bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of alkaline phosphatase isoenzymes in individual mouse bone marrow fibroblast cells based on capillary electrophoresis with on‐capillary enzyme‐catalyzed reaction and electrochemical detection
Authors: Sun Xuemei , Jin Wenrui , Li Dong , Bai Zengliang 
Published: June 2004

AbstractA novel method for the determination of alkaline phosphatase (ALP) isoenzymes in individual fibroblast cells of mouse bone marrow was developed by combining capillary electrophoresis with an on‐capillary enzyme‐catalyzed reaction and electrochemical detection. In this method, a single an cell, followed by 5.0×10−2 mol/L Na2B4O7– 3.0×10−2 mol/L NaCl (pH 9.8) as cell lysis solution, was injected into the inlet of the separation capillary by electromigration. The cell was lysed by applying a voltage of 2 kV. The ALP isoenzymes in the cell were preseparated at 20 kV for 1 min, and then allowed to react for 30 min with disodium phenyl phosphate as enzyme substrate in the running buffer. ALP converted disodium phenyl phosphate into its product, phenol, at a relatively high reaction rate without consumption, with resultant amplification of the signal on prolonged reaction time, producing an adequate amount of product for final detection. A mass detection limit as low as 3.5×10−21 mol/L (corresponding to 1.5 nU) was achieved. Finally, the two zones of products generated by ALP isoenzymes were detected at the outlet of the capillary by using the end‐capillary amperometric detection at a carbon fiber microdisk bundle electrode with a constant potential.
Enzyme‐catalyzed amperometric oxidation of neurotransmitters in chip‐capillary electrophoresis
Authors: Schwarz Maria A. 
Published: June 2004

AbstractThe determination of biogenic monoamines by enzyme‐catalyzed oxidation after electrophoretical separation on a microfluidic chip decreases their detection limits significantly. An amperometric system with a chemically amplified response for neurotransmitters and their metabolites is presented. The principle is the rapid cyclic oxidation of the analyte on the amperometric detector in the presence of the redoxactive enzyme glucose oxidase in the capillary electrophoresis buffer. With this approach, detection limits in the range of 10−7–10−8 M could be reached. Because of the good linearity between the current response and the concentration of catecholamines and their metabolites at concentrations up to 300 μM, this method is attractive for the analytical detection at low concentration levels such as in biological fluids.
Multichannel homogeneous immunoassay for detection of 2,4,6‐trinitrotoluene (TNT) using a microfabricated capillary array electrophoresis chip
Authors: Bromberg Avraham , Mathies Richard A. 
Published: June 2004

AbstractA high‐throughput homogeneous immunoassay for the sensitive detection of 2,4,6‐trinitrotoluene (TNT) has been developed using radial capillary array electrophoresis microdevices. Samples consisting of equilibrium mixtures of anti‐TNT antibody (Ab), fluorescein‐labeled TNT, and various concentrations of unlabeled TNT were electrokinetically injected into 48 channels of a radial capillary array electrophoresis microchannel plate. The rapid electrophoretic separation allows us to analyze the equilibrium ratio formed by the competition between the labeled and the unlabeled TNT for Ab binding. The simultaneous parallel TNT separations facilitate determination of a calibration curve for the TNT assay, which has high sensitivity (LOD, 1 ng/mL) and a wide dynamic range (1–300 ng/mL).
Preparative isoelectric focusing of proteins using binary buffers in a vortex‐stabilized, free‐flow apparatus
Authors: Tracy Noah I. , Ivory Cornelius F. 
Published: June 2004

AbstractRecombinant proteins are often produced as isoforms with different kinds and amounts of post‐translational modifications that alter their function. Isoelectric focusing in shallow pH gradients, less than 0.5 pH/cm, might be capable of fractionating these isoforms. The synthetic carrier ampholyte mixtures typically used to generate these pH gradients are expensive and may adversely interact with proteins. Using defined buffers instead of synthetic carrier ampholytes reduces these problems. We tested two defined buffer systems in a vortex‐stabilized electrophoresis device to see if they could form shallow pH gradients useful for separating isoforms. These pH gradients were formed by pouring a two‐component concentration gradient. The poured gradients were smooth, reproducible, and stable for at least 1.5 h at 5 kV. One poured gradient focused 20 mg of cytochrome c. A second poured gradient separated glucose oxidase from amyloglucosidase. The breadth of the amyloglucosidase band indicates that the shallow, poured pH gradients can only partially separate protein isoforms at 10 kV. Proteins with pI < 0.2 pH units apart will have overlapping bands in these shallow, poured pH gradients.
A compactly integrated laser‐induced fluorescence detector for microchip electrophoresis
Authors: Li Hai‐Fang , Lin Jin‐Ming , Su Rong‐Guo , Uchiyama Katsumi , Hobo Toshiyuki 
Published: June 2004

AbstractA simple and easy‐to‐use integrated laser‐induced fluorescence detector for microchip electrophoresis was constructed and evaluated. The fluid channels and optical fiber channels in the glass microchip were fabricated using standard photolithographic techniques and wet chemical etching. A 473 nm diode‐pumped laser was used as the excitation source, and the collimation and collection optics and mirrors were discarded by using a multimode optical fiber to couple the excitation light straight into the microchannel and placing the microchip directly on the top of the photomultiplier tube. A combination of filter systems was incorporated into a poly(dimethylsiloxane) layer, which was reversibly sealed to the bottom of the microchip to eliminate the scattering excitation light reaching to the photomultiplier tube. Fluorescein/calcein samples were taken as model analytes to evaluate the performance with respect to design factors. The detection limits were 0.05 μM for fluorescein and 0.18 μM for calcein, respectively. The suitability of this simple detector for fluorescence detection was demonstrated by baseline separation of fluorescein isothiocyanate (FITC)‐labeled arginine, phenylalanine, and glycine and FITC within 30 s at separation length of 3.8 cm and electrical field strength of 600 V/cm.
Dispersion control in microfluidic chips by localized zeta potential variation using the field effect
Authors: Lee Gwo‐Bin , Fu Lung‐Ming , Lin Che‐Hsin , Lee Chia‐Yen , Yang Ruey‐Jen 
Published: June 2004

AbstractA new technique to minimize the effects of turn‐induced dispersion within U‐shaped separation channels by using the field effect within a capacitor to vary the zeta potential along the channel walls in the vicinity of the microchannel is described. The effects of the separation channel geometry, the fluid velocity profile, and the use of the field effect to control the zeta potential on the band distribution in the detection area are extensively discussed. The results for a U‐shaped separation channel indicate that varying the zeta potential by controlling the field effect significantly reduces the band dispersion induced by the 90° turns within the channel. Finally, it is shown that the application of the proposed localized zeta potential variation method also results in a correction of the band tilting phenomenon and a reduction in the racetrack effect.
Performance of throughout in‐capillary derivatization capillary electrophoresis employing an on‐line sample and run buffer loading device
Authors: Oguri Shigeyuki , Hibino Misako , Mizunuma Makiko 
Published: June 2004

AbstractWe report on the effect on performance of varying the length of the capillary during throughout in‐capillary derivatization (TICD) capillary electrophoresis (CE). Performance was evaluated by on‐line coupling with a sample and CE runbuffer loading device that was newly introduced for this study. The device was assembled with a low cost using two 5 mm inner diameter (ID) disposable polyethylene syringes. First, a sequence was manually formed consisting of a 200 μL run buffer solution plug, a 100 μL sample plug and another 200 μL run buffer solution plug. Each plug was separated from its neighbor by a 100 μL air plug. When each plug reached the injection point where both a platinum‐wire anode and the end of the separation capillary tube were located, 340 V/cm separation voltage (electrophoresis voltage) and 34 V/cm injection voltage were applied to the capillary for 3 s. Then the analytes were derivatized during migration in 50 μm ID capillaries filled with 2 mM o‐phthalaldehyde (OPA)/N‐acetylcysteine (NAC) in a 20 mM phosphate‐borate buffer (pH 10), followed by separating and detecting of OPA derivatives by absorbance of 340 nm. Derivatization, separation, and detection were performed systematically using capillaries which varied in length from 5 to 80 cm. In the case of TICD‐CE of a mixture containing 1 mM aspartic acid (Asp) and 20 mM m‐nitorophenol (MNP) as a test solution, it was determined that peak area and peak width ratios of Asp to MNP did not depend on capillary length. Enantiomeric separations of DL‐alanine (Ala) and Asp were examined using a run buffer consisting of a 45 μM β‐cyclodextrin (CD) – 2 mM OPA/NAC – 20 mM phosphate‐borate buffer (pH 10). Even though the resolution of these enantiomeric pairs decreased with decreasing capillary length, as expected, the peaks corresponding to both enantiomeric amino acids were identified even when a 5 cm capillary was used. An 8‐component amino acid mixture was also tested with 5 cm and 10 cm capillaries.
Repeatedly usable immobilized pH gradient in a monolithic capillary column
Authors: Yang Chun , Zhu Guijie , Zhang Lihua , Zhang Weibing , Zhang Yukui 
Published: June 2004

AbstractGlycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) were used to synthesize a monolithic capillary column containing reactive epoxy groups. Glutaraldehyde was introduced and linked to the monolith after a process of amination. An aqueous solution of commercial carrier ampholytes (CAs, Ampholine) was focused in such a polymer column. The primary amino groups of CAs reacted with glutaraldehyde along the capillary. CAs were immobilized at different positions in the column according to their isoelectric points (pI), resulting in a monolithic immobilized pH gradient (M‐IPG). Isoelectric focusing (IEF) was performed without CAs in such an M‐IPG column. Due to the covalent attachment of the CAs this M‐IPG can be repeatedly used after its preparation. Good stability, linearity, and reproducibility were obtained.
An immersed boundary finite difference method for LES of flow around bluff shapes
Authors: Li C. W. , Wang L. L. 
Published: June 2004

AbstractA three‐dimensional numerical model using large eddy simulation (LES) technique and incorporating the immersed boundary (IMB) concept has been developed to compute flow around bluff shapes. A fractional step finite differences method with rectilinear non‐uniform collocated grid is employed to solve the governing equations. Bluff shapes are treated in the IMB method by introducing artificial force terms into the momentum equations. Second‐order accurate interpolation schemes for all sorts of grid points adjacent to the immersed boundary have been developed to determine the velocities and pressure at these points. To enforce continuity, the methods of imposition of pressure boundary condition and addition of mass source/sink terms are tested. It has been found that imposing suitable pressure boundary condition (zero normal gradient) can effectively reproduce the correct pressure distribution and enforce mass conservation around a bluff shape. The present model has been verified and applied to simulate flow around bluff shapes: (1) a square cylinder and (2) the Tsing Ma suspension bridge deck section model. Complex flow phenomena such as flow separation and vortex shedding are reproduced and the drag coefficient, lift coefficient, and pressure coefficient are calculated and analyzed. Good agreement between the numerical results and the experimental data are obtained. The model is proven to be an efficient tool for flow simulation around bluff bodies in time varying flows. Copyright © 2004 John Wiley & Sons, Ltd.
Inhibitory effect of pollen and propolis extracts
Authors: Özcan Musa , Ünver Ahmet , Ceylan Durmus Ali , Yetisir Ramazan 
Published: June 2004

AbstractBee pollen and propolis were collected from Apis mellifera colonies in five regions of Turkey. The antifungal properties of methanol extracts of pollen and propolis (2% and 5% concentrations) were determined on Alternaria alternata and Fusarium oxysporium f. sp. melonis. The least active concentration towards the tested fungi was 2% concentration of both extracts. The inhibitory effect of all propolis extracts on growth of F. oxysporium and A. alternata were generally higher when compared with pollen extracts. The growth of A. alternata and F. oxysporium were not affected at both concentrations of pollens. However, F. oxysporium against propolis extracts was more sensitive than A. alternata (P < 0.01). None of the pollen extracts tested completely inhibited mycelial growth of fungi used in our experiment. Percent inhibition of both pollen concentrations against A. alternata and F. oxysporium was lower than 50%. However, both concentrations of Alanya and Beys?ehir propolis extracts were 100% effective on mycelial growth of F. oxysporium until the 7th day of incubation (P < 0.01). 2% Alanya and Beys?ehir pollen extracts completely stimulated mycelial growth of F. oxysporium on the 7th day of incubation. Both concentrations of propolis extract showed more than 50% inhibition against F. oxysporium. It is suggested that high concentrations of propolis extract could be used as an antifungal agent against tested fungi.
Change in glyceride composition of olive pomace oil during enzymatic esterification
Authors: Göǧüs Fahrettin , Fadıloǧlu Sibel , Çiftçi Ozan Nazım 
Published: June 2004

AbstractEnzymatic esterification of free fatty acids of olive pomace oil with glycerol was investigated. The esterification reaction was carried out in the absence and presence of glycerol (glycerol to free fatty acids (FFA) molar ratio of 1/3 and 1/6). In the absence of glycerol, the FFA concentration decreased from 32 to 21% while the triglyceride concentration increased from 33 to 40% after of 8 h of reaction time. The most significant decrease in FFAs and increase in triglycerides was observed at the limiting concentration of glycerol (glycerol to FFA molar ratio of 1/3). The FFA concentration decreased to 2.5% and the triglyceride concentration increased up to 78%. The change in both FFA and triglyceride concentrations was found to be statistically significant (P < 0.05).
Metabolic activities of Lactobacillus spp. strains isolated from kefir
Authors: Yüksekdaǧ Zehra Nur , Beyath Yavuz , Aslım Belma 
Published: June 2004

AbstractA total of 21 strains of Lactobacillus species were isolated from Turkish kefir samples, in order to select the most suitable strains according to their metabolic activities including probiotic properties. As a result of the identification tests, 21 Lactobacillus isolates were identified as L. acidophilus (4%), L. helveticus (9%), L. brevis (9%), L. bulgaricus (14%), L. plantarum (14%), L. casei (19%) and L. lactis (28%). The amount of produced lactic acid, hydrogen peroxide, proteolytic activity, and acetaldehyde productions of Lactobacillus spp. were determined. Different amounts of lactic acid were produced by strains studies; however, lactic acid levels were 1.7–11.4 mg/mL. All strains produced hydrogen peroxide. L. bulgaricus Z14L strain showed no proteolytic activity, L. casei Z6L strain produced the maximum amount (0.16 mg/mL) of proteolytic activity. Acetaldehyde concentration produced in Lactobacillus strains ranged between 0.88–3.52 μg/mL.
Composition and in vitro digestibility of raw versus cooked white‐ and colour‐flowered peas
Authors: Pastuszewska Barbara , Vitjazkova Maija , Swiech Ewa , Taciak Marcin 
Published: June 2004

AbstractTen pea cultivars (four white‐flowered, Pisum sativum ssp. hortense, and six colour‐flowered, Pisum sativum ssp. arvense) grown in Latvia were analyzed and tested in in vitro experiments, as raw and cooked seeds. The colour‐flowered (CF) had a greater proportion of hulls and a higher acid detergent fibre (ADF) content than white‐flowered (WF) pea seeds (10.7 vs. 8.2% and 92.2 vs. 84.5 g/kg dry matter (DM), respectively). Three out of six CF varieties had a significantly greater amount of protein bound to neutral detergent fibre (NDF) than WF peas. The tannin content was higher in CF than in WF peas (8.46 vs. 0.37 g/kg DM). In vitro protein and amino acid digestibility was about 8% higher in WF than in CF varieties. Cooking decreased the tannin content in CF peas (8.46 vs. 5.51 g/kg DM) but had no effect on in vitro protein digestibility. Heat treatment reduced significantly trypsin inhibitor activity and amount of protein bound to NDF in CF and WF varieties (from 6.50 to 0.52 and from 6.54 to 0.46 trypsin inhibitor units (TIU)/mg DM; from 1.250 to 0.831 and 0.761 to 0.209 g N/100 g NDF, respectively). However, the protein bound to NDF content in pea DM increased in CF and decreased in WF varieties (from 1.525 to 2.145 and from 0.913 to 0.502 g N/kg DM, respectively). Cooking resulted in an increased NDF content over two times in both CF and WF pea seeds (from 122 to 259 and from 120 to 262 g/kg DM, respectively). The results suggest that colour‐flowered pea may be considered as an interesting dietary alternative to white‐flowered pea since cooking removes trypsin inhibitor activity (TIA), decreases tannins, and increases dietary fibre contents.
Preparation and functional properties of extracts from bee bread
Authors: Nagai Takeshi , Nagashima Toshio , Myoda Takao , Inoue Reiji 
Published: June 2004

AbstractThree extracts, namely hot‐water fraction (HWF), water‐soluble fraction (WSF), and ethanol‐soluble fraction (ESF), were prepared from fresh bee bread imported from Lithuania. The protein and total phenolic contents of these samples were very high. Among them, WSF at 100% concentration showed the highest antioxidative ability and scavenging ability. On the other hand, ESF at 10% concentration possessed the highest ability against 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and hydroxyl radicals. Bee bread will apply more and more as health food and medicine due to its functional properties such as antioxidative ability and scavenging activities of reactive oxygen species.
Influence of cooking and microwave heating on microstructure and mechanical properties of transgenic potatoes
Authors: Błaszczak Wioletta , Sadowska Jadwiga , Fornal Józef , Vacek Josef , Flis Bogdan , Zagórski‐Ostoja Włodzimierz 
Published: June 2004

AbstractThe transgenic potato clones of cultivar Irga with improved resistance to a necrotic strain of potato virus Y (PVYN) were subjected to heat treatment in order to determine their technological quality. The technological quality was determined on the basis of differences between mechanical properties of unmodified potato and transgenic clones during cooking and microwave heating. The compression test was applied in order to evaluate the mechanical resistance of raw, cooked and microwave‐treated potatoes. Compression resistance was expressed by fracture stress F (kPa), fracture strain D (mm/mm), and Young modulus E (kPa). The differences in microstructure of potato tubers (unmodified and modified) were investigated using scanning electron microscopy (SEM). The observed differentiation in the mechanical properties of heat‐treated potatoes was less connected with genetic modification but most of all with a kind of the process used. The heat processes caused a distinct decrease in mechanical resistance in all the examined tubers. However, the process of microwave heating resulted in more significant changes in mechanical properties of tubers than cooking. Deformation of parenchyma cells during cooking was directly connected with starch gelatinisation and gel formation. Microwave heating affected significantly cellular water evaporation which resulted in intercellular failure, collapsing of cells, and limitation of starch gelatinisation.
In vivo neuroprotective adaptation of the glutamate/glutamine cycle to neuronal death
Authors: Ramonet D. , Rodríguez M.J. , Fredriksson K. , Bernal F. , Mahy N. 
Published: June 2004

AbstractSynaptic increase of glutamate level, when not coupled to a heightened energy production, renders neurons susceptible to death. Astrocyte uptake and recycling of synaptic glutamate as glutamine is a major metabolic pathway dependent on energy metabolism, which interrelationships are not fully understood and remain controversial. We examine how the glutamate‐glutamine cycle and glucose metabolism are modified in two in vivo models of severe and mild brain injury. Graded reductions of glutaminase, the glutamate synthetic enzyme, were evidenced combined with increases in glutamine synthetase, the inactivating glutamate enzyme. Increased lactate dhydrogenase (LDH) activity was only present after a more severe injury. These results indicate an in vivo adaptation of the glutamate‐glutamine cycle in order to increase the net glutamine output, reduce glutamate excitotoxicity, and avoid neuronal death. We conclude that the graded modification of the glutamate‐glutamine correlation and neuronal lactate availability may be key factors in the apoptotic and necrotic neuronal demise, whose control may prove highly useful to potentiate neuronal survival. © 2004 Wiley‐Liss, Inc.
Characteristics of solidification and melting in the water‐saturated porous medium cooled from the top (response of solid–liquid interface due to time‐varying cooling temperature)
Authors: Kimura Shigeo , Okajima Atsushi , Kiwata Takahiro , Nakamura Taiki 
Published: June 2004

AbstractThis paper describes the response of a solid–liquid interface in a water‐saturated porous box to a time‐varying cooling temperature. Spherical soda glass beads with an average diameter of 5 mm constitute a porous matrix. The lower boundary of the matrix is kept at 8°C at all times during the experiments, while the upper plate is set at a temperature, lower than the liquids 0°C. After a steady state is reached, the cooling temperature is varied periodically with a fixed amplitude of 4°C. The solid–liquid interface positions are measured and the characteristic amplitudes and the phase delays are determined for different periods ranging from one hour to ten hours at four different cooling temperatures. It has been found that the amplitude of the interface is proportional to the cooling temperature period length, and that a thicker solid layer causes larger phase delays. The proposed one‐dimensional model has been found appropriate for predicting the response of the horizontally averaged position of the solid–liquid interface. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(5): 330–341, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20015