bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism of lysosome rupture by dipeptides
Authors: Bird Susan J. , Lloyd John B. 
Published: May 2005

AbstractLow concentrations of some neutral dipeptides, such as L‐Ala‐L‐Ala, rapidly disrupt rat liver lysosmes. The phenomenon has been attributed to an osmotic imbalance generated by the production of amino acids in the lysosme by lysosomal dipeptidase activity. This hypothesis is challenged by testing several pairs of dipeptides available in both D‐ and L‐forms and a range of dipeptides whose susceptibility to lysosomal dipeptidase activity is known. A good correlation was found between the lytic ability of dipeptides and their capacity to cross the lysosome membrane and be hydrolysed by lysosomal dipeptidase. The osmotic‐imbalance hypothesis is critically evaluated in the light of the results and of recent information concerning the carrier‐mediated transport of amino acids and dipeptides across the lysosome membrane. It is concluded that intralysosomal generation of amino acids remains the most plausible explanation of the lytic activity of dipeptides, and that the dipeptide proter(s) in the lysosome membrane must have higher Km than the amino acid porters.
Subpopulations of tau interact with microtubules and actin filaments in various cell types
Authors: Henríquez Juan P. , Cross Daniel , Vial Clarisa , Maccioni Ricardo B. 
Published: May 2005

AbstractIt has been demonstrated that microtubule‐associated proteins (MAPs) interact with tubulin in vitro and in vivo. However, there is no clear evidence on the possible roles of the interactions of MAPs in vivo with other cytoskeletal components in maintaining the integrity of the cell architecture. To address this question we extracted the neuronal cytoskeleton from brain cells and studied the selective dissociation of specific molecular isospecies of tau protein under various experimental conditions. Tau, and in some cases MAP‐2, were analysed by the use of anti‐idiotypic antibodies that recognize epitopes on their tubulin binding sites. Fractions of microtubule‐bound tau isoforms were extracted with 0·35 M NaCl or after the addition of nocodazole to allow microtubule depolymerization. Protein eluted with this inhibitor contained most of the assembled tubulin dimer pool and part of the remaining tau and MAP‐2. When the remaining cytoskeletal pellet was treated with cytochalasin D to allow depolymerization of actin filments, only tau isoforms were extracted. Immunoprecipitation studies along with immunolocalization experiments in cell lines containing tau‐like components supported the findings on the roles of tau isospecies as linkers between tubulin in the microtubular structure with actin filaments. Interestingly, in certain types of cells, antibodyreactive tau isospecies were detected by immunofluorescence with a discrete distribution pattern along actin filaments, which was affected by cytochalasin disruption of the actin filament network. These results suggest the possible in vivo roles of subsets of tau protein in modulating the interactions between microtubules and actin filaments.
Characterization of the effect of peak shifts on the performance of the Kalman filter in multicomponent analyses
Authors: Webster Gail Hartmann , Cecil Todd L. , Rutan Sarah C. 
Published: May 2005

AbstractThe effect of peak shifts on the performance of a Kalman filter multicomponent analysis algorithm has been investigated. A series of Gaussian test systems were employed to characterize the concentration estimation errors and the morphology of the on‐line residuals (the innovations sequence). Both forward and reverse filters were used in the generation of the innovations sequences. It was found that the difference between the forward and reverse innovations sequences gave an accurate indication of the direction and magnitude of the peak shift. A series of overlapped two‐component systems were also investigated. Again, a correlation between the difference innovations and the degree of the response shift was observed. The behavior of the Kalman filter in fitting the shifted fluorescence emission spectrum of benzo[a]pyrene was also examined. The response for benzo[a]pyrene in cyclohexane solution was compared to that obtained on the surface surface of a reversed phase thin layer chromatography plate. A red shift of 4 nm was detected for the surface spectrum by observing the difference innovations sequence. This approach holds promise for correction of response shifts in multicomponent systems.
Three‐way methods for the calibration of chromatographic systems: Comparing PARAFAC and three‐way PLS
Authors: Smilde Age K. , Doornbos Durk A. 
Published: May 2005

AbstractFor the calibration of chromatographic systems, different methods can be used. One class of methods utilizes three‐way approaches. The calibration problem is stated in such a way that the decomposition of a three‐way array can serve for the prediction of retention on new stationary phases.Two three‐way approaches are presented: the Unfold‐PCA and PARAFAC models. The theory of both methods is presented and the differences are highlighted, the main difference being that PARAFAC is a trilinear decomposition whereas Unfold‐PCA is not. Both three‐way methods are evaluated on a small data set consisting of retention measurements of eight solutes at six mobile phase compositions on six stationary phases. The differences in performance of the two models are minor.For calibration purposes, two variants of the methods are discussed: three‐way PLS and an extension of PARAFAC. Again the theory and differences between the two methods are explained. The predictive performance of the two methods is compared using the same data set as earlier. The differences in predictive performance, however, are minor. Both methods are capable of predicting 98% of the variation in the test sets. Yet, there are other considerations when comparing methods than predictive performance, e.g. the quality of the predictions.
Comments on the PLS kernel algorithm
Authors: De Jong Sijmen , Ter Braak Cajo J. F. 
Published: May 2005

AbstractLindgren et al. (J. Chemometrics, 7, 45–49 (1993)) published a so‐called kernel algorithm for PLS regression of Y against X when the number of objects is very large. The algorithm is based solely on deflation of the cross‐product matrices XTX, YTY and XTY. The algorithm is now described in a shorter and more transparent way and compared with a similar algorithm for the singular value decomposition of XTY.
Metal‐organic vapor phase epitaxial growth of cubic Gallium selenide, Ga2Se3
Authors: Ng Tat Lin , Maung Nicolas , Fan Guanghan , Poole Ian B. , Williams John O. , Wright Andrew C. , Foster Douglas F. , Cole‐Hamilton David J. 
Published: May 2005

AbstractWe present results of a study using metal‐organic vapor phase epitaxy (MOVPE) to synthesize thin films of cubic Ga2Se3 on both nearly lattice matched GaP and mismatched GaAs substrates. We find that trimethylgallium (TMGa) pre‐reacts with the hydride H2Se in the gas phase to yield films which are only partially epitaxial and that the combination of TMGa with ditertiarybutylselenide produces films of the best crystal quality under steady state flow conditions. We also show that GaAs is an unsuitable substrate for MOVPE growth of gallium selenide due to exchange reactions at the interface leading to poorly bonded films.
Enhancer trapping with a red fluorescent protein reporter in Drosophila
Authors: Akimoto Ai , Wada Housei , Hayashi Shigeo 
Published: May 2005

AbstractEnhancer trapping allows the detection of genomic transcriptional enhancers and provides a rich source of cell‐ and region‐specific markers in Drosophila. We report here the development of a P‐element–based enhancer‐trap vector with a nuclear red fluorescent protein (DsRed) reporter for enhancer detection. We demonstrate that this vector can be used for a standard enhancer‐trap screen as well as for targeted replacement of previously characterized P‐element insertions. We isolated DsRed insertion strains of hedgehog, patched, apterous, teashirt, and dachshund that label specific regions of imaginal discs. The time required for red fluorescence maturation in the eye imaginal disc was estimated to be 22.5 hr. The DsRed markers can be combined with green fluorescent protein markers for double labeling of living Drosophila tissues. Developmental Dynamics 233:993–997, 2005. © 2005 Wiley‐Liss, Inc.
NeuroD1 in the endocrine pancreas: Localization and dual function as an activator and repressor
Authors: Itkin‐Ansari P. , Marcora E. , Geron I. , Tyrberg B. , Demeterco C. , Hao E. , Padilla C. , Ratineau C. , Leiter A. , Lee J.E. , Levine F. 
Published: May 2005

AbstractThe basic helix–loop–helix transcription factor NeuroD1 regulates cell fate in the nervous system but previously has not been considered to function similarly in the endocrine pancreas due to its reported expression in all islet cell types in the newborn mouse. Because we found that NeuroD1 potently represses somatostatin expression in vitro, its pattern of expression was examined in both strains of mice in which lacZ has been introduced into the NeuroD1 locus by homologous recombination. Analysis of adult transgenic mice revealed that NeuroD1 is predominantly expressed in β‐cells and either absent or expressed below the limit of lacZ detection in mature α‐, δ‐, or PP cells. Consistent with a previous report, NeuroD1 colocalizes with glucagon as well as insulin in immature islets of the newborn mouse. However, no colocalization of NeuroD1with somatostatin was detected in the newborn. In vitro, ectopic expression of NeuroD1 in TRM‐6/PDX‐1, a human pancreatic δ‐cell line, resulted in potent repression of somatostatin concomitant with induction of the β‐cell hormones insulin and islet amyloid polypeptide. Additionally, NeuroD1 induced expression of Nkx2.2, a transcription factor expressed in β‐ but not δ‐cells. Transfection studies using insulin and somatostatin promoters confirm the ability of NeuroD1 to act as both a transcriptional repressor and activator in the same cell, suggesting a more complex role for NeuroD1 in the establishment and/or maintenance of mature endocrine cells than has been recognized previously. Developmental Dynamics 233:946–953, 2005. © 2005 Wiley‐Liss, Inc.
Ammonium detection using an ion‐selective electrode array in flow‐injection analysis
Authors: de Viteri F. J. Sáez , Diamond Dermot 
Published: May 2005

AbstractAn ammonium detection system using ion‐selective electrodes (ISEs) in flow‐injection analysis (FIA) is described. Because of the low selectivity of the nonactin ammonium selective electrode toward some common ions, notably potassium, different selectivity enhancement techniques have been examined. An array of ISEs selective for ammonium, sodium, potassium, and calcium was used as the FIA detector, and the array response was modeled via the Nikolskii‐Eisenmann equation and the Projection Pursuit regression model. The interfacing of the system to a PC‐386SX computer using an Analog Devices RTI‐815 I/O card is also described. The results show that the use of an array of ISEs under FIA regimes for the detection of ammonium in the activity range 10 to 0.01 mM gives much improved results for the determination of ammonium in aqueous samples than the use of a single ammonium electrode. The performance of the array under steady‐state and FIA conditions is compared.
Electrocatalytic oxidation and amperometric determination of sulfhydryl compounds at a copper hexacyanoferrate film glassy carbon electrode in liquid chromatography
Authors: Zhou Jianxun , Wang Erkang 
Published: May 2005

AbstractElectrocatalytic oxidation of sulfhydryl compounds was effective on a copper hexacyanoferrate (CuHCF) film glassy carbon electrode, at a significantly reduced overpotential (0.55 to 0.65 V) and for a broader pH range (2.0 to 7.0). The electrocatalysis was evaluated in terms of several preliminary experimental parameters, such as buffer pH, surface adsorbent concentration, operating potential, mobile‐phase flow rate, and concentration dependence in batch and flow systems. Electrochemical liquid chromatography (LCEC) of sulfhydryl compounds gave a linearity over two orders of magnitude and detection limits at picomole level. Overlaying the CuHCF film electrode surface with a Nafion layer is essential for improving the catalysis stability and offers enhancement of the liquid chromatography electro chemistry (LCEC) response.
Determination of oxidase enzyme substrates using cross‐flow thin‐layer amperometry
Authors: Yang Liu , Kissinger Peter T. 
Published: May 2005

AbstractThin‐layer cross‐flow amperometric detectors with enzyme modified working electrodes were developed for the determination of oxidase substrates in flowing streams. The enzyme was covalently immobilized in an osmium redox polymer film on the electrode surface. Electrodes modified with glucose oxidase or lactate oxidase were prepared for the continuous monitoring of glucose or lactate. A peroxidase electrode coupled with oxidase enzyme reactors was also explored for the determination of glucose, lactate, and acetylcholine/choline in continuous monitoring systems or following liquid chromatography. The effects of interferences, oxygen, mass transfer limiting membrane, and perfusate composition on electrode performance are discussed.
Determination of free formaldehyde in nail preparations by differential pulse voltammetry
Authors: Wang Lai‐Hao , Chen Zong‐Shiow 
Published: May 2005

AbstractFree formaldehyde in nail preparations, extracted with dichloromethane and 0.002 M hydrochloric acid (1:2v./v.), was determined by differential pulse voltammetry(DPV) using a thin‐film mercury electrode (TFME) in a basic solution. The various factors such as deposition time, concentration of mercury (II) and of coexisting organic and inorganic interferences on the precision of the analysis have been explored. Under optimum conditions the peak potential of formaldehyde was −1.652V [vs. the saturated calomel electrode(SCE)], and a linear current vs. concentration relationship was over 2.0–80.0 mg L−1. The results obtained were in good agreement with those of the official European Economic Community(EEC) acetylacetone method.
Voltammetric determination of dopamine in the presence of ascorbic acid at a chemically modified electrode
Authors: Zen Jyh‐Myng , Chen I‐Lang 
Published: May 2005

AbstractA Nafion/ruthenium oxide pyrochlore chemically modified electrode (CME) was used for the selective determination of dopamine (DA) in the presence of a high concentration of ascorbic acid by square‐wave voltammetry. Compared to a bare glassy carbon electrode, the CME exhibits an apparent shift of the oxidation potentials in cathodic direction and a marked enhancement of the current response. The selective sensing of DA is achieved by combining the electrocatalytic function of the ruthenium oxide pyrochlore catalyst with the charge‐exclusion and preconcentration features of Nation. With a preconcentration time of 60 s at a potential of −0.3 V (vs. Ag/AgCl), linear calibration plots are obtained for dopamine in 0.1 M, phosphate buffer (pH 7.4) over 0–20 μM with a detection limit (3σ) of 0.1 μM.
Lead‐selective membrane electrodes based on dithiophenediazacrown ether derivatives
Authors: Yang Xinhao , Kumar Naresh , Chi Hua , Hibbert D. Brynn , Alexander Peter W. 
Published: May 2005

AbstractThree double‐armed diazacrown ethers with two thiophene side groups, 7,16‐dithenyl‐1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane (DTDC), 7,16‐dithenoyl‐1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane (DTODC), and 7,16‐di‐(2‐thiopheneacetyl)‐1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane (DTAODC), have been synthesized and used as novel neutral lead(II) ionophores in ion selective electrode applications. The relationship between the molecular structure of these ionophores and electrochemical properties (linear range, response time, selectivity) of the membrane electrode is discussed. The optimum conditions for the preparation of the electrodes are described. The optimized dithenoyldiazacrown had a detection limit of pPb = 5.7, and Nernstian range with slope 29.2 mV decade−1 from pPb = 5.0 to 2.7. Mercury and silver ions are the major interferences. These electrodes are applied to potentiometric titrations of lead(II) ions and show promise for the determination of lead ions in water samples.
Electrochemical and surface characterization of pH sensor based on bisulfate‐doped poly(pyrrole)
Authors: Jovanovic Vladislava M. , Dekanski Aleksander , Vlajnic Goran , Jovanovic Momir S. 
Published: May 2005

AbstractPyrrole was electrochemically polymerized on glassy carbon support in NaHSO4 solutions under different conditions (method applied, concentration of monomer, concentration of the main solution, thickness of the film). These variables were used to study the preparation effect on the resulting properties, in particular on the potentiometric response of the PPy‐HSO4 electrodes. The electrodes were characterized by cyclic voltammetry, as well as by STM and AES techniques. Utilities of the polymer application as a sensor were studied by direct potentiometric measurements. The results obtained show that poly(pyrrole) doped with bisulfate ions can serve as pH sensor, with the slope of E/pH curves approaching the theoretical value.
Field Strnegth changes during isoelectric focusing
Authors: Jackiw B. Andrew , Brown Ray K. 
Published: May 2005

AbstractConductivity gaps in electrofocusing gels were measured as a function of the duration of isoelectric focusing, using a device for the determination of segmental voltage along the gel length (Jackiw, B. A., et al., Electrophoresis 1980, 1, 102–106 Transient and permanent conductance gaps were found on electrofocusing with both commercial and home‐made carrier ampholytes of a variety of pH‐ranges and chemical compositions. All pH gradients investigated exhibited conductance gaps. The dynamics of conductance gap formation and the relative magnitude of voltage maxima were compared in electrofocusing gels made with the various types of carrier ampholytes, With ampholyte‐ampholyte mixtures, and with ampholyte‐amino acid mixtures.
A continuous‐flow isoelectric focusing system for protein fractionation: Its description and application in the partial purification of choline acetyltransferase
Authors: Basset Paul , Froissart Chantal , Vincendon Guy , Massarelli Raffaele 
Published: May 2005

AbstractA continuous‐flow isoelectric focusing (IEF) system for protein fractionation, using a non‐commercial separation chamber and carrier ampholytes synthesized in the laboratory, is described. The resolving power and the sample‐loading capacity have been tested by the fractionation of hemoglobin mixtures. Hb A2and HbA (ΔpI 0.4) were separated with a sample loading of 4 g of hemoglobin per day. The maximal temperature in the gel was 5 °C, the average field strength 30 V/cm and the residence time 6 h. The continuous‐flow IEF system was further used as a preliminary step in the purification of choline acetyltransferase (EC. 3.2.1.6) from human placenta. The results obtained with choline acetyltransferase indicated that continuous‐flow IEF can be used for the purification of enzymes when other preparative IEF systems are not effective, particularly when the sample is present in large volume.
Acrylamide gel electrophoresis of hydrophobic proteins: Gas vacuole protein
Authors: Simon Robert D. 
Published: May 2005

AbstractThe hydrophobic protein comprising the gas vacuoles of a variety of procaryotic microorganisms is insoluble in detergents (e.g. sodium dodecyl sulfate) and cannot be electrophoresed in detergent‐containing systems. The protein is solubilized by mixtures of phenol‐acetic acid‐urea (PAU) and the development of a slab gel system containing PAU which successfully separates the gas vacuole protein is described. In the system, phenol is polymerized directly into the gel, and the high background staining which results can be minimized by the proper choice of gel thickness, acrylamide/Bis ratio, and polymerization conditions. There is a direct relationship between the electrophoretic mobility and molecular weight of protein standards in the PAU system; however, several proteins including histones H2, H3, H4 and bovine serum albumin have a faster rate of gration than expected. It has been possible to separate and identify the gas vacuole protein from Halobacterium halobium, Halobacterium salinarium strain 5, and the two species of cyanobacteria, Anabaena flos‐aquae and Microcystis aeruginosa. Mobility of the gas vacuole proteins in the four species are consistent with molecular weights of 16 800, 16 800, 14 700 and 15 700 respectively. Gels produced using the PAU system can be successfully fluorographed.
Amylase1polymorphism of human parotid saliva: Detection of a new allele, AMY by isoelectric focusing and AMY1population data from Germany
Authors: Kühnl Peter , Tischberger Hubert 
Published: May 2005

AbstractProlonged isoelectric focusing (IEF) of human saliva in narrow pH range polyacrylamide gels (pH 5–7) gave evidence for the existence of a new allele in the amylase1(AMY1) system. It has tentatively been designated AMY15and, inherited in an autosomal codominant way, as the variant phenotype AMY15–1, was observed in four individuals of a Yugoslavian family through three generations. The isoelectric point (pI) of the AMY15gene product is intermediate to AMY11 and AMY12. The allele frequencies of AMY1in 170 healthy, unrelated individuals from Hesse, Germany, were determined as follows: AMY11= 0.909, AMY12= 0.070, and AMY13= 0.021. With a single exclusion chance of 8.0 % for non‐fathers, AMY1might become a useful genetic marker in cases of disputed paternity as well as for “gene mapping” the fine structure of chromosome 1 in man.
Characterization of mouse lymphocytes by analytical automatic cell electrophoresis
Authors: Shimizu Motomu , Iwaguchi Takao 
Published: May 2005

AbstractMouse splenic lymphocytes were examined for electrophoretic mobility by an automatic cell electrophoresis. The whole population of lymphocytes showed a bimodal histogram of electrophoretic mobility. In contrast, adherent cells to a nylon wool column (B cell‐rich) and nonadherent cells treated with anti‐mouse IgG and complement (T cell‐rich) gave a unimodal histogram. A linear relationship existed between the electrophoretic mobility of mixture of T and B cells and their ratio detected by the method of immunofluorescence, suggesting that the ratio of T to B cells can easily be determined from the electrophoretic mobility of lymphocytes.
Horizontal gradient polyacrylamide gel electrophoresis
Authors: Altland Klaus , Hackler Rolf 
Published: May 2005

AbstractA simple Technique for horizontal gradient polyacrylamide gel electrophoresis (PAGE) in discontinuous buffer systems is described, in which one‐dimensional, two‐dimensional and double one‐dimensional separation patterns can be obtained. The advantages of this technique are: (i) that samples can be applied by overlaying on a variable broad area of the concentrating gel, (ii) that the complete separating gel and the contact with the concentrating gel remain sandwiched between glass plates from the moment of gel polymerization till the end of electrophoretic separation, (iii) that many gels are poured from one gel solution, and (iv) that the gels can be stored, due to an identical buffer composition in the concentrating and separating gel.