8):2138-2155
Superoxide dismutase (SOD, EC 1.15.1.1) is a metalloenzyme or antioxidant enzyme that catalyzes the disproportionation of
the harmful superoxide anionic radical to hydrogen peroxide and molecular oxygen. Due to its antioxidative effects, SOD has
long been applied in medicinal treatment, cosmetic, and other chemical industries. Fifteen Zingiberaceae plants were tested
for SOD activity in their rhizome extracts. The crude homogenate and ammonium sulfate cut fraction of Curcuma aeruginosa were found to contain a significant level of SOD activity. The SOD enzyme was enriched 16.7-fold by sequential ammonium sulfate
precipitation, diethylaminoethyl cellulose ion exchange, and Superdex 75 gel filtration column chromatography. An overall
SOD yield of 2.51 % with a specific activity of 812.20 U/mg was obtained. The enriched SOD had an apparent MW of 31.5 kDa,
as judged by sodium dodecyl sulfate polyacrylamide gel electrophoresis, and a pH and temperature optima of 4.0 and 50 °C.
With nitroblue tetrazolium and riboflavin as substrates, the K
m values were 57.31 ± 0.012 and 1.51 ± 0.014 M, respectively, with corresponding V
max values of 333.7 ± 0.034 and 254.1 ± 0.022 μmol min−1 mg protein−1. This SOD likely belongs to the Fe- or Mn-SOD category due to the fact that it was insensitive to potassium cyanide or hydrogen
peroxide inhibition, but was potentially weakly stimulated by hydrogen peroxide, and stimulated by Mn2+and Fe2+ ions. Moreover, this purified SOD also exhibited inhibitory effects on lipopolysaccharide-induced nitric oxide production
in cultured mouse macrophage cell RAW 264.7 in a dose-dependent manner (IC50 = 14.36 ± 0.15 μg protein/ml). 相似文献
19.
Tadasuke Tsuji Shinya Kitagawa Hajime Ohtani 《Analytical and bioanalytical chemistry》2009,394(3):835-843
Voltage-induced impedance variation of the minicolumn (i.d. 0.53 mm, length 2 mm) packed with cation exchanger was investigated
to develop a sensing method. An aqueous sample solution containing the metal cations was continuously supplied to the minicolumn
during the impedance measurement with the simultaneous application of both alternating current voltage (amplitude, 1.0 V;
frequency, 200 kHz to 6 Hz) and direct current (DC) offset voltage (0.1 to 1.0 V). On a complex plane plot, the profile of
the column impedance consisted of a semicircle (200 kHz to 100 Hz) and a straight line (<100 Hz), of which slope varied with the magnitude of the applied DC offset voltage (V
DC). The slope–V
DC relation depended on the kind of the metal cation and its concentration; in particular, the slope–V
DC relations of monovalent cations (Na+ and K+) and divalent ones (Mg2+ and Ca2+) were significantly different. With the change in the concentration of minor divalent salt of MgCl2 or CaCl2 (60 to 140 μM) in the sample solution containing 10 mM NaCl, the slopes showed almost linear relationships between those
with application of V
DC = 0.1 V and 1.0 V both for magnesium and calcium additions. In the case of plural addition of both MgCl2 and CaCl2 to the solution, the data points in the slope0.1
V–slope1.0
V plot were located between the two proportional lines for single additions of magnesium and calcium, reflecting both the mixing
ratio and net concentrations of the divalent cations. Thus, simulations determination of Mg2+ and Ca2+ can be attained on the basis of the slope0.1
V–slope1.0
V relation obtained by the impedance measurements of the minicolumn. Actually, the contents of both magnesium and calcium cations
in the bottled mineral waters determined simultaneously using the proposed method were almost equivalent to those obtained
by the atomic absorption spectrometric measurement. 相似文献
20.
Repizo LM Martinez LD Olsina RA Cerutti S Raba J 《Analytical and bioanalytical chemistry》2012,402(2):965-973
A novel, simple, and rapid reversed-phase liquid chromatography–tandem mass spectrometric methodology was developed for the
analysis of natamycin in wine samples. Natamycin was protonated to form singly charged ions in an electrospray positive ion
mode. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring (MRM) of three fragment ion transitions
(666.3 → 648.2, 666.3 → 503.3, and 666.3 → 485.2) to provide a high degree of sensitivity and specificity. Chromatographic
separation was performed on a rapid resolution column using a mobile phase consisting of an acetonitrile/water mixture with
a total run time of 5.0 min. After only filtration as pretreatment, the sample was injected into the chromatographic system.
The proposed method was validated in terms of selectivity, trueness, precision, decision limit (CCα), and detection capability (CCβ) according to 2002/657/EC Commission decision. The values for trueness, reported as bias (%), agreed with those established
by the aforementioned document. Repeatability (intraday variability) values were 12.37% at a concentration of 1.0 μg L−1 and 8.99–4.19% at concentrations between 2.5 and 10 μg L−1. The overall within-laboratory (interday variability) reproducibility was 15.47% at a concentration of 1.0 μg L−1, which was significantly lower than the indicative value reported in the EU decision. The results indicated that the proposed
approach is a sensitive, fast, reproducible, and robust methodology suitable for the analysis of natamycin levels in wine
samples. 相似文献