bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and characterization of 5‐fluorouracil‐loaded poly(ϵ‐caprolactone) microspheres for drug administration
Authors: Sastre Roberto L. , Blanco M. Dolores , Teijón César , Olmo Rosa , Teijón José María
Published: January 2005

Microspheres of 5‐fluorouracil‐loaded poly(ϵ‐caprolactone) (PCL) were prepared by spray‐drying procedure. The degradation characteristics and 5‐fluorouracil release in vitro as well as in vivo were investigated. The average molecular weight, weight loss, crystallinity, and morphology of microspheres were determined using GPC, DSC, and SEM, at different times during the in vitro degradation process. The size distribution of the microspheres indicated that most of the particles were smaller than 3 µm. A 30% weight loss as well as an increase of crystallinity were observed on day 330 of incubation. The percentage of entrapment efficiency of 5‐FU was 49% (44 µg of drug/mg of microspheres). The in vitro total release of 5‐FU took place in 8 days. Determination of plasma 5‐FU concentration in vivo using s.c. injection of 5‐FU‐loaded microspheres in Wistar rats by HPLC with analysis of data using a non‐compartmental model showed drug in plasma 18 days after administration with a maximum drug concentration of 1.5 µg/ml at 96 h. Pharmacokineticallly, a significant increase of AUC and MRT of 5‐FU with regard to the administration of the drug in solution. Scanning electron microscopy and histological studies indicated that the microspheres were surrounded by connective tissue and inflammatory processes were not evident. As a result of these characteristics, the 5‐FU‐loaded PCL microspheres could be used for drug delivery. Drug Dev Res 63:41–53, 2004. © 2004 Wiley‐Liss, Inc.
A mouse model to assess endothelial activation in vivo by targeted insertion of alkaline phosphatase into the E‐selectin gene
Authors: Luyten Marcel A. , Hofmann Matthias , Käslin Edgar , Klanke Bernd , Pally Charles , Kawai Ryosei , Zerwes Hans‐Günter
Published: January 2005

We have developed a novel and noninvasive animal model in which the activity of a marker enzyme in plasma is used to measure endothelial cell activation. Secreted heat‐stable human placental alkaline phosphatase (SeAP) was placed under the transcriptional control of the E‐selectin promoter by targeted integration into the mouse E‐selectin locus. Two transgenic mouse lines were generated: (1) ESAP‐1, coding for an extended mRNA containing SeAP and part of the 3′ E‐selectin mRNA and (2) ESAP‐2, coding for a short mRNA containing SeAP followed by the SV40 late mRNA polyadenylation site. Wild‐type mice did not express SeAP mRNA or detectable enzyme activity in plasma. Baseline SeAP activity was 8.1±0.4 ng/mL for ESAP‐1 mice and 12.3±0.4 µg/mL for ESAP‐2 mice. Upon treatment with lipopolysaccharide or tumor necrosis factor TNF‐α (but not interferon‐γ), SeAP activity increased 7–11‐fold in plasma obtained from both mouse lines, with 500‐fold higher levels and prolonged expression kinetics in the ESAP‐2 mice compared to ESAP‐1 mice. Enzyme histochemistry indicated endothelial origin of the alkaline phosphatase activity. Administration of dexamethasone, an antiinflammatory steroid, inhibited TNFα‐induced SeAP expression in mice from both lines. The model described here allows monitoring of the E‐selectin expression in vivo, offering a noninvasive means to quantitate inflammatory endothelial cell activation and to evaluate therapeutic approaches designed to inhibit endothelial cell activation. Drug Dev. Res. 63:54–65, 2004. © 2004 Wiley‐Liss, Inc.
Differential effect of the PDE5 inhibitors, sildenafil and zaprinast, in aging‐ and lipopolysaccharide‐induced cognitive dysfunction in mice
Authors: Patil Chandrashekhar S. , Jain Naveen K. , Singh Vijay Pal , Kulkarni Shrinivas K.
Published: January 2005

In the present study, we have investigated the effects of exogenously administered cyclic GMP‐specific PDE5 inhibitors, sildenafil and zaprinast, on cognitive performance in aged‐ and lipopolysaccharide (LPS)‐treated mice using passive avoidance and plus‐maze tasks. Aged and LPS‐treated mice showed poor retention of memory in step‐through passive avoidance and plus‐maze task. Administration of PDE5 inhibitors reversed the age‐induced retention deficits in both of the test paradigms. Also, PDE5 inhibitors on acute administration in young mice showed improvement in memory retention when tested in both of the paradigms. However, the effect of two PDE5 inhibitors was more pronounced in aged animals than that in young mice. PDE5 inhibitors enhanced the retention deficits in LPS‐treated animals, which might be due to elevation of cGMP levels caused by sildenafil and zaprinast. In conclusion, these results indicated that differential effects of PDE5 inhibitors in aging and LPS‐treated mice, but its prudential effect in aged mice may suggest new therapeutic use of these compounds. Drug Dev. Res. 63:66–75, 2004. © 2004 Wiley‐Liss, Inc.
A new carboxamide compound exerts immuno‐suppressive activity by inhibiting dendritic cell maturation
Authors: Carbonnelle Delphine , Ebstein Frederic , Rabu Catherine , Petit Jean‐Yves , Gregoire Marc , Lang François
Published: January 2005

The immunosuppressive properties of a benzamide derivative, JM34, previously characterized as an anti‐inflammatory compound are described. The immunosuppressive potential of JM34 was evidenced by inhibition of PBMC proliferation in vitro with an IC50 of 20 µM. In contrast with classical immunosuppressive drugs, JM34 affected neither cytokine production nor IL‐2R expression from activated T cell clones, and displayed only moderate inhibition of IL‐2‐induced or anti‐CD3/anti‐CD28‐induced proliferation. We investigated its effects on dendritic cells (DC) in vitro. Addition of JM34 during DC maturation inhibited the expression of some maturation markers: specifically, MHC molecule up‐regulation was totally inhibited and CD83 expression was significantly reduced, while up‐regulation of CD86, CD80 or CD40 was less affected. Moreover, JM34‐treated DC showed impaired IL‐12 but not IL‐10 secretion, and a markedly reduced ability to present antigens to naive T lymphocytes in vitro. We provide evidence that these JM34‐induced alterations of DC were associated with a marked inhibition of NF‐κB nuclear translocation. Finally, JM34 inhibited delayed type hypersensitivity dose dependently in mice. In conclusion, our data suggest that JM34 inhibited T lymphocyte activation mainly by targeting DC, and thus may represent a new class of therapeutic agents in the fields of transplantation and autoimmune diseases.
SLP‐76 is recruited to CD22 and dephosphorylated by SHP‐1, thereby regulating B cell receptor‐induced c‐Jun N‐terminal kinase activation
Authors: Mizuno Kazuya , Tagawa Yuko , Watanabe Noriyuki , Ogimoto Mami , Yakura Hidetaka
Published: January 2005

Despite the important role in the development and activation of T cells, NK cells, mast cells, and macrophages, the expression and function of SLP‐76 in B cells have been largely unknown. Here we demonstrate that SLP‐76 is expressed in all mouse B cell lines tested and in normal splenic B cells, and serves as an SHP‐1 substrate. Dephosphorylation of SLP‐76 by SHP‐1 inhibits its association with Nck, down‐regulating c‐Jun N‐terminal kinase (JNK) activation and exerting a positive effect on apoptosis. Knockdown of SLP‐76 in WEHI‐231 cells by small interfering RNA attenuated JNK activation, but showed little effects on extracellular signal‐regulated kinase (ERK) or p38 activation. Although WEHI‐231 does not express linker for activation of T cells (LAT), SLP‐76 localizes in membrane fraction, which increases following B cell receptor (BCR) cross‐linking. Further analyses revealed that SLP‐76 complexed with Gads is associated with tyrosine‐phosphorylated CD22 through the SH2 domains of SLP‐76 and Gads. Given that SHP‐1 binds to CD22 upon BCR ligation, our findings suggest that dephosphorylation of SLP‐76 recruited to CD22 by SHP‐1 inhibits BCR‐induced JNK activation, dictating apoptosis.
In vivo quercitrin anti‐inflammatory effect involves release of quercetin, which inhibits inflammation through down‐regulation of the NF‐κB pathway
Authors: Comalada Mònica , Camuesco Desirée , Sierra Saleta , Ballester Isabel , Xaus Jordi , Gálvez Julio , Zarzuelo Antonio
Published: January 2005

Quercetin is a common antioxidant flavonoid found in vegetables, which is usually present in glycosylated forms, such as quercitrin (3‐rhamnosylquercetin). Previous in vitro experiments have shown that quercetin exerts a bigger effect than quercitrin in the down‐regulation of the inflammatory response. However, such results have not been reproduced in in vivo experimental models of intestinal inflammation, in which quercetin did not show beneficial effects while its glycosides, quercitrin or rutin, have demonstrated their effectiveness. In this study, we have reported that the in vivo effects of quercitrin in the experimental model of rat colitis induced by dextran sulfate sodium can be mediated by the release of quercetin generated after glycoside's cleavage by the intestinal microbiota. This is supported by the fact that quercetin, but not quercitrin, is able to down‐regulate the inflammatory response of bone marrow‐derived macrophages in vitro. Moreover, we have demonstrated that quercetin inhibits cytokine and inducible nitric oxide synthase expression through inhibition of the NF‐κB pathway without modification of c‐Jun N‐terminal kinase activity (both in vitro and in vivo). As a conclusion, our report suggests that quercitrin releases quercetin in order to perform its anti‐inflammatory effect which is mediated through the inhibition of the NF‐κB pathway.
Ethnophaulisms for ethnic immigrant groups: the contributions of group size and familiarity
Authors: Mullen Brian , Rozell Drew , Johnson Craig
Published: January 2005

An archival analysis was conducted on the ethnophaulisms for ethnic immigrant groups as a function of the size and the familiarity of those groups. Cognitive representation was operationalized as the degree of complexity in, and the valence of, the ethnophaulisms applied to ethnic immigrant groups in the United States during each of 15 consecutive 10‐year time periods. Group size was operationalized as the number of first‐generation persons in these ethnic groups during each of these same 15 10‐year time periods. Familiarity was operationalized in terms of the number of times each ethnic immigrant group was mentioned in social histories and popular songs for each of these same 15 10‐year time periods. Ethnophaulisms for smaller groups tended to be less complex and more negative and ethnophaulisms for less familiar groups tended to be less complex and more negative. Analyses delineate the interrelations between ethnic immigrant group size, ethnic immigrant group familiarity, and the cognitive representations of these groups. The implications of these results for research on intergroup perceptions are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Blatant and subtle prejudice: dimensions, determinants, and consequences; some comments on Pettigrew and Meertens
Authors: Coenders Marcel , Scheepers Peer , Sniderman Paul M. , Verberk Geneviève
Published: January 2005

Although it has become common to suggest a conceptual distinction between traditional and contemporary forms of prejudice, Pettigrew and Meertens have actually attempted to distinguish the two empirically and developed measures to gauge each. Replication of their study, on the distinction between blatant and subtle prejudice, discloses a number of methodological flaws that have led to debatable substantial conclusions. We found two distinct measures, however, substantially different from the ones proposed by Pettigrew and Meertens. Our model shows, by all available indices, a better fit to the data: a first broad factor labelled general prejudice, and a small second factor labelled perceived cultural differences. The first factor is well explained by a number of social characteristics; the second is rather poorly explained and has a rather poor discriminatory power. The first one has strong effects on some consequential variables whereas the second has hardly any effects. Other evidence, considered to be crucial by Pettigrew and Meertens, contains other methodological flaws, i.e. the neglect of interdependent items. After this correction, their piece of evidence turns out to be artificial. As a benefit to future research, we try to clarify conditions for distinguishing empirically and conceptually between traditional and contemporary prejudice. Copyright © 2001 John Wiley & Sons, Ltd.
In defense of the subtle prejudice concept: a retort
Authors: Pettigrew Thomas F. , Meertens Roel W.
Published: January 2005

With no theory and the use of different methods and assumptions, Coenders and his colleagues not surprisingly produce a different analysis of prejudice from ours of 1995. But we see no reason to withdraw our claims for both the concept and measurement of subtle prejudice. By obscuring our theoretical structure and offering none of their own, our critics follow their empirical preferences to reach a meaningless solution. In doing so, they disregard the social psychological literature on prejudice—especially that of Rokeach and Tajfel. Moreover, their reanalysis of the 1988 Eurobarometer survey data does not replicate our analysis in important ways. We answer their objections to our use of orthogonal varimax rotation and our demonstrations of the predictive value of the Subtle Prejudice Scale, and we show that when tested appropriately our theoretically derived model performs as well as and often significantly better than their atheoretical model. We also find the six conditions set down by Coenders et al. for differentiating the two forms of prejudice are largely met by our analysis. Finally, repeated replications by other investigators in ten countries with diverse outgroups and new samples support both our original analysis and the usefulness of our Blatant and Subtle Prejudice Scales. Copyright © 2001 John Wiley & Sons, Ltd.
False consensus and the outgroup homogeneity effect: interference in measurement or intrinsically dependent processes?
Authors: De La Haye Anne‐Marie
Published: January 2005

In studies on the Outgroup Homogeneity Effect (OHE), a common measure is percentage estimates. A possible difficulty is that percentage estimates are also sensitive to the False Consensus Effect (FCE). I present an experiment aimed at analysing how these two phenomena interact. Engineering and business students indicated whether behaviour descriptions were true or false for themselves, then estimated the percentages of members of each group who would self‐ascribe the same items. In order to bring the OHE to light while controlling for self‐ascription, an item‐per‐item analysis is necessary. In such an analysis, the OHE must appear as over‐attribution of any item by members of the group for which the item is not typical. I examined whether this effect appeared among subjects who either did or did not ascribe each item to themselves. This was done through an ANOVA where items were entered as the random factor. The False Consensus and the Outgroup Homogeneity effects both showed up in this analysis, but they interacted with each other in such a way that they could be different aspects of the same phenomenon. The consequences of this unexpected finding for the definition of the OHE are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
‘Seek and ye shall find’: antecedents of assimilation and contrast in social comparison
Authors: Mussweiler Thomas
Published: January 2005

Based on a Selective Accessibility (SA) model of comparison consequences, it is suggested that the self‐evaluative effects of social comparisons depend on the nature of the hypothesis that is tested as a starting‐point of the comparison process. If judges test the hypothesis that they are similar to the standard, then standard‐consistent self‐knowledge is rendered accessible so that self‐evaluations are assimilated towards the standard. If judges test the hypothesis that they are dissimilar from the standard, however, standard‐inconsistent self‐knowledge is made accessible so that self‐evaluations are contrasted away from the standard. These predictions are tested by inducing participants to test for similarity versus dissimilarity to the standard via a procedural priming manipulation. Consistent with the SA model, assimilation occurs if participants are procedurally primed to focus on similarities to the standard, whereas contrast results if they are primed to focus on dissimilarities. These findings suggest that similarity versus dissimilarity testing is a crucial determinant of assimilation versus contrast. It is proposed that distinguishing between these two alternative hypotheses may provide an integrative framework for an understanding of the self‐evaluative consequences of social comparisons. Copyright © 2001 John Wiley & Sons, Ltd.
Sample stacking for the analysis of eight penicillin antibiotics by micellar electrokinetic capillary chromatography
Authors: Puig Patricia , Borrull Francesc , Calull Marta , Aguilar Carme
Published: January 2005

We studied the use of micellar electrokinetic capillary chromatography for separating eight penicillins. The method consists of (i) an electrophoretic separation based on micellar electrokinetic capillary chromatography, which uses sodium dodecyl sulfate (SDS) as surfactant; (ii) a sample stacking technique called reverse electrode polarity stacking mode (REPSM); and (iii) direct UV detection. The background electrolyte that gave complete separation contained 20 mM sodium borate buffer and 60 mM SDS. The sensitivity of the method was improved by an enrichment step that used on‐column stacking. The limits of detection were at the μg·L−1 level for the penicillins and did not detract from the peak resolution.
Comparison of the use of single capillaries and coupled capillaries based on micellar electrokinetic chromatography (MEKC) and sweeping‐MEKC modes
Authors: Shih Chun‐Min , Lin Cheng‐Huang
Published: January 2005

The use of single capillaries (25 and 50 μm inner diameter (ID)) and coupled capillaries of different diameters (100–50 and 75–25 μm ID) based on micellar electrokinetic chromatography (MEKC) and sweeping‐MEKC modes is compared and reported. Naphthalene‐2,3‐dicarboxaldehyde (NDA)‐derivatized dopamine was selected as the model compound by examining the fluorescence intensity when a violet (410 ± 7 nm, ˜2 mW) light‐emitting‐diode (LED) was used as the light source. When a single capillary (50 μm ID) was used, the detection limit for NDA‐derivatized dopamine was determined to be 2.0 × 10−7 M (Signal‐to‐nose ratio S/N = 3) based on the MEKC mode. This was improved to 4.0 × 10−9 M when the sweeping‐MEKC mode was applied. In addition, this can be further improved to 1.0 × 10−9 M and 5.6 × 10−10 M when 100–50 and 75–25 μm ID coupled capillaries are used. The use of the coupled capillary is also helpful for improving the separation efficiency. Based on the sweeping‐MEKC mode, the number of theoretical plates (N) for the detected peaks were determined to be 6.3 ± 2.7 × 105 by means of a single capillary (50 μm ID). This can be improved to 9.4 ± 3.6 × 105 and 9.4 ± 0.9 × 106 when the 100–50 and 75–25 μm ID coupled capillaries were applied.
Micellar electrokinetic chromatographic and capillary zone electrophoretic methods for screening urinary biomarkers of human disorders: A critical review of the state‐of‐the‐art
Authors: Iadarola Paolo , Cetta Giuseppe , Luisetti Maurizio , Annovazzi Laura , Casado Begona , Baraniuk James , Zanone Chiara , Viglio Simona
Published: January 2005

Human urine plays a central role in clinical diagnostic being one of the most‐frequently used body fluid for detection of biological markers. Samples from patients with different diseases display patterns of biomarkers that differ significantly from those obtained from healthy subjects. The availability of fast, reproducible, and easy‐to‐apply analytical techniques that would allow identification of a large number of these analytes is thus highly desiderable since they may provide detailed information about the progression of a pathological process. From among the variety of methods so far applied for the determination of urinary metabolites, capillary electrophoresis, both in the capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) modes, represents a robust and reliable analytical tool widely used in this area. The aim of the present article is to focus the interest of the reader on recent applications of MEKC and CZE in the field of urinary biomarkers and to discuss advantages and/or limitations of each mode.
Analysis of lamotrigine and its metabolites in human plasma and urine by micellar electrokinetic capillary chromatography
Authors: Pucci Vincenzo , Bugamelli Francesca , Baccini Cesare , Raggi Maria Augusta
Published: January 2005

A reliable micellar electrokinetic capillary chromatographic method was developed and validated for the determination of lamotrigine and its metabolites in human plasma and urine. The variation of different parameters, such as pH of the background electrolyte (BGE) and Sodium dodecyl sulfate (SDS) concentration, were evaluated in order to find optimal conditions. Best separation of the analytes was achieved using a BGE composed of 10 mM borate and 50 mM SDS, pH 9.5; melatonin was selected as the internal standard. Isolation of lamotrigine and its metabolites from plasma and urine was accomplished with an original solid‐phase extraction procedure using hydrophilic‐lypophilic balance cartridges. Good absolute recovery data and satisfactory precision values were obtained. The calibration plots for lamotrigine and its metabolites were linear over the 1–20 μg/mL concentration range. Sensitivity was satisfactory; the limits of detection and quantitation of lamotrigine were 500 ng/mL and 1 μg/mL, respectively. The application of the method to real plasma samples from epileptic patients under therapy with lamotrigine gave good results in terms of accuracy and selectivity, and in agreement with those obtained with an high‐performance liquid chromatography (HPLC) method.*
Microemulsion and micellar electrokinetic chromatography of Hematoporphyrin D: A starting material of hematoporphyrin derivative
Authors: Li Qi , Chang C. K. , Huie Carmen W.
Published: January 2005

An investigation of the basic factors which govern the microemulsion electrokinetic chromatography (MEEKC) and micellar electrokinetic chromatography (MEKC) separation of Hematoporphyrin D and its base hydrolysis product, hematoporphyrin derivative (HpD), was performed. These model compounds contain a complex mixture of porphyrin monomers, dimers and/or oligomers, and were utilized to gain insights into the MEEKC/micellar electrokinetic chromatography (MEKC) separation of samples containing highly lipophilic substances. For example, the organic modifier/cosurfactant (1‐butanol) and/or oil phase (e.g., 1‐octanol in comparison to ethyl acetate) were found to have an apparent influence on the separation selectivity of Hematoporphyrin D, the extent of which was dependent on the chemical nature of the surfactant employed (e.g., sodium dodecyl sulfate vs. sodium cholate). An interesting and important finding was that the presence of an organic modifier (methanol or acetonitrile at a concentration of 20% or higher) in the sample matrix as well as in the run buffer was essential for the optimal MEEKC or MEKC separation of a number of porphyrin monomers (including hematoporphyrin IX and its acetates, most likely hydroxyacetate, diacetate, and vinyl acetate, as well as its dehydration products, hydroxyethylvinyldeuteroporphyrin and protoporphyrin) contained in Hematoporphyrin D. On the other hand, the use of these optimized conditions for the MEEKC or MEKC separation of various oligomeric porphyrin species in HpD were unsatisfactory. As HpD is a well‐known and effective photosensitizing agent in photodynamic therapy (a new approach for cancer treatment), the improved separation and characterization of various monomeric and oligomeric porphyrin species in HpD and its starting material, such as Hematoporphyrin D, is a challenging and important task.
How Fanconi anemia proteins promote the four Rs: Replication, recombination, repair, and recovery
Authors: Thompson Larry H. , Hinz John M. , Yamada N. Alice , Jones Nigel J.
Published: January 2005

The genetically complex disease Fanconi anemia (FA) comprises cancer predisposition, developmental defects, and bone marrow failure due to elevated apoptosis. The FA cellular phenotype includes universal sensitivity to DNA crosslinking damage, symptoms of oxidative stress, and reduced mutability at the X‐linked HPRT gene. In this review article, we present a new heuristic molecular model that accommodates these varied features of FA cells. In our view, the FANCA, ‐C, and ‐G proteins, which are both cytoplasmic and nuclear, have an integrated dual role in which they sense and convey information about cytoplasmic oxidative stress to the nucleus, where they participate in the further assembly and functionality of the nuclear core complex (NCCFA = FANCA/B/C/E/F/G/L). In turn, NCCFA facilitates DNA replication at sites of base damage and strand breaks by performing the critical monoubiquitination of FANCD2, an event that somehow helps stabilize blocked and broken replication forks. This stabilization facilitates two kinds of processes: translesion synthesis at sites of blocking lesions (e.g., oxidative base damage), which produces point mutations by error‐prone polymerases, and homologous recombination‐mediated restart of broken forks, which arise spontaneously and when crosslinks are unhooked by the ERCC1‐XPF endonuclease. In the absence of the critical FANCD2 monoubiquitination step, broken replication forks further lose chromatid continuity by collapsing into a configuration that is more difficult to restart through recombination and prone to aberrant repair through nonhomologous end joining. Thus, the FA regulatory pathway promotes chromosome integrity by monitoring oxidative stress and coping efficiently with the accompanying oxidative DNA damage during DNA replication. Environ. Mol. Mutagen., 2005. Published 2005 Wiley‐Liss, Inc.
Molecular nature of intrachromosomal deletions and base substitutions induced by environmental mutagens
Authors: Nohmi Takehiko , Masumura Ken‐ichi
Published: January 2005

Cellular DNA is exposed to a variety of exogenous and endogenous mutagens. A complete understanding of the importance of different types of DNA damage requires knowledge of the specific molecular alterations induced by different types of agents in specific target tissues in vivo. The gpt delta transgenic mouse model provides the opportunity to characterize tissue‐specific DNA alterations because small and large deletions as well as base substitutions can be analyzed. Here, we summarize the characteristics of intrachromosomal deletions and base substitutions induced by ionizing radiation in liver and spleen, ultraviolet B (UVB) radiation in epidermis, mitomycin C (MMC) in bone marrow, 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine (PhIP) in colon, and aminophenylnorharman (APNH) in liver of gpt delta mice. Carbon‐ion radiation, UVB, and MMC induced large deletions of more than 1 kb. About half of the large deletions occurred between short direct‐repeat sequences and the remainder had flush ends, suggesting the involvement of nonhomologous end joining of double‐stranded breaks (DSBs) in DNA. UV photoproducts and interstrand crosslinks by MMC may block DNA replication, thereby inducing DSBs. In contrast, PhIP and APNH mainly generated 1 bp deletions in runs of guanine bases. As for base substitutions, UVB and MMC induced G:C→A:T transitions at dipyrimidine sites and tandem base substitutions at GG sites, respectively. PhIP and APNH induced G:C→T:A transversions. Translesion DNA synthesis across the lesions, i.e., UV photoproducts, intrastrand crosslinks by MMC, and guanine adducts by the heterocyclic amines, may be involved in the induction of base substitutions. These results indicate the importance of sequence information to elucidate the mechanisms underlying deletions and base substitutions induced in vivo by environmental mutagens. Environ. Mol. Mutagen., 2005. © 2005 Wiley‐Liss, Inc.
A reduced‐order modeling technique for tall buildings with active tuned mass damper
Authors: Qu Zu‐Qing , Shi Yinming , Hua Hongxing
Published: January 2005

It is impractical to install sensors on every floor of a tall building to measure the full state vector because of the large number of degrees of freedom. This makes it necessary to introduce reduced‐order control. A kind of system reduction scheme (dynamic condensation method) is proposed in this paper. This method is iterative and Guyan condensation is looked upon as an initial approximation of the iteration. Since the reduced‐order system is updated repeatedly until a desired one is obtained, the accuracy of the reduced‐order system resulting from the proposed method is much higher than that obtained from the Guyan condensation method. Another advantage of the method is that the reduced‐order system is defined in the subspace of the original physical space, which makes the state vectors have physical meaning. An eigenvalue shifting technique is applied to accelerate the convergence of iteration and to make the reduced system retain all the dynamic characteristics of the full system within a given frequency range. Two schemes to establish the reduced‐order system by using the proposed method are also presented and discussed in this paper. The results for a tall building with active tuned mass damper show that the proposed method is efficient for the reduced‐order modelling and the accuracy is very close to exact only after two iterations. Copyright © 2001 John Wiley & Sons, Ltd.
Seismic isolation of cable‐stayed bridges for near‐field ground motions
Authors: Wesolowsky Michael J. , Wilson John C.
Published: January 2005

This study examines the efficacy of using seismic isolation to favorably influence the seismic response of cable‐stayed bridges subjected to near‐field earthquake ground motions. In near‐field earthquake ground motions, large amplitude spectral accelerations can occur at long periods where many cable‐stayed bridges have significant structural response modes. This combination of factors can result in large tower accelerations and base shears. In this study, lead–rubber bearing seismic isolators were modeled for three cable‐stayed bridges, and three cases of isolation were examined for each bridge. The nine isolated bridge configurations, plus three non‐isolated configurations as references, were subjected to near‐field earthquake ground motions using three‐dimensional time‐history analyses. Introduction of a small amount of isolation is shown to be very beneficial in reducing seismic accelerations and forces while at the same time producing only a modest increase in the structural displacements. There is a low marginal benefit to continue to increase the amount of isolation by further lengthening the period of the structure because structural forces and accelerations reduce at a diminishing rate whereas structural displacements increase substantially. In virtually all cases the base shears in the isolated bridges were reduced by at least 50several instances by up to 80individual near‐field records showed large variability from one record to the next, with coefficients of variation about the mean as large as 50assessing the characteristics of near‐field ground motion for use in isolation design of cable‐stayed bridges. Copyright © 2003 John Wiley & Sons, Ltd.
Dynamic behavior of perimeter lateral‐system structures with flexible diaphragms
Authors: Fleischman R. B. , Farrow K. T.
Published: January 2005

Building structures are typically designed using the assumption that the floor systems serve as a rigid diaphragm between the vertical elements of the lateral load‐resisting system. However, long‐floor span structures with perimeter lateral load‐resisting systems possess diaphragms which behave quite flexibly. The dynamic behaviour of such structures is dissimilar to the behavior expected of typical structures. This difference can lead to unexpected force and drift patterns. If force levels are sufficiently under‐estimated, inelastic diaphragm behaviour can occur, exacerbating the effects of diaphragm flexibility. Such response may lead to a non‐ductile diaphragm failure or structural instability due to high drift demands in the gravity system.

Analytical models were developed which capture the diaphragm flexibility of structures with long‐floor spans and perimeter lateral‐systems. Modal examination and time‐history analyses were performed to determine the effect of diaphragm flexibility and diaphragm inelastic behaviour on the dynamic behaviour of these structures. Copyright © 2001 John Wiley & Sons, Ltd.
Seismic isolation of rigid cylindrical tanks using friction pendulum bearings
Authors: Wang Yen‐Po , Teng Min‐Cheng , Chung Kuo‐Whie
Published: January 2005

Storage tanks are vulnerable to earthquakes, as numerous major earthquakes have demonstrated. The trend of recent revisions to make seismic design criteria for large‐scale industrial storage tanks increasingly stringent has made development of cost‐effective earthquake‐resistant design and retrofit techniques for industrial tanks imperative. This study assesses the feasibility of seismic base isolation for making liquid‐filled storage tanks earthquake resistant. The sliding‐type friction pendulum seismic (FPS) bearings are considered rather than the elastomeric bearings because the dynamic characteristics of an FPS‐isolated tank remain unchanged regardless of the storage level. This work has devised a hybrid structural‐hydrodynamic model and solution algorithm, which would permit simple, accurate and efficient assessment of the seismic response of rigid cylindrical storage tanks in the context of seismic isolation. Extensive numerical simulations confirm the effectiveness of seismic base isolation of rigid cylindrical tanks using FPS bearings. Copyright © 2001 John Wiley & Sons, Ltd.
Overview of the application of active/semiactive control to building structures in Japan
Authors: Nishitani Akira , Inoue Yutaka
Published: January 2005

Perhaps one of the most significant technological innovations in the structural engineering field is the practical application of active and semiactive control to civil structures. A number of structures integrating active, hybrid, and semiactive response control technologies have been constructed in Japan. Most of them are building structures. This paper provides an overview of those building structures, focusing mainly on the types of buildings that are controlled, and on the types of control devices that are implemented. Future directions of structural engineering are also discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Active variable stiffness system with non‐resonant control
Authors: Nasu Tadashi , Kobori Takuji , Takahashi Motoichi , Niwa Naoki , Ogasawara Katsura
Published: January 2005

The active variable stiffness (AVS) system is proposed as a seismic response control system. It actively controls structural stiffness of a building to establish a non‐resonant state against earthquake excitations, thus suppressing the building's response. It consumes a relatively small amount of energy and maintains the safety of the building in moderate to severe earthquakes. In order to accumulate and analyse practical data, a building was constructed as a trial structure about ten years ago. This paper describes the control algorithm, the applied system, some observed earthquake records, verification of control effectiveness based on simulation analyses, and some issues concerning system maintenance. Through earthquake observations, it was confirmed that the system could select the appropriate stiffness that assures a non‐resonant state, which results in a minimum response. Copyright © 2001 John Wiley & Sons, Ltd.
A hybrid mass damper system controlled by H∞ control theory for reducing bending–torsion vibration of an actual building
Authors: Fujinami Takeyoshi , Saito Yoshihito , Morishita Masayuki , Koike Yuji , Tanida Koji
Published: January 2005

A pair of hybrid mass dampers has been installed on an actual 23‐storey building located in Tokyo. The aim of the dampers is to counteract wind and smaller earthquake excited oscillations. H∞ control theory has been applied to control the dampers for reducing both bending and torsion vibrations simultaneously. For the design of the controller, identification parameters resulting from the forced vibration test of the building are adopted. The target of the controller performance is to reduce the vibration of first mode and to keep robust stabilization over the second or higher mode. From the results of forced vibration tests conducted after installation of the controller, it was confirmed that this system has proven control effect, largely satisfying what was aimed for in the design. Furthermore, system performance has been continually recorded during earthquakes, and analysis of the data has proved control effect. Copyright © 2001 John Wiley & Sons, Ltd.
Vibration control characteristics of a hybrid mass damper system installed in tall buildings
Authors: Saito Tomoo , Shiba Keiji , Tamura Kazuo
Published: January 2005

A large‐scale hybrid mass damper (HMD) system was developed to reduce building response during strong winds and earthquakes of up to medium strength. The HMD consists of an auxiliary mass supported by multi‐stage rubber bearings and actuators driven by AC servomotors.

Two HMDs were installed on the top floor of a target building to suppress both translational and torsional vibration. The system was installed in two high‐rise buildings. One was a 50‐storey, 200‐m high, steel‐frame building. The dynamic characteristics of both the building and the HMDs were identified through forced vibration tests using the HMD system. The effectiveness of the HMD system was confirmed by these tests and both wind and earthquake observation data.

The other building was a triangular‐plan, 43‐storey, steel‐frame building. The dynamic characteristics of the building were estimated using two different methods. One method comprised a series of vibration tests using the HMDs to excite the building. The other method was an analysis of the earthquake response records of the building, which showed the additional damping effect of the HMD system. The performance of the HMD system during a strong typhoon was also analysed. Copyright © 2001 John Wiley & Sons, Ltd.
Practical applications of active mass dampers with hydraulic actuator
Authors: Yamamoto Masashi , Aizawa Satoru , Higashino Masahiko , Toyama Kotaro
Published: January 2005

The application of active mass damper (AMD) systems into buildings has been studied analytically and experimentally during the 1980s. The main purpose of these systems is to reduce the vibrations of buildings during strong winds or small earthquakes in order to improve the comfort of the building occupants. The authors have worked on the study and development of an AMD system using an electro‐servo‐type hydraulic actuator.

First, the control technique of AMD with hydraulic actuator is formulated. Hydraulic actuators have an advantage of high durability and high cost performance, however, they also have non‐linear dynamics, which makes their control difficult.

Second, the applications of this system in the buildings are shown. The authors have applied this AMD system to four buildings in Japan. The outlines of these AMDs and buildings are described individually. To verify the control performance of the AMD in these buildings, free vibration tests were carried out just before their completion. Free vibration test results of each building demonstrated good control performance. After the completion, wind and earthquake observations were conducted. The records have shown a good performance of energy absorption of the vibration during wind excitation and small level earthquakes. Copyright © 2001 John Wiley & Sons, Ltd.
Hybrid mass dampers using two types of electric servomotors: AC servomotors and linear‐induction servomotors
Authors: Nakamura Y. , Tanaka K. , Nakayama M. , Fujita T.
Published: January 2005

A hybrid mass damper (HMD) using an electric servomotor for vibration control of buildings has been developed. The developed HMD has been installed in three buildings in order to improve habitability during strong winds and small‐to‐moderate earthquakes. We speculated that its high performance, compactness, and high reliability are important factors in its practical application to actual buildings. We have designed and installed the HMD system with suitable specifications for the size and demands of various object buildings. Several improvements were required for each application, e.g., the adoption of an active/passive‐mode switching mechanism and fault diagnosis method, countermeasures for scaling up of the device, a linear‐induction servomotor, and a design controller based on the H‐infinity control theory. In this paper, techniques relevant to vibration‐control system design, an outline of applied HMD, the design of the control system, and the verified results of control performance are presented. Through several vibration tests and field observations on each building during high winds and earthquakes, the efficiency of the applied HMD system was examined and verified. Copyright © 2001 John Wiley & Sons, Ltd.
Seismic interaction in linearly connected electrical substation equipment
Authors: Der Kiureghian A. , Sackman J. L. , Hong K‐J.
Published: January 2005

An electrical substation consists of a complex set of equipment items that are interconnected through conductor buses or cables. If the connections are not sufficiently flexible, significant dynamic interaction may occur between the connected equipment items during a seismic excitation. This interaction is believed to be responsible for some of the observed substation equipment damage in recent earthquakes. This paper investigates the interaction between two equipment items connected by a linear spring‐dashpot or spring‐dashpot‐mass element representing a conductor bus. It is found that the interaction between the two equipment items may significantly amplify the response of the higher‐frequency equipment item. The influences of various key parameters on the interaction effect are quantified. Means for reducing the adverse interaction effect are described. Copyright © 2001 John Wiley & Sons, Ltd.
The production of digital elevation models for experimental model landscapes
Authors: Hancock Greg , Willgoose Garry
Published: January 2005

Automated digital photogrammetry was used to produce digital elevation models of experimental model landscapes under controlled laboratory conditions as part of a series of rainfall erosion experiments looking at the evolution of landforms in response to erosion. The method allowed the elevations of the experimental landscapes to be studied in great detail on a regular grid digital terrain map with relatively very little effort. Digital photogrammetry produced elevation data at a resolution of 6 mm with a standard deviation of 2·0 mm over an experimental catchment relief of approximately 200 mm; this resolution is considerably better than that achievable by conventional manual photogrammetry. The density of grid points was sufficiently high that small‐scale details such as knickpoints developing in channels were represented. The method can facilitate the study of both experimental and natural landscapes in great detail. Copyright © 2001 John Wiley & Sons, Ltd.
Gully‐head erosion processes on a semi‐arid valley floor in Kenya: a case study into temporal variation and sediment budgeting
Authors: Oostwoud Wijdenes D. J. , Bryan R.
Published: January 2005

A three year monitoring programme of gully‐head retreat was established to assess the significance of sediment production in a drainage network that expanded rapidly by gully‐head erosion on the low‐angled alluvio‐lacustrine Njemps Flats in semi‐arid Baringo District, Kenya. This paper discusses the factors controlling the large observed spatial and temporal variation in gully‐head retreat rates, ranging from 0 to 15 m a−1. The selected gullies differed in planform and in runoff‐contributing catchment area but soil material and land use were similar. The data were analysed at event and annual timescales. The results show that at annual timescale rainfall amount appears to be a good indicator of gully‐head retreat, while at storm‐event timescale rainfall distribution has to be taken into account. A model is proposed, including only rainfall (P) and the number of dry days (DD) between storms:

which explains 56 per cent of the variation in retreat rate of the single‐headed gully of Lam1.

A detailed sediment budget has been established for Lam1 and its runoff‐contributing area (RCA). By measuring sediment input from the RCA, the sediment output by channelized flow and linear retreat of the gully head for nine storms, it can be seen that erosion shifts between different components of the budget depending on the duration of the dry period (DD) between storms. Sediment input from the RCA was usually the largest component for the smaller storms. The erosion of the gully head occurred as a direct effect of runoff falling over the edge (GHwaterfall) and of the indirect destabilization of the adjacent walls by the waterfall erosion and by saturation (GHmass/storage). The latter component (GHmass/storage) was usually much larger that the former (GHwaterfall). The sediment output from the gully was strongly related to the runoff volume while the linear retreat, because of its complex behaviour, was not.

Overall, the results show that the annual retreat is the optimal timescale to predict retreat patterns. More detailed knowledge about relevant processes and interactions is necessary if gully‐head erosion is to be included in event‐based soil erosion models. Copyright © 2001 John Wiley & Sons, Ltd.