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1.
An effective protocol was developed for in vitro regeneration of the Cassia angustifolia via indirect organogenesis from petiole explants excised from 21-day-old axenic seedlings. Organogenic callus were induced
on Murashige and Skoog (MS) medium supplemented with 5.0 μM 2,4-dichlorophenoxy acetic acid and 2.5 μM thidiazuron (TDZ).
Adventitious shoot regeneration was achieved on MS medium supplemented with 5.0 μM TDZ as it induced 8.5 ± 0.98 shoots in
85% cultures. The number of shoots and shoot length was significantly enhanced when cultures were subcultured on auxin–cytokinin-containing
medium. The highest number of shoots (12.5 ± 1.10) and shoot length (4.3 ± 0.20 cm) was recorded on MS medium supplemented
with 5.0 μM TDZ and 1.5 μM indole-3-acetic acid. Regenerated shoots were rooted best on MS medium supplemented with 10.0 μM
indole-3-butyric acid followed by their transfer to liquid MS filter paper bridge medium. The plants were successfully hardened
off in sterile soilrite followed by their establishment in garden soil with 70% survival rate. The plants showed normal morphological
characteristics similar to the field grown plants. 相似文献
2.
Xiaolin Pei Qiuyan Wang Xiaofeng Qiu Longbin Ying Junhua Tao Tian Xie 《Applied biochemistry and biotechnology》2010,162(5):1423-1434
2-Deoxyribose-5-phosphate aldolase (DERA) catalyzes a sequential aldol reaction useful in synthetic chemistry. In this work,
the effect of a feeding strategy on the production of a thermophilic DERA was investigated in fed-batch cultures of recombinant
Escherichia coli BL21 (pET303-DERA008). The predetermined specific growth rate (μ
set) was evaluated at 0.20, 0.15, and 0.10 h−1, respectively. The DERA concentration and volumetric productivity were associated with μ
set. The cells synthesized the enzyme most efficiently at μ
set = 0.15 h−1. The maximum enzyme concentration (5.12 g/L) and total volumetric productivity (0.256 g L−1 h−1) obtained were over 10 and five times higher than that from traditional batch cultures. Furthermore, the acetate concentration
remained at a relatively low level, less than 0.4 g/L, under this condition which would not inhibit cell growth and target
protein expression. Thus, a specific growth rate control strategy has been successfully applied to induce fed-batch cultures
for the maximal production of the thermophilic 2-deoxyribose-5-phosphate aldolase. 相似文献
3.
A flow system designed with solenoid valves is proposed for determination of weak acid dissociable cyanide, based on the reaction
with o-phthalaldehyde (OPA) and glycine yielding a highly fluorescent isoindole derivative. The proposed procedure minimizes the
main drawbacks related to the reference batch procedure, based on reaction with barbituric acid and pyridine followed by spectrophotometric
detection, i.e., use of toxic reagents, high reagent consumption and waste generation, low sampling rate, and poor sensitivity.
Retention of the sample zone was exploited to increase the conversion rate of the analyte with minimized sample dispersion.
Linear response (r = 0.999) was observed for cyanide concentrations in the range 1–200 μg L−1, with a detection limit (99.7% confidence level) of 0.5 μg L−1 (19 nmol L−1). The sampling rate and coefficient of variation (n = 10) were estimated as 22 measurements per hour and 1.4%, respectively. The results of determination of weak acid dissociable
cyanide in natural water samples were in agreement with those achieved by the batch reference procedure at the 95% confidence
level. Additionally to the improvement in the analytical features in comparison with those of the flow system with continuous
reagent addition (sensitivity and sampling rate 90 and 83% higher, respectively), the consumption of OPA was 230-fold lower. 相似文献
4.
Biomass Productivities in Wild Type and Pigment Mutant of <Emphasis Type="Italic">Cyclotella</Emphasis> sp. (Diatom) 总被引:1,自引:0,他引:1
Huesemann MH Hausmann TS Bartha R Aksoy M Weissman JC Benemann JR 《Applied biochemistry and biotechnology》2009,157(3):507-526
Microalgae are expected to play a significant role in greenhouse gas mitigation because they can utilize CO2 from power plant flue gases directly while producing a variety of renewable carbon-neutral biofuels. In order for such a
microalgal climate change mitigation strategy to become economically feasible, it will be necessary to significantly improve
biomass productivities. One approach to achieve this objective is to reduce, via mutagenesis, the number of light-harvesting
pigments, which, according to theory, should significantly improve the light utilization efficiency, primarily by increasing
the light intensity at which photosynthesis saturates (I
s). Employing chemical (ethylmethylsulfonate) and UV mutagenesis of a wild-type strain of the diatom Cyclotella, approximately 10,000 pigment mutants were generated, and two of the most promising ones (CM1 and CM1-1) were subjected to
further testing in both laboratory cultures and outdoor ponds. Measurements of photosynthetic oxygen production rates as a
function of light intensity (i.e., P–I curves) of samples taken from laboratory batch cultures during the exponential and linear growth phase indicated that the
light intensity at which photosynthesis saturates (I
s) was two to three times greater in the pigment mutant CM1-1 than in the wild type, i.e., 355–443 versus 116–169 μmol/m2 s, respectively. While theory, i.e., the Bush equation, predicts that such a significant gain in I
s should increase light utilization efficiencies and thus biomass productivities, particularly at high light intensities, no
improvements in biomass productivities were observed in either semi-continuous laboratory cultures or outdoor ponds. In fact,
the maximum biomass productivity in semi-continuous laboratory culture was always greater in the wild type than in the mutant,
namely 883 versus 725 mg/L day, respectively, at low light intensity (200 μmol/m2 s) and 1,229 versus 1,043 mg/L day, respectively, at high light intensity (1,000 μmol/m2 s). Similarly, the biomass productivities measured in outdoor ponds were significantly lower for the mutant than for the
wild type. Given that these mutants have not been completely characterized in these initial studies, the exact reasons for
their poor performance are not known. Most likely, it is possible that the mutation procedure affected other photosynthetic
or metabolic processes. This hypothesis was partially validated by the observation that the pigment mutant had a longer lag
period following inoculation, a lower maximum specific growth rate, and poorer stability than the wild type. 相似文献
5.
The phytohormone abscisic acid (ABA) is the major player in mediating the adaptation of plants to stress. Previously developed
phytohormonal biosensors usually employed indirect detection of the products of conjugated oxidase reactions. A label-free
electrochemical impedance immunosensor for ABA detection was developed using an anti-ABA antibody adsorbed directly on a porous
nanogold film. The film was produced electrochemically on a glassy carbon electrode in 0.008 mol/L hydrogen tetrachloroaurate
solution containing 0.004 mol/L lead acetate with an applied potential of −0.5 V (versus Ag/AgCl) for 50 s. The anti-ABA antibody
was immobilized onto the porous nanogold through electrostatic adsorption and covalent conjugation. Electrochemical impedance
spectroscopy was used to characterize the successful construction of the porous nanogold film and the stepwise modification
of the glassy carbon electrode. The concentration increase of the antigen brought about a decrease of the interfacial electron
transfer, which also meant an increase of the impedance signal. The experimental parameters pH, antibody incubation time,
and antibody concentration were optimized. The results showed significant linearity R = 0.9942, with the content of ABA in the range 0.5–5,000 ng/mL with a detection limit at about 0.1 ng/mL. 相似文献
6.
Shirong Yuan Ruo Yuan Yaqin Chai Ying Zhuo Xia Yang Yali Yuan 《Applied biochemistry and biotechnology》2010,162(8):2189-2196
In this work, an enzyme biosensor based on the immobilization of horseradish peroxidase (HRP) on SiO2/BSA/Au/thionine/nafion-modified gold electrode was fabricated successfully. Firstly, nafion was dropped on the surface of
the gold electrode to form a nafion film followed by chemisorption of thionine (Thi) as an electron mediator via the ion-exchange
interaction between the Thi and nafion. Subsequently, the SiO2/BSA/Au composite nanoparticles were assembled onto Thi film through the covalent bounding with the amino groups of Thi. Finally,
HRP was immobilized on the SiO2/BSA/Au composite nanoparticles due to the covalent conjugation to construct an enzyme biosensor. The surface topographies
of the SiO2/BSA/Au composite nanoparticles were investigated by using scanning electronic microscopy. The stepwise self-assemble procedure
of the biosensor was further characterized by means of cyclic voltammetry and chronoamperometry. The enzyme biosensor showed
high sensitivity, good stability and selectivity, a wide linear response to hydrogen peroxide (H2O2) in the range of 8.0 × 10-6 ∼ 3.72 × 10-3 mol/L, with a detection limit of 2.0 × 10-6 mol/L. The Michaelies-Menten constant KMapp K_M^{app} value was estimated to be 2.3 mM. 相似文献
7.
Daniela de Araújo Viana Carolina de Albuquerque Lima Rejane Pereira Neves Cristina Souza Mota Keila Aparecida Moreira José Luiz de Lima-Filho Maria Taciana Holanda Cavalcanti Attilio Converti Ana Lúcia Figueiredo Porto 《Applied biochemistry and biotechnology》2010,162(3):830-842
Cow raw milk from dairy cooperatives was examined for its microbial composition. Among the isolates identified, 17.6% were
yeasts. The most frequent genus was Candida, although members belonging to the genera Brettanomyces, Dekkera, and Geotricum were also identified. Although qualitative and quantitative tests for extracellular proteolytic activity were positive for
all the species isolated, Candida buinensis showed the highest response (23.5 U/mg); therefore, it was selected for subsequent investigation. The results of fermentations
carried out at variable temperature, pH, and soybean flour concentration, according to a 23 full factorial design, demonstrated that this yeast ensured the highest production of extracellular proteases (573 U/mL)
when cultivated at 35 °C, pH 6.5, and using soybean flour concentrations in the range 0.1–0.5% (w/v). The cell-free supernatants showed the highest activity at 25 °C and pH 7.0, and satisfactory stability in the ranges 25–30 °C
and pH 7–9. The first-order rate constants of protease inactivation in the cell-free supernatants were calculated at different
temperatures from semi-log plots of the residual activity versus time and then used in Arrhenius and Eyring plots to estimate
the main thermodynamic parameters of thermoinactivation (E* = 40.0 kJ/mol; ΔH* = 37.3 kJ/mol; ΔS* = −197.5 J/mol K; ΔG* = 101 kJ/mol). 相似文献
8.
Raluca-Ioana Stefan-van Staden Jacobus F. van Staden Hassan Y. Aboul-Enein 《Journal of Solid State Electrochemistry》2010,14(6):997-1000
Three types of monocrystalline diamond: natural diamond 1 μm, synthetic diamond 50 μm (synthetic-1), and synthetic diamond
1 μm (synthetic-2) were used for the design of diamond paste electrodes for the determination of sildenafil citrate (Viagra)
using square wave voltammetry. The linear concentration ranges recorded for sildenafil citrate when natural diamond, synthetic-1,
and synthetic-2 based electrodes were used were between 10−12 and 10−8, 10−12 and 10−9, and 10−11 and 10−9 mol/L, respectively. Low detection limits which lie between 0.1 and 1 pmol/L proves the sensitivity of the electrodes. It
was found that sildenafil citrate yielded a peak at about +0.175 ± 0.025 V (versus Ag/AgCl) for all the electrodes. Sildenafil
citrate was determined with high reliability from its pharmaceutical formulation. 相似文献
9.
Alternative solvent‐based methyl benzoate vortex‐assisted dispersive liquid–liquid microextraction for the high‐performance liquid chromatographic determination of benzimidazole fungicides in environmental water samples
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Vortex‐assisted dispersive liquid–liquid microextraction using methyl benzoate as an alternative extraction solvent for extracting and preconcentrating three benzimidazole fungicides (i.e., carbendazim, thiabendazole, and fluberidazole) in environmental water samples before high‐performance liquid chromatographic analysis has been developed. The selected microextraction conditions were 250 μL of methyl benzoate containing 300 μL of ethanol, 1.0% w/v sodium acetate, and vortex agitation speed of 2100 rpm for 30 s. Under optimum conditions, preconcentration factors were 14.5–39.0 for the target fungicides. Limits of detection were obtained in the range of 0.01–0.05 μg/L. The proposed method was then applied to surface water samples and the recovery evaluations at three spiked concentration levels of 5, 30, and 50 μg/L were obtained in the range of 77.4–110.9% with the relative standard deviation <7.4%. The present method was simple, rapid, low cost, sensitive, environmentally friendly, and suitable for the trace analysis of the studied fungicides in environmental water samples. 相似文献
10.
To investigate the production of cellulases and xylanases from Penicillium echinulatum 9A02S1, solid-state fermentation (SSF) was performed by using different ratios of sugar cane bagasse (SCB) and wheat bran
(WB). The greatest filter paper activity obtained was 45.82 ± 1.88 U gdm−1 in a culture containing 6SCB/4WB on the third day. The greatest β-glucosidase activities were 40.13 ± 5.10 U gdm−1 obtained on the third day for the 0SCB/10WB culture and 29.17 ± 1.06 U gdm−1 for the 2SCB/8WB culture. For endoglucanase, the greatest activities were 290.47 ± 43.57 and 276.84 ± 15.47 U gdm−1, for the culture 6SCB/4WB on the fourth and fifth days of cultivation, respectively. The greatest xylanase activities were
found on the third day for the cultures 6SCB/4WB (36.38 ± 5.38 U gdm−1) and 4SCB/6WB (37.87 ± 2.26 U gdm−1). In conclusion, the results presented in this article showed that it was possible to obtain large amounts of cellulases
and xylanases enzymes using low-cost substrates, such as SCB and WB. 相似文献
11.
Maher Kammoun Imed Koubaa Yassine Ben Ali Raoudha Jarraya Youssef Gargouri Mohamed Damak Sofiane Bezzine 《Applied biochemistry and biotechnology》2010,162(3):662-670
The aim of the present work was to evaluate the anti-inflammatory properties of Cynara cardunculus L. (Asteraceae) during its growth using various solvents such as n-hexane, dichloromethane, acetone, and methanol for air-dried leaves and stems. The anti-inflammatory activities of crude
extracts were evaluated by measuring the inhibition potency of mammalian non-pancreatic phospholipases A2 (hG-IIA). The methanol
and acetone extracts of leaves harvested in February exhibit potent inhibition of hG-IIA (IC50 = 50 and 70 μg/ml, respectively). However, the acetone extract of stems harvested in December inhibits the hG-IIA with a
lower IC50 around 130 μg/ml. Fractionation on silica gel and hydrophobic gel of the methanol extract of leaves harvested in February
increases the inhibitory effect, and the IC50 reached 10 μg/ml. 相似文献
12.
Letao Wang Yan Zhang Yongling Du Daban Lu Yuzhen Zhang Chunming Wang 《Journal of Solid State Electrochemistry》2012,16(4):1323-1331
Simultaneous determination of catechol (CC) and hydroquinone (HQ) were investigated by voltammetry based on glassy carbon
electrode (GCE) modified by poly (diallyldimethylammonium chloride) (PDDA) functionalized graphene (PDDA-G). The modified
electrode showed excellent sensitivity and selectivity properties for the two dihydroxybenzene isomers. In 0.1 mol/L phosphate
buffer solution (PBS, pH 7.0), the oxidation peak potential difference between CC and HQ was 108 mV, and the peaks on the
PDDA-G/GCE were three times as high as the ones on graphene-modified glass carbon electrode. Under optimized conditions, the
PDDA-G/GCE showed wide linear behaviors in the range of 1 × 10−6−4 × 10−4 mol/L for CC and 1 × 10−6−5 × 10−4 mol/L for HQ, with the detection limits 2.0 × 10−7 mol/L for CC and 2.5 × 10−7 mol/L for HQ (S/N = 3) in mixture, respectively. Some kinetic parameters, such as the electron transfer number (n), charge transfer coefficient (α), and the apparent heterogeneous electron transfer rate constant (k
s), were calculated. The proposed method was applied to simultaneous determine CC and HQ in real water samples of Yellow River
with satisfactory results. 相似文献
13.
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
14.
Jaisson S Gorisse L Pietrement C Gillery P 《Analytical and bioanalytical chemistry》2012,402(4):1635-1641
Homocitrulline (HCit), an amino acid formed by the carbamylation of ε-amino groups of lysine residues, is considered a promising
biomarker for monitoring diseases such as chronic renal failure and atherosclerosis. This paper describes a tandem mass spectrometric
method for total, protein-bound and free HCit measurement in plasma samples. HCit was separated from other plasma components
by hydrophilic interaction liquid chromatography. Detection was achieved by monitoring transitions of 190.1 > 127.1 and 190.1 > 173.1
for HCit, and 183.1 > 120.2 for d7-citrulline used as internal standard. This method allowed HCit quantification within 5.2 min and was precise (inter-assay
CV < 5.85%), accurate (mean recoveries ranging from 97% to 106%), and exhibited a good linearity from 10 nmol/L to 1.6 μmol/L.
Plasma samples from control and uremic mice (n = 10) were analyzed. In control mice, mean total plasma HCit concentration was 0.78 ± 0.12 μmol/mol amino acids, whereas
it was increased 2.7-fold in uremic mice plasma, reaching 2.10 ± 0.50 μmol/mol amino acids (p < 0.001). In conclusion, this method exhibits good analytical performances and meets the criteria of sensitivity suitable
for HCit concentration assessment in plasma samples. 相似文献
15.
S. Schumacher R. Wüstneck B.-R. Paulke R. Cartier U. Pison 《Colloid and polymer science》2009,287(2):203-214
The binding of Gd3+ to two carboxylated polyglycidyl methacrylate latices was investigated. The latices differed in size (60 and 140 nm for CL6
and CL3, respectively) and surface charge density. The Gd3+ concentration in aqueous suspension was determined using an arsenazo (III) assay. Using 153Gd3+, the bound amount was determined directly. Because of the high binding affinity, ligand depletion became evident. The binding
was pH dependent, investigated in buffer solutions not influencing the arsenazo (III) assay. Optimal binding occurs by formation
of sodium salts of the carboxylic groups and replacement of Na+ and H+ by Gd3+. The dissociation constants of the particles were k
D ≈ 5 × 10−5 mol/L (CL3) and 10−4 mol/L (CL6), without cooperativity (Hill plot). Colloidal stability was investigated.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
16.
《Journal of heterocyclic chemistry》2018,55(6):1494-1498
A series of novel isatin‐ciprofloxacin hybrids inhaling oxime, semicarbazone, and thiosemicarbazone groups with hydrogen bonding capacity were designed, synthesized, and evaluated for their in vitro antitubercular activities against Mycobacterium tuberculosis (MTB) H37Rv and multidrug‐resistant‐TB (MDR‐TB). All hybrids endowed with potential activities against the tested MTB H37Rv and MDR‐TB strains with minimum inhibitory concentration (MIC) in a range of 0.20 to 128 μg/mL. In particular, the most active hybrid 5e (MIC: 0.20 and 0.5 μg/mL) was four and two times more active than the parent ciprofloxacin (MIC: 0.78 μg/mL) and rifampicin (MIC: 0.39 μg/mL) against MTB H37Rv, and 4–>256 times more potent than the three references ciprofloxacin (MIC: 2.0 μg/mL), rifampicin (MIC: 32 μg/mL), and isoniazid (>128 μg/mL) against MDR‐TB. Thus, this kind of hybrids holds great promise as future anti‐TB agents against both drug‐sensitive and drug‐resistant MTB strains infection. 相似文献
17.
Zhirong Mo Faqiong Zhao Fei Xiao Baizhao Zeng 《Journal of Solid State Electrochemistry》2010,14(9):1615-1620
Gold–platinum (AuPt) alloy particles were fabricated directly on multi-walled carbon nanotubes (MWNT)–ionic liquid (i.e.,
trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide, [P6,6,6,14][NTf2]) composite coated glassy carbon electrode (GCE) by electrodeposition method. Scanning electron microscope image showed that
they were well-dispersed nanocluster consisting of smaller nanoparticles, and their size was about 70 nm. X-ray diffraction
experiment showed that they were single-phase alloy nanomaterial, and the calculated composition was consisting with that
obtained by energy dispersive X-ray spectroscopy. The resulting modified electrode (i.e., AuPt–MWNT–[P6,6,6,14][NTf2]/GCE) presented high catalytic activity for the electrochemical oxidation of cysteine. The peak potential of cysteine shifted
to 0.42 V (versus saturated calomel electrode) in 0.1 M H2SO4 and the peak current increased greatly in comparison with that on the corresponding Pt (or Au)–MWNT–[P6,6,6,14][NTf2]/GCE. Under the optimized conditions, the oxidation current of cysteine at 0.45 V was linear to its concentration in the
range of 5.0 × 10−7 ∼ 4.0 × 10−5 M with a sensitivity of 43.8 mA M−1. 相似文献
18.
Montserrat Solé Jennifer P. Shaw Patricia E. Frickers James W. Readman Thomas H. Hutchinson 《Analytical and bioanalytical chemistry》2010,396(2):649-656
Environmental risk assessments of human pharmaceuticals and other ‘emerging contaminants’ should integrate both population-relevant
endpoints and biomarkers of potential modes of action in a range of species. Adult Mytilus galloprovincialis were exposed to the beta-adrenergic receptor blocker propranolol or to the anti-inflammatory drug acetaminophen (paracetamol),
both commonly used therapeutic drugs present in aquatic ecosystems. Mussels were exposed under semi-static conditions for
10 days to either acetaminophen (CAS number 103-90-2; mean measured concentrations 23 and 403 μg/L) or propranolol hydrochloride
(CAS number 318-98-9; mean measured propranolol concentrations 11 and 147 μg/L) at 15 ± 1 °C sea water. Feeding rate was assessed
as an indicator of general toxicity. For propranolol, the 10-day no-observed effect concentration (feeding rateNOEC) and lowest observed effect concentration (feeding rateLOEC) were 11 and 147 μg/L, respectively. For acetaminophen, feeding rate was increased at both 23 and 403 μg/L, suggesting
a 10-day feeding rateNOEC of 403 μg/L. Primarily, phase I carboxylesterase (CbE), phase II glutathione S-transferase (GST) and the anti-oxidant catalase activities were evaluated in digestive gland. Gill GST and acetylcholinesterase
(AChE) activities were also measured. Lipid peroxidation (LPO) levels were measured in both tissues to assess oxidative stress.
Some enzymatic activities in liver were also reduced after propranolol exposure whilst acetaminophen enhanced them (CbE p < 0.05). Acetaminophen exposure significantly increased hepatic LPO levels and inhibited AChE activity in gill (10-day NOEC
and LOEC of 23 and 403 μg/L, respectively), whereas propranolol (11 μg/L) enhanced gill GST. 相似文献
19.
Mika Furukawa Raymond S. Farinato Etsuo Kokufuta 《Colloid and polymer science》2008,286(12):1425-1434
This study aimed to investigate the effect of COOH group distribution within a polymer network having amide groups, with which
the COOH could form hydrogen bonds. We employed here two polyelectrolyte gels composed of N-isopropylacrylamide (NIPA) networks, either copolymerized with acrylic acid (AA) or within which poly(acrylic acid) (PAA)
was entrapped. Both gels (AA–NIPA ∼ 1:4 mol/mol) were prepared by aqueous red-ox polymerization with N,N’-methylenebisacrylamide as the cross-linker. Finely divided gels in NaCl solutions (0.025 and 0.1 M) were titrated with NaOH
and back-titrated with HCl at 25 °C. The results of the copolymer gel (CG) agreed well with those of a linear copolymer and
a nanoscale gel which had a similar AA content to CG. However, marked differences were observed in the titration behaviors
of the AA-copolymerized and PAA-entrapped gels, mainly due to the hydrogen bonding between the entrapped PAA chain and its
surrounding NIPA network. 相似文献
20.
Takeshi Kumazawa Koichi Saeki Isao Yanagisawa Seisaku Uchigasaki Chika Hasegawa Hiroshi Seno Osamu Suzuki Keizo Sato 《Analytical and bioanalytical chemistry》2009,394(4):1161-1170
This paper describes a fully automated on-line method combining in-tube solid-phase microextraction (SPME) in which sample
clean-up and enrichment are conducted through an open tubular fused-silica capillary column and high-performance liquid chromatography
(HPLC)/tandem mass spectrometry (MS/MS) detection for the determination of six butyrophenone derivatives (moperone, floropipamide,
haloperidol, spiroperidol, bromperidol, and pimozide) in human plasma samples. The six butyrophenones were extracted by repeatedly
aspirating and dispensing plasma sample solutions on a DB-17 capillary column (60 cm × 0.32 mm i.d., film thickness 0.25 μm).
The analytes retained on the inner surface of the capillary column were then eluted into an acetonitrile-rich mobile phase
using a gradient separation technique. Extraction efficiencies ranged from 12.7% to 31.8% for moperone, spiroperidol, and
pimozide, and from 1.08% to 4.86% for floropipamide, haloperidol, and bromperidol. The regression equations for all compounds
showed excellent linearity, ranging from 0.05 to 50 ng/0.1 mL of plasma, except for moperone and spiroperidol (0.01 to 50 ng/0.1 mL).
The limits of detection and quantification in plasma for each drug were 0.03–0.2 and 0.1–0.5 ng/mL, respectively. The intra-
and inter-day coefficients of variation for all compounds in plasma were not greater than 13.7%. 相似文献