bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modified micellar electrokinetic chromatography in the analysis of catechins and xanthines in chocolate
Authors: Gotti Roberto , Fiori Jessica , Mancini Francesca , Cavrini Vanni 
Published: October 2004

AbstractModified micellar electrokinetic chromatography (MEKC) analysis of monomeric flavanols (catechin and epicatechin) and methylxanthines (caffeine and theobromine) in chocolate and cocoa was performed by using sodium dodecyl sulfate (SDS) as a principal component of the running buffer. Because of the reported poor stability of catechins in alkaline solutions, acidic conditions (pH 2.5) were chosen and consequently the electroosmotic flow (EOF) was significantly suppressed; this resulted in a fast anodic migration of the analytes partitioned into the SDS micelles. Under these conditions, variations of either pH value in acidic range or SDS concentration, showed to be not suitable to modulate the selectivity. To overcome this limit, use of additives to the SDS‐based running buffer was successfully applied and three different systems were optimized for the separation of (+)‐catechin, (−)‐epicatechin, caffeine, and theobromine in chocolate and cocoa powder samples. In particular, two mixed micelle systems were applied; the first consisted of a mixture of SDS and 3‐[(3‐cholamidopropyl)dimethylammonio]‐1‐propansulfonate (CHAPS) with a composition of 90 mM and 10 mM, respectively; the second was SDS and taurodeoxycholic acid sodium salt (TDC) with a composition of 70 mM and 30 mM, respectively. A further MEKC approach was developed by addition of 10 mM hydroxypropyl‐β‐cyclodextrin (HP‐β‐CD) to the SDS solution (90 mM); it provided a useful cyclodextrin(CD)‐modified MEKC. By applying the optimized conditions, different separation profiles of the flavanols and methylxanthines were obtained showing interesting potential of these combined systems; their integrated application showed to be useful for the identification of the low level of (+)‐catechin in certain real samples. The CD‐MEKC approach was validated and applied to the determination of catechins and methylxanthines in aqueous extracts from four different commercial chocolate types (black and milk) and two cocoa powders.
Pyrimidine 5'‐nucleotidase activities detected in real samples by means of micellar electrokinetic chromatography
Authors: Zanone Chiara , Chiarelli Laurent R. , Valentini Giovanna , Perani Eleonora , Annovazzi Laura , Viglio Simona , Iadarola Paolo 
Published: October 2004

AbstractA micellar electrokinetic chromatographic method that allows simultaneous determination of both nucleotidase and transferase activities of cytosolic 5'‐nucleotidase III is presented. This electrophoretic approach was successfully applied to human erythrocyte lysates to monitor the enzyme activities indicated above, using either physiological substrate or the nucleoside analogue 3'‐azido‐3'‐deoxythymidine as the phosphate acceptor.
Capillary electrophoresis studies on the aggregation process of β‐amyloid 1‐42 and 1‐40 peptides
Authors: Sabella Stefania , Quaglia Milena , Lanni Cristina , Racchi Marco , Govoni Stefano , Caccialanza Gabriele , Calligaro Alberto , Bellotti Vittorio , De Lorenzi Ersilia 
Published: October 2004

AbstractThe possibility to monitor, in solution, the steps of β‐amyloid (Aβ) nucleation and therefore to describe this dynamic process by using capillary electrophoresis and under optimized experimental conditions is described. Striking differences in the electrophoretic patterns of Aβ 1‐42 and Aβ 1‐40 over time are here shown, and different aggregation states are elucidated, which reflect the very diverse oligomerization behavior of two very similar peptides. The isolation of one aggregated species of high molecular weight by ultracentrifugation allowed us to assess its role as toxic oligomer. The perturbation of the existing equilibrium among the identified species by the addition of small molecules can in principle interfere with the aggregation process of the peptides and ultimately prevent the plaque formation in vitro.
Microscale fractionation facilitates detection of differentially expressed proteins in Alzheimer's disease brain samples (vol. 25, Issue 15, pp. 2557‐2563)
Authors: Lopez Mary F. , Mikulskis Alvydas , Golenko Eva , Melov Simon , Bennett David , Cherkasskiy Alex , Kuzdzal Scott , Kramer Susan , Sissors Dan 
Published: October 2004

AbstractSee original http://dx.doi.org/10.1002/elps.200406011
Synthesis of Optically Active Diols by Escherichia coli Transformant Cells that Express the Glycerol Dehydrogenase Gene of Hansenula polymorphaDL‐1
Authors: Yamada‐Onodera K. , Kawahara N. , Tani Y. , Yamamoto H. 
Published: October 2004

AbstractChiral alcohols are useful as intermediates for the synthesis of drugs. In the production of chiral alcohols, microbial enzymes are promising since high optical purity is required. Under these conditions, the reaction by resting cells is more convenient and inexpensive than by an enzyme reaction. Chiral 1,2‐propanediol and 2,3‐butanediol were obtained using cells expressing the enzyme which demonstrated high stereospecificity. By means of recombinant cells expressing the glycerol dehydrogenase of Hansenula polymorpha DL‐1, the medium was enriched with (S)‐1,2‐propanediol (98 % enantiometric excess, e.e.) during a 24‐h incubation, whereas the (R)‐form was removed from 100 mM of the racemate (R:S = 1:1). For an asymmetric reduction, a recombinant was constructed which also expressed the glucose dehydrogenase gene of Bacillus subtilis origin as an NADH reproducer. In the resting cell reaction, the pH control at 7.5 promoted the conversion from ketone to alcohol. (2R,3R)‐2,3‐butanediol (e.e. > 99.9 %; 308 mM) was produced from 800 mM acetoin (R:S = 3:4); (R)‐1,2‐propanediol (e.e. > 99.9 %; 550 mM) from 800 mM acetol in a 33‐h incubation by the addition of glucose and ketone with pH control. In this reaction, (S)‐forms of both 2,3‐butanediol and 1,2‐propanediol were not produced. The pH control and feeding of the substrates were uncomplicated. The production process of the chiral alcohol by the recombinants which expresses glycerol dehydrogenase proved convenient.
Development of Bifidobacterium lactis Bb 12 on β‐(2,6)‐Linked Fructan‐Containing Substrate
Authors: Semjonovs S.P. , Marauska M. , Linde R. , Grube M. , Zikmanis P. , Bekers M. 
Published: October 2004

Abstractβ‐(2,1)‐linked fructan of plant origin (inulin) and the related oligosaccharides (FOS) as non‐digestible carbohydrates, i.e., potent prebiotics, can stimulate the growth of various probiotic lactic acid bacteria, including a number of bifidobacteria strains. The related β‐(2,6)‐linked fructans of microbial origin (levan and FOS), however, have scarcely been investigated in this respect. Therefore, the bifidogenic properties of various fructans, i.e., inulin, levan, fructooligosaccharides (FOS) and fructan syrup (FS), were tested as glucose substitutes in MRS media and were compared concerning their effect on the commercial strain Bifidobacterium lactis Bb 12. Although glucose was the preferred substrate for growth and biomass formation, FS exhibited a comparable cell growth (8.4 × 107 counts/mL and 1.0 × 107 counts/mL, respectively) and acidification power (84 °T and 74 °T, respectively) during 48 h of fermentation, as well as an increase in lactic acid and decrease in acetic acid formation. Bifidobacterium lactis Bb 12 did not utilize inulin as a sole carbon source as judged from the 60 % decrease in cell count and the insignificant (0.1 pH unit) acidification of the growth medium, whereas levan provided a noticeable increase in cell count and acidification (0.4 pH units) during 48 h of fermentation. FOS preparation appeared to be a satisfactory carbon source for this strain, but lower acidification power (56 °T) and cell counts were observed as compared to glucose‐ or FOS‐containing media (2.6 % and 22 %, respectively). The products obtained under conditions of mild lactic acid hydrolysis of levan (37 °C, pH 3.3, 24 h) enhanced the cell count (7–10 %) and acidification power (by a factor of 2.7) of Bifidobacterium lactis Bb 12.
Gene Cloning of Dihydroxyacetone Reductase from a Methylotrophic Yeast, Hansenula ofunaensis, and its Expression in Escherichia coli HB101 for Production of Optically Active 2‐Pentanol
Authors: Yamada‐Onodera K. , Nariai H. , Tani Y. , Yamamoto H. 
Published: October 2004

AbstractOptically active alcohols are important building blocks as versatile chiral synthons for asymmetric syntheses of pharmaceuticals and agrochemicals. The aim of this paper is to efficiently prepare chiral 2‐pentanol by means of microorganisms. The gene of dihydroxyacetone reductase (EC 1.1.1.6) from a methylotrophic yeast, Hansenula ofunaensis, was cloned and chiral 2‐pentanol was produced by the recombinant Escherichia coli harboring the gene. The gene encoding the enzyme was cloned from an H. ofunaensis genomic library. In the deduced amino acid sequence of 364 residues, the NAD(H) binding motif and the cysteine residues that correspond to the cysteine ligands in the zinc atom were conserved, as they are in alcohol dehydrogenases from other origins. Dihydroxyacetone reductase was similar to alcohol dehydrogenases of prokaryotes. For the production of chiral compounds, an E. coli HB101 strain was transformed. The H. ofunaensis gene product, dihydroxyacetone reductase, catalyzed the NAD+‐dependent oxidation of 2‐pentanol to 2‐pentanone as well as the corresponding reverse reactions, showing specificity towards the secondary alcohol in (R)‐configuration. From 100 mM 2‐pentanone, (R)‐2‐pentanol (98 mM, > 99.9 % enantiometric excess, e.e.) was obtained in a 30‐min reaction with resting cells of the E. coli HB101 strain harboring the expression plasmid, pSG‐HOD1, which possesses the genes of both dihydroxyacetone reductase and glucose dehydrogenase as an NADH reproducing system. The stereospecificity changed during the reduction, depending on the pH. E. coli HB101 was also transformed by the expression plasmid, pSE‐HOD4, in which the gene of glucose dehydrogenase was removed from pSG‐HOD1, and designated as E. coli HB101 (pSE‐HOD4). E. coli HB101 (pSE‐HOD4) oxidized only (R)‐2‐pentanol in 100 mM of the racemate (R:S = 52:48), and the reaction medium was enriched with (S)‐2‐pentanol (48 mM, 98 % e.e.) after 30 min of incubation. The reaction was sufficiently promoted without the other additives. E. coli transformants expressing the gene of this enzyme could be particularly advantageous to the production of optically active 2‐pentanol.
Analysis of streptonigrin‐induced incomplete chromosome elements and interstitial fragments in Chinese hamster cells using a telomeric PNA probe
Authors: Bolzán Alejandro D. , Bianchi Martha S. 
Published: October 2004

AbstractWe investigated the induction of incomplete chromosome elements (ICEs; i.e., elements with a telomeric signal at only one terminal end) and interstitial fragments induced by the antibiotic streptonigrin (SN) in a Chinese hamster embryo (CHE) cell line using FISH with a telomeric peptide nucleic acid probe. CHE cells were treated with 0–250 ng/ml SN and chromosomal aberrations were analyzed in the first mitosis after treatment using the telomeric probe. Exposure of CHE cells to SN resulted in a linear concentration‐related increase in all of the aberration types analyzed (P < 0.05) except ring chromosomes. Depending on the SN concentration employed, 33–68% of the metaphases contained one or more pairs of ICEs (an incomplete chromosome accompanied by a terminal fragment or two incomplete chromosomes accompanied by a compound fragment). Pooled data from all SN concentrations revealed that 77.8% of the acentric fragments were terminal fragments, 18.8% interstitial fragments, and 3.4% compound fragments. Furthermore, it was estimated that about 80% of excess acentric fragments induced by SN originated from incomplete exchanges or terminal deletions and 20% from complete exchanges (interstitial deletions). These results show that incomplete chromosomes and terminal fragments are the most frequent asymmetrical chromosomal aberrations induced by SN and indicate that true incompleteness is a very common event following exposure to SN. Environ. Mol. Mutagen. 44:277–282, 2004. © 2004 Wiley‐Liss, Inc.
The MMA1 gene family of cancer‐testis antigens has multiple alternative splice variants: Characterization of their expression profile, the genomic organization, and transcript properties
Authors: de Wit Nicole J. W. , Cornelissen Ine M. H. A. , Diepstra J. Heleen S. , Weidle Ulrich H. , Ruiter Dirk J. , van Muijen Goos N. P. 
Published: October 2004

AbstractPreviously, we reported the identification of MMA1A by screening for differential gene expression in two human melanoma cell lines displaying diverse metastatic behavior after subcutaneous inoculation into nude mice. Splice variant MMA1B, which also was identified through database homology searches, showed a high degree of similarity with the MMA1A for exons 1, 2, and 4, but was missing exon 3. Through extensive expression profiling among normal and tumor samples, both MMA1A and ‐1B were found to belong to the family of cancer‐testis antigens. In this study, we identified four additional alternatively spliced MMA1 variants, named MMA1C, MMA1D, MMA1E, and MMA1F. Generally, these novel MMA1 transcripts differ from MMA1A in that exon 2 or exon 3 is enlarged because of the use of alternative splice sites in intron 2 of the MMA1 gene. Moreover, MMA1E also lacks exon 3, as was previously seen in MMA1B. In screening for expression of the novel MMA1 transcripts in normal and tumor tissues, we demonstrated that MMA1C, ‐1D, and ‐1E also are members of the cancer‐testis antigen family. MMA1F was found in only one melanoma metastasis sample and therefore is believed to have been expressed incidentally. Furthermore, we comprehensively elucidated the genomic structure of the MMA1 gene and the characteristic features of the alternatively spliced MMA1 transcripts. © 2004 Wiley‐Liss, Inc.
Number of oligodendrocyte progenitors recruited to the lesioned spinal cord is modulated by the levels of the cell cycle regulatory protein p27Kip‐1
Authors: Crockett David P. , Burshteyn Mark , Garcia Corina , Muggironi Michela , Casaccia‐Bonnefil Patrizia 
Published: October 2004

AbstractRemyelination is a critical step for recovery of function after demyelination and defines the ability to generate new myelin. This repair process is dependent on the presence of resident oligodendrocyte progenitors (OLPs) that have been shown to remyelinate axons after demyelination. We have previously shown that the levels of the cell cycle inhibitor p27Kip‐1 modulate the number of neonatal cortical OLPs. We now asked whether this cell cycle molecule plays also a role in regulating the number of adult OLP in the spinal cord after demyelination induced by lysolecithin injection. The proliferative response of OLP in the spinal cord of injected wild‐type (wt) and p27Kip‐1 null mice was evaluated 3 days after lesion. In vivo labeling with bromodeoxyuridine (BrdU) was used to identify cells in S phase. Double immunofluorescence for the OLP marker NG2, and for BrdU was used to count the number of proliferating progenitors. Consistent with a role of p27Kip‐1 in regulating the number of adult OLP in the injured spinal cord, a larger number of proliferating OLPs was observed in p27Kip‐1null mice compared with wild‐type controls. These cells were able to differentiate as assessed by the presence of MBP+ cells in the spinal cord 14 days after injury. We conclude that the cellular levels of the cell cycle inhibitor p27Kip‐1 modulate the repair response of OLPs to injury in the adult spinal cord. © 2004 Wiley‐Liss, Inc.
High‐voltage‐activated calcium channels in Müller cells acutely isolated from tiger salamander retina
Authors: Welch Nicole C. , Wood Stephanie , Jollimore Christine , Stevens Kelly , Kelly Melanie E.M. , Barnes Steven 
Published: October 2004

AbstractMüller cells mediate retinal function by stabilizing the ionic environment and signal glial network activity via calcium waves. Using whole‐cell patch clamp recording, we describe a high‐voltage‐activated, slowly inactivating Ca channel current in isolated salamander Müller cells that has unusual pharmacological properties. The Ca channel current has an activation midpoint of ∼−8 mV and an inactivation midpoint of ∼−26 mV in 10 mM Ba2+. The time constant for inactivation is ∼380 ms at potentials positive to zero. The current is blocked by Cd2+ with an EC50 of <100 nM. nisoldipine (10 μM) blocks ∼50%, while nifedipine (1 μM), diltiazem (20 μM), and verapamil (50 μM) each block one‐third of the current. In contrast to its typical actions, BayK 8644 blocks the current by ∼ 25%. Blockers of other Ca channel subtypes were also tested: ω‐agatoxin IVA (200 nM) blocked only 13% of the Ca channel current, while ω‐conotoxin GVIA (1 μM) blocked 84% of the current. Immnohistochemistry supported the presence of α1A, α1B, α1C, and α1D Ca channel subunits. Mapping of dihydropyridine‐binding sites with DM‐BODIPY revealed a distribution of channels over the entire membrane of the Müller cell with a higher density at the apical region. Overall, these observations suggest either the presence of a mix of L‐ and N‐type Ca channels or a single, unconventional HVA Ca channel subtype sharing L‐ and N‐type Ca channel characteristics. © 2004 Wiley‐Liss, Inc.
Boiling heat transfer in a narrow space controlled by punched interference plate
Authors: Shimada Ryohachi , Izumi Masaaki , Kumagai Satoshi , Adachi Takeshi 
Published: October 2004

AbstractAn experiment on pool boiling in methanol was performed for a case in which the boiling space was controlled by an interference plate with many holes. The narrow space, 0.12 mm in thickness, between the heat transfer surface and the interference plate was hermetically sealed at the perimeter. Therefore, the vapor and liquid were only exchanged through the holes in the interference plate. The degree of superheat at the onset of boiling was 0.7 K without overshoot at 10‐mm plate thickness, 1‐mm hole diameter, and 3.85‐mm hole pitch. The critical heat flux obtained was the same value without the interference plate mentioned above. The interference plate disturbed free convection and a superheat layer was provided under small heat flux on the heat transfer surface. The critical bubble diameter for the onset of boiling was decreased as the temperature of the superheat layer was increased. Thus, the degree of superheat at the onset of boiling was decreased. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(7): 462–471, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20028
A simplified model of gas–liquid two‐phase flow pattern transition
Authors: Ito Koji , Inoue Mitsuru , Ozawa Mamoru , Shoji Masahiro 
Published: October 2004

AbstractAn experiment of upward gas–liquid two‐phase flow was conducted in an air–water isothermal system under atmospheric pressure. The differential pressure was measured at the fully developed section by using a variable reluctance type transducer to classify the flow patterns and their transitions. The flow behavior was observed with a high‐speed video camera. The probability density function (PDF) of the differential pressure signal was employed to identify the flow pattern. A simplified one‐dimensional flow model was proposed to clarify dominant factors affecting the formation and transitions of flow patterns. The model dealt with the gas‐component advection based on the spatiotemporal void fraction behaviors by considering the gas compressibility, the wake, and the liquid phase redistribution mechanism. The simulation results of the model indicated four kinds of the void wave patterns (ripple‐like, rectangular, distorted rectangular, and uniform wave patterns) depending on gas and liquid volumetric fluxes. These void wave patterns corresponded well to the experimentally observed flow patterns. The transitions among void wave patterns agree well with the Mishima–Ishii flow pattern map. The friction loss estimated by the present model coincides fairly well with Chisholm's empirical formula. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(7): 445–461, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20029
The heat transfer and pressure drop characteristics of finned tube banks in forced convection (comparison of the pressure drop characteristics of spiral fins and serrated fins)
Authors: Kawaguchi Kiyoshi , Okui Kenichi , Kashi Takaharu 
Published: October 2004

AbstractIn recent years there has been a growing need for reduction of energy consumption in an effort to solve problems of global warming and the shortage of petroleum resources. For example, in the power generation field, thermal power generation now occupies 60% of the power generation demand, and the need for improved thermal efficiency is thus considerable. In this paper, the pressure drop characteristics of the finned tube banks used for the heat exchanger in thermal power generation were clarified by testing the serrated finned tube banks for improvement of higher heat transfer and the conventional spiral finned tube banks under the same test conditions, and equations for predicting the pressure drop coefficient which is necessary to design the heat exchanger were proposed. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(7): 431–444, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20030
Cytokine secretion from mononuclear cells cultured in vitro with starch‐based polymers and poly‐L‐lactide
Authors: Marques Alexandra P. , Reis Rui L. , Hunt John A. 
Published: October 2004

AbstractThe cytokine network is one of the major controlling systems of the inflammatory process, driving the magnitude and duration of the host response against invading microorganisms, foreign materials, or altered internal stimuli. Pro‐ and antiinflammatory cytokines were quantified after in vitro culture of a mixed population of monocytes/macrophages and lymphocytes with biodegradable polymers. Different blends of starch‐based polymers and their composites filled with hydroxyapatite were studied and compared with poly‐L‐lactide. Interleukin (IL)‐1β, IL‐6, and tumour necrosis factor‐α were investigated as the markers of immunological reactivity because they are known to act at the early stages of injury/invasion. Interferon‐γ, recognized as a proinflammatory cytokine, although not present during early responses was also investigated. Contrarily, IL‐4 derived from T lymphocytes, was investigated because it is an immunoregulator that counteracts some aspects of inflammation. T lymphocyte activation was also determined by quantifying IL‐2. The results support the hypothesis that different biodegradable polymers can affect mononuclear cell activation and the production of several cytokines associated with the inflammatory process. No IL‐2 or interferon‐γ was found in the culture supernatants after 3, 7, and 14 days in the presence of any of the materials. IL‐6 was detected in the highest amounts, for all the conditions, followed by tumour necrosis factor‐α. IL‐1β was produced in very low amounts, being undetectable with some of the starch‐based materials. IL‐4 was the only cytokine that did not demonstrate any significant difference within this group of materials. Starch‐based polymers and composites induced lower production of proinflammatory cytokines in comparison to poly‐L‐lactide. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 71A: 419–429, 2004