bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow cytometric measurement of circulating endothelial cells: The effect of age and peripheral arterial disease on baseline levels of mature and progenitor populations
Authors: Shaffer Rebecca Gusic , Greene Sam , Arshi Arash , Supple Greg , Bantly Andrew , Moore Jonni S. , Mohler Emile R.
Published: February 2006

Background:

Age and cardiovascular disease status appear to alter numbers and function of circulating endothelial progenitor cells (EPCs). Despite no universal phenotypic definition, numerous studies have implicated progenitors with apparent endothelial potential in local responses to vascular injury and with cardiovascular disease in general. To further define the role of this lineage in peripheral artery disease (PAD), we developed a multiparameter flow cytometry assay to analyze multiple phenotypic definitions of progenitor cells (PCs), EPCs, and mature endothelial cells (ECs) and evaluate effects of age and PAD on baseline levels of each subset.

Methods:

Blood was collected from young healthy subjects (N = 9, mean age 33 ± 8 years), older healthy subjects (N = 13, mean age 66 ± 8 years), and older subjects with PAD (N = 15, mean age 69 ± 8 years). After ammonium chloride lysis, cells were stained and analyzed on a Becton‐Dickinson LSR II with a 5‐color antibody panel: FITC‐anti‐CD31, PE‐anti‐CD146, PE‐anti‐CD133, PerCP‐Cy5.5‐anti‐CD3,‐CD19,‐CD33 (lineage panel), PE‐Cy7‐anti‐CD34, and APC‐anti‐VEGF‐R2. Viability was assessed by propidium iodide exclusion, and only viable, low to medium side scatter lineage‐negative singlets were analyzed. In some studies, cells were sorted for morphological studies. Subsets were defined as indicated later.

Results:

Our results, using a comprehensive flow cytometric panel, indicate that CD133+, CD34+, and CD133+/CD34+ PCs are elevated in younger healthy individuals compared to older individuals, both healthy and with PAD. However, the number of EPCs and mature ECs did not significantly differ among the three groups. Assessment of endothelial colony forming units and dual acLDL‐lectin staining supported the flow cytometric findings.

Conclusions:

We describe a comprehensive flow cytometric method to detect circulating mature and progenitor endothelial populations confirmed by conventional morphological and functional assays. Our findings suggest that aging may influence circulating levels of PCs, but not EPCs or ECs; PAD had no effect on baseline levels of any populations investigated. This study provides the basis for evaluating the potential effects of acute stress and therapeutic intervention on circulating progenitor and endothelial populations as a biomarker for cardiovascular status. © 2005 International Society for Analytical Cytology
No evidence for a major effect of two common polymorphisms of the catalase gene in type 1 diabetes susceptibility
Authors: Pask Rebecca , Cooper Jason D. , Walker Neil M. , Nutland Sarah , Hutchings Jayne , Dunger David B. , Nejentsev Sergey , Todd John A.
Published: February 2006

Background

Type 1 diabetes (T1D) is a multifactorial disease, the genetic analysis of which has yielded few true positive linkage and association results. Replication of association in independent, large‐sample studies is essential to further identify the genes involved in T1D. Two single nucleotide polymorphisms (SNPs) in the catalase gene have been reported to be associated with T1D.

Methods

Major effects of two SNPs, C1167T (rs769217) and C(‐262)T (rs1001179), of the catalase gene on T1D susceptibility have been reported previously in Russians from Moscow. We genotyped C1167T and C(‐262)T in large family (1642 families) and British case–control (3530 cases and 3930 controls) collections and tested for association with T1D.

Results

We found no evidence of an association between T1D and C1167T or C(‐262)T in either the family or case–control collections, or for the D11S2008 microsatellite polymorphism in families. However, we did find limited statistical evidence of an association at C1167T in USA families (P = 0.033; RR for 1167C = 1.23, 95% CI = 1.02–1.49) and C(‐262)T in UK families (P = 0.046; RR for (‐262)C = 0.86, 95% CI = 0.75–0.99).

Conclusion

We found no evidence for a major effect of C1167T or C(‐262)T on T1D susceptibility in two large sample collections. Limited statistical evidence of an association at C1167T in USA families and C(‐262)T in UK families was found, but these results are likely to be false positives. The previously reported association of these SNPs may also have been a false positive, or a population specific association in Russians from Moscow. Copyright © 2006 John Wiley & Sons, Ltd.
Induced peripheral regulatory T cells: The family grows larger
Authors: Höglund Petter
Published: February 2006

In order to control immune reactions and to prevent autoimmunity, the immune system relies on a multitude of regulatory T cells (Treg). Most work in this field has focussed on Treg of the CD4+ T cell subset because of the central role CD4+ T cells play as initiators and regulators of immune responses. One discovery of particular importance was the identification of naturally occurring CD4+CD25+ Treg that arise in the thymus and express the transcription factor Foxp3; however, Treg can also be induced in the periphery after immune activation. A paper in this issue of the European Journal of Immunology identifies a novel type of induced murine CD8+ Treg that arise in TCR HY transgenic female mice after injection of MHC class I tetramers loaded with HY peptide. These Treg prevent subsequent rejection of male skin grafts suggesting that their manipulation may represent a new way of improving graft rejections against minor histocompatibility barriers.

See accompanying article http://dx.doi.org/10.1002/eji.200535064
Sulfur–Sulfur‐Based Ligands Derived from D‐Sugars: Synthesis of PdII Complexes, Application in Palladium‐Catalyzed Allylic Alkylation for the Synthesis of Both Members of Enantiomer Pairs, and Structural Studies
Authors: Khiar Noureddine , Serrano Araújo Cristina , Suárez Bélen , Fernández Inmaculada
Published: February 2006

A divergent synthetic approach for the synthesis of optically pure bis(thioglycosides) of type I is reported. A common chiral intermediate with up to eight free hydroxy groups is obtained in only two steps, and from this common intermediate a large number of ligands can be synthesized. A strategy resembling positional scanning enabled the rapid discovery of an efficient catalyst for the palladium‐catalyzed asymmetric allylation of malonate. Both enantiomers of the allylated product could be obtained in up to 90 % ee values through the use of natural D‐sugars as catalyst precursors, thanks to the structural similarity of α‐D‐arabinose and β‐L‐galactose. Treatment of several C2‐symmetric bis(thioglycosides) with [PdCl2(CH3CN)2] always resulted in single diastereomeric PdII complexes. Dynamic NMR studies of various PdII complexes have shown that there is efficient stereochemical control over the sulfur configuration upon coordination to the palladium, as a consequence of the exo‐anomeric effect. An explanatory model for the observed enantioselectivity based on NMR studies is discussed.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Reduction of Multiple Bonds without Hydrogen or Hydride Complexes: Samarium Diiodide as a Mild Reducing Reagent
Authors: Concellón José M. , Rodríguez‐Solla Humberto
Published: February 2006

The use of samarium diiodide as a mild and selective reducing agent has become an important tool in organic synthesis. Many reducing agents are reported in the literature. However, due to their low chemoselectivities and various other drawbacks, samarium diiodide has become a useful and readily available reagent. This manuscript provides an update on earlier reviews describing conventional reduction processes of multiple bonds promoted by samarium diiodide. The most recent developments in the use of samarium metal in this field are also discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
4‐exo‐dig Cyclocarbopalladation: A Straightforward Synthesis of Cyclobutanediols from Acyclic γ‐Bromopropargylic Diols under Microwave Irradiation Conditions
Authors: Bour Christophe , Suffert Jean
Published: February 2006

Treatment of acyclic γ‐bromopropargylic diols with tributylstannylated alkynes under palladium catalysis and microwave irradiation conditions gives high yields of the bis(alkylidene)cyclobutanediol derivatives and cyclobutenediols through an efficient 4‐exo‐dig cyclocarbopalladation. The cyclization is general with a wide variety of alkyne derivatives and gives access to new cyclobutane ring systems bearing one exocyclic double bond and one eneyne substituent as well as bicyclic dienes sharing a common double bond that may be of interest for further elaborations of complex molecules. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Total Synthesis of Altenuene and Isoaltenuene
Authors: Altemöller Martina , Podlech Joachim , Fenske Dieter
Published: February 2006

Total synthesis of altenuene and isoaltenuene, toxins produced by various alternaria fungi, were achieved for the first time in ten steps, starting with quinic acid and commercially available acetal‐protected phloroglucinic acid, with the longest linear sequence consisting of seven steps. The key reactions are palladium‐catalyzed Suzuki‐type couplings between an arene boronate and iodinated cyclohexenes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Samarium Diiodide Induced Reactions of Cyclopropyl Ketones: Reductive Ring Cleavage and Dimerization Leading to 1,8‐Diketones – Scope, Limitations, Mechanisms
Authors: Aulenta Francesca , Hölemann Alexandra , Reißig Hans‐Ulrich
Published: February 2006

Reactions of the samarium diiodide/HMPA complex with alkyl cyclopropyl ketones such as 3, 5, and 7 provided dimers incorporating a 1,8‐diketone moiety. The products 4, 6, and 8 were isolated in moderate to good yields. The aryl‐substituted cyclopropyl ketones afforded a broader product spectrum, which results from the attack of samarium intermediates to the aryl group. Cyclopropyl phenyl ketone (13) gave dimer 14, where one cyclopropane ring was reductively cleaved, whereas the second one is still present. The reductive dimerization of cyclopropyl 2‐thienyl ketone (21) furnished the product 22, which still contains two cyclopropyl groups. Further examples demonstrate the diversity of samarium diiodide induced reductions of cyclopropyl ketones. Plausible reaction mechanisms involving samarium ketyl intermediates are presented.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Sol‐Gel Entrapped Pyridinium Hydrobromide Perbromide as a Recyclable Bromination Agent: Its Application to a One‐Pot Bromination and Dehydrobromination Process
Authors: Levin Yevgenia , Hamza Khalil , Abu‐Reziq Raed , Blum Jochanan
Published: February 2006

Silica sol‐gel encaged pyridinium hydrobromide perbromide can be used for clean, odorless bromination of a variety of substrates, including alkenes, ketones, and arenes. The used heterogenized bromination reagent can be recharged with bromine and recycled. In the presence of sol‐gel entrapped 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene, dibromides are dehydrobrominated to give vinyl monobromides and/or alkynes. Encapsulation of the pyridinium derivative and the guanidine base within separate sol‐gel matrices enables the use of both opposing reagents in one‐pot reactions without their mutual destroying each other. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Horseradish‐root‐modified carbon paste bioelectrode
Authors: Wang Joseph , Lin Meng Shan
Published: February 2006

The incorporation of horseradish roots into the carbon paste matrix results in an effective bioelectrode for sensing hydrogen peroxide. The response is based on the hydrogen peroxidase activity in the tissue. Because of the intimate contact between the biocatalytic and sensing sites, a very fast response is observed, as desired for practical biosensing applications. The behavior of the new bioelectrode is characterized using a flow injection system. Response time (t95%) as low as 11 s has been determined. The limit of detection is 3 × 10−7 M (1 ng), the relative standard deviation is 1.4%, and the response is linear up to 1.2 × 10−4 M. Oxidizable biological compounds do not interfere in the determination of hydrogen peroxide. The response is characterized also with respect to paste composition, flow rate, applied potential, reducing‐agent concentration, injection volume, and other variables. Rapid and sensitive flow‐injection measurements of glucose are illustrated. The tissue‐modified electrode possesses many of the features desirable for use as an amperometric sensor for oxidase substrates.
Amperometric determination of free fatty acids by utilizing five sequential enzyme reactions
Authors: Sode Koji , Tamiya Eiichi , Karube Isao , Kameda Yuko
Published: February 2006

An enyme electrode for determination of free fatty acids was constructed. Five sequential enzyme reactions are involved in this biosensor. Acyl‐CoA synthetase (EC 6.2.1.3) was used as a specific enzyme for free fatty acids, and produced AMP. AMP was then hydrolyzed with four other sequential enzyme reactions involving oxygen consumption. The oxygen consumed was measured by an oxygen electrode. Using this sensor, a good linearity was obtained between current decrease and free fatty acid concentration below 15 mM. The minimum concentration for the determination was 1.77 mM. The assay procedure was completed within 5 min.
Ion exchange voltammetry with electroactive ionomers
Authors: Espenscheid Mark W. , Martin Charles R.
Published: February 2006

Ion exchange voltammetry is a newly proposed electroanalytical technique that uses an ionomer film coated onto an electrode surface to separate and preconcentrate an analyte ion prior to electrochemical determination at the substrate‐electrode surface. One problem with this proposed technique is that after analysis, the ionomer film is loaded with the analyte ion, and this ion must be removed prior to subsequent analyses. In this paper, we show that this film regeneration step can be accomplished electrochemically using a new type of electroreleasing polymer called an electroactive ionomer. Furthermore, we show that these electroactive ionomer film‐coated electrodes can preconcentrate an analyte cation at the substrate‐electrode surface, thus producing markedly better detection limits than analogous uncoated electrodes.
Comparison of physicochemical speciation procedures with metal toxicity to Chlorella pyrenoidosa. Copper complexation capacity
Authors: Morrison G. M. P. , Florence T. M.
Published: February 2006

A comparison was made of methods for measuring the copper complexation capacity of natural and synthetic organic ligands in freshwaters. Complexation capacity values close to theoretical were obtained for nitrilotriacetic acid (NTA) and ethylenediaminetetraacetic acid, when the following separation or analysis methods were used to detect ionic copper: algal assay (Chlorella pyrenoidosa), an aluminum hydroxide resin, ion‐selective electrode (ISE), and anodic stripping voltammetry (ASV) at the mercury film electrode (MFE) and Nafion‐coated MFEs. No complexation capacity could be measured for Cu‐NTA when the hanging mercury drop electrode (HMDE) was used.

Results from the ISE and a resin with adsorbed aluminum hydroxide agreed closely with algal assay for the copper complexation capacity of solutions of fulvic acid and Fe‐humic colloids. Analysis by ASV at the HMDE, MFE, and Nafion‐coated MFE gave values‐of more than an order of magnitude lower than the other techniques because these methods failed to detect the end point for partially labile complexes with a large complexation capacity. On the other hand, the use of differential pulse polarography (DPP) detected these labile copper complexes and yielded results comparable with those for algal assay. Comparable copper complexation capacities for pristine river water samples were obtained by algal assay (2.5–4.1 × 10−6 M Cu) and DPP (2.0–3.7 × 10−6 M Cu), with lower values for the aluminum hydroxide resin (0.8–1.1 × 10−6 M Cu). Because the ASV techniques gave much lower results (0.1–0.4 × 10−6 M Cu), they are clearly unsuitable for the determination of the complexation capacity of freshwaters.
Evaluation of flow‐through photochemical reactors for liquid chromatography with electrochemical detection
Authors: Barisci Jose N. , Wallace Gordon G.
Published: February 2006

A method which allows evaluation of the irradiation efficiency of flow‐through photoelectrochemical detector cells for liquid chromatography and flow injection analysis has been developed. The method is based on the determination of the light intensity incident inside of the irradiation cell using the potassium ferrioxalate actinometer. The concentration of the actinometer is measured electrochemically in the flowing system. Typical detector cells used for photoelectrochemical detection were evaluated to demonstrate the method.
Differential pulse adsorptive voltammetric determination of chromium in aluminum
Authors: Sarnaik K. M. , Palrecha M. M. , Dhaneshwar R. G.
Published: February 2006

A method is presented for determining the trace amount of chromium in aluminum. Aluminum is dissolved in sodium hydroxide containing hydrogen peroxide. The method is based on the catalytic activity of nitrate ions on the reduction of Cr(III)—triethylenetetraminehexaacetic acid (—TTHA) complex. The sensitivity of this method is further improved by adsorptive preconcentration of Cr(III)—TTHA complex at a hanging mercury drop electrode (HMDE). The adsorbed complex is then reduced at a peak potential of −1.28 V, and the peak height of Cr(III) reduction is measured. The Cr(III) formed at the electrode surface by the reduction of Cr(VI), which is present in the bulk solution, is immediately complexed by TTHA. This method is suitable for the determination of chromium at levels as low as 0.5 μg g−1 (with about 25 mg of sample) and a relative standard deviation of 15%.
The determination of organochlorine compounds by adsorptive stripping voltammetry, part II: 2,4‐dichlorophenoxyacetic acid and 2,4,5‐trichlorophenoxyacetic acid
Authors: Li Chiang , James Bruce D. , Magee Robert J.
Published: February 2006

An indirect procedure for the determination of 2,4‐dichlorophenoxyacetic acid (2,4‐D) and 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T) in mixtures via adsorptive stripping voltammetry is reported. This method takes advantage of the formation of a new pH‐dependent peak, which is obtained when these acids interact with Fe(II). The limits of detection are 1.7 ppb for 2,4‐D and 1.5 ppb for 2,4,5‐T. The relative standard deviations (for 10 determinations) are 6.2 and 5.7%, respectively.
Flow‐reversal injection analysis for improved stripping voltammetry
Authors: Wang Joseph , Huiliang Huang , Kubiak Wladyslaw
Published: February 2006

The use of repeated reversals of the flow direction offers significant improvements in the sensitivity of flow‐injection stripping voltammetric measurements. The multiple passage of the same sample plug over the working electrode addresses the time restriction of conventional flow‐injection stripping measurements. The plating efficiency and the resulting stripping peak currents are greatly enhanced. The flow‐reversal stripping response of a mercury‐coated carbon fiber electrode is evaluated with respect to delay time, number of flow reversals, sample volume, and other variables. The prolonged deposition period obtained with 10 flow oscillations gives a 13‐fold enhancement of the response and a detection limit of 7 × 10−9 M (compared with 9 × 10−8 M for conventional flow‐injection operation). The stripping measurements are supported by amperometric monitoring of the current during the passage of the sample plug.
Thermal stability and regeneration of plastic membrane ion‐selective electrodes
Authors: Shoukry A. F. , Badawy S. S. , Farghali R.
Published: February 2006

The effect of temperature changes on the potential response of hexadecylpyridinium (HDP) and cetyltri‐methylammonium (CTA) plastic‐membrane, cation‐selective electrodes was studied. These electrodes were found to be thermally stable up to 60 and 70°C, respectively. The isothermal temperature coefficients of the electrodes calculated from the standard electrode potentials at different temperatures were 0.00222 and 0.00097 V/°C. A method for regenerating such electrodes was applied successfully in case of the HDP electrodes.
Nafion‐coated carbon fiber electrodes for neurochemical studies in brain tissue
Authors: Capella Peter , Ghasemzadeh Behnam , Mitchell Kim , Adams Ralph N.
Published: February 2006

Extensive studies of the characteristics of electrochemically pretreated, Nafion‐coated carbon fibers used for in vivo electrochemistry are summarized. While electrochemical pretreatment provides high sensitivity for the monitoring of catecholamine neurotransmitters, it causes fibers to respond slowly. The ionomer film, which confers selectivity, adds relatively little to the electrode time constant. In terms of sensitivity and time constant changes, serious interactions occur during the course of the in vivo experiments while the electrodes are exposed to brain tissue. Fortunately, selectivity characteristics do not change during in vivo experiments. Postcalibration procedures and other measurement techniques that provide reliable experimental measurements are discussed.
Determination of microscopic electrode kinetics with electrogenerated chemiluminescence imaging
Authors: Pharr Christine M. , Engstrom Royce C. , Klancke James , Unzelman Patty L.
Published: February 2006

Light produced by the electrogenerated chemiluminescence reaction of luminol in alkaline peroxide was monitored with a sensitive imaging system. The light images were taken to represent the level of microscopically local activity on the electrode surface with a spatial resolution in the submicrometer domain. The temporal resolving capabilities of the imaging system permitted the construction of time‐sequenced images and intensity‐potential profiles, the latter being equivalent to a microscopically local voltammogram. Spatial variation in luminol oxidation kinetics were observed at porphyrin‐coated glassy carbon, carbon paste, and anodized glassy carbon electrodes. Implications for other composites and microelectrodes are discussed.
State‐of‐the‐art microelectrodes for in vivo voltammetry
Authors: Broderick Patricia A.
Published: February 2006

A comprehensive view of in vivo electrochemistry (voltammetry) is presented with a detailed evaluation of electrodes and waveforms. Special attention is given to specific kinds of electrode fabrication. The article is presented in an historical format to emphasize both the progression of the electrochemical technology and the inherent stability of the technique. Future prospects relevant to voltammetry are discussed, and 189 references are included.
Analytical and mechanistic aspects of the polarographic reduction of the herbicide pyrazon
Authors: Méndez J. Hernández , Martínez R. Carabias , Gonzalo E. Rodríguez
Published: February 2006

This article describes a study of the polarographic reduction of the herbicide pyrazon, which yields two polarographic reduction waves: one in acidic media and the other in alkaline media. Coulometric data indicate the exchange of two electrons per molecule, while infrared spectroscopic data reveal that the reduction process involves the azomethine (>CN) rather than the carbonyl group or the NN bond. A mechanism for the electrode reaction is postulated, and a pulse polarographic method for the quantitative determination of pyrazon is proposed. The detection limit achieved by differential pulse polarography in a 1.0 M sulfuric medium is 7 × 10−8 M (0.015 ppm).
A split‐disk, dual‐electrode amperometric cell and its application to the detection of biogenic amines with galvanostatic activation of the glassy carbon working electrodes
Authors: Mattusch Jürgen , Werner Gerhard , Štulík Karel , Pacáková Věra
Published: February 2006

A split‐disk, dual‐electrode amperometric cell was constructed and tested using biogenic amines as the model analytes. Advantages of the cell include a small working volume (less than 1.8 μL), favorable hydrodynamic conditions, and the fact that the system can be used in parallel‐adjacent and series arrangements with the same geometry. The collection efficiency on the downstream electrode in the series arrangement is high (around 38% for reversible electrode reactions) and is very close to the theoretical value. The differences in the collection efficiencies for electrode reactions with different degrees of reversibility can improve the selectivity of measurement and assist identification of the substances. Selectivity is greatly improved in the parallel‐adjacent arrangement where one electrode is activated by galvanostatic pretreatment while the other is only mechanically polished.
Electrochemical Detection of Abasic Site‐Containing DNA
Authors: Dolinnaya Nina G. , Jan Mohammad Rasul , Kawde Abdel‐Nasser , Oretskaya Tatiana S. , Tashlitsky Vadim N. , Wang Joseph
Published: February 2006

A simple and rapid approach for detecting apurinic (AP) sites in DNA, based on direct stripping chronopotentiometric measurements of the adenine and guanine nucleobases at a graphite electrode is described. Tetrahydrofuranyl residues, lacking a nucleobase moiety, were utilized for designing the AP sites and were incorporated in 19‐mer oligonucleotides. The change of adenine‐to‐guanine response ratio (A/G) in one‐, two‐ or three‐substituted adenosine residues for stable analogs of AP sites was exploited for electrochemical measurements of the adenine loss. The resulting A/G response ratio decreases linearly upon increasing the number of AP sites in the oligonucleotides; the values of A/G electrochemical signals were slightly enhanced when compared to the actual purine content. HPLC analysis of the released nucleobases confirmed that the sulfuric acid‐induced oligonucleotide cleavage provides complete apurination and dissolution of the released nucleobases in aqueous solution. Additional experiments with mixtures of free nucleobases and purine nucleosides reveal that the larger A/G ratio observed in the electrochemical analysis of AP‐site‐containing oligomers is attributed to the influence of the acid and/or thermal decomposition products (particularly the sugar fragments). This study represents the first step in developing a simple and direct electrochemical assay of AP sites in single‐stranded DNA.
Assessment of Joule heating and its effects on electroosmotic flow and electrophoretic transport of solutes in microfluidic channels
Authors: Tang Gongyue , Yan Deguang , Yang Chun , Gong Haiqing , Chai John Chee , Lam Yee Cheong
Published: February 2006

Joule heating is inevitable when an electric field is applied across a conducting medium. It would impose limitations on the performance of electrokinetic microfluidic devices. This article presents a 3‐D mathematical model for Joule heating and its effects on the EOF and electrophoretic transport of solutes in microfluidic channels. The governing equations were numerically solved using the finite‐volume method. Experiments were carried out to investigate the Joule heating associated phenomena and to verify the numerical models. A rhodamine B‐based thermometry technique was employed to measure the solution temperature distributions in microfluidic channels. The microparticle image velocimetry technique was used to measure the velocity profiles of EOF under the influence of Joule heating. The numerical solutions were compared with experimental results, and reasonable agreement was found. It is found that with the presence of Joule heating, the EOF velocity deviates from its normal “plug‐like” profile. The numerical simulations show that Joule heating not only accelerates the sample transport but also distorts the shape of the sample band.
A method for simultaneously determining the zeta potentials of the channel surface and the tracer particles using microparticle image velocimetry technique
Authors: Yan Deguang , Yang Chun , Nguyen Nam‐Trung , Huang Xiaoyang
Published: February 2006

The zeta potentials of channel surfaces and tracer particles are of importance to the design of electrokinetic microfluidic devices, the characterization of channel materials, and the quantification of the microparticle image velocimetry (microPIV) measurement of EOFs. A method is proposed to simultaneously measure the zeta potentials of the channel surface and the tracer particles in aqueous solutions using the microPIV technique. Through the measurement of the steady velocity distributions of the tracer particles in both open‐ and closed‐end rectangular microchannels under the same water chemistry condition, the electrophoretic velocity of the tracer particles and the EOF field of the microchannel are determined using the expressions derived in this study for the velocity distributions of charged tracer particles in the open‐ and closed‐end rectangular microchannels. Thus, the zeta potentials of the tracer particles and the channel surfaces are simultaneously obtained using the least‐square method to fit the microPIV measured velocity distribution of the tracer particles. Measurements were carried out with a microPIV system to determine the zeta potentials of the channel wall and the fluorescent tracer particles in deionized water and sodium chloride and boric acid solutions of various concentrations.
Oscillating electrolytes
Authors: Hruška Vlastimil , Jaroš Michal , Gaš Bohuslav
Published: February 2006

Chemical oscillations are driven by the gradient of the chemical potential so that they can appear in systems where the substances are not in chemical equilibrium. We show that under the influence of the electric field, concentrations of electrically charged substances in solutions can oscillate even if the system is in chemical equilibrium. The driving force here is not the gradient of the chemical potential but rather the gradient of the electric potential. Utilizing CE we found periodic structures invoked by the application of a constant driving voltage in BGEs possessing complex eigenmobilities. By analogy with the behavior of dynamic systems, complex eigenmobilities implicate that the system will be unstable. Instead of forming system zones (system peaks) in the separation channel (capillary) the originally uniform concentration of electrolyte constituents becomes periodically disturbed when the electric current passes through it.
Theoretical and nomenclatural considerations of capillary electrochromatography with monolithic stationary phases
Authors: Végvári Ákos , Guttman András
Published: February 2006

During the past decade, CEC has been one of the few novel achievements in the field of separation science attracting a wide interest. The technology progress permitted the realization of the long‐sought idea to employ an electroosmotically driven flow through the columns improving the separations in terms of both resolution and efficiency. The early practical obstacles related to the use of conventional bead‐packed columns have been solved by the introduction of continuous beds, also known as monoliths. Hitherto, various synthesis approaches have been successfully developed producing monolithic beds in situ in capillary columns, sharing similar physical structure built up of tiny particles (in the sub‐µm range) that are covalently linked together and to the capillary wall. Parallel with the practical column technology studies, the theory of electrochromatography has been continuously developed, focusing on such basic issues as EOF characterization, separation efficiency, and peak dispersion effects. This review provides a short introduction to the theory of CEC with special attention to monolithic separation beds. The paper also summarizes the latest achievements in CEC and discusses the nomenclature, EOF characteristics, and some specific advantages of monolithic column technology.
The historical evolution and basic concepts of social network analysis
Authors: Fredericks Kimberly A. , Durland Maryann M.
Published: February 2006

This chapter provides a brief history of the development of network analysis, an overview of the methodology, and an exploration of its key concepts.
Histochemical evidence of osteoclastic degradation of extracellular matrix in osteolytic metastasis originating from human lung small carcinoma (SBC‐5) cells
Authors: Li Minqi , Amizuka Norio , Takeuchi Kiichi , Freitas Paulo H.L. , Kawano Yoshiro , Hoshino Masaaki , Oda Kimimitsu , Nozawa‐Inoue Kayoko , Maeda Takeyasu
Published: February 2006

The aim of this study was to assess the dynamics of osteoclast migration and the degradation of unmineralized extracellular matrix in an osteolytic metastasis by examining a well‐standardized lung cancer metastasis model of nude mice. SBC‐5 human lung small carcinoma cells were injected into the left cardiac ventricle of 6‐week‐old BALB/c nu/nu mice under anesthesia. At 25–30 days after injection, the animals were sacrificed and their femora and/or tibiae were removed for histochemical analyses. Metastatic lesions were shown to occupy a considerable area extending from the metaphyses to the bone marrow region. Tartrate resistant acid phosphatase (TRAPase)‐positive osteoclasts were found in association with an alkaline phosphatase (ALPase)‐positive osteoblastic layer lining the bone surface, but could also be localized in the ALPase‐negative stromal tissues that border the tumor nodules. These stromal tissues were markedly positive for osteopontin, and contained a significant number of TRAPase‐positive osteoclasts expressing immunoreactivity for CD44. We thus speculated that, mediating its affinity for CD44, osteopontin may serve to facilitate osteoclastic migration after their formation associated with ALPase‐positive osteoblasts. We next examined the localization of cathepsin K and matrix metallo‐proteinase‐9 (MMP‐9) in osteoclasts. Osteoclasts adjacent to the bone surfaces were positive for both proteins, whereas those in the stromal tissues in the tumor nests showed only MMP‐9 immunoreactivity. Immunoelectron microscopy disclosed the presence of MMP‐9 in the Golgi apparatus and in vesicular structures at the baso‐lateral cytoplasmic region of the osteoclasts found in the stromal tissue. MMP‐9‐positive vesicular structures also contained fragmented extracellular materials. Thus, osteoclasts appear to either select an optimized function, namely secreting proteolytic enzymes from ruffled borders during bone resorption, or recognize the surrounding extracellular matrix by mediating osteopontin/CD44 interaction, and internalize the extracellular matrices. Microsc. Res. Tech. 69:73–83, 2006. © 2006 Wiley‐Liss, Inc.
Morphogenesis of the different types of photoreceptors of the chicken (Gallus domesticus) retina and the effect of amblyopia in neonatal chicken
Authors: Wai Maria Sen Mun , Lorke Dietrich Ernst , Kung Lai Sin , Yew David Tai Wai
Published: February 2006

Despite the great variety in chicken photoreceptors, existing morphogenetic studies only deal with two types: rods and cones. We have therefore examined by scanning electron microscopy the first appearance and maturation of different retinal photoreceptors in 36 chicken embryos (Gallus domesticus), aged 5–19 days prehatching. On day 5 of incubation, chicken retinae were only composed of proliferating ventricular cells devoid of photoreceptors. On day 8, outer mitotic cells were separated from inner differentiating photoreceptors, by the transient layer of Chievitz. Ball‐like protrusions appeared at the ventricular surface, representing the first signs of photoreceptor inner segment formation. From day 10 onward, double cones, single cones, and rods could be clearly distinguished, and occasional cilia were detected at their tip. On day 12, inner segments had increased in length and diameter, and frequently carried a cilium representing the beginning of outer segment formation. On day 14, most photoreceptors displayed a distinct outer segment. On day 19, photoreceptors had essentially assumed adult morphology. Based on the shape of their outer segments, two subtypes of cones and three subtypes of double cones could be distinguished. Throughout development, we observed microvilli close to maturing photoreceptors, either originating from their lateral sides, from their tip, or from Müller cells. Microvillus density peaked between day 12 and 14, indicating an important role in photoreceptor morphogenesis. Unilateral occlusion of the eyes of posthatching chicken reduced the proportion of double cones to single cones in the retina, indicating dependence of retinal morphogenesis upon functional activity of visual cells. Microsc. Res. Tech. 69:99–107, 2006. © 2006 Wiley‐Liss, Inc.
Low‐field compact magnetic resonance imaging system for the hand and wrist in rheumatoid arthritis
Authors: Yoshioka Hiroshi , Ito Satoshi , Handa Shinya , Tomiha Sadanori , Kose Katsumi , Haishi Tomoyuki , Tsutsumi Akito , Sumida Takayuki
Published: February 2006

Purpose

To investigate the feasibility of an originally developed compact MRI system for evaluating rheumatoid arthritis (RA), and determine its advantages and disadvantages as an imaging modality for evaluating RA.

Materials and Methods

We prospectively studied 13 healthy controls with no clinical symptoms of arthritis, and 13 patients with hand and wrist pains (including pain from RA) with a 0.2 T permanent‐magnet compact MR imager. All MR images were obtained while the subjects were in a sitting position. Coronal three‐dimensional spin‐echo T1‐weighted images and coronal two‐dimensional short tau inversion recovery (STIR) images were obtained with image matrix = 256 × 128 and field of view (FOV) = 20.48 cm. Plain radiograph findings and MRI findings of patients were compared.

Results

In three of the patients with suspected early RA (N= 7), early RA was evaluated based on STIR images. All RA patients showed morphologic or signal intensity changes that allowed an evaluation of RA from MR findings. Four of five RA patients showed high signal intensity on STIR images in the wrist, proximal interphalangeal (PIP) joint, or metacarpophalangeal (MCP) joint that suggested synovitis. Multiple erosions in the hand and wrist were seen in four RA patients, with low signal intensity on T1‐weighted images.

Conclusion

RA was correctly evaluated, and early RA could be identified with the compact MRI system. However, the current system has limitations, such as the nonselective STIR sequence used and magnetic field inhomogeneity. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
B0 homogeneity throughout the monkey brain is strongly improved in the sphinx position as compared to the supine position
Authors: Valette Julien , Guillermier Martine , Boumezbeur Fawzi , Poupon Cyril , Amadon Alexis , Hantraye Philippe , Lebon Vincent
Published: February 2006

Purpose

To map B0 distortions throughout the monkey brain in the two positions commonly used for NMR studies (the prone sphinx position and the supine position) in order to test the hypothesis that B0 homogeneity in the sphinx position is significantly improved as compared to the supine position.

Materials and Methods

Three macaque monkeys were installed in the two positions in a 3T whole‐body MR system without shim correction. B0 maps were acquired using a 3D gradient double‐echo sequence, and field dispersion throughout the brain was quantified. In addition, field maps and localized 1H spectra were acquired after first‐order shimming was performed.

Results

The field maps collected in the three animals were highly reproducible. B0 dispersion throughout the brain was typically two to three times greater in the supine position than in the sphinx position. Although first‐order shimming proved relatively more efficient in the supine position, B0 dispersion still remained greater in the supine than in the sphinx position. These findings can be explained by the thickness of outer brain tissues.

Conclusion

This work demonstrates that the sphinx position is highly favorable in terms of B0 homogeneity. It should prove useful for NMR exploration of the monkey brain, particularly at high fields where B0 inhomogeneity associated with susceptibility artifacts is increased. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Calcium‐dependent volume reduction in regenerating ganglion cell axons in vitro
Authors: Edmonds B. T. , Koenig E.
Published: February 2006

The effects of increasing [Ca2+]i on volume regulatory behavior was investigated by phase‐contrast videomicroscopy in immature axons regenerating from goldfish retinal explants in vitro. Elevating [Ca2+]i by using EGTA‐buffered, ionomycin‐containing bathing media with either ≥ 100 μM [Ca2+]o or 1 μM [Ca2+]o with N‐methylglucamine substituted for Na+ caused axons to undergo a “syneresis.” The syneresis was characterized by a marked loss in volume and condensation of axoplasm, accompanied by a proliferation of lateral processes, which resulted ultimately in an arrest of visible particle transport. The random appearance of dynamic phase‐lucent axial protrusions in the distal axon, apparently caused by microtubules, was a frequent early manifestation. Syneresis was also produced by increasing the tonicity of the Cortland saline with sorbitol or treating axons with either valinomycin or with permeant cyclic AMP analogs in normal Cortland saline. In the latter case, extracellular Ca2+ was required. Preterminal axons showed an increase in phalloidin fluorescence after syneresis, suggesting polymerization and/or rearrangement of the actin cytoskeleton. Digitonin‐permeabilized axonal field models, which maintained good morphology and particle transport, failed to develop a syneresis even when [Ca2+]o was increased to 250 μM. Cytochalasin D did not interfere with the development of a syneresis, but did suppress the proliferation of lateral processes. Syneresis could be blocked by high [K+]o, putative antagonists of Ca2+‐activated K+ channels, or by calmidazolium, a calmodulin antagonist. The experimental findings suggest that cytoskeletal changes associated with volume reduction in growing retinal ganglion cell axons are secondary to a loss of cell water and that calcium/ calmodulin‐activated K+ channels very likely play a primary role in dehydration through the loss of K+ and osmotically obligated water.
Changes with aging in the levels of amino acids in rat CNS structural elements: III. Large neutral amino acids
Authors: Banay‐Schwartz M. , Lajtha A. , Palkovits M.
Published: February 2006

This paper reports the concentrations of valine, leucine, isoleucine, phenylalanine, and tyrosine as determined in 53 discrete brain areas of 3‐ and 29‐month‐old male Fischer 344 rats microdissected by the punch technique. The levels of other amino acids in the same areas are reported in other papers of this series. The essential amino acids reported in this paper showed great regional heterogeneity, with concentrations in areas of the highest content being 9 to 12 times higher than levels in areas of the lowest content. The relative distributions of these amino acids were fairly similar in that in a number of areas the amino acids were all at very high levels and in some other areas they were all at low levels, with a few exceptions. With aging, levels of some amino acids increased and levels of some others did not change, but the predominant change was a significant decrease in levels with age. The results indicate high regional heterogeneity in amino acid levels and in the changes of these levels with age.
Three‐dimensional structure of western Mediterranean cyclones
Authors: Campins Joan , Jansà Agustí , Genovés Ana
Published: February 2006

As many studies reveal, the western Mediterranean exhibits a high frequency of cyclone centres. Most of them are small and weak, but in some cases they are related to heavy rain and/or strong wind events. The climatological study of Mediterranean cyclones is the first crucial step to the better understanding and forecasting of such events.

In the present paper, a method to objectively detect and track mean sea‐level (MSL) cyclones for the western Mediterranean is described. Furthermore, the three‐dimensional characterization of each MSL cyclone is performed by means of several parameters. This includes the vorticity, thermal and humidity fields at different pressure levels where the cyclone is detected, as well as the wind speed profile and the moist stability over the MSL cyclone. Both methodologies are illustrated and validated by a real case: an intense event of the well‐known Genoa cyclone. Detection, tracking and three‐dimensional characterization are applied to an 8‐year (from June 1995 to May 2003) database of numerical analyses. The result is a MSL cyclone database for the western Mediterranean with a description of their three‐dimensional structure. For a better analysis, cyclones are grouped in three different ways: by thickness, season and region of detection. Results show that western Mediterranean cyclones are located in specific geographical regions and that their location depends on the season. Several cyclones are weak and shallow, mainly because of thermal and/or orographic causes. On the contrary, other cyclones are large and intense and extend throughout the whole troposphere. Differences in cyclone structure depending on the location and season are also discussed. Copyright © 2006 Royal Meteorological Society.
Europe's 2003 heat wave: a satellite view of impacts and land–atmosphere feedbacks
Authors: Zaitchik Benjamin F. , Macalady Alison K. , Bonneau Laurent R. , Smith Ronald B.
Published: February 2006

A combination of satellite imagery, meteorological station data, and the NCEP/NCAR reanalysis has been used to explore the spatial and temporal evolution of the 2003 heat wave in France, with focus on understanding the impacts and feedbacks at the land surface. Vegetation was severely affected across the study area, especially in a swath across central France that corresponds to the Western European Broadleaf (WEB) Forests ecological zone. The remotely sensed surface temperature anomaly was also greatest in this zone, peaking at +15.4 °C in August. On a finer spatial scale, both the vegetation and surface temperature anomalies were greater for crops and pastures than for forested lands. The heat wave was also associated with an anomalous surface forcing of air temperature. Relative to other years in record, satellite‐derived estimates of surface‐sensible heat flux indicate an enhancement of 48–61% (24.0–30.5 W m−2) in WEB during the August heat wave maximum. Longwave radiative heating of the planetary boundary layer (PBL) was enhanced by 10.5 W m−2 in WEB for the same period. The magnitude and spatial structure of this local heating is consistent with models of the late twenty‐first century climate in France, which predict a transitional climate zone that will become increasingly affected by summertime drought. Models of future climate also suggest that a soil‐moisture feedback on the surface energy balance might exacerbate summertime drought, and these proposed feedback mechanisms were tested using satellite‐derived heat budgets. Copyright © 2006 Royal Meteorological Society.