bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of shear‐lag effects in framed‐tube structures with internal tube(s)
Authors: Lee Kang‐Kun , Lee Li‐Hyung , Lee Eun‐Jin
Published: January 2005

The shear‐lag phenomenon is a critical consideration in high‐rise building analysis and design. The shear‐lag behaviour of framed‐tube (including tube, tube‐in‐tube and tubes‐in‐tube constructions) is investigated for the behavioural characteristics of the structures and their performance in relation to the various structural parameters. The stiffness factor in terms of the axial stiffness of the columns and the bending stiffness of columns and beams is chosen as a main parameter to explain the shear‐lag phenomenon and the global behaviour of the structures. A simple numerical technique is also proposed for estimating the shear‐lag behaviour of framed‐tube systems with and without multiple internal tubes. Further work is carried out to demonstrate the simplicity and accuracy of the proposed method through the analysis of three framed‐tube structures (of different heights) without internal tubes and three other framed‐tube structures with single, two and three internal tubes. The shear‐lag phenomenon of such structures is studied taking into account the additional bending stresses in the tubes. Copyright © 2002 John Wiley & Sons, Ltd.
Simplified analysis of asymmetric high‐rise structures with cores
Authors: Hoenderkamp J. C. D.
Published: January 2005

A simplified elastic hand‐method of analysis for asymmetric multi‐bent structures with cores subjected to horizontal loading is presented. The structures may consist of combinations of framed structures such as coupled walls, rigid frames and braced frames with planar and non‐planar shear walls. Results for structures that are uniform with height compare closely with results from stiffness matrix analyses. The method is developed from coupled‐wall deflection theory which is expressed in non‐dimensional structural parameters. It accounts for bending deformations in all individual members, axial deformations in the vertical members as well as torsion and warping in nonplanar walls. A closed solution of coupled differential equations for deflection and rotation gives the deflected shape along the height of the building from which all internal forces can be obtained. The proposed method of analysis offers a relatively simple and rapid means of comparing the deformations and internal forces of different stability systems for a proposed tall building in the preliminary stages of the design. The derivation of equations for analysis shown in this paper are for unisymmetric stability systems only, but the method is also applicable to general asymmetric structures with cores. Copyright © 2002 John Wiley & Sons, Ltd.
Optimum design of active/passive control devices for tall buildings under earthquake excitation
Authors: Xu Y.L. , Teng J.
Published: January 2005

To economically enhance the performance of active/passive control devices for seismic response reduction of tall buildings, this paper investigates the optimal placement and optimal parameter of control devices using the linear quadratic performance index as an objective function. The linear relation between the increment of performance index and the change of the position matrix of control devices is first established based on the assumption that the control gain remains unchanged. The optimal placement of control devices is then determined in terms of the sequence of the calculated performance index increments and the number of control devices to be used. With the control devices at their optimal places, the seismic response of the building is finally computed using the suboptimal control gain derived using the minimum error principle, from which the equivalent optimal parameters of passive devices can be also determined. The applicability of the proposed approach and its limitation are carefully examined through numerical examples. The results from the numerical examples show that the suggested approach is quite accurate and effective in determining the optimal placement and optimal parameter of control devices if the number of removed control devices is limited to a certain range. Copyright © 2002 John Wiley & Sons, Ltd.
Field measurements of amplitude‐dependent damping in a 79‐storey tall building and its efects on the structural dynamic responses
Authors: Li Q. S. , Yang K. , Zhang N. , Wong C. K. , Jeary A. P.
Published: January 2005

This paper describes some results obtained from full‐scale measurements of wind effects on a super‐tall building, Di‐Wang Tower, located in Shenzhen, China. This tall building has 79‐storeys with a height of approximately 324 m. Field measurements including wind speed, wind direction and wind‐induced acceleration responses have been made. The amplitude‐dependent characteristics of damping are obtained by using the random decrement technique from the detailed analysis of the field acceleration measurements. The main objective of this paper is to present detailed investigations into the effects of nonlinear damping on the dynamic responses of the tall building subjected to various types of applied loads based on the measured amplitude‐dependent damping characteristics. The predicted dynamic responses of the building obtained by using the measured damping characteristics were compared with those computed by using constant damping parameters assumed by the structural designers. It is concluded from the investigations that knowledge of actual damping characteristics are very important in the accurate prediction of the dynamic responses of a tall building when the major harmonic components of the applied loads overlap with the lowest natural frequencies of the building. The design damping level for tall building structures currently used by structural engineering practitioners appears to be high and not conservative. Copyright © 2002 John Wiley & Sons, Ltd.
Motion visualization of human left ventricle with a time‐varying deformable model for cardiac diagnosis
Authors: Choi Soo‐Mi , Kim Myoung‐Hee
Published: January 2005

We present a time‐varying deformable model to visualize and analyze the motion of the left ventricle from a time series of 3‐D images. The model is composed of a non‐rigid body that deforms around a reference shape obtained from the previous time step. At each time step, the position and orientation of the left ventricle are extracted from the feature points of images. This information gives the position and orientation of the coordinate system attached to the non‐rigid body. To compute a dense non‐rigid motion field over the entire endocardial wall of the left ventricle, we introduce a 3‐D blob finite element and Galerkin interpolants based on 3‐D Gaussian, and use a physically based finite element method and a modal analysis. Then, cinematic attributes are visualized in pseudo colors on the reconstructed surface in order to help medical doctors in their interpretation of the data. Using the presented model, we estimate clinically useful quantitative parameters such as regional wall motion and ejection fraction. Experimental results are shown in a time series of X‐ray angiographic images. Copyright ©2001 John Wiley & Sons, Ltd.
Reproducing works of Calder
Authors: Lee Dongkyoo , Bae Hee‐Jung , Tae Kim Chang , Lee Dong‐Chun , Jung Dae‐Hyun , Lee Nam‐Kyung , Lee Kyoo‐Ho , Baek Nakhoon , Won Lee J. , Woo Ryu Kwan , Hahn James K.
Published: January 2005

Many fine art pieces have been reproduced in digital form. The digital reproductions have been used to store and transmit the original work. In contrast, mobiles, or moving sculptures, such as those designed by Alexander Calder cannot be reproduced realistically by photographs and/or static images. The real characteristics of mobiles come from the motions generated by interactive external forces applied to their structures. Hence people could not fully enjoy them through static images or even static three‐dimensional models. We present a virtual mobile system where users can easily control the mobile and can feel the impressions that the artist originally intended to provide. Virtual winds are generated by blowing on a microphone which then exert external forces to the mobile. This microphone interface lets users control the mobile while they are watching it through a monitor. We introduce a linear time solution for the constraint dynamics and an improved impulse dynamics to speed up the simulation. Using these techniques, we achieve a real‐time simulation of the mobile on personal computers. The techniques presented can easily be extended to simulate other interactive dynamics systems. Copyright ©2001 John Wiley & Sons, Ltd.
Open issues on TCP for mobile computing
Authors: Tsaoussidis Vassilis , Matta Ibrahim
Published: January 2005

We discuss the design principles of TCP within the context of heterogeneous wired/wireless networks and mobile networking. We identify three shortcomings in TCP's behavior: (i) the protocol's error detection mechanism, which does not distinguish different types of errors and thus does not suffice for heterogeneous wired/wireless environments, (ii) the error recovery, which is not responsive to the distinctive characteristics of wireless networks such as transient or burst errors due to handoffs and fading channels, and (iii) the protocol strategy, which does not control the tradeoff between performance measures such as goodput and energy consumption, and often entails a wasteful effort of retransmission and energy expenditure. We discuss a solution‐framework based on selected research proposals and the associated evaluation criteria for the suggested modifications. We highlight an important angle that did not attract the required attention so far: the need for new performance metrics, appropriate for evaluating the impact of protocol strategies on battery‐powered devices. Copyright © 2001 John Wiley & Sons, Ltd.
An Internet‐style approach to wireless link errors
Authors: Eckhardt David A. , Steenkiste Peter
Published: January 2005

Wireless links differ from traditional ‘wired’ links in two ways that challenge the existing Internet. On wireless links packet loss or corruption due to transmission errors is not rare, which calls into question the standard Internet assumptions that transmission errors should be corrected by transport‐level protocols at end systems and that end‐to‐end packet loss typically indicates network congestion. Also, the severity and location‐ dependent nature of these errors calls into question the meaning of ‘fair’ scheduling, per‐flow quality of service, and even looser notions such as service level agreements, when applied to wireless links. An important question is whether the two unique problems posed by wireless links can be successfully addressed within the standard Internet architecture, as opposed to requiring new transport protocols designed specifically for wireless links or requiring wireless links to ‘fix up’ the operation of specific end‐to‐end protocols. We provide experimental evidence that a combination of protocol‐blind link‐level local error control, which lessens the damage, and error‐sensitive link scheduling, which ensures sensible outcomes in response to link capacity loss, provides a good operating environment while adhering to traditional Internet design practices. Copyright © 2001 John Wiley & Sons, Ltd.
Throughput and energy performance of TCP on a wideband CDMA air interface
Authors: Zorzi Michele , Rossi Michele , Mazzini Gianluca
Published: January 2005

In this paper, we present a study on the performance of TCP, in terms of both throughput and energy consumption, in the presence of a wideband CDMA radio interface typical of third generation wireless systems. The results show that the relationship between throughput and average error rate is largely independent of the network load, making it possible to introduce a universal throughput curve, empirically characterized, which gives throughput predictions for each value of the user error probability. Furthermore, the study of the energy efficiency shows the possibility to select an optimal power control threshold to maximize the trade‐off between throughput and energy, thereby potentially achieving very significant energy gains. Copyright © 2001 John Wiley & Sons, Ltd.
Performance evaluation of TCP algorithms in multi‐hop wireless packet networks
Authors: Xu Shugong , Saadawi Tarek
Published: January 2005

Wireless packet ad hoc networks are characterized by multi‐hop wireless connectivity and limited bandwidth competed among neighboring nodes. In this paper, we investigate and evaluate the performance of several prevalent TCP algorithms in this kind of network over the wireless LAN standard IEEE 802.11 MAC layer. After extensively comparing the existing TCP versions (including Tahoe, Reno, New Reno, Sack and Vegas) in simulations, we show that, in most cases, the Vegas version works best. We reveal the reason why other TCP versions perform worse than Vegas and show a method to avoid this by tuning a TCP parameter— maximum window size. Furthermore, we investigate the performance of these TCP algorithms when they run with the delayed acknowledgment (DA) option defined in IETF RFC 1122, which allows the TCP receiver to transmit an ACK for every two incoming packets. We show that the TCP connection can gain 15 to 32 per cent good‐put improvement by using the DA option. For all the TCP versions investigated in this work, the simulation results show that with the maximum window size set at approximately 4, TCP connections perform best and then all these TCP variants differ little in performance. Copyright © 2001 John Wiley & Sons, Ltd.
Using statistical data for reliable mobile communications
Authors: Jobin J. , Tripathi Satish K. , Faloutsos Michalis , Gokhale Swapna
Published: January 2005

We examine the extent to which statistical mobility information can increase the reliability of the service experienced by users in mobile networks. Interrupted or dropped calls are an aspect of reliability that stems from the mobility of users. An existing user can move to a cell where there are no resources available to support their call. A natural solution is the reservation of resources in multiple cells that the user is likely to move to. This scheme is calledselective reservationsand it relies on predicting the next move of the user. Recently, there has been some work on estimating the movement probabilities (also known as themobility profile) of the user. In this paper, we quantify the usefulness of the mobility profile to improve the reliability of the service perceived by the mobile users. We identify two parameters which characterize the profile:Accuracy and Focus. Accuracy expresses the probability that the host will move as we expect it to. Focus describes how well we can identify patterns in the movement of the users. In our simulations, we examine the effect of the quality of the predictions on the performance of the system. We show that Accuracy and Focus have great impact on the performance of selective reservations. We also show how flexibility in hand‐offs can help in decreasing the dropping probability, and how this can be facilitated by letting the users make a second try at moving in case it fails the first time. Copyright © 2001 John Wiley & Sons, Ltd.
Effect of crystal structure on the background intensity in XRF
Authors: Verkhovodov Petro O.
Published: January 2005

A new model for the origin of diffraction peaks in x‐ray fluorescence was developed, using the concept of a virtual primary radiation source. The method offers the possibility of calculating the background intensity formed by characteristic radiation and bremsstrahlung. Bragg diffraction may significantly modify the intensity of primary radiation reflected by crystal planes of a polycrystalline material. Copyright © 2005 John Wiley & Sons, Ltd.
Identification and functional analysis of the Saccharomyces cerevisiae nicotinamidase gene, PNC1
Authors: Ghislain Michel , Talla Emmanuel , François Jean M.
Published: January 2005

Nicotinamidase (NAMase) from the budding yeast, Saccharomyces cerevisiae, was purified by Ni2+ affinity chromatography and gel filtration. N‐terminal microsequencing revealed sequence identity with a hypothetical polypeptide encoded by the yeast YGL037C open reading frame sharing 30% sequence identity with Escherichia coli pyrazinamidase/nicotinamidase. A yeast strain in which the NAMase gene, hereafter named PNC1, was deleted shows a decreased intracellular NAD+ concentration, consistent with the loss of NAMase activity in the null mutant. In wild‐type strains, NAMase activity is stimulated during the stationary phase of growth, by various hyperosmotic shocks or by ethanol treatment. Using a PPNC1::lacZ gene fusion, we have shown that this stimulation of NAMase activity results from increased levels of the protein and requires stress response elements in the 5′ non‐coding region of PNC1. These results suggest that NAMase helps yeast cells to adapt to various stress conditions and nutrient depletion, most likely via the activation of NAD‐dependent biological processes. Copyright © 2002 John Wiley & Sons, Ltd.
Phenotypic analysis of gene deletant strains for sensitivity to oxidative stress
Authors: Higgins Vincent J. , Alic Nazif , Thorpe Geoffrey W. , Breitenbach Michael , Larsson Veronica , Dawes Ian W.
Published: January 2005

Ascertaining the impact of inhibitors on the growth phenotype of yeast mutants can beuseful in elucidating the function of genes within the cell. Microtitre plates and robotics have been used to screen over 600 deletions from EUROSCARF, constructed in an FY1679 strain background, for sensitivity to various oxidants. These included the inorganic hydroperoxide, H2O2, an organic peroxide (cumene hydroperoxide) and a lipid hydroperoxide (linoleic acid hydroperoxide). These produce within the cell several different reactive oxygen species that can cause damage to DNA, proteins and lipids. Approximately 14% of deletants displayed sensitivity to at least one of the oxidants and there was also a distribution of deletants that showed sensitivity to all or different combinations of the oxidants. Deletants included genes encoding proteins involved in stress responses, heavy metal homeostasis and putative cell wall proteins. Although global mechanisms have been identified that provide general stress responses, these results imply that there are also distinct mechanisms involved in the protection of the cell against specific damage caused bydifferent oxidants. Further analysis of these genes may reveal unknown mechanisms protecting the cell against reactive oxygen species. Copyright © 2002 John Wiley & Sons, Ltd.
Involvement of Nst1p/YNL091w and Msl1p, a U2B″ splicing factor, in Saccharomyces cerevisiae salt tolerance
Authors: Goossens Alain , Forment Javier , Serrano Ramon
Published: January 2005

Cell tolerance to salt stress depends on many physiological functions, including the best characterized of osmotic adjustment, ion transport and sodium‐sensitive sulphate metabolism. From a screening designed to identify novel determinants of salt tolerance we have isolated the YNL091w gene, probably an Ascomycete‐specific gene encoding a protein of unknown function. This gene negatively affects salt tolerance and therefore has been designated NST1. The salt tolerance mechanism of nst1 mutants is novel because it is not related to osmoregulation, altered cation accumulation or sulphate metabolism. Genome‐wide two‐hybrid analysis has suggested that Nst1p interacts with the splicing factor Msl1p and, accordingly, the impact of NST1 on salt tolerance is dependent on a functional MSL1 gene. Loss of MSL1 and NST1 function has pleiotropic phenotypes including increased sensitivity to divalent cations (manganese and zinc) and to caffeine (a cell wall‐weakening agent). On the other hand, msl1 mutants but not nst1 mutants are sensitive to thiabendazole (a microtubule‐destabilizing agent) and to osmotic stress. Copyright © 2002 John Wiley & Sons, Ltd.
Analysis of the RAP1 protein binding to homogeneous telomeric repeats in Saccharomyces castellii
Authors: Wahlin Johan , Cohn Marita
Published: January 2005

The repressor activator protein 1 (RAP1) plays a role in telomere structure and function inS. cerevisiae. Here, the RAP1 homologue was identified and cloned from the budding yeast Saccharomyces castellii (scasRAP1). The scasRAP1 gene encodes a protein of 826 amino acids and shares an overall high degree of similarity with the S. cerevisiae RAP1 (scerRAP1). We demonstrate that the scasRAP1 is able to complement scerRAP1 in temperature‐sensitive S. cerevisiae strains and is able to function as a regulator to maintain the original telomere lengths. Binding analyses of the E. coli‐expressed scasRAP1 protein demonstrate that it needs two consecutive telomeric repeats in order to bind the S. castellii telomeric DNA sequences, and that it binds adjacent sites having a 16 bp centre‐to‐centre spacing. The binding affinity to telomeric DNA of several other yeasts is similar to that of scerRap1p. However, in contrast to scerRap1p, scasRap1p was found to bind the human telomeric sequence. Moreover, the scasRap1p was found to incorporate a variant repeat in its binding to the otherwise homogeneous telomeric DNA of S. castellii. This ability to bind various sites differing in DNA sequence indicates a high degree of adjustability in the binding of scasRap1p to DNA. The GenBank Accession No. for scasRAP1 is AF401990. Copyright © 2002 John Wiley & Sons, Ltd.
Efficient PCR‐based gene disruption in Saccharomyces strains using intergenic primers
Authors: Reid Robert J.D. , Sunjevaric Ivana , Kedacche Mehdi , Rothstein Rodney
Published: January 2005

An Erratum has been published for this article in Yeast 19(9) 2002, 803.

Gene disruptions are a vital tool for understanding Saccharomyces cerevisiae gene function. An arrayed library of gene disruption strains has been produced by a consortium of yeast laboratories; however their use is limited to a single genetic background. Since the yeast research community works with several different strain backgrounds, disruption libraries in other common laboratory strains are desirable. We have developed simple PCR‐based methods that allow transfer of gene disruptions from the S288C‐derived strain library into any Saccharomyces strain. One method transfers the unique sequence tags that flank each of the disrupted genes and replaces the kanamycin resistance marker with a recyclable URA3 gene from Kluyveromyces lactis. All gene‐specific PCR amplifications for this method are performed using a pre‐existing set of primers that are commercially available. We have also extended this PCR technique to develop a second general gene disruption method suitable for any transformable strain of Saccharomyces. Copyright © 2002 John Wiley & Sons, Ltd.
ABC transporters Cdr1p, Cdr2p and Cdr3p of a human pathogen Candida albicans are general phospholipid translocators
Authors: Smriti  , Krishnamurthy S. , Dixit B.L. , Gupta C.M. , Milewski S. , Prasad R.
Published: January 2005

We have used fluorescent 7‐nitrobenz‐2‐oxa‐1,3‐diazol‐4‐yl (NBD)‐tagged phospholipid analogues, NBD‐PE (phosphatidylethanolamine), NBD‐PC (phosphatidylcholine) and NBD‐PS (phosphatidylserine), to demonstrate that Cdr1p and its other homologues, Cdr2p and Cdr3p, belonging to the ATP‐binding cassette (ABC) superfamily behave as general phospholipid translocators. Interestingly, CDR1 and CDR2, whose overexpression leads to azole resistance in C. albicans, elicit in‐to‐out transbilayer phospholipid movement, while CDR3, which is not involved in drug resistance, carries out‐to‐in translocation of phospholipids between the two monolayers of plasma membrane. Cdr1p, Cdr2p and Cdr3p could be further distinguished on the basis of their sensitivities to different inhibitors. For example, the in‐to‐out activity associated with Cdr1p and Cdr2p is energy‐dependent and sensitive to sulphydryl blocking agents such as N‐ethylmaleimide (NEM) and cytoskeleton disrupting agent cytochalasin E, while Cdr3p‐associated out‐to‐in activity is energy‐dependent but insensitive to NEM and cytochalasin E. We found that certain drugs, such as fluconazole, cycloheximide and miconazole, to which Cdr1p confers resistance could also affect in‐to‐out transbilayer movement of NBD‐PE, while the same drugs had no effect on Cdr3p‐mediated out‐to‐in translocation of NBD‐PE. The ineffectiveness of these drugs to affect Cdr3p mediated out‐to‐in phospholipid translocation further confirms the inherent difference in the directionality of phospholipid translocation between these pumps. Notwithstanding the role of some of the Cdrps in drug resistance, this study clearly demonstrates that these ABC transporters of C. albicans are phospholipid translocators and this function could represent one of the physiological functions of such large family of proteins. Copyright © 2002 John Wiley & Sons, Ltd.
HSP12 is essential for biofilm formation by a Sardinian wine strain of S. cerevisiae
Authors: Zara Severino , Antonio Farris G. , Budroni Marilena , Bakalinsky Alan T.
Published: January 2005

Sardinian sherry strains of S. cerevisiae form a biofilm on the surface of wine at the end of the ethanolic fermentation, when grape sugar is depleted and when further growth becomes dependent on access to oxygen. A point mutation in HSP12 or deletion of the entire gene results in inability to form this film. HSP12 encodes a heat‐shock protein previously foundby others to be active during stationary phase, in cells depleted for glucose, and in cells metabolizing ethanol and fatty acids, all conditions associated with sherry biofilms. The DNA sequence of HSP12 allele of strain Ar5‐H12 has GenBank Accession No. AY046957. Copyright © 2002 John Wiley & Sons, Ltd.
Overproduction of pentose phosphate pathway enzymes using a new CRE–loxP expression vector for repeated genomic integration in Saccharomyces cerevisiae
Authors: Johansson Björn , Hahn‐Hägerdal Bärbel
Published: January 2005

Two new vectors are described, the expression vector pB3 PGK and the CRE recombinase vector pCRE3. The pB3 PGK has a zeocin‐selectable marker flanked by loxP sequences and an expression cassette consisting of the strong PGK1 promoter and the GCY1 terminator. The S. cerevisiae genes RKI1, RPE1, TAL1 and TKL1 were cloned in pB3 PGK and integrated in the locus of the respective gene, resulting in overexpression of the genes. S. cerevisiae TMB 3026, simultaneously overexpressing the RKI1, RPE1, TAL1 and TKL1 genes, was created by successive integrations and removal of the loxP–zeocin–loxP cassette using pCRE3. The 2µ‐based pCRE3 carries the aureobasidin A, zeocin and URA3 markers. pCRE3 proved to be easily cured without active counter‐selection. The zeocin marker is present on both the pB3 PGK and on pCRE3, so that screening for zeocin sensitivity indicates both chromosomal marker loss and loss of the pCRE3 vector. This feature saves time, since only one screening step is needed between successive chromosomal integrations. Marker recycling did not lead to increased zeocin resistance, indicating that the zeocin marker could be used for more than four rounds of transformation. The use of the CRE/loxP system proved to be a practical strategy to overexpress multiple genes without exhausting available markers. Copyright © 2002 John Wiley & Sons, Ltd.
Decreasing acetic acid accumulation by a glycerol overproducing strain of Saccharomyces cerevisiae by deleting the ALD6 aldehyde dehydrogenase gene
Authors: Eglinton Jeffrey M. , Heinrich Anthony J. , Pollnitz Alan P. , Langridge Peter , Henschke Paul A. , de Barros Lopes Miguel
Published: January 2005

Glycerol is a major fermentation product of Saccharomyces cerevisiae that contributes to the sensory character of wine. Diverting sugar to glycerol overproduction and away from ethanol production by overexpressing the glycerol 3‐phosphate dehydrogenase gene,GPD2, caused S. cerevisiae to produce more than twice as much acetic acid as the wild‐type strain (S288C background) in anaerobic cell culture. Deletion of the aldehyde dehydrogenase gene, ALD6, in wild‐type and GPD2 overexpressing strains (GPD2‐OP) decreased acetic acid production by three‐ and four‐fold, respectively. In conjunction with reduced acetic acid production, the GPD2‐OP ald6Δ strain produced more glycerol and less ethanol than the wild‐type. The growth rate and fermentation rate were similar for the modified and wild‐type strains, although the fermentation rate for the GPD2 ald6Δ strain was slightly less than that of the other strains from 24 h onwards. Analysis of the metabolome of the mutants revealed that genetic modification affected the production of some secondary metabolites of fermentation, including acids, esters, aldehydes and higher alcohols, many of which are flavour‐active in wine. Modification of GPD2 and ALD6 expression represents an effective strategy to increase the glycerol and decrease the ethanol concentration during fermentation, and alters the chemical composition of the medium such that, potentially, novel flavour diversity is possible. The implications for the use of these modifications in commercial wine production require further investigation in wine yeast strains. Copyright © 2002 John Wiley & Sons, Ltd.
The adaptive response of Saccharomyces cerevisiae to mercury exposure
Authors: Westwater John , McLaren Niall F. , Dormer Ulla H. , Jamieson Derek J.
Published: January 2005

The budding yeast Saccharomyces cerevisiae has been shown to possess a number of discrete but overlapping adaptive stress responses. We show here that yeast has an adaptive stress response towards mercury and that this response overlaps to some extent with the H2O2 and cadmium‐inducible stress responses. Expression of the yeast GSH1 gene, encoding γ‐glutamylcysteine synthetase, is known to be regulated by hydrogen peroxide; in this study we show that expression of a GSH1–lacZ reporter gene is shown to be regulated by exposure to heavy metals, such as mercury and cadmium. Other redox‐active metals, including copper and iron, were found not to induce GSH1 expression. We show that mercury‐mediated regulation of the GSH1 gene is not by the same mechanism used by cadmium. Moreover, our experiments suggest the possibility that the oxidative stress produced by mercury exposure is similar to that produced by treatment with H2O2, consistent with our finding that the Yap1 protein is also involved in the response of yeast towards mercury. Copyright © 2002 John Wiley & Sons, Ltd.
Inhibitory effect of nikkomycin Z on chitin synthases in Candida albicans
Authors: Kim Min‐Kyoung , Park Hyun‐Sook , Kim Chi‐Hwa , Park Hee‐Moon , Choi Wonja
Published: January 2005

Nikkomycin Z is a competitive inhibitor of chitin synthases in fungi. It has been reported that it inhibits chitin synthases (Chs) 1 and 3, but not 2, of Saccharomyces cerevisiae. In our study, we found that: (a) nikkomycin Z inhibited all three Chs isozymes of Candida albicans (CaChs). The IC50 value for CaChs1 is 15 µM, for CaChs2 0.8 µM, and for CaChs3 13 µM; (b) nikkomycin Z inhibits vegetative growth of C. albicans differently in different growth media; growth inhibition was observed on Spider and corn meal agar plate, but not on Lee's plate; (c) growth inhibition by nikkomycin Z accompanied by the absence of septum and cell wall chitin, which in turn brought about cell lysis. Nikkomycin Z did not lyse cells in Lee's media and lysis was partially prevented in the presence of sorbitol as an osmostabilizer in Spider medium. Therefore, nikkomycin Z prevented the formation of septum and cell wall chitin by inhibiting chitin synthase activities in a growth medium‐dependent manner. Copyright © 2002 John Wiley & Sons, Ltd.
Proliferation of the endoplasmic reticulum occurs normally in cells that lack a functional unfolded protein response
Authors: Larson Lynnelle L. , Parrish Mark L. , Koning Ann J. , Wright Robin L.
Published: January 2005

Increased expression of certain ER membrane proteins leads to biogenesis of novel ER membrane arrays. These structures provide models in which to explore the mechanisms by which cells control the size and organization of organelles in response to changing physiological demands. In yeast, elevated levels of HMG‐CoA reductase induce ER arrays known as karmellae. Cox and co‐workers (1997) discovered that karmellae assembly is toxic to ire1 mutants. These mutants are unable to initiate the unfolded protein response, which enables cells to adjust levels of ER chaperones in response to stresses. We sought to determine whether the karmellae‐dependent death of ire1 mutants was due to karmellae assembly or to increased levels of HMG‐CoA reductase activity. Unexpectedly, we found that ire1 cells could assemble normal levels of karmellae that were structurally identical to those of wild‐type cells. In addition, karmellae assembly did not itself induce the unfolded protein response. Certain ire1 strains produced significant numbers of transformants that were unable to utilize galactose as sole carbon source. These results suggest that the karmellae‐dependent death of certain ire1 strains may simply reflect their inability to grow on galactose. Copyright © 2002 John Wiley & Sons, Ltd.
Siderophore uptake by Candida albicans: effect of serum treatment and comparison with Saccharomyces cerevisiae
Authors: Lesuisse Emmanuel , Knight Simon A. B. , Camadro Jean‐Michel , Dancis Andrew
Published: January 2005

Iron uptake systems often function as virulence factors in pathogenic organisms. Candida albicans is a fungal pathogen that infects immunocompromised hosts, such as AIDS patients or granulocytopenic bone marrow transplant recipients. Here we show that iron uptake from siderophores occurs in C. albicans and is mediated by one or more high‐affinity transport systems. Iron carried on ferrioxamine B, triacethyl‐fusarinine, ferrichrome, or ferricrocin was actively taken up via a high‐affinity mechanism. The kinetic parameters of uptake were similar to those found in S. cerevisiae. Furthermore, for ferrichrome and ferrioxamine B, cellular uptake of fluorescent analogues was observed. In C. albicans, iron uptake from siderophores was regulated by iron availability, with iron deprivation inducing uptake. Serum exposure, which induces a morphogenic shift from yeast to filamentous forms known to be required for virulence, also resulted in induction of iron transport from ferrichrome‐type siderophores. In a tup1/tup1 strain which grows constitutively in the filamentous form, iron transport was derepressed for all siderophores tested. The genes mediating uptake and utilization of iron from siderophores in C. albicans have not been identified; however, the transcript abundance for CaSIT1 was regulated in a manner consistent with the pattern of iron uptake from ferrichrome‐type siderophores. Furthermore, CaSIT1 overexpression in S. cerevisiae resulted in inhibited siderophore iron uptake, suggesting that the expressed protein may interact with proteins of S. cerevisiae involved in iron uptake from siderophores. In summary, iron uptake from ferrichrome‐type siderophores was induced in filamentous C. albicans, and a potential role of this iron acquisition system in pathogenicity should be considered. Copyright © 2002 John Wiley & Sons, Ltd.
Sets of integrating plasmids and gene disruption cassettes containing improved counter‐selection markers designed for repeated use in budding yeast
Authors: Akada Rinji , Hirosawa Isao , Kawahata Miho , Hoshida Hisashi , Nishizawa Yoshinori
Published: January 2005

Counter‐selection is a useful gene manipulation technique for repeated gene disruptions, gene shufflings and gene replacements in yeasts. We developed a novel counter‐selection system using a galactose‐inducible growth inhibitory sequence (Kawahata et al.1999. Yeast 15: 1–10). This counter‐selection marker, named GAL10p–GIN11, has several advantages over previous counter‐selection markers, i.e. use of an inexpensive galactose medium for counter‐selection, combined use with any transformation markers for gene introduction, and no requirement of specific mutations in the host strains. The GIN11 sequence, which is a part of an X‐element of the subtelomeric regions, contained a conserved autonomously replicating sequence, causing the possibility of inefficient chromosomal integration. We isolated GIN11 mutants that lost the replication activity but retained the growth‐inhibitory effect when overexpressed. A mutant GIN11M86 sequence was selected and fused to the CUP1 promoter for the counter‐selection on a copper‐containing medium. The GALp–GIN11M86 and the CUPp–GIN11M86 were used for constructing sets of integrating plasmids containing auxotrophic markers involving HIS3, TRP1, LEU2, URA3 or ADE2, or a drug‐resistant marker PGKp–YAP1. In addition, a set of gene disruption cassettes that contained each of the auxotrophic markers and the GALp–GIN11M86, which were flanked by direct repeats of a hisG sequence, were constructed. The counter‐selectable integrating plasmids and the gene disruption cassettes can allow the markers to be used repeatedly for yeast gene manipulations. Copyright © 2002 John Wiley & Sons, Ltd.
Functional characterization of the Candida albicans homologue of secretion‐associated and Ras‐related (Sar1) protein
Authors: Jiang Linghuo , Lee Chang‐Muk , Shen Shi‐Hsiang
Published: January 2005

Secretion‐associated and Ras‐related protein (Sar1p) plays an essential role during the protein transport from the endoplasmic reticulum to the Golgi apparatus. The cDNA sequence of the Sar1 gene has been identified and characterized from the human yeast pathogen, Candida albicans. This cDNA encodes a protein of 190 amino acids, which shares a 78% sequence identity with Saccharomyces cerevisiae Sar1p and contains the conserved GTP‐binding motifs of the small GTPase superfamily. Complementation studies confirmed that this cDNA encodes the functional homologue of ScSar1p. The recombinant C. albicans Sar1p exhibits GTP‐binding activity in vitro that was abolished by deletion of one of the three GTP‐binding motifs. Copyright © 2002 John Wiley & Sons, Ltd.
Systematic analysis of sporulation phenotypes in 624 non‐lethal homozygous deletion strains of Saccharomyces cerevisiae
Authors: Briza Peter , Bogengruber Edith , Thür Albert , Rützler Michael , Münsterkötter Martin , Dawes Ian W. , Breitenbach Michael
Published: January 2005

A new high throughput mutant screening procedure for the detection of sporulation mutants was developed and used to analyse a set of 624 non‐lethal homozygous deletion mutants created in the European joint research program EUROFAN. The screening procedure involved determination of LL‐ and DL‐dityrosine, sporulation‐specific compounds, which were shown to be robust markers of the extent and arrest stage of sporulation mutants. Secondary screens consisted of light microscopy to detect mature and immature spores and DAPI staining to monitor the progress of meiotic nuclear divisions. We discovered new phenotypic classes of mutants defective in spore wall synthesis that were not discovered by previous screens for sporulation mutants. The genes corresponding to the sporulation mutants fell in several functional classes, some of which were previously unknown to be involved in spore formation. Peroxisomes seem to play a role in spore wall synthesis. Mitochondria play a role in sporulation that is not simply restricted to supply of ATP from respiratory metabolism. The deletion mutants included in the set were functionally unknown at the start of EUROFAN; however, within the last few years the importance to sporulation of some of them was also reported by other authors. Taken together, about 8% of all single gene deletion mutants of non‐essential genes of Saccharomyces cerevisiae seem to display a clear and reproducible sporulation phenotype. Copyright © 2002 John Wiley & Sons, Ltd.
Saccharomyces cerevisiae and Zygosaccharomyces mellis exhibit different hyperosmotic shock responses
Authors: Vindeløv Jannik , Arneborg Nils
Published: January 2005

The effect of hyperosmotic shock on cell volume, vacuole volume, and intracellular pH (pHi) of individual cells of Saccharomyces cerevisiae and Zygosaccharomyces mellis was investigated. After transfer from a high water activity (aw) medium to low aw media, the growth latency periods of Z. mellis were shorter than those of S. cerevisiae. These results demonstrate that Z. mellis manages hyperosmotic shock better than S. cerevisiae. As a response to acute hyperosmotic shock, i.e. the first minute of perfusion with hypertonic buffers, the vacuoles shrank and the pHi decreased in both yeasts. Furthermore, in the presence of glucose, vacuole shrinkage and intracellular acidification were more pronounced in S. cerevisiae than in Z. mellis. These results may be explained by the fact that the S. cerevisiae cells shrank more than the Z. mellis cells as a response to acute hyperosmotic shock. In the presence of glucose, the vacuoles and the cells of both S. cerevisiae and Z. mellis shrank simultaneously and in proportion to a minimum level during acute hyperosmotic shock, and remained constant at this level throughout the experiment (11 min). These results indicate that vacuoles do not act as water reserves in yeasts after acute hyperosmotic shock. Finally, Z. mellis was able to maintain its pHi near normal physiological levels after acute hyperosmotic shock, whereas S. cerevisiae was not. These results suggest that pHi regulation may be important for the ability of yeasts to manage hyperosmotic shock. Copyright © 2002 John Wiley & Sons, Ltd.
Psychological symptoms and drug use severity among Israeli adolescents presenting for outpatient drug abuse treatment
Authors: Diamond Gary M. , Izzard Miriam C. , Kedar Tami , Hutlzer Anat , Mell Haim
Published: January 2005

The objective of this study was to assess the rates of externalizing and internalizing symptoms, and the relation between psychological symptoms and drug use severity, among 117 Israeli adolescents presenting for outpatient drug abuse treatment. Psychological symptoms were assessed via both adolescent self‐report and parent report. Drug use was assessed using both adolescent self‐report and urinalysis. Results showed that 58% of the sample evidenced clinical levels of psychological symptoms, with girls evidencing higher rates of externalizing and mixed symptomatology than boys. Parents’ report of adolescents’ internalizing symptoms predicted severity of drug use. These findings suggest that treatment for this population should be multidimensional, and address not only drug use per se, but also psychological risk factors.
Developing and validating a stress appraisal measure for minority adolescents
Authors: Rowley Anthony A. , Roesch Scott C. , Jurica Bradford J. , Vaughn Allison A.
Published: January 2005

Although there are a number of measures designed to assess the cognitive appraisal of stress in adult populations, currently there are no measures that are specifically designed to assess this important construct in adolescents. To overcome this limitation, the factorial validity and dimensionality of a dispositional measure of stress appraisal was examined in the current study. Using a multiethnic adolescent sample, both exploratory and confirmatory factor analyses resulted in a three‐factor representation of appraisal. The three factors included two primary appraisal dimensions (Threat and Challenge) and one secondary appraisal dimension (Resources). This three‐factor model, however, is inconsistent with four‐ and six‐factor models found previously in adult samples. Thus, these findings suggest that the cognitive appraisals made by adolescents are less complex or differentiated than those of adults. Moreover, these findings suggest thatdispositionalmeasures are relevant for adolescent samples and should be incorporated into stress and coping paradigms.
Variability of ribosomal RNA genes in Rauwolfia species: parallelism between tissue culture‐induced rearrangements and interspecies polymorphism
Authors: Andreev I.O. , Spiridonova K.V. , Solovyan V.T. , Kunakh V.A.
Published: January 2005

An analysis of 18S–25S and 5S rRNA genes in intact plants and cultured tissues of some Rauwolfia species was performed to compare these sequences variability occurred as a result of the species evolution in nature and that induced by tissue culture. The restriction fragment length polymorphism of 18S–25S and 5S rDNA was found both in intact plants of various Rauwolfia species and in long‐term Rauwolfia serpentina tissue cultures. In addition, changes in the amount of 18S–25S rRNA genes were observed in long‐term R. serpentina tissue cultures. The results demonstrate that rDNA variability observed in intact plants as well as in long‐term cultures is attributed to differences in the same regions of ribosomal RNA genes.
Opioid switch in palliative care, opioid choice by clinical need and opioid availability
Authors: Müller‐Busch H.C. , Lindena G. , Tietze K. , Woskanjan S.
Published: January 2005

Availability of different WHO‐step 3 opioids has encouraged the discussion on their value and led to the concepts of opioid rotation. Rotation is suggested, when other measures fail to achieve optimal analgesia and tolerability in cancer pain treatment. Opioid use was assessed in a prospective cohort study of 412 palliative care patients from 14 inpatient and outpatient palliative care facilities in Germany. The most frequently used opioids at baseline were morphine and fentanyl. The most frequent changes in medication (N = 106) occurred from oral to parenteral morphine. Only in 49 cases true switches to other long acting opioids were recorded. This is far less than expected from other reports. True switches and adverse side effects were found to occur more frequently in inpatients, while efficacy problems were more frequently recorded in outpatients. There was no correlation between the opoid used at baseline and switch frequency, but numbers of cases receiving other opioids than fentanyl or morphine were low.

Reasons for and frequencies of changes in medication were found to be largely shaped by the setting reflecting patients' needs and clinical necessities. Recommendation of first line therapy and availability of opioid formulations define the frequency of opioid use. This impedes evaluation of specific differences between the opioids.
Intracerebral pain processing in a Yoga Master who claims not to feel pain during meditation
Authors: Kakigi Ryusuke , Nakata Hiroki , Inui Koji , Hiroe Nobuo , Nagata Osamu , Honda Manabu , Tanaka Satoshi , Sadato Norihiro , Kawakami Mitsumasa
Published: January 2005

We recorded magnetoencephalography (MEG) and functional magnetic resonance imaging (fMRI) following noxious laser stimulation in a Yoga Master who claims not to feel pain when meditating. As for background MEG activity, the power of alpha frequency bands peaking at around 10 Hz was much increased during meditation over occipital, parietal and temporal regions, when compared with the non‐meditative state, which might mean the subject was very relaxed, though he did not fall asleep, during meditation. Primary pain‐related cortical activities recorded from primary (SI) and secondary somatosensory cortices (SII) by MEG were very weak or absent during meditation. As for fMRI recording, there were remarkable changes in levels of activity in the thalamus, SII‐insula (mainly the insula) and cingulate cortex between meditation and non‐meditation. Activities in all three regions were increased during non‐meditation, similar to results in normal subjects. In contrast, activities in all three regions were weaker during meditation, and the level was lower than the baseline in the thalamus. Recent neuroimaging and electrophysiological studies have clarified that the emotional aspect of pain perception mainly involves the insula and cingulate cortex. Though we cannot clearly explain this unusual condition in the Yoga Master, a change of multiple regions relating to pain perception could be responsible, since pain is a complex sensory and emotional experience.