bluuebunny/crossref_metadata_2025_split huggingface dataset:
Capillary electrochromatography with monolithic silica column: I. Preparation of silica monoliths having surface‐bound octadecyl moieties and their chromatographic characterization and applications to the separation of neutral and charged species
Authors: Allen Darin , El Rassi Ziad 
Published: February 2003

AbstractMonolithic silica columns with surface‐bound octadecyl (C18) moieties have been prepared by a sol‐gel process in 100 μm ID fused‐silica capillaries for reversed‐phase capillary electrochromatography of neutral and charged species. The reaction conditions for the preparation of the C18‐silica monoliths were optimized for maximum surface coverage with octadecyl moieties in order to maximize retention and selectivity toward neutral and charged solutes with a sufficiently strong electroosmotic flow (> 2 mm/s) to yield rapid analysis time. Furthermore, the effect of the pore‐tailoring process on the silica monoliths was performed over a wide range of treatment time with 0.010 M ammonium hydroxide solution in order to determine the optimum time and conditions that yield mesopores of narrow pore size distribution that result in high separation efficiency. Under optimum column fabrication conditions and optimum mobile phase composition and flow velocity, the average separation efficiency reached 160 000 plates/m, a value comparable to that obtained on columns packed with 3 μm C18‐silica particles with the advantages of high permeability and virtually no bubble formation. The optimized monolithic C18‐silica columns were evaluated for their retention properties toward neutral and charged analytes over a wide range of mobile phase compositions. A series of dimensionless retention parameters were evaluated and correlated to solute polarity and electromigration property. A dimensionless mobility modulus was introduced to describe charged solute migration and interaction behavior with the monolithic C18‐silica in a counterflow regime during capillary electrochromatography (CEC )separations. The mobility moduli correlated well with the solute hydrophobic character and its charge‐to‐mass ratio.
An exactly solvable Ogston model of gel electrophoresis: X. Application to high‐field separation techniques
Authors: Gauthier Michel G. , Slater Gary W. 
Published: February 2003

AbstractRecently, we generalized our lattice model of gel electrophoresis to study the net velocity of particles being pulled by a high‐intensity electric field through an arbitrary distribution of immobile obstacles (Gauthier, M. G., Slater, G. W., J. Chem. Phys. 2002, 117, 6745–6756). In this article, we show how the high‐field version of our model can be used to compare the velocity of particles with different electric charges and/or physical sizes. We then investigate specific two‐dimensional distributions of obstacles that can be used to separate particles, e.g., in a microfluidic device. More precisely, we compare the velocity of differently charged or sized analytes in sieving, trapping and deflecting systems to model various electrophoretic separation techniques. In particular, we study the nonlinear effects present in ratchet systems and how they can be combined with time‐asymmetric pulsed fields to provide new modes of separation.
Integrated on‐capillary instrumentation for gene expression measurement directly from cells
Authors: Matsunaga Hiroko , Anazawa Takashi , Yeung Edward S. 
Published: February 2003

AbstractWe studied the fundamental instrumental issues relevant to a capillary‐based integrated system to measure expression of a specific gene directly from cells. Samples were introduced into a capillary by use of a syringe pump. All reactions were carried out in a microthermocycler, where a part of the capillary having 1 μL inner volume was used as a reaction vessel. First, cells were lysed by heating to release RNA, followed by deoxyribonuclease (DNase) treatment. Then, reverse transcription‐polymerase chain reaction (RT‐PCR) was performed to obtain amplified products from the targeted mRNA. Finally, the product was verified by capillary electrophoresis (CE) with laser‐induced fluorescence detection. The whole protocol was completed in the system in 3 h. PCR product from β‐actin mRNA in 16 human lymphoblast cells was obtained with a signal‐to‐noise ratio (S/N) of 3400 ± 730 (n = 3). Therefore, the system is reproducible and sensitive enough to measure gene expression from a single cell. We show that the amplified fragment from breast cancer‐specific mRNA was obtained from cells of breast cancer cell line, but was not obtained from cells of hepatoma cell line. These results therefore lay the foundations for future CE or microchip instrumentation for high‐throughput automated gene‐expression analysis.
Product Design in Food Industry Using the Example of Emulsification
Authors: Schuchmann H.P. , Schubert H. 
Published: February 2003

AbstractDesigning a product according to the consumers’ needs is one of the key targets in food industry. Having once defined the target product properties, it is of imperative importance to know which microstructure of the product is required (property function) and how the target microstructure can then be determined by process parameters (process function). Many food products are emulsions, either during production and/or in the moment of distribution and consumption. This review intends to depict the design of emulsions according to target needs. Even if we concentrate on typical food emulsions as an example, the concept can be widely applied, since emulsification in other branches of industry is governed by the same principles.
Hydrothermal Oxidation of Oily Wastes: an Alternative to Conventional Treatment Methods
Authors: Portela J.R. , Sanchez‐Oneto J. , López J. , Nebot E. , Martínez de la Ossa E. 
Published: February 2003

AbstractUnder current legislations most oils used are considered hazardous wastes and its safe collection and disposal must be ensured. Since conventional treatment methods are often inefficient or environmentally unacceptable, the development and application of new technologies is highly necessary. Wet Air Oxidation (WAO) and Supercritical Water Oxidation (SCWO) are two forms of hydrothermal oxidation that have been proved to be effective processes to treat a wide variety of industrial wastes, but they have hardly been tested for oily wastes. In this work, the suitability of hydrothermal oxidation to the treatment of oily wastewaters is described by the results obtained with three different substrates: free fatty acids, cutting oils and bilge wastes. The efficiency of the treatment process is demonstrated for the three oily wastes tested. At temperatures below 350 °C and reaction times of 40 minutes, a 70‐‐90 % of COD elimination is achieved, obtaining an effluent with low molecular weight compounds, mainly carboxylic acids. At 500 °C, a 99 % of COD removal is achieved in less than one minute. At this temperature the reaction seems to proceed mainly through total mineralization to carbon dioxide and water.
The Ozonolysis of Longifolene: A Tool for the Preparation of Useful Chiral Compounds. Configuration Determination of New Stereogenic Centers by NMR Spectroscopy and X‐Ray Crystallography
Authors: Dimitrov Vladimir , Hopp Rentsch Gudrun , Linden Anthony , Hesse Manfred 
Published: February 2003

AbstractThe ozonolysis of (+)‐longifolene (1) in different solvents (Et2O, CH2Cl2, CHCl3, acetone) at −80° provided quantitatively longifolene epoxide (3) as a single diastereoisomer in which the O‐atom is endo‐positioned (Scheme 2). Upon warming to room temperature, the epoxide remained stable only in acetone and was isolated as a low‐melting crystalline compound. In CH2Cl2, Et2O, or CHCl3 solution, epoxide 3 rapidly rearranged to the isomeric enols 4 and 5, which underwent further rearrangement to give the exo‐aldehyde 6. On standing for several weeks in CH2Cl2 solution, or in CHCl3 and Et2O as well, at room temperature, aldehyde 6 slowly rearranged into its epimer 7. The aldehydes 6 and 7 were isolated on the preparative scale for further synthetic use. The addition of methylmagnesium iodide to 6 and 7 provided the corresponding alcohols 13/14 and 15/16, respectively, which were isolated as pure diastereoisomers (Scheme 4). The configurations of the new chiral centers in 13–16 were determined by NMR methods and X‐ray crystallography.
Conodirinines A and B, Novel Vobasine‐Iboga Bisindoles Incorporating an Additional Tetrahydro‐1,3‐oxazine Unit on the Vobasinyl Moiety
Authors: Kam Toh‐Seok , Sim Kooi‐Mow 
Published: February 2003

AbstractTwo novel bisindole alkaloids of the vobasine‐Iboga type, viz., conodirinines A and B, in which the vobasinyl unit has incorporated an additional tetrahydrooxazine ring, were obtained from the leaf extract of the Malayan species Tabernaemontana corymbosa, and their structures were established by spectroscopic analysis.
X‐Ray Crystal Structure Analysis of Oxindole Alkaloids
Authors: Laus Gerhard , Wurst Klaus 
Published: February 2003

AbstractThe single‐crystal X‐ray structures of speciophylline, mitraphylline, and rhynchophylline, oxindole alkaloids from the Peruvian climbing vine Uncaria tomentosa (Rubiaceae), were determined. The three compounds show N⋅⋅⋅HN hydrogen bonding, which has not been observed in the crystal structures of the related alkaloids pteropodine and isopteropodine. In the tetracyclic alkaloid rhynchophylline, the side chain is rotated out of the ring plane into a position perpendicular to it. This is in contrast to the situation of the pentacyclic analogue mitraphylline, which possesses a conformationally rigid tricyclic core. This conformational difference possibly causes the competitive antagonism of these two types of alkaloids.
Multistep Parallel Synthesis of Quinazoline‐2,4‐diones by a Fluorous Biphasic Concept without Perfluorinated Solvents
Authors: Schwinn Dominik , Glatz Heiko , Bannwarth Willi 
Published: February 2003

AbstractBased on perfluoro‐tagged benzyl alcohol adsorbed via fluorous–fluorous interactions on fluorous reversed‐phase silica gel (FRPSG), we have performed a multistep synthesis leading finally to a small library of quinazoline‐2,4‐diones. The whole reaction sequence runs without isolation of intermediates and most importantly, without the need of perfluorinated solvents.
Ein neuer Zugang zu 2′‐O‐(2‐Methoxyethyl)ribonucleosiden ausgehend von D‐Glucose
Authors: Martin Pierre 
Published: February 2003

AbstractA New Access to 2′‐O‐(2‐Methoxyethyl)ribonucleosides Starting from D‐GlucoseA new synthesis of 2′‐O‐(2‐methoxyethyl)ribonucleosides, building blocks for second‐generation antisense oligonucleotides, starting from D‐glucose is presented. The key‐step is the transformation of 3‐O‐methoxyethylallofuranose to 2‐O‐(2‐methoxyethyl)ribose by NaIO4 oxidation. Together with the 4′‐phenylbenzoyl protecting group, which results in crystalline intermediates, this synthesis provides an easy and cheap access to 2′‐O‐(2‐methoxyethyl)‐substituted ribonucleosides.
Spectroscopic Study of Egyptian Blue Mixed with Other Pigments
Authors: Edreira M. Carmen , Feliu M. José , Fernández‐Lorenzo Concepción , Martín Joaquin 
Published: February 2003

AbstractThe Romans used a vast array of colors in their mural paints. The applied pigment mixtures containing Egyptian blue resulting in green, ochre, brown, gray, and white hues were studied. The chromatic characterization of wall paintings by electronic spectroscopy provided an easy and reliable procedure for the grouping of the samples to be studied (see Table). Subsequent use of other spectroscopic techniques such as Fourier‐transform (FT) IR and energy‐dispersive X‐ray spectroscopy (EDS), combined with X‐ray diffraction (XRD), led to convenient identification of the pictorial layer components that define and differentiate each chromatic group. Colors impossible to produce with only one pigment can be obtained by mixing Egyptian blue with other pigments. The dominant wavelength is displaced in such way that the artist obtains new tonalities.
Pteridines, Part CXIII
Authors: Yao Qizheng , Pfleiderer Wolfgang 
Published: February 2003

AbstractThe low solubility of pterins can drastically be improved by N2‐acylation or formation of the N2‐[(dimethylamino)methylene] derivatives. Both types of compounds can be alkylated under Mitsunobu conditions to form from N2‐acylpterins (see 2 and 3) and their derivatives (see 5, 6, 8, 9, 11, 13, 15, and 17) selectively the O4‐alkyl derivatives 22–31, whereas the electron‐donating [(dimethylamino)methyleneamino function in 46–51 gives, in a selective reaction, the N(3)‐substitution (→52–61). N2,N2‐Dimethylpterins and 18 and 19 and N2‐methylpterins 20 and 21 direct alkylation also to the O4‐position (→32–35, 38 and 39). Deacylation can be achieved under very mild conditions by solvolysis with MeOH (22→40, 26→41), and displacement of the O4‐[2‐(4‐nitrophenyl)ethyl] group proceeds with ammonia at room temperature to the corresponding pteridin‐2,4‐diamines 42–45. Cleavage of the N2‐[(dimethylamino)methylene] group works well with ammonia (→62–67). The advantage of applying the 2‐(4‐nitrophenyl)ethyl (npe) group as blocking group is seen in its selective removal by 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) under aprotic conditions without harming the other substituents.
Rapamycin inhibits proliferation of human neuroblastoma cells without suppression of MycN
Authors: Misawa Akiko , Hosoi Hajime , Tsuchiya Kunihiko , Sugimoto Tohru 
Published: February 2003

AbstractMYCN and insulin‐like growth factor (IGF) system are important for the pathogenesis and development of neuroblastoma. We previously reported evidence of a direct linkage between MycN and the IGF system in KP‐N‐RT human neuroblastoma cells, where IGF‐I induced both MycN expression at the RNA level and G1‐S cell cycle progression through the IGF‐I receptor (IGF‐IR)/ MEK/ mitogen‐activated protein kinase (MAPK) pathway (A. Misawa et al., Cancer Res, 2000; 60:64–9). Our data also showed the possibility of a potent IGF‐IR downstream signal cascade that accelerates progression into the S‐phase, other than the MAPK pathway. In this study, we further investigated the role of this alternative pathway in the growth of neuroblastoma cells. A phosphoinositide 3‐kinase (PI3K) inhibitor wortmannin blocked IGF‐I‐mediated induction of MycN. Our data suggest that the inhibition of MycN by wortmannin was transmitted through the MAPK pathway. Progression of the cell cycle from G1 to S phase was inhibited up to 90% by wortmannin or rapamycin, an inhibitor of mTOR, which acts downstream of PI3K. Despite its effects on induction of MycN and on progression through S phase, wortmannin did not block proliferation of neuroblastoma cells. On the other hand, rapamycin inhibited both IGF‐I‐induced cell cycle progression and cell proliferation in complete medium, although it had no effect on IGF‐I‐mediated MycN induction. Our study indicates maintenance of cell proliferation requires mTOR function, which is independent of MycN induction in human neuroblastoma cells. © 2003 Wiley‐Liss, Inc.
Regulation of the H19 imprinting gene expression in human nasopharyngeal carcinoma by methylation
Authors: Ng Aylwin , Tang Jing P. , Goh Christopher H.K. , Hui Kam M. 
Published: February 2003

AbstractIn East Asia and Singapore, the human nasopharyngeal carcinoma (NPC) presented clinically is mainly of the undifferentiated type. In contrast, the well‐differentiated squamous NPC is more commonly detected in the West. To study the potential differences in carcinogenesis between undifferentiated and differentiated human NPC, we employed cDNA microarrays to isolate genes that might be specific for human undifferentiated NPC. One of the genes identified to be specifically upregulated in the undifferentiated human NPC cell line CNE‐2 is the human imprinting gene H19. Interestingly, H19 is not expressed in the well‐differentiated human HK1 NPC cells. Northern blot and in situ hybridization analyses also confirmed that the H19 gene is strongly expressed in the undifferentiated CNE‐2 human NPC cell line but not in the well‐differentiated HK1 human NPC cell line. In situ hybridization and reverse transcriptase‐polymerase chain reaction also demonstrated that H19 is specifically expressed in NPC biopsies and not in non‐NPC human tissue biopsies. Furthermore, we demonstrated that deregulation of H19 gene expression in the well‐differentiated human HK1 NPC cells could be induced by the hypomethylation of CpG sites of the H19 promoter region. Hypermethylation of gene promoter regions might therefore be an important epigenetic event that plays a role in the differentiation of human NPC cells and the transcriptional silencing of imprinted genes. © 2003 Wiley‐Liss, Inc.
Ovulation and risk of epithelial ovarian cancer
Authors: Purdie David M. , Bain Christopher J. , Siskind Victor , Webb Penelope M. , Green Adèle C. 
Published: February 2003

AbstractIncessant ovulation is thought to be one of the primary causes of epithelial ovarian cancer. However, the effects of ovulation at different ages and of the various exposures or events that suppress ovulation have not been established. We used data from an Australian case‐control study of 791 ovarian cancer cases and 853 controls to examine the effect of ovulation on ovarian cancer risk. The total number of lifetime ovulations was calculated using information provided in a monthly contraceptive/reproductive calendar, as well as incorporating other information such as average menstrual cycle length. An increase of 1 year's worth of ovulation was associated with a 6% increase in risk of ovarian cancer (95% confidence interval [CI] = 4–8%). Ovulations in the 20–29‐year age group were associated with the greatest risk, with a 20% increase in risk associated with each year of ovulation during this age period (95% CI = 13–26%). When the effects of different exposures that suppress ovulation were compared, there was an indication that some factors may have a greater effect than others. These findings support the theory that incessant ovulation is a major contributor to the occurrence of ovarian cancer and suggest that ovulations during the 20s may be those most associated with disease risk. © 2003 Wiley‐Liss, Inc.
Identification of a naturally processed HLA‐A*0201 HPV18 E7 T cell epitope by tumor cell mediated in vitro vaccination
Authors: Kather Angela , Ferrara Alfonso , Nonn Marion , Schinz Manuela , Nieland John , Schneider Achim , Dürst Matthias , Kaufmann Andreas M. 
Published: February 2003

AbstractImmunotherapy of HPV‐associated disease such as cervical cancer is moving from preclinical investigation to clinical trials. The viral oncoproteins E6 and E7 are ideal target antigens because their expression is mandatory in HPV‐transformed tumor cells. T cells are the most important effector cells for therapeutic vaccination strategies. Therefore, the identification and characterization of HPV E6 and E7 T cell epitopes is necessary. Methods to date rely on screening for immunogenicity of peptides predicted by algorithms. Presentation of the identified peptides on tumor cells, however, needs to be confirmed. In our study, we have improved the method to identify peptide epitopes of HPV18 E7 that are actually presented by tumor cells. We induced allogeneic T‐cell lines by stimulation with HPV18‐positive, CD80 and HLA‐A*0201 transfected cervical cancer cells. Sensitized T cells were probed against an array of a HPV18 E7 20mer peptide‐library. We found specific reactivity to one of the 20mer peptides. This sequence was then screened via algorithms for putative epitopes. One putative HLA‐A2 restricted epitope was confirmed to bind to HLA‐A2, to be immunogenic and to induce IFNγ‐release in ELISpot assays. Epitope‐specific T cells were cytolytic toward autologous peptide pulsed targets and HPV18 transformed tumor cells. The identification of epitope‐specific T cells in tumor infiltrating lymphocytes of a HPV18‐positive HLA‐matched cervical cancer patient suggests an in vivo relevance of the identified epitope. We suggest that our approach is advantageous over conventional methods, because it yields candidate peptides that are relevant CTL epitopes that are expressed, processed and presented by tumor cells. © 2003 Wiley‐Liss, Inc.
Suppression of invasion and peritoneal carcinomatosis of ovarian cancer cell line by overexpression of bikunin
Authors: Suzuki Mika , Kobayashi Hiroshi , Tanaka Yoshiko , Hirashima Yasuyuki , Kanayama Naohiro , Takei Yuji , Saga Yasushi , Suzuki Mitsuaki , Itoh Hiroshi , Terao Toshihiko 
Published: February 2003

AbstractBikunin (bik), a Kunitz‐type protease inhibitor, also known as urinary trypsin inhibitor, is proposed as a main participant in the inhibition of tumor cell invasion and metastasis, possibly through the direct inhibition of cell‐associated plasmin activity and suppression of urokinase‐type plasminogen activator (uPA) mRNA expression. In the present study, we transfected the human ovarian carcinoma cell line HRA, highly invasive cells, with an expression vector harboring a cDNA encoding for human bik. Our study was designed to investigate the effect of bik overexpression and changes in tumor cell phenotype and invasiveness in the stably transfected clones. Bik gene transfection of HRA gave the following results: 1) transfection of HRA with the bik cDNA resulted in 5 variants stably expressing functional bik; 2) bik+ clones exhibited a significantly reduced uPA mRNA expression as compared to the parental cells; 3) bikunin negatively regulates the ERK1/2 activity; 4) secretion‐blocking treatments of bik+ clones abrogated bik‐mediated suppression of ERK1/2 activation and uPA expression; 5) the regulation of invasion seen in the HRA cells is mainly mediated by the uPA‐plasmin‐MMP‐2 system; 6) transfection of HRA with the bik gene significantly reduced invasion, but not proliferation, adhesion, or migration relative to the parental cells; and 7) animals with bik+ clones induced reduced peritoneal dissemination and long term survival. We conclude that transfection of HRA cells with the bik cDNA constitutively suppresses ERK1/2 activation, which results in inhibition of uPA expression and subsequently reduces dissemination of bik+ clones. © 2003 Wiley‐Liss, Inc.
Human papillomavirus infection as a prognostic factor in carcinomas of the oral cavity and oropharynx
Authors: Ritchie Justine M. , Smith Elaine M. , Summersgill Kurt F. , Hoffman Henry T. , Wang Donghong , Klussmann Jens P. , Turek Lubomir P. , Haugen Thomas H. 
Published: February 2003

AbstractAlthough studies have established human papillomaviruses (HPVs) as a risk factor for oral and oropharyngeal cancer, it is not clear whether viral infection affects survival in head and neck malignancies. This investigation examined the relationship between HPV and survival in carcinomas of the oral cavity and oropharynx. Formalin‐fixed, paraffin‐embedded tumor specimens from 139 newly diagnosed cases were tested for HPVs by PCR and DNA sequencing. Patient and tumor characteristics were obtained from questionnaires, pathology reports and cancer registries. Odds ratios (ORs) and relative risks (RRs) were based on logistic and Cox regression models, respectively. HPVs were detected in 21% of the tumors; 83% were HPV‐16. Greater risk of HPV infection was associated with males (OR = 2.9, 95% CI = 1.0–8.6), a history of oral‐genital sex (OR = 4.2, 95% CI = 1.5–11.7), and oropharyngeal tumors (OR = 10.4, 95% CI = 3.5–31.2). As tobacco usage increased, the odds of HPV detection decreased (OR = 0.97/pack‐year, 95% CI = 0.96–0.99). HPV infected patients had better overall survival (RR = 0.3, 95% CI = 0.1–0.8) than those with HPV‐negative tumors. There was an interaction between gender and HPV for overall (p= 0.05) and disease‐specific (p= 0.03) survival that suggested that HPV infected males had better prognosis than HPV‐negative males, but this was not the case among females. HPV status was identified as an independent prognostic factor in oral and oropharyngeal cancers. This result appeared to be gender‐specific, suggesting the need for further study of the interaction between HPV and gender on survival. © 2003 Wiley‐Liss, Inc.