bluuebunny/crossref_metadata_2025_split huggingface dataset:
Redox and Conformational Equilibria and Dynamics of Cytochrome c at High Electric Fields
Authors: Wackerbarth Hainer , Hildebrandt Peter 
Published: July 2003

AbstractCytochrome c (Cyt‐c) adsorbed in the electrical double layer of the Ag electrode/electrolyte interface has been studied by stationary and time‐resolved surface‐enhanced resonance Raman spectroscopy to analyse the effect of strong electric fields on structure and reaction equilibria and dynamics of the protein. In the potential range between +0.1 and −0.55 V (versus saturated calomel electrode), the adsorbed Cyt‐c forms a potential‐dependent reversible equilibrium between the native state B1 and a conformational state B2. The redox potentials of the bis‐histidine‐coordinated six‐coordinated low‐spin and five‐coordinated high‐spin substates of B2 were determined to be −0.425 and −0.385 V, respectively, whereas the additional six‐coordinated aquo‐histidine‐coordinated high‐spin substate was found to be redox‐inactive. The redox potential for the conformational state B1 was found to be the same as in solution in agreement with the structural identity of the adsorbed B1 and the native Cyt‐c. For all three redox‐active species, the formal heterogeneous electron transfer rate constants are small and of the same order of magnitude (3–13 s−1), which implies that the rate‐limiting step is largely independent of the redox‐site structure. These findings, as well as the slow and potential‐dependent transitions between the various conformational (sub‐)states, can be rationalized in terms of an electric field‐induced increase of the activation energy for proton‐transfer steps linked to protein structural reorganisation. Further increasing the electric field strength by shifting the electrode potential above +0.1 V leads to irreversible structural changes that are attributed to an unfolding of the polypeptide chain.
Determination of mono‐ and disaccharides by capillary electrophoresis with contactless conductivity detection
Authors: Carvalho Alexandre Zatkovskis , da Silva José A. F. , do Lago Claudimir L. 
Published: July 2003

AbstractThe separation and detection of common mono‐ and disaccharides by capillary electrophoresis (CE) with contactless conductivity detection (CCD) is presented. At high values of pH, the sugars are converted to anionic species that can be separated by CE and indirectly detected by CCD. The main anionic species present in the running electrolytes are hydroxide and phosphate, which have greater mobility than the ionized sugars, and, thus, the indirect detection is possible. The method was applied to analysis of glucose, fructose, and sucrose in soft drinks, isotonic beverages, fruit juice, and sugarcane spirits. Galactose was used as internal standard in all cases. Plate numbers range from ca. 70 700 to 168 200 and the limits of detection from 13 to 31 μM.
Validated capillary electrophoresis method for small‐anions measurement in wines
Authors: Saavedra Luis , Barbas Coral 
Published: July 2003

AbstractA capillary electrophoresis method has been developed and validated for acetic, citric, fumaric, lactic, malic, oxalic, succinic, and tartaric acids plus the measurement of nitrate and sulfite ions in white and red wines. The separation was carried out in a neutral coated capillary. Separation was performed at –14 kV of applied potential. Temperature was maintained at 20°C. The background electrolyte used was 200 mM phosphate buffer at pH 7.50. Separation was obtained in less than 13 min. Validation parameters obtained for the method permit it to be considered adequate for routine analysis.
Trace determination of arsenic species by capillary electrophoresis with direct UV detection using sensitivity enhancement by counter‐ or co‐electroosmotic flow stacking and a high‐sensitivity cell
Authors: Sun Baoguo , Macka Miroslav , Haddad Paul R. 
Published: July 2003

AbstractStacking techniques used independently and also with a high‐sensitivity cell (HSC) were employed to optimise sensitivity and detection limits in the direct photometric detection of the following eight arsenic species by capillary zone electrophoresis (CZE): arsenite, arsenate, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), 4‐hydroxy‐3‐nitrophenylarsonic acid (Roxarsone), p‐aminophenylarsonic acid (p‐ASA), 4‐nitrophenylarsonic acid (4‐NPAA), and phenylarsonic acid (PAA) (target analytes). The stacking mechanisms, optimised stacking and separation conditions, and concentration sensitivity enhancement factors were discussed and compared for (i) normal stacking mode (NSM, sometimes also referred to as field‐amplified stacking) in an uncoated fused‐silica capillary in the counter‐electroosmotic flow (EOF) mode, (ii) large‐volume sample stacking (LVSS) with polarity switching, and (iii) the less often applied stacking method of co‐EOF NSM stacking with EOF reversal using a poly(diallydimethylammonium chloride) (PDDAC)‐coated capillary. The optimal injection volumes were 7.4, 60 and 17.2% of the total capillary volume, for the above three methods, respectively. LVSS with polarity switching gave the lowest limit of detection (LOD). The use of the HSC further reduced the LOD of each target analytes by a factor of 5–8 times. By combining LVSS and HSC, LODs of the target analytes could be reduced by a factor of 218–311, to 5.61, 9.15, 11.1, and 17.1 μg/L for As(III), DMA, MMA, and As(V), respectively. The method was demonstrated to be applicable to the determination of the target analytes in tap water and lake water, with recoveries in the range of 89.4–103.3%.
Effect of NaOH on large‐volume sample stacking of haloacetic acids in capillary zone electrophoresis with a low‐pH buffer
Authors: Tu Chuanhong , Zhu Lingyan , Ang Chay Hoon , Lee Hian Kee 
Published: July 2003

AbstractLarge‐volume sample stacking (LVSS) is an effective on‐capillary sample concentration method in capillary zone electrophoresis, which can be applied to the sample in a low‐conductivity matrix. NaOH solution is commonly used to back‐extract acidic compounds from organic solvent in sample pretreatment. The effect of NaOH as sample matrix on LVSS of haloacetic acids was investigated in this study. It was found that the presence of NaOH in sample did not compromise, but rather help the sample stacking performance if a low pH background electrolyte (BGE) was used. The sensitivity enhancement factor was higher than the case when sample was dissolved in pure water or diluted BGE. Compared with conventional injection (0.4% capillary volume), 97–120‐fold sensitivity enhancement in terms of peak height was obtained without deterioration of separation with an injection amount equal to 20% of the capillary volume. This method was applied to determine haloacetic acids in tap water by combination with liquid‐liquid extraction and back‐extraction into NaOH solution. Limits of detection at sub‐ppb levels were obtained for real samples with direct UV detection.
Capillary electrophoresis speciation of chromium in leather tanning liquor
Authors: Poboży Ewa , Knell Mark , Kilian Krzysztof , Kataky Ritu , Trojanowicz Marek 
Published: July 2003

AbstractWe present a method for the speciation of chromium by capillary electrophoresis. Cr(III) was complexed with diethylenetriaminepentaacetic acid (DTPA) to form a negatively charged complex. Using 20 mM phosphate buffer of pH 8 containing 0.5 mM tetradecyltrimethylammonium hydroxide (TTAOH) at a separation voltage of –15 kV, both forms of chromium CrDTPA2– and CrO42– were separated in less than 6 min. Direct UV detection at 214 nm was used. The effect of the presence of interfering ions was investigated. The application of the developed method to speciation of chromium in tanning liquor is demonstrated. The obtained results have shown a good correlation with those of flame atomic absorbance spectrometry (FAAS), inductively coupled plasma‐mass spectrometry (ICP‐MS) and UV/VIS spectrophotometry.
Determination of chlorophenoxy acid herbicides by capillary electrophoresis with integrated potential gradient detection
Authors: Qin Weidong , Li Sam F. Y. 
Published: July 2003

AbstractThis report describes separation and detection of chlorophenoxy acid herbicides spiked in drinking water by the technique combining solid‐phase extraction, field‐amplified sample stacking, capillary electrophoresis, and potential gradient detection. The herbicide solution (400 mL) was concentrated to 0.1 mL by the solid‐phase extraction procedure. The buffer containing 3 mM ammonia and 0.3 mM hydroxypropyl‐β‐cyclodextrin was adjusted to pH 9.0 with ammonia. The sample solution was injected into the capillary to 30% of the whole length, and −9 kV and 9 kV were employed for field‐amplified sample stacking and separation, respectively. The herbicides were baseline separated and the detection limits with the above combined techniques were in the range of 1–4×10−2 ng/mL.
Determination of lactate or oxalate using injected lactate oxidase and peroxidase by capillary electrophoresis with UV detection
Authors: Qi Lining , Danielson Neil D. 
Published: July 2003

AbstractTwo reactions, catalyzed by lactate oxidase (LO) and peroxidase, are initiated by a single injection of the enzymes and the substrate 2,2'‐azino‐bis(3‐ethylene‐thiazoline‐6‐sulfonic acid) (ABTS) into the capillary previously filled with the sample (lactate or lactate‐oxalate mixture) and the run buffer containing NADH. The oxidized ABTS product upon reaction with NADH is converted to NAD+ which is separated and detected in less than 2 min at 266 nm with a sample throughput of 7 min (including wash steps between samples). Simplex™ software is used to optimize the enzyme concentrations and reaction temperature. Consumption of the more expensive LO enzyme is only 1.4×10−3 U per assay assuming 27 nL per injection. Linearity is established within the range from 0.0025 to 1 mM with R2 of 0.9982. Recoveries of lactate from five spiked serum samples averaged 101%. Application of this method for the determination of oxalate as an inhibitor of LO is demonstrated.
Electrophoretic separations on chips with hydrodynamically closed separation systems
Authors: Kaniansky Dušan , Masár Marián , Bodor Róbert , Žúborová Mária , Ölvecká Eva , Jöhnck Matthias , Stanislawski Bernd 
Published: July 2003

AbstractThis review focuses on capillary electrophoretic separations performed on capillary electrophoresis chips (CE chips) with hydrodynamically closed separation systems in a context with transport processes (electroosmotic flow (EOF)) and hydrodynamic flow (HDF)) that may accompany the separations in these devices. It also reflects some relevant works dealing with conventional CE operating under such hydrodynamic conditions. The use of zone electrophoresis (ZE), isotachophoresis (ITP) and their on‐line combination (ITP‐ZE) on the single‐column and column‐coupling CE chips with the closed separation systems and related problems are key topics of the review. Some attention is paid to sample pretreatment in the separations performed on the CE chips. Here, mainly potentialities of the ITP‐ZE combination in trace analysis applications of the miniaturized systems are discussed in a broader extent. Links between the ZE separation and detection provide a frame for the discussion of current status of the detection on the CE chips. Analytical applications illustrate potentialities of the CE chips operating with the closed separation systems (suppressed HDF and EOF) to the determination of small ions present in various matrices by ZE, ITP and ITP‐ZE.
Interpersonal psychotherapy for chronic depression
Authors: Markowitz John C. 
Published: July 2003

AbstractInterpersonal psychotherapy (IPT) is a time‐limited, manualized, life‐event‐based treatment of demonstrated efficacy for acute major depression. This article describes its adaptation and application to chronic forms of unipolar depression. The interpersonal difficulties of chronically depressed patients present a potentially good fit for a therapy that builds interpersonal functioning, but the chronicity of illness and paucity of life events of dysthymic patients complicate the use of IPT. Recent outcome research is reviewed. A case example illustrates the clinical approach and potential benefits. Based on a limited number of studies, the benefits of acute IPT for chronic depression appear non‐specific and modest. © 2003 Wiley Periodicals, Inc. J Clin Psychol/In Session.
Supportive–expressive therapy for chronic depression
Authors: Mark David G. , Barber Jacques P. , Crits‐Christoph Paul 
Published: July 2003

AbstractWe describe our clinical experience with a subset of chronically depressed patients characterized as introverted, with an early onset of feeling different from, and often feeling more sensitive than, others. We outline six central issues that concern a psychodynamic approach to chronically depressed people. This article describes and illustrates how a modified supportive–expressive psychotherapy influenced by the relational perspective can help in the treatment of these patients. In particular, we facilitate an interaction in which the patient speaks from rather than merely about his or her depressed self. A couple of clinical moments are presented to illustrate how a lack of recognition by the therapist of the self the depressed patient is at the moment leads to a kind of lifeless despair, and conversely, how the therapist's recognition facilitates the patient talking from his depressed state rather than merely about it. © 2003 Wiley Periodicals, Inc. J Clin Psychol/In Session.
Hepatitis B core antigen is a potent inductor of interleukin‐18 in peripheral blood mononuclear cells of healthy controls and patients with hepatitis B infection
Authors: Manigold Tobias , Böcker Ulrich , Chen Jingsan , Gundt Jutta , Traber Petra , Singer Manfred V. , Rossol Siegbert 
Published: July 2003

AbstractClearance of hepatitis B virus infection (HBV) infection implies a polyclonal vigorous T‐helper 1 (Th1) and cytotoxic T‐lymphocyte (CTL) response. Interleukin‐18 (IL‐18), a monokine that shares functional abilities with IL‐12, is a potent inductor of interferon‐γ (IFN‐γ) by Th1 and natural killer (NK) cells. However, the role and regulation in HBV infection of IFN‐γ have not been defined. This study therefore sought to determine hepatitis B core antigen (HBcAg)‐mediated regulation of IL‐18 production in peripheral blood mononuclear cells (PBMCs) from healthy controls (HC) and patients with chronic hepatitis B (CHB) or acute hepatitis B (AHB); 31 HC, 27 patients with CHB and 8 patients with AHB infection were included in the study. HBcAg‐mediated induction of IL‐18 was determined by quantitative reverse transcription‐polymerase chain reaction (RT‐PCR) and specific enzyme‐linked immunosorbent assay (ELISA). HBcAg induced IL‐18 gene transcription and dose‐dependent secretion of mature IL‐18 protein in HC, CHB, and AHB. HBcAg‐dependent IL‐18 levels were abrogated by inhibition of Caspase‐1, but not by blockade of CD40‐CD154 interaction. Serum levels of IFN‐γ correlated inversely with viremia in patients with CHB (ρ = − 0.54, P < 0.05), but not with serum levels of IL‐12 or IL‐18. Interestingly, in PBMCs of HBeAg‐negative patients, HBcAg induced significantly higher amounts of IL‐18 than in those of HBeAg‐positive patients. A variant, lacking the histone‐like arginine‐rich domain, did not induce IL‐18 in either HC or CHB in vitro. Taken together, these results indicate that HBcAg induces IL‐18 secretion by induction of Caspase‐1. Differential regulation in HBeAg‐negative and positive patients suggests an important role of IL‐18 in CHB infection. J. Med. Virol. 71:31–40, 2003. © 2003 Wiley‐Liss, Inc.
Hepatitis C virus genetic variability in 52 human immunodeficiency virus‐coinfected patients
Authors: Neau Didier , Jouvencel Anne‐Christine , Legrand Elisabeth , Trimoulet Pascale , Galperine Tatiana , Chitty Isabelle , Ventura Michel , Le Bail Brigitte , Morlat Philippe , Lacut Jean‐Yves , Ragnaud Jean‐Marie , Dupon Michel , Fleury Hervé , Lafon Marie‐Edith 
Published: July 2003

AbstractThe aim of this study was to examine whether hepatitis C virus (HCV) pretreatment quasispecies complexity was linked to virological response or other clinical and biological parameters, in human immunodeficiency virus (HIV)‐coinfected patients undergoing anti‐HCV treatment. In addition, HCV quasispecies composition is described longitudinally in these patients before, during, and after treatment. The 52 HIV‐coinfected patients were included in a randomized therapeutic trial. At inclusion, they had CD4+ counts of >250/μl, HIV plasma load of <10,000 copies/ml, and chronic HCV infection with genotype 1 (n = 27), 2 (n = 2) or 3 (n = 23). These values were compared at baseline with 32 HCV‐only‐infected, interferon‐naive patients who were infected with genotype 1, 2, or 3 (n = 16, 1, or 15, respectively). HCV complexity was studied by single‐strand conformation polymorphism (SSCP) in E2 hypervariable region 1 (HVR1), and diversity was evaluated at inclusion in 20 coinfected patients by sequencing four major SSCP bands. The baseline number of SSCP bands was identical in HIV‐infected and control patients. In HIV‐infected patients, HCV complexity was not predictive of sustained virological response to anti‐HCV treatment and was unrelated to epidemiological factors, immunological parameters linked to HIV infection (CD4+ counts, T CD4+ proliferative responses to HIV‐1 p24), protease inhibitor treatment, HCV plasma load, or genotype. HCV diversity was lower in genotype 2‐ and 3‐infected patients. Six months after completion of the anti‐HCV treatment, in comparison with baseline, SSCP profiles were modified in 13 of the 21 nonresponding coinfected patients with analyzable samples. In conclusion, in HIV‐infected patients, HCV variability had no significant influence on virological response to anti‐HCV treatment. J. Med. Virol. 71:41–48, 2003. © 2003 Wiley‐Liss, Inc.
Relevance of B19 markers in serum samples for a diagnosis of parvovirus B19‐correlated diseases
Authors: Gallinella G. , Zuffi E. , Gentilomi G. , Manaresi E. , Venturoli S. , Bonvicini F. , Cricca M. , Zerbini M. , Musiani M. 
Published: July 2003

AbstractIn order to evaluate the optimal and essential diagnostic test(s) for a correct diagnosis of B19 diseases, 344 consecutive serum samples were tested from 344 patients with clinical suspicion of B19 infection during an epidemic period (early Spring–Autumn 2000). Sera were tested for B19 DNA by a standardized competitive polymerase chain reaction‐enzyme‐linked immunosorbent assay (PCR‐ELISA) and dot‐blot hybridization and for specific IgM and IgG by ELISA. Of 344 patients examined, 125 were positive for markers of B19‐associated disease: 49 had both B19 DNA and IgM, 50 had B19 DNA without IgM, and 26 had IgM without B19 DNA. After examination of the different patterns of B19 markers as diagnostic tools for B19 infection, IgM determination detected only 60% of B19‐documented infections. IgM tests were nevertheless fundamental, as they were the unique diagnostic marker in 20.8% of documented infections (26 of 125 patients), in the diagnosis of recent, but still symptomatic infections when B19 DNA was no longer detectable. The determination of B19 DNA with PCR permitted detection of 79.2% of infections and therefore represented an essential test. PCR was fundamental for the diagnosis of B19 disease, as the unique diagnostic marker in 32% of documented infections (50 of 125 patients), both in acute infections at the onset of symptoms before the appearance of immunological response, and during the course of persistent B19 infections in which IgM had cleared. The contemporaneous determination of B19 DNA by PCR and specific IgM appears to be the most appropriate diagnostic protocol for the correct laboratory diagnosis of B19 infection. J. Med. Virol. 71:135–139, 2003. © 2003 Wiley‐Liss, Inc.
Relationship of TT virus and Helicobacter pylori infections in gastric tissues of patients with gastritis
Authors: Maggi Fabrizio , Marchi Santino , Fornai Claudia , Tempestini Elena , Andreoli Elisabetta , Lanini Letizia , Vatteroni Maria Linda , Bellini Massimo , De Bortoli Nicola , Costa Francesco , Pistello Mauro , Specter Steven , Bendinelli Mauro 
Published: July 2003

AbstractBlood and gastric tissue biopsies of 34 patients with gastritis were tested for the presence of TT virus (TTV), a ubiquitous virus found in the blood of most humans. Thirty‐one of these patients were TTV positive, and 27 patients had virus in both tissues. In addition, 13 of the patients who had TTV in gastric tissue were Helicobacter pylori positive. There was an association of higher TTV titers in gastric tissues of patients who were H. pylori positive than in those in whom the bacterium could not be detected. Furthermore, this association was stronger in H. pylori‐positive patients with the presence of the cagA protein. Of 10 specimens in which genogroup determination was carried out in the gastric corpus, 5/5 that were H. pylori positive showed the presence of TTV genogroup 3, while for those that were H. pylori negative, 5/5 showed the presence of genogroup 1t. By contrast, genogroup 1 was found in the corpus of only one H. pylori‐positive patient, and genogroup 3 in only one H. pylori‐negative patient. The histological severity of gastritis did correlate significantly with loads in the gastric tissues. There was no significant difference in TTV titer in blood of patients regardless of H. pylori infection status. These findings pique interest in clarifying the role of TTV, alone or in association with H. pylori infection, in the pathogenesis of gastritis. J. Med. Virol. 71:160–165, 2003. © 2003 Wiley‐Liss, Inc.
Importance of amino acid 216 in nonstructural protein 2B for replication of hepatitis A virus in cell culture and in vivo
Authors: Graff Judith , Emerson Suzanne U. 
Published: July 2003

AbstractClinical isolates of hepatitis A virus (HAV) replicate inefficiently in cell culture unless mutations are acquired throughout the genome. An Ala‐to‐Val substitution in the nonstructural protein 2B (2B‐216) was known to have a major impact on replication in cell culture. Analysis of chimeric viruses confirmed that the 2B‐A[216]V change was critical for efficient replication and that Leu or Ile could substitute for Val. Viruses containing Val, Ile, or Leu at 2B‐216 all replicated with similar kinetics in cell culture, whereas the virus containing Ala at this position grew 10‐ to 20‐fold less efficiently. In contrast, in vivo, virus with either Ala or Val at 2B‐216 replicated equally efficiently when tested in a chimpanzee and in tamarins, and each amino acid was stably maintained. Attempts to complement wild‐type 2B in trans with adapted 2B provided by co‐infection with a second viable HAV mutant failed to enhance replication of the virus containing the wild‐type 2B sequence. J. Med. Virol. 71:7–17, 2003. © 2003 Wiley‐Liss, Inc.