bluuebunny/crossref_metadata_2025_split huggingface dataset:
Supramolecular Derivatives of 9,10‐Anthraquinone. Electrochemistry at Regular‐ and Low Ionic Strength and Complexing Properties
Authors: Zon Agnieszka , Palys Marcin , Stojek Zbigniew , Sulowska Hanna , Ossowski Tadeusz 
Published: April 2003

AbstractThree newly synthesized polyanthraquinone derivatives: 7,13‐bis(9,10‐dioxo‐1‐anthryl)‐1,4,10‐trioxa‐7,13‐diazacyclopentadecane, (AQ)A215C5, 7,16‐bis(9,10‐dioxo‐1‐anthryl)‐1,4,10,13‐tetraoxa‐7,16‐diazacyclooctadecane, (AQ)A218C6, and tris[(9,10‐diokso‐1‐antryl)‐aminoethyl]amine, (AQNet)3N, were examined by cyclic and normal pulse voltammetry. All anthraquinone groups in these compounds were electroactive and formed the radicals and dianions similarly to simple anthraquinone. The differences between the voltammograms obtained in the absence and presence of supporting electrolyte are discussed, and the diffusion coefficients of the compounds and the rates of the chemical reactions following the first reduction step were evaluated. (AQNet)3N appears to be a good model compound for multi electron transfers in aprotic solvents. It offers two consecutive nearly reversible 3‐electron redox systems: 0/−3 and −3/−6. The interactions of the radicals and dianions of the above compounds with alkali metal cations were examined.
Genetic differentiation and subspecies development of the giant panda as revealed by DNA fingerprinting
Authors: Wan Qiu‐Hong , Fang Sheng‐Guo , Wu Hua , Fujihara Tsutomu 
Published: April 2003

AbstractOver the last 100 years giant pandas (Ailuropoda melanoleuca) have been separated into six completely isolated mountain ranges. DNA fingerprinting revealed different differentiation patterns in giant pandas, including early‐stage, late‐stage, recent divergence and recent genetic depression. A separation around 10 000 years ago resulted in highly significant differences in DNA fingerprints and morphological characteristics between Qinling and Sichuan populations. Supported by morphological differences, the genetic data were used to classify the Qinling population as a new subspecies, A. m. qinlingensis, while the Sichuan populations were classified into the original subspecies, A. m. melanoleuca. Thus, the Qinling population deserves management as a separate unit. In the Sichuan populations, two management units were defined, including Qionglai‐Minshan and Daxiangling‐Xiaoxiangling‐Liangshan. Our data suggest urgent measures are needed to establish green corridors between subpopulations in each mountain range to increase gene flow and genetic variation to ensure long‐term survival.
Capillary electrophoresis with end‐column amperometric detection of urinary 8‐hydroxy‐2'‐deoxyguanosine
Authors: Mei Su‐Rong , Yao Qing‐Hong , Cai Ling‐suang , Xing Jun , Xu Guo‐Wang , Wu Cai‐ying 
Published: April 2003

AbstractUrinary 8‐hydroxy‐2'‐deoxyguanosine (8OHdG) is an excellent marker of oxidative DNA damage. Until now, urinary 8OHdG has been measured by high‐performance liquid chromatography with electrochemical detection. A simple and sensitive method for the analysis of urinary 8OHdG by capillary electrophoresis with end‐column amperometric detection has been developed in our laboratory. A single‐step solid‐phase extraction procedure was optimized and used for extracting 8OHdG from human urine. To improve the sensitivity of this method, a new focusing technique based on a dynamic pH junction was used. The limit of detection was 20 nM (signal‐to‐noise ratio S/N = 3), the linear range was 50 nM–10 μM, and the correlation coefficient was better than 0.999. The relative standard deviation (RSD) was found to be 0.57% for migration time, and 4.79% for peak current. To show the usefulness of the method, the urinary concentration of 8OHdG in nine healthy persons and ten cancer patients was determined. The urinary concentration of 8OHdG in cancer patients was significantly higher than that in healthy persons.
Determination of enantiomeric purity of a novel COX‐2 anti‐inflammatory drug by capillary electrophoresis using single and dual cyclodextrin systems
Authors: Pérez‐Maseda Carlos , Calvet Carme , Cuberes Rosa , Frigola Jordi 
Published: April 2003

AbstractE‐6087 is the most advanced compound among the cyclooxygenase‐2 (COX‐2) inhibitor drugs developed in our company. Its activity is mainly associated with the S(−)‐enantiomer (E‐6232), whereas the R(−)‐enantiomer (E‐6231) becomes an impurity whose content should be determined. Five main impurities and degradation products of E‐6232 have been found (E‐6144, E‐6024, E‐6072, E‐6397 and E‐6132), and some of them co‐elute with the distomer when using a chiral high‐performance liquid chromatography (HPLC) method. Consequently, we have optimized the separation of all the impurities from the two enantiomers of E‐6087 by capillary electrophoresis (CE), in order to use the method for the enantiomeric purity determination of E‐6232. The effect of the methanol (MeOH) content in the background electrolyte (BGE), the sulfobutyl ether‐β‐cyclodextrin (SBE‐β‐CD) and heptakis‐(2,6‐di‐O‐methyl)‐β‐cyclodextrin (DM‐β‐CD) concentration, and the capillary temperature have been studied. Separation of all compounds could be achieved in different systems, either in a single CD‐system (with SBE‐β‐CD) or in a dual CD‐system (with DM‐β‐CD as a neutral CD). By using the dual CD system a limit of detection (LOD) and a limit of quantitation (LOQ) of 0.03% and 0.1% of distomer, respectively, were achieved*.
Capillary electrophoresis separation of high molecular weight glutenin subunits in bread wheat (Triticum aestivum L.) and related species with phosphate‐based buffers
Authors: Yan Yueming , Yu Jianzhong , Jiang Yi , Hu Yingkao , Cai Minhua , Hsam Sai L. K. , Zeller Friedrich J. 
Published: April 2003

AbstractThis study focused on optimizing phosphate‐based buffers and other capillary electrophoresis (CE) parameters for separating and characterizing high molecular weight glutenin subunits (HMW‐GS) in bread wheat (Triticum aestivum L., AABBDD, 2n = 6x = 42), emmer (Triticum dicoccum, AABB, 2n = 4x = 28) and Aegilops tauschii (DD, 2n = 2x = 14). The fast and high‐resolution separation of HMW‐GS was achieved using 0.1 M phosphate‐glycine buffer (pH 2.5, containing 20% acetonitrile and 0.05% hydroxypropylmethylcellulose) at 12.5 kV and 40°C with 25 μm inside diameter (ID)×27 cm uncoated fused‐silica capillary. In general, one sample separation can be analyzed in 15 min. The good run‐to‐run repeatable separation of HMW‐GS could be obtained with a relative standard deviation of less than 1% when capillaries were rinsed with 1 M phosphoric acid for 2 min, followed by separation buffer for 2 min after each separation. The HMW‐GS from some bread wheat cultivars as well as tetraploid and diploid accessions was separated by the CE method described above, and all subunits detected were well characterized and readily identified. Some HMW‐GS showed reversed mobilities and elution order compared to the methods of sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) and SDS‐CE. Particularly, most of the HMW‐GS analyzed with the CE buffer used were separated into multiple peaks, generally a high peak plus a minor peak. CE appears to be capable of separating and characterizing HMW‐GS with fast and high‐resolution features, therefore it is expected to be useful for specific germplasm screening and desirable HMW‐GS identification in wheat quality improvement.
ADAM‐10 and ADAM‐17 in the inflamed human CNS
Authors: Kieseier Bernd C. , Pischel Heidrun , Neuen‐Jacob Eva , Tourtellotte Wallace W. , Hartung Hans‐Peter 
Published: April 2003

AbstractInflammatory demyelinating disorders of the CNS, such as multiple sclerosis (MS), are mediated, at least in part, by various cytokines and proteases. In the present study, we investigated the expression of A disintegrin and metalloproteinase (ADAM)‐17, an important sheddase for various proteins, including tumor necrosis factor‐α (TNF‐α), and the p75‐ and p55‐TNF receptors, as well as ADAM‐10, a protease implicated in myelin degradation, in post mortem CNS tissue samples from patients with MS, and normal brain tissue (as control) by immunohistochemistry. ADAM‐10 was found to be expressed by astrocytes in all MS and control sections studied; however, in some MS sections, perivascular macrophages were determined as an additional cellular source as well. ADAM‐17 could be observed exclusively in acute and chronic active MS plaques and localized to invading T lymphocytes. The staining pattern of ADAM‐17 in MS plaques was mirrored in distribution and extent by the pattern obtained with an antibody against the p75–TNF‐receptor (TNFR‐2), whereas TNF‐α was found to be expressed primarily by perivascular macrophages. In studying cerebrospinal fluid (CSF) samples from MS patients, we were able to detect increased protein levels of ADAM‐17 as compared with noninflammatory controls. In addition, increased levels of soluble TNFR‐2 could be measured, suggestive of an active shedding process mediated by ADAM‐17. The stimulation of peripheral blood mononuclear cells (PBMC) obtained from MS patients and healthy individuals corroborated these findings by revealing expression of ADAM‐17 by T lymphocytes and ADAM‐10 by macrophages in vitro. Our results indicate that ADAM‐10 is expressed constitutively by astrocytes in the normal and inflamed human CNS. In contrast, under inflammatory conditions, ADAM‐10, expressed by perivascular macrophages, and ADAM‐17, expressed by invading T cells, may actively contribute to the pathogenesis of inflammatory disorders of the CNS. GLIA 42:398–405, 2003. © 2003 Wiley‐Liss, Inc.
Expression of complement messenger RNAs and proteins by human oligodendroglial cells
Authors: Hosokawa Masato , Klegeris Andis , Maguire John , McGeer Patrick L. 
Published: April 2003

AbstractNeurons, astrocytes, microglia, and endothelial cells are capable of synthesizing most, if not all, of the complement proteins. Little is known, however, about the capacity of oligodendroglial cells to generate complement components. This study evaluated expression of complement mRNAs and their protein products by human oligodendrocytes. Cells were isolated and cultured from white matter of seven adult cases that had undergone surgical temporal lobe resection for epilepsy. Oligodendroglial cultures were characterized by the expression of such cell type‐specific mRNAs as myelin proteolipid protein (PLP), oligodendrocyte‐specific protein (OSP), and 2′,3′‐cyclic nucleotide 3′‐phosphodiesterase (CNPase) and were further characterized by immunostaining for such differentiation markers as myelin basic protein (MBP), PLP, CNPase, and O4. RT‐PCR analysis showed that the oligodendroglial cells expressed detectable levels of complement mRNAs for the C1q B‐chain, C1r, C1s, C2, C3, C4, C5, C6, C7, C8 γ subunit, and C9. Immunostaining was positive for C1q, C1s, C2, C3, C4, C5, C6, C7, C8, and C9. Double immunostaining for the oligodendrocyte marker O4 and the complement protein C3 demonstrated that all O4‐positive cells were also positive for C3, indicating constitutive C3 expression. These results indicate that oligodendroglial cells may be a source of complement proteins in human brain and thus could contribute to the pathogenesis of several neurodegenerative and inflammatory diseases of the CNS, such as Alzheimer's disease, multiple sclerosis, and progressive supranuclear palsy, where complement‐activated oligodendrocytes are abundant. GLIA 42:417–423, 2003. © 2003 Wiley‐Liss, Inc.
Pressure inside Small Cavities: A Possible Factor in Enzyme Catalysis and Selectivity
Authors: Saunders Martin 
Published: April 2003

AbstractThere are many different examples where atoms or molecules are found in cavities within larger (cage) molecules. The term host–guest chemistry has been used to describe this situation. This paper considers the possibility that pressure within the cavities can be measured or calculated in several possible ways. The various values for pressure for different systems can serve to compare them. It is suggested that pressure might be related to the rate of escape of the contents through an opening in the cage wall and to the equilibrium between inside and outside. Furthermore, in the case of substrates within enzyme active sites, it is suggested that the pressure is anisotropic. Pressure localized along certain directions may play an important role in the catalytic function of the enzyme.
Mapping the Geometry of Metal Three‐Coordination Using Crystal Structure Data: Reaction Pathway for Ligand Addition to Linear HgII Species
Authors: Allen Frank H. , Mondal Raju , Pitchford Nigel A. , Howard Judith A. K. 
Published: April 2003

AbstractSymmetry‐modified principal‐component analysis has been used to visualise the geometrical distortions of three‐coordinate metal centres observed in crystal structures retrieved from the Cambridge Structural Database. It is shown that compounds of Cu, Ag, Hg, Zn, and Au dominate the dataset, and exhibit distortions away from the trigonal planar archetype towards a) T‐shaped and b) Y‐shaped geometries. A small number of compounds, principally of Cu and Ag, also show distortions towards trigonal pyramidal geometries. The interconversions from Y‐shaped geometries, through the trigonal planar form to T‐shaped geometries are clearly mapped by the PC analysis. For HgII complexes, it is possible to interpret the transition from T‐shaped geometries to the trigonal planar form in terms of a reaction pathway for ligand addition to linear L1HgIIL2 species.
Synthesis and Some Biochemical Properties of a Novel 5,6,7,8‐Tetrahydropyrimido[4,5‐c]pyridazine Nucleoside
Authors: Loakes David , Brown Daniel M. , Salisbury Stephen A. , McDougall Mark G. , Neagu Constantin , Nampalli Satyam , Kumar Shiv 
Published: April 2003

AbstractA novel nucleoside analogue is described based on the pyridazine ring system. The nucleoside was successfully incorporated into DNA via both its phosphoramidite and 5′‐triphosphate derivatives. Enzymatically, the analogue behaves essentially as thymidine: it is a good substrate for the DNA polymerases Taq and exonuclease‐free Klenow fragment, leading to full‐length products when present in either the primer or template strands. In hybridisation studies, the nucleoside displays ambiguous base‐pairing properties, including universal base properties.
1,2,4,5‐Tetrazines vs. Carboxylic Acid Dimers: Molecular Chemistry vs. Supramolecular Chemistry
Authors: Infantes Lourdes , Mahon Mary F. , Male Louise , Raithby Paul R. , Teat Simon J. , Sauer Jürgen , Jagerovic Nadine , Elguero José , Motherwell Sam 
Published: April 2003

AbstractThe structures of six new tetrazines have been determined and their molecular packing has been compared to the supermolecular architecture observed in related carboxylic acid dimers. In the tetrazines, covalent NN bonds are considered to replace the intermolecular OH⋅⋅⋅O hydrogen bonds of the carboxylic acids. In the systems investigated, it is apparent that, in the majority of cases, the covalent six‐membered ring of the tetrazine is an appropriate replacement for the carboxylic acid synthon. This apparent interplay between molecular and supramolecular units may have applications in the crystal engineering of new materials.
Crystal Structure of an EMAP‐II‐Like Cytokine Released from a Human tRNA Synthetase
Authors: Yang Xiang‐Lei , Liu Jianming , Skene Robert J. , McRee Duncan E. , Schimmel Paul 
Published: April 2003

AbstractAminoacyl‐tRNA synthetases catalyze the first step of protein synthesis by aminoacylation of tRNAs. Remarkably, biological fragments of two human enzymes – tyrosyl‐tRNA synthetase (TyrRS) and tryptophanyl‐tRNA synthetase – are active cytokines produced by proteolysis or alternative splicing. One is a C‐terminal fragment of TyrRS (C‐TyrRS) that has potent activity for chemotaxis of leukocytes and monocytes and for stimulating production of other cytokines. Significantly, the cytokine activity of C‐TyrRS is absent in the context of the full‐length native protein. Unknown is the mechanism by which domain‐release from the dimeric native protein activates the cytokine. Here, the crystal structure of C‐TyrRS is presented at 2.2 Å resolution. This structure is similar to that of endothelial monocyte‐activating protein II (EMAP‐II), with critical residues of a heptapeptide element important for chemotaxis activity exposed on the first strand of a β‐barrel of the monomeric unit. In contrast, the same residues of C‐TyrRS are buried in an operational model for native TyrRS. Importantly, C‐TyrRS is shown here to be monomeric when released from dimeric native TyrRS. Further analysis suggests that the critical residues are exposed when tRNA is bound. Thus, tRNA binding to native TyrRS may be an additional or alternative way to activate cytokine signaling.
Comparing Intrinsic Reactivities of the First‐ and Second‐Generation Ruthenium Metathesis Catalysts in the Gas Phase
Authors: Adlhart Christian , Chen Peter 
Published: April 2003

AbstractAn experimental comparison of the gas‐phase reactivity of the 14‐electron reactive intermediates produced by phosphine dissociation from the first‐ and second‐generation ruthenium metathesis catalysts, (L)Cl2RuCHR (L=PCy3 or NHC), supports Grubbs's contention that the second‐generation catalysts show hundred‐fold higher phenomenological activity despite a slower phosphine dissociation because of a much more‐favorable partitioning of the 14‐electron active species towards product‐forming steps. The gas‐phase study finds, in ring‐opening metathesis of norbornene as well as acyclic metathesis of ethyl vinyl ether, that the first‐generation systems display evidence for a higher barrier above that for phosphine dissociation; the second‐generation systems, on the other hand, behave as if there is no significantly higher barrier.
The influence of infant irritability on maternal sensitivity in a sample of very premature infants
Authors: Meier Petra , Wolke Dieter , Gutbrod Tina , Rust Libi 
Published: April 2003

AbstractThe relationship between maternal sensitivity and infant irritability was investigated in a short‐term longitudinal study of 29 very preterm infants. Infant irritability was assessed at term with the Brazelton NBAS, the Mother and Baby Scales (MABS) and the Crying Pattern Questionnaire (CPQ). Maternal sensitivity was assessed by nurses' ratings in the neonatal care unit and at three months during mother–infant interaction observation. Cross‐lagged panel analysis indicated that neonatal irritability did not influence sensitivity at 3 months nor did maternal sensitivity in the newborn period lead to reduced irritability at 3 months. Both irritability and maternal sensitivity showed moderate stability over time (r = 0.55 and r = 0.60, respectively). It is concluded that in early infancy maternal sensitivity shows little influence on infant irritability in very preterm infants. Copyright © 2003 John Wiley & Sons, Ltd.
Placental transfer of naturally acquired, maternal cytomegalovirus antibodies in term and preterm neonates
Authors: Mussi‐Pinhata Marisa Márcia , Gomes Pinto Patrícia Cristina , Yamamoto Aparecida Yulie , Berencsi Klara , de Souza Cleonice Barbosa Sandoval , Andrea Mauro , Duarte Geraldo , Jorge Salim Moyses 
Published: April 2003

AbstractMaternal antibodies may protect the fetus and neonate against severe forms of CMV‐caused disease, therefore this study investigated the efficiency of the placental transfer of naturally acquired, maternal total anti‐cytomegalovirus (CMV) IgG and neutralizing antibodies at different gestational ages. The study was conducted on 182 healthy CMV‐seropositive Brazilian mothers and their 196 infants who were not infected congenitally with CMV, as determined by CMV detection in urine. The study groups were composed of 44 infants aged 28–30 weeks; 51 infants aged 31–33 weeks; 62 infants aged 34–36 weeks, and 39 infants of gestational age ≥37 weeks. Quantitative detection of total CMV IgG was carried out using EIA and virus neutralizing titers were determined by a microneutralization assay in sera from mothers and infants. CMV IgG levels and neutralizing titers of the infants correlated with maternal levels (r = 0.873 and r = 0.841, respectively). The efficiency of placental transfer of these antibodies was enhanced significantly as gestation progressed until 34–36 weeks, when values similar to those of full‐term infants (90–100%) were found. Transfer ratios were significantly higher for neutralizing compared to total CMV IgG antibodies at gestational age 31–33 weeks (100% vs. 84%, respectively) and at gestational age 28–30 weeks (75% vs. 60%, respectively). We conclude that placental transfer of naturally acquired maternal CMV neutralizing and total CMV IgG antibodies are similarly efficient above 34 weeks of gestational age. At less than 34 weeks of gestational age, transfer of neutralizing antibodies may be favored and these antibodies reach the neonatal serum of 99% of these premature infants. J. Med. Virol. 69:232–239, 2003. © 2003 Wiley‐Liss, Inc.
Reaction Mechanism of Enzymatic Degradation of Poly(butylene succinate‐co‐terephthalate) (PBST) with a Lipase Originated from Pseudomonas cepacia
Authors: Honda Nozomi , Taniguchi Ikuo , Miyamoto Matsatoshi , Kimura Yoshiharu 
Published: April 2003

AbstractAn aliphatic/aromatic copolyester, poly(butylene succinate‐co‐terephthalate) (PBST), was prepared to investigate the effect of the aromatic units on the enzymatic degradation of the poly(butylene succinate) (PBS) derivatives in the presence of a lipase originated from Pseudomonas cepacia (Lipase PS®). The degradability of PBST was found to increase with increasing BS content. The degradation products were analyzed in detail by liquid chromatograph mass spectrometry (LC‐MS). A hexamer containing one terephthalate unit was the largest fragment among the diverse fragments detected, while a pentamer was the largest one consisting only of succinate units. The oligomeric fragments cut out from the polymer chain were involved in the secondary hydrolysis into 4‐hydroxybutyl succinate (BSH) and terephthalate (BTH). The trimeric fragments tetramethyl disuccinate (SBSH) and succinate terephthalate (SBTH), having both carboxyl end groups, were slowly hydrolyzed by a nonspecific mechanism. Based on these data, the overall mechanism of the enzymatic hydrolysis of this aliphatic/aromatic copolyester is proposed, in which PBST undergoes endo hydrolysis.A plausible mechanism of enzymatic hydrolysis of PBST with Lipase PS®.magnified imageA plausible mechanism of enzymatic hydrolysis of PBST with Lipase PS®.
UV/Visible Study of the Reaction of Oxidoreductases and Model Compounds with H2O2
Authors: Ferreira María Luján 
Published: April 2003

AbstractOxidative dehydrogenation/polymerization of aromatic compounds such as phenol or aniline and derivatives has been reported using a peroxidase‐H2O2 system. In the search for alternatives for expensive peroxidase, it is important to provide similar advantages to those of HRP while decreasing the catalyst cost. Knowledge of the mechanism details is important for achieving this objective. UV/Visible studies are useful to study mechanistic details and electronic changes in the compounds. These data are reported for the reaction of Catalase from Aspergillus Niger (CAP), Peroxidase from Horseradish (HRPC), Hematin and 2,6‐bis[1‐2,6‐diisopropylphenyliminoethyl]pyridine iron(II) chloride (FeB) with H2O2. Detailed spectral analysis reveals differences for Catalase, Peroxidase, and model compounds in the presence of H2O2. The possibility of hematin or FeB‐H2O2 as models for the peroxidase‐H2O2 reaction is discussed. The published mechanisms for the peroxidase‐H2O2 and Catalase‐H2O2 reactions are analyzed. The results are discussed taking into account theoretical studies on some key aspects of the mechanism.
UV/Visible spectra of CAP (Catalase concentration 72.4 U/mL).magnified imageUV/Visible spectra of CAP (Catalase concentration 72.4 U/mL).