bluuebunny/crossref_metadata_2025 huggingface dataset:
Leucine transport in membrane vesicles from Chironomus riparius larvae displays a mélange of crown‐group features
Authors: Parenti Paolo , Forcella Matilde , Pugliese Anna , Giacchini Roberto , Rossaro Bruno , Hanozet Giorgio M.
Published: August 2002

Leucine uptake into membrane vesicles from larvae of the midge Chironomus riparius was studied. The membrane preparation was highly enriched in typical brush border membrane enzymes and depleted of other membrane contaminants. In the absence of cations, there was a stereospecific uptake of l‐leucine, which exhibited saturation kinetics. Parameters were determined both at neutral (Km 33 ± 5 μM and Vmax 22.6 ± 6.8 pmol/7s/mg protein) and alkaline (Km 46 ± 5 μM and Vmax 15.5 ± 2.5 pmol/7s/mg protein) pH values. At alkaline pH, external sodium increased the affinity for leucine (Km 17 ± 1 μM) and the maximal uptake rate (Vmax 74.0 ± 12.5 pmol/7s/mg protein). Stimulation of leucine uptake by external alkaline pH agreed with lumen pH measurements in vivo. Competition experiments indicated that at alkaline pH, the transport system readily accepts most L‐amino acids, including branched, unbranched, and α‐methylated amino acids, histidine and lysine, but has a low affinity for phenylalanine, β‐amino acids, and N‐methylated amino acids. At neutral pH, the transport has a decreased affinity for lysine, glycine, and α‐methylleucine. Taken together, these data are consistent with the presence in midges of two distinct leucine transport systems, which combine characters of the lepidopteran amino acid transport system and of the sodium‐dependent system from lower neopterans. Arch. Insect Biochem. Physiol. 48:51–62, 2001. © 2001 Wiley‐Liss, Inc.
Form and function: The impact of query term and operator usage on Web search results
Authors: Lucas Wendy , Topi Heikki
Published: August 2002

Conventional wisdom holds that queries to information retrieval systems will yield more relevant results if they contain multiple topic‐related terms and use Boolean and phrase operators to enhance interpretation. Although studies have shown that the users of Web‐based search engines typically enter short, term‐based queries and rarely use search operators, little information exists concerning the effects of term and operator usage on the relevancy of search results. In this study, search engine users formulated queries on eight search topics. Each query was submitted to the user‐specified search engine, and relevancy ratings for the retrieved pages were assigned. Expert‐formulated queries were also submitted and provided a basis for comparing relevancy ratings across search engines. Data analysis based on our research model of the term and operator factors affecting relevancy was then conducted. The results show that the difference in the number of terms between expert and nonexpert searches, the percentage of matching terms between those searches, and the erroneous use of nonsupported operators in nonexpert searches explain most of the variation in the relevancy of search results. These findings highlight the need for designing search engine interfaces that provide greater support in the areas of term selection and operator usage.
A context vector model for information retrieval
Authors: Billhardt Holger , Borrajo Daniel , Maojo Victor
Published: August 2002

In the vector space model for information retrieval, term vectors are pair‐wise orthogonal, that is, terms are assumed to be independent. It is well known that this assumption is too restrictive. In this article, we present our work on an indexing and retrieval method that, based on the vector space model, incorporates term dependencies and thus obtains semantically richer representations of documents. First, we generate term context vectors based on the co‐occurrence of terms in the same documents. These vectors are used to calculate context vectors for documents. We present different techniques for estimating the dependencies among terms. We also define term weights that can be employed in the model. Experimental results on four text collections (MED, CRANFIELD, CISI, and CACM) show that the incorporation of term dependencies in the retrieval process performs statistically significantly better than the classical vector space model with IDF weights. We also show that the degree of semantic matching versus direct word matching that performs best varies on the four collections. We conclude that the model performs well for certain types of queries and, generally, for information tasks with high recall requirements. Therefore, we propose the use of the context vector model in combination with other, direct word‐matching methods.
Effect of intermittent and continuous exposure to electromagnetic fields on cultured hippocampal cells
Authors: Boland A. , Delapierre D. , Mossay D. , Dresse A. , Seutin V.
Published: August 2002

This study was designed to assess the effect of 50 Hz electromagnetic fields (EMFs) on hippocampal cell cultures in the presence or absence of either sodium nitroprusside (SNP, a NO donor) or Fe2+ induced oxidative stress. One week old cultured rat hippocampal cells were exposed to either intermittent EMFs (IEMFs, 50 Hz, 0–5 mT, 1 min ON/OFF cycles, repeated 10 times every 2 h, 6 times/day during 48 h) or continuous EMFs (CEMFs, 50 Hz, 0–5 mT for 48 h). In a second set of experiments, the effect on such EMFs applied in combination with oxidative stress induced by 0.5 μM Fe2+ or SNP was estimated. At the end of both sets of experiments, cell mortality was assessed by lactate dehydrogenase measurements (LDH). Neither type of exposure to EMFs was observed to modify the basal rate of cell mortality. The exposure to CEMFs in presence of either NO or Fe2+ did not induce any significant increase in cell death. However, when cells were exposed to EMFs in the presence of NO, we observed a significant increase in cell death of 11 and 23% (P<0.001) at 2.5 and 5 mT, respectively. This effect had some specificity because IEMFs did not modify the effect of Fe2+ on cell mortality. Although the effects of IEMFs reported in this study were only observed at very high intensities, our model may prove valuable in trying to identify one cellular target of EMFs. Bioelectromagnetics 23:97–105, 2002. © 2002 Wiley‐Liss, Inc.
Missing link in firefly bioluminescence revealed: NO regulation of photocyte respiration
Authors: Greenfield Michael D.
Published: August 2002

Sexual communication in most species of fireflies is a male–female dialogue of precisely timed flashes of bioluminescent light. The biochemical reactions underlying firefly bioluminescence have been known for 30 years and are now exploited in biomedical assays and other commercial applications. Several aspects of flash regulation are also understood: flash rhythm is controlled by a central pattern generator, and individual flashes are neurally triggered, with octopamine serving as the transmitter. The molecular oxygen needed by the biochemical reactants is delivered by a network of tracheal arborizations extending throughout the light organ (lantern). However, the actual means by which oxygen quickly reaches the reactants packaged within specialized photocytes and the specific event(s) triggered by neural action have not been identified; termination of axons away from the photocytes has exacerbated the latter problem. A recent paper(1) by a consortium of cell and evolutionary biologists, however, reports that nitric oxide (NO), manufactured and released in response to neuronal discharge, is the missing link by which neural action in the firefly lantern yields a sudden flash of light. BioEssays 23:992–995, 2001. © 2001 John Wiley & Sons, Inc.
Effects of parent training on parent and child behavior using procedures based on functional analyses
Authors: Marcus Bethany A. , Swanson Victoria , Vollmer Timothy R.
Published: August 2002

We evaluated the effects of parent training for four children whose aberrant behaviors were maintained by social positive or negative reinforcement. Interventions were based on the behavioral function of the problem behavior. Child participants were four children (ages 3 to 5 years) who had developmental delays and exhibited significant aberrant behaviors (tantrums and aggression). The children's mothers were the parent participants. The children's behavior improved as a function of the parents' performance. Copyright © 2001 John Wiley & Sons, Ltd.
Teaching social‐learning procedures to paraprofessionals working with individuals with severe mental illness in a maximum‐security forensic hospital
Authors: Jones Nicole T. , Menditto Anthony A. , Geeson Lynn R. , Larson Elaine , Sadewhite Lisa
Published: August 2002

This study describes an integrated technical method for teaching learning‐based interventions to paraprofessionals working in a maximum‐security psychiatric facility as a social‐learning program was implemented. This training approach combines brief didactic instruction with live demonstration and guided practice in specific procedures. Comparisons between baseline and post‐training functioning of staff were made using ongoing direct observational assessment data. Results revealed that following training and program implementation staff were much more active overall, interacted with clients far more often, and engaged in much lower rates of job‐irrelevant activity. Moreover, following training direct observational data of the patterns of staff–client interactions showed that staff were much more likely to demonstrate interactions reflective of learning‐based interventions than at baseline. These results have important implications for clinicians and administrators attempting to implement behavioral rehabilitation programs. Copyright © 2001 John Wiley & Sons, Ltd.
Upper electron‐excited states in bioluminescence: experimental indication
Authors: Kudryasheva N. S. , Nemtseva E. V. , Meshalkin Yu. P. , Sizykh A. G.
Published: August 2002

The involvement of upper electron‐excited states in bacterial bioluminescence process was studied with excitation energy‐accepting molecules. The fluorescent aromatic compounds, anthracene and 1.4‐bis(5‐phenyloxazol‐2‐yl)benzene, were chosen. Energies of their lowest excited singlet states are higher than the energy of the analogous state of the bioluminescence emitter; their absorption spectra and bioluminescence do not overlap. Hence, the excitation of these molecules by singlet–singlet energy transfer or by light absorption is excluded. Sensitized fluorescence of these compounds in the bioluminescence systems has been recorded, indicating the activity of upper electron‐excited states in the bioluminescent process. Copyright © 2001 John Wiley & Sons, Ltd.
An optimized solid phase synthesis strategy— including on‐resin lactamization—of astressin, its retro‐, inverso‐, and retro–inverso isomers as corticotropin releasing factor antagonists
Authors: Rijkers Dirk T. S. , den Hartog Jack A. J. , Liskamp Rob M. J.
Published: August 2002

This report describes an optimized solid phase synthesis strategy for astressin and new derivatives thereof. The synthesis is based on 9‐fluorenylmethyloxycarbonyl/allyl/tert‐butyl chemistry. The glutamic acid and lysine residue, which together form the cyclic constraint by coupling of their side chains, were protected by allyl functionalities during the synthesis of the linear peptide. Allyl removal by Pd(0) and the construction of the lactam bridge have been performed on‐resin after completion of the chain assembly. This synthetic methodology resulted in high chemical yields (58–72%) and excellent purities of the crude peptides. The peptides were tested for their binding at the corticotropin releasing factor receptor, type 1, and their corticotropin releasing factor antagonistic activity. Furthermore, astressin and its analogs were studied by CD in order to determine the secondary structure in solution. Since the linear form of astressin and also the cyclic inverso isomer were found to be fully inactive, it can be concluded that a cyclic constraint and a right‐handed α‐helix, respectively, are of utmost importance for these peptides to act as corticotropin releasing factor antagonists. © 2002 John Wiley & Sons, Inc. Biopolymers 63: 141–149, 2002
Photomodulation of conformational states. III. Water‐soluble bis‐cysteinyl‐peptides with (4‐aminomethyl) phenylazobenzoic acid as backbone constituent*
Authors: Renner Christian , Behrendt Raymond , Heim Nicola , Moroder Luis
Published: August 2002

In previous studies we have shown that light‐induced cis/trans isomerization of the azobenzene moiety in cyclo‐[Ala–Cys–Ala–Thr–Cys–Asp–Gly–Phe–AMPB] [AMPB: (4‐aminomethyl)phenylazobenzoic acid] leads both in the monocyclic and in the oxidized bicyclic form to markedly differentiated conformational states in DMSO, a fact that lends itself for photomodulation of the redox potential of such bis‐cysteinyl‐peptides. For this purpose water‐soluble systems are required, and this was achieved by replacing three residues outside the Cys–Ala–Thr–Cys active‐site motif of thioredoxin reductase with lysines. The resulting cyclo‐[Lys–Cys–Ala–Thr–Cys–Asp–Lys–Lys–AMPB] fully retains its photoresponsive properties in water as well assessed by uv and CD measurements. Paralleling results of the previously investigated azobenzene‐containing cyclic peptides, the trans → cis isomerization of the water‐soluble monocyclic and oxidized bicyclic peptide is accompanied by a marked transition from a well‐defined conformation to an ensemble of possible conformations. However, the conformational preferences are very dissimilar from those of the DMSO‐soluble peptides. In fact, hydrogen bonds as well as secondary structure elements were found that change in the mono‐ and bicyclic peptide upon irradiation. The photo switch between different turn types and hydrogen bonding networks offers the structural rational for the significantly differentiated redox potentials, but also the possibility of monitoring by femtosecond uv‐vis and ir spectroscopy fast and ultra fast backbone rearrangement processes following the electronic trans → cis isomerization. © 2002 Wiley Periodicals, Inc. Biopolymers 63: 382–393, 2002
Influence of netropsin's charges on the minor groove width of d(CGCGAATTCGCG)2
Authors: Wellenzohn Bernd , Flader Wolfgang , Winger Rudolf H. , Hallbrucker Andreas , Mayer Erwin , Liedl Klaus R.
Published: August 2002

The exact understanding of the interaction of minor groove binding drugs with DNA is of interest due to their importance as transcription controlling drugs. In this study we performed four molecular dynamics simulations, one of the uncomplexed d(CGCGAATTCGCG)2 dodecamer and three simulations of the DNA complexed with the minor groove binder netropsin. The charged guanidinium and amidinium ends of the small ligand were in one simulation formally uncharged, in the second one normally charged, and in the third simulation we doubled the charges of the two ends. So we are able to filter out the influence the charges exert on the DNA structure. The positive charges reduce the width of the minor groove showing that charges are able to modify the groove width by charge neutralization of the negative phosphate groups. The quality of the used force field was successfully tested by comparing the results of the uncomplexed dodecamer with already reported NMR and x‐ray studies. Thus our simulations should be able to describe the minor groove width of DNA in a correct manner underlying the validity of the results. © 2002 Wiley Periodicals, Inc. Biopolymers 61: 276–286, 2002
Contribution of secondary structure to the heat capacity and enthalpy distribution of the unfolded state in proteins
Authors: Poland Douglas
Published: August 2002

We have recently shown that one can construct the enthalpy distribution for protein molecules from experimental knowledge of the temperature dependence of the heat capacity. For many proteins the enthalpy distribution evaluated at the midpoint of the denaturation transition (corresponding to the maximum in the heat capacity vs temperature curve) is broad and biphasic, indicating two different populations of molecules (native and unfolded) with distinctly different enthalpies. At temperatures above the denaturation point, the heat capacity for the unfolded state in many proteins is quite large and using the analysis just mentioned, we obtain a gaussian‐like enthalpy distribution that is very broad. A large value of the heat capacity indicates that there are structural changes going on in the unfolded state above the transition temperature. In the present paper we investigate the origin of this large heat capacity by considering the presence of changing amounts of secondary structure (specifically, α‐helix) in the unfolded state. For this purpose we use the empirical estimates of the Zimm–Bragg σ and s factors for all of the native amino acids in water as determined by Scheraga and co‐workers. Using myoglobin as an example, we calculate probability profiles and distribution functions for the total number of helix states in the specific‐sequence molecule. Given the partition function for the specific‐sequence molecule, we can then calculate a set of enthalpy moments for the molecule from which we obtain a good estimate of the enthalpy distribution in the unfolded state. This distribution turns out to be quite narrow when compared with the distribution obtained from the raw heat capacity data. We conclude that there must be other major structural changes (backbone and solvent) that are not accounted for by the inclusion of α‐helix in the unfolded state. © 2002 John Wiley & Sons, Inc. Biopolymers 63: 59–65, 2002
Surface transformation of bioactive glass in bioreactors simulating microgravity conditions. Part II: Numerical simulations
Authors: Gao H. , Ayyaswamy P. S. , Ducheyne P. , Radin S.
Published: August 2002

The effects of simulated microgravity on the surface modification of bioactive glass (BG) in solution were studied using a numerical method. Models were developed for estimating the mass transfers of different chemical species from the surface of bioactive glass particles (microcarriers) suspended in the rotating liquid medium of a NASA‐designed high aspect ratio vessel (HARV) bioreactor and on the bottom surface of a static vial. The concentration profiles resulting from chemical reactions and ionic transports were ascertained. Numerical results for the transport under simulated microgravity in the HARV and at normal gravity in the static vial were compared. These results were also compared with those of experiments to verify the enhancement of the reaction kinetics under simulated microgravity conditions. The experimental and numerical studies confirm that simulated microgravity conditions lead to the quick achievement of bioactive glass surface modification. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 379–385, 2001.
Quantification of toluene dioxygenase induction and kinetic modeling of TCE cometabolism by Pseudomonas putida TVA8
Authors: Shingleton J.T. , Applegate B.A. , Baker A.J. , Sayler G.S. , Bienkowski P.R.
Published: August 2002

As measured by the toluene‐induced bioluminescent response of Pseudomonas putida TVA8 in batch experiments, toluene dioxygenase (Tod) enzyme activities are dependent on toluene concentration between 0 and 30 mg/L. To provide a measure of the Tod activity for use in Michaelis‐Menten competitive‐inhibition kinetics, a correlation between toluene concentration and induced Tod activity as measured by an induced bioluminescent response of P. putida TVA8 is presented as a nondimensional Tod activity parameter. A packed‐bed, radial‐flow bioreactor (RFB) using the bioreporter P. putida TVA8A serves as the model system for studying the effect of the enzyme activity parameter on model predictions of vapor‐phase toluene oxidation and trichloroethylene (TCE) cometabolism. Mass balances were performed on a differential section of the RFB to describe the radial transport of vapor‐phase toluene and TCE through a bulk gas phase and the concomitant biological reaction in a stationary biofilm phase. The finite‐element Galerkin weak‐statement formulation with first‐order basis functions was used to find the optimum solution to the highly nonlinear, coupled equations. For this RFB system with toluene concentrations less than 1 mg/L in the bulk gas phase, the Tod activity parameter enables accurate predictions of steady‐state TCE degradation rate (0.27 μg TCE/min). © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 341–350, 2001.
Effects of furfural on anaerobic continuous cultivation of Saccharomyces cerevisiae
Authors: Horváth Ilona Sárvári , Taherzadeh Mohammad J. , Niklasson Claes , Lidén Gunnar
Published: August 2002

Furfural is an important inhibitor of yeast metabolism in lignocellulose‐derived substrates. The effect of furfural on the physiology of Saccharomyces cerevisiae CBS 8066 was investigated using anaerobic continuous cultivations. Experiments were performed with furfural in the feed medium (up to 8.3 g/L) using three different dilution rates (0.095, 0.190, and 0.315 h−1). The measured concentration of furfural was low (< 0.1 g/L) at all steady states obtained. However, it was not possible to achieve a steady state at a specific conversion rate of furfural, qf, higher than approximately 0.15 g/g·h. An increased furfural concentration in the feed caused a decrease in the steady‐state glycerol yield. This agreed well with the decreased need for glycerol production as a way to regenerate NAD+, i.e., to function as a redox sink because furfural was reduced to furfuryl alcohol. Transient experiments were also performed by pulse addition of furfural directly into the fermentor. In contrast to the situation at steady‐state conditions, both glycerol and furfuryl alcohol yields increased after pulse addition of furfural to the culture. Furthermore, the maximum specific conversion rate of furfural (0.6 g/g·h) in dynamic experiments was significantly higher than what was attainable in the chemostat experiments. The dynamic furfural conversion could be described by the use of a simple Michaelis–Menten‐type kinetic model. Also furfural conversion under steady‐state conditions could be explained by a Michaelis–Menten‐type kinetic model, but with a higher affinity and a lower maximum conversion rate. This indicated the presence of an additional component with a higher affinity, but lower maximum capacity, either in the transport system or in the conversion system of furfural. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 540–549, 2001.
Electric field induced desorption of bacteria from a conditioning film covered substratum
Authors: Poortinga Albert T. , Smit Jelly , van der Mei Henny C. , Busscher Henk J.
Published: August 2002

Desorption of three oral bacterial strains from a salivary conditioning film on an indium tin oxide electrode during application of a positive (bacterial adhesion to the anode) or a negative electric current was studied in a parallel plate flow chamber. Bacterial adhesion was from a flowing suspension of high ionic strength, after which the bacterial suspension was replaced by a low ionic strength solution without bacteria and currents ranging from −800 to +800 μA were applied. Streptococcus oralis J22 desorbed during application of a positive and negative electric current with a desorption probability that increased with increasing electric current. Two actinomyces strains, however, could not be stimulated to desorb by the electric currents applied. The desorption forces acting on adhering bacteria are electroosmotic in origin and working parallel to the electrode surface in case of a positive current, whereas they are electrophoretic and electrostatic in origin and working perpendicular to the surface in case of a negative current. By comparison of the effect of positive and negative electric currents, it can be concluded that parallel forces are more effective in stimulating bacterial desorption than perpendicular forces. The results of this study point to a new pathway of cleaning industrial and biomedical surfaces without the use of detergents or biocides. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 395–399, 2001.
Metabolic flux analysis for succinic acid production by recombinant Escherichia coli with amplified malic enzyme activity
Authors: Hong Soon Ho , Lee Sang Yup
Published: August 2002

A pfl ldhA double mutant Escherichia coli strain NZN111 was used to produce succinic acid by overexpressing the E. coli malic enzyme. Escherichia coli strain NZN111 harboring pTrcML produced 6 and 8 g/L of succinic acid from 20 g/L of glucose in flask culture at 37°C and 30°C, respectively. When NZN111(pTrcML) was cultured at 30°C with intermittent glucose feeding the final succinic acid concentration obtained was 9.5 g/L and the ratio of succinic acid to acetic acid was 13:1. This system could not be analyzed by conventional metabolic flux analysis techniques, since some pyruvate and succinic acid were accumulated intracellularly. Therefore, a new flux analysis method was proposed by introducing intracellular pyruvate and succinic acid pools. By this new method the concentrations of intracellular metabolites were successfully predicted and the differences between the measured and calculated reaction rates could be considerably reduced. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 74: 89–95, 2001.
Prediction of the pilot‐scale recovery of a recombinant yeast enzyme using integrated models
Authors: Varga E. G. , Titchener‐Hooker N. J. , Dunnill P.
Published: August 2002

This article describes the rapid prediction of recovery process performance for a new recombinant enzyme product on the basis of a broad portfolio of computer models and highly targeted experimentation. A process model for the recombinant system was generated by linking unit operation models in an integrated fashion, with required parameter estimation and physical property determination accomplished using data from scale‐down studies. This enabled the generic modeling framework established for processing of a natural enzyme from bakers' yeast to be applied. An experimental study of the same operations at the pilot scale showed that the process model gave a conservative prediction of recombinant enzyme recovery. The model successfully captured interactions leading to a low overall product yield and indicated the need for further study of precipitate breakage in the feed zone of a disc stack centrifuge in order to improve performance. The utility of scale‐down units as an aid to fast model generation and the advantage of integrating computer modeling and scale‐down studies to accelerate bioprocess development are highlighted. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 74: 96–107, 2001.
Performance of batch membrane reactor: Glycerol‐3‐phosphate synthesis coupled with adenosine triphosphate regeneration
Authors: Li Tao , Yeh Henry , Kim Ji‐Hyeon , Ryu Dewey D. Y.
Published: August 2002

Glycerol‐3‐phosphate (G3P) was synthesized from glycerol using glycerol kinase (GK). This reaction requires adenosine triphosphate (ATP) and was coupled with the ATP regeneration reaction using acetate kinase (AK) in a batch‐operated ultrafiltration hollow‐fiber reactor. By taking into consideration the dynamic nature of the bioreactor performance under non–steady‐state conditions, a model for the performance of a batch membrane reactor for G3P synthesis coupled with ATP regeneration was developed and studied. The simulation results showed good agreement with the experimental results. The simulation studies have provided some insight into the process dynamics of the coupled reactions in the reactor system studied. For the reactor operational model used, in which the enzymes are retained in the shell side and the substrates are also initially placed in the shell side, it was found that the substrate concentration in the lumen side increased to a level higher than that in the shell side, and a backdiffusion occurred from the lumen side to the shell side during reactor operation. The ratio of the reaction rate to diffusion rate goes through a sharp peak during the time that the direction of diffusion is reversed. For another reactor operational model, in which the substrates were initially placed in the lumen side and enzymes were retained in the shell side, it was found that the rate‐controlling step between the reaction and diffusion was switched during the reactor operation. Initially, the reaction rate increased while the diffusion rate was high and the substrate concentrations increased in the shell side. The ratio of reaction rate to diffusion rate increased to a maximum and remained at a constant level as the diffusion rate decreased to a low level due to the nonlinear characteristics of mass transfer process. This study provides information that is useful for optimization of batch membrane enzyme reactor operation and for a fed‐batch‐type process with an intermittent feeding strategy for efficient use of substrates. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 74: 326–334, 2001.
Towards more active biocatalysts in organic media: Increasing the activity of salt‐activated enzymes
Authors: Ru Michael T. , Wu Kahn C. , Lindsay John P. , Dordick Jonathan S. , Reimer Jeffrey A. , Clark Douglas S.
Published: August 2002

The activation of freeze‐dried subtilisin Carlsberg (SC) in hexane has been systematically studied and partially optimized with respect to the freezing method, the addition of inorganic salts and lyoprotectants, the initial concentration and final weight percent of additives, and the amount of water added to the organic solvent. Activity and water content were found to correlate directly with the kosmotropicity of the activating salt (kosmotropic salts bind water molecules strongly relative to the strength of water‐water interactions in bulk solution). Combinations of kosmotropic salts with known lyoprotectants such as poly(ethylene glycol) (PEG) and sugars did not yield an appreciably more active catalyst. However, the combination of the kosmotropic sodium acetate with the strongly buffering sodium carbonate activated the enzyme more than the individual additives alone. Enzyme activity was enhanced further by the addition of small amounts of water to the organic solvent. Under optimal conditions, enzyme activity in hexane was improved over 27,000‐fold relative to the salt‐free enzyme, reaching a catalytic efficiency that was within one order of magnitude of kcat/Km for hydrolysis of the same substrate in aqueous buffer. Further activation to attain even higher catalytic efficiencies may be possible with additional optimization. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 187–196, 2001.
Estimation of steady‐state culture characteristics during acceleration‐stats with yeasts
Authors: van der Sluis Catrinus , Westerink Brenda H. , Dijkstal Maikel M. , Castelein Sipke J. , van Boxtel Antonius J.B. , Giuseppin Marco L.F. , Tramper Johannes , Wijffels René H.
Published: August 2002

Steady‐state culture characteristics are usually determined in chemostat cultivations, which are very time‐consuming. In contrast, acceleration‐stat (A‐stat) cultivations in which the dilution rate is continuously changed with a constant acceleration rate are not so time‐consuming, especially at high acceleration rates. Therefore, the A‐stat could be advantageous to use instead of the chemostat. However, the highest acceleration rate, meaning the fastest A‐stat that can be applied for estimating steady‐state culture characteristics, is not known yet. Experimental results obtained with Zygosaccharomyces rouxii, an important yeast in soy sauce processes, showed that the culture characteristics during the A‐stat with an acceleration rate of 0.001 h−2 were roughly comparable to those of the chemostat. For higher acceleration rates the deviation between the culture characteristics in the A‐stat and those in the chemostat obtained at the same dilution rate generally started to increase. The source of these deviations was examined by simulation for Saccharomyces cerevisiae. The simulations demonstrated that this deviation was not only dependent on the metabolic adaptation rate of the yeast, but also on the rate of change in environmental substrate concentrations during A‐stats. From this work, it was concluded that an A‐stat with an acceleration rate of 0.001 h−2 is attractive to be used instead of chemostat whenever a rough estimation of steady‐state culture characteristics is acceptable. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 267–275, 2001.
Managing environmental risk in existing light industrial estates
Authors: Jayne Michael Ross
Published: August 2002

In order to optimize the role of light industrial estates in the environment, it is desirable to follow the principles of ecological modernization and factor the environmental considerations into the development process. This is not possible with existing estates, where a different approach must be taken. This paper examines research conducted at five light industrial estates and considers the role of the landlord in determining an alternative strategy. The results suggest that occupiers are still not taking all the reasonable steps available to them in order to mitigate their potential for environmental damage, nor are they fully exploiting the opportunities that exist for environmental improvements. Landlords of light industrial estates have long term interests in property and, consequently, have a role in ensuring that existing estates are better managed from an environmental point of view. As such landlords have the potential to contribute to the process of ecological modernization. Copyright © 2001 John Wiley & Sons, Ltd and ERP Environment
Unusual origin and course of the left pulmonary artery
Authors: Gerlis Leon M. , Anderson Robert H.
Published: August 2002

An infant with a cardiac murmur was found to have a patent arterial duct and an anomalous left pulmonary artery. The duct was surgically ligated at the age of 8 months, and she remained free of cardiac or respiratory symptoms up to her death at 6 years from an unrelated intestinal condition. An anomaly was discovered at post mortem examination; the left pulmonary artery arose from the right pulmonary artery and passed behind the trachea to enter the left lung. We describe and illustrate the anatomic features of this well‐recognized entity, discuss the embryological substrate, and refer to the clinical implications. Clin. Anat. 5:373–378, 2001. © 2001 Wiley‐Liss, Inc.
Meeting the training needs of GP registrars in child abuse and neglect
Authors: Bannon Michael J. , Carter Yvonne H. , Jackson Neil R. , Pace Melanie , Thorne Wendy
Published: August 2002

A questionnaire survey undertaken among general practitioner registrars in North Thames in 1998 revealed significant deficiencies in their child protection training. A minority expressed confidence at the prospect of dealing with child protection cases in the future. A new, interactive training package was subsequently developed and delivered to a sample of GP registrars in Northeast Thames in 1999. Preliminary evaluation confirmed that the new training material was sensitive to the needs of recipients and levels of perceived confidence with participation in child protection work were increased. Further work is needed to develop the package and to oversee its successful incorporation into general practitioner vocational training. Copyright © 2001 John Wiley & Sons, Ltd.
Closure of the femoral vein puncture site after transcatheter procedures using Angio‐Seal
Authors: Coto Humberto A.
Published: August 2002

The use of anchor‐based, collagen‐derived vascular sealing devices in femoral vein punctures during right and left heart catheterizations or coronary interventions necessitating venous access for temporary pacemaker or hemodynamic monitoring has not been studied. We hypothesized that using these devices in the femoral vein would be practical and reliable. One hundred and ten consecutive patients undergoing right and left heart catheterization (56 patients, 51%) or coronary intervention (54 patients, 49%) were included in this study. Forty‐five of the interventions received IIb/IIIa inhibitors in combination with heparin, enoxaparin, aspirin, and clopidogrel. The Angio‐Seal device was successfully deployed in the femoral vein in all patients, whereas 93 (85%) received arterial Angio‐Seal, 8 received Perclose, and 9 (8%) had manual pressure or a Fem‐Stop applied to control arterial bleeding after deployment. We conclude that in patients undergoing transcatheter procedures requiring venous access, the use of an 8 Fr Angio‐Seal to seal the femoral vein is safe and feasible. Cathet Cardiovasc Intervent 2002;55:16–19. © 2002 Wiley‐Liss, Inc.
Comparison of myocardial fractional flow reserve and intravascular ultrasound for the assessment of slotted‐tube stents
Authors: Katritsis Demosthenes G. , Ioannidis John P.A. , Korovesis Socrates , Giazitzoglou Eleftherios , Parissis John , Kalivas Pericles , Webb‐Peploe Michael M.
Published: August 2002

Intravascular ultrasound (IVUS) and myocardial fractional flow reserve (FFR) have been reported to provide similar results for assessment of coil stent deployment. Their relative value in slotted‐tube stents has not been investigated. Fourteen patients subjected to coronary angioplasty and IVUS‐guided elective stenting with a slotted‐tube stent underwent IVUS assessment and FFR measurement following stent implantation at inflation pressures of 12 and 18 atm. FFR values (mean ± SD) preangioplasty, postangioplasty, and poststenting at 12 atm and 18 atm, were 0.58 ± 0.07, 0.83 ± 0.05, 0.94 ± 0.02, and 0.94 ± 0.02, respectively. After inflation at 12 atm, the area under the receiver operating characteristic (ROC) curve for the concordance of IVUS and FFR measurements was 0.89 (P = 0.02). Six patients had either an abnormal IVUS (n = 2) or FFR < 0.94 (n = 1) or both abnormal IVUS and FFR < 0.94 (n = 3) after the first inflation and had a second inflation at 18 atm. The area under the ROC curve for the concordance between IVUS and FFR final measurements was 0.855 (P = 0.10). Perfect concordance between IVUS and FFR was seen only for FFR values less than 0.91 or larger than 0.94. Overall, IVUS and FFR have substantial concordance with respect to slotted‐tube stent deployment. However, FFR values between 0.91 and 0.94 after inflation are difficult to interpret. Cathet Cardiovasc Intervent 2001;52:322–326. © 2001 Wiley‐Liss, Inc.
Percutaneous transluminal angioplasty of ostial lesions of internal mammary artery grafts
Authors: Jacq Laureut , Lancelin Bernard , Brenot Philippe , Caussin Christophe
Published: August 2002

The internal mammary artery (IMA) is currently the best graft for coronary bypass surgery and is therefore preferentially anastomosed to major arteries, usually the left anterior descending (LAD) artery. This graft may develop a stenosis, most often at the distal anastomosis. Ostial stenoses are rare and their pathophysiology uncertain. While angioplasty of distal anastomotic lesions provides adequate results, the very small number of published cases of angioplasty of ostial lesions explains the lack of knowledge on results of this type of procedure. The authors report six procedures of this type on five patients, including two with stenting. The primary success rate was 100%, with only one hospital complication in the form of pulmonary edema. Mean follow‐up for 35 months revealed one sudden death due to probable restenosis, another death 3 years after angioplasty from rapid fatal shock without complementary investigation, and one case of unstable angina secondary to intrastent restenosis. These results suggest that this type of angioplasty is technically feasible with low risk, and that the restenosis rate seems relatively high, potentially presenting as sudden death, in the same way as unprotected dilatation of the native left main artery. A very close clinical follow‐up of these patients is therefore necessary, with angiographic control in case of suspected ischemia. Cathet Cardiovasc Intervent 2001;52:368–372. © 2001 Wiley‐Liss, Inc.
Use of fractional flow reserve in the treatment of a calcific bifurcation left anterior descending coronary stenosis with rotational atherectomy
Authors: Holmes David G. , Kern Morton J.
Published: August 2002

We report the results of an intervention in a high‐risk surgical patient undergoing rotational atherectomy in a bifurcating lesion. The use of fractional flow reserve (FFR) was especially helpful due to the inability to visualize clearly the angiographic anatomy both before and following intervention. Cathet Cardiovasc Intervent 2001;53:64–67. © 2001 Wiley‐Liss, Inc.
Thermography of human arterial system by means of new thermography catheters
Authors: Stefanadis Christodoulos , Toutouzas Konstantinos , Tsiamis Eleftherios , Vavuranakis Manolis , Kallikazaros Ioannis , Toutouzas Pavlos
Published: August 2002

In this case report, we present the first clinical application of three thermography catheters for temperature measurements in the coronary arteries, the aorta, and the femoral arteries. The entire procedure was performed successfully without complications. Larger clinical studies are required in order to examine the feasibility for the application of the aortic and the peripheral artery thermography catheters and the clinical significance of temperature measurements in these arteries. Cathet Cardiovasc Intervent 2001;54:51–58. © 2001 Wiley‐Liss, Inc.
Lactones. 6. Microbial lactonization of γ,δ‐epoxy esters
Authors: Olejniczak Teresa , Gawroński Jacek , Wawrzeńczyk Czesław
Published: August 2002

The ability of 19 microorganisms to perform the enantioselective lactonization of racemic γ,δ‐epoxy ester 3a and its 7‐methyl homolog 3b was checked. It was found that Rhodotorula rubra preferentialy transformed both substrates to (−)‐enantiomers of trans δ‐hydroxy‐γ‐lactones with ee 76% for 3a and 24% for 3b. The best efficiency (20–30%) and enantioselectivity (ee 60–100%) of formation of (−)‐γ‐hydroxy‐δ‐lactones 6a and 6b was observed for lactonization by Botrytis cinerea and Fusarium semitectum, respectively. Chirality 13:302–307, 2001. © 2001 Wiley‐Liss, Inc.
Enantioselective inhibition of the binding of rac‐profens to human serum albumin induced by lithocholate
Authors: Bertucci Carlo
Published: August 2002

The reversible binding of lithocholate to human serum albumin determines a decrease of the binding of rac‐ketoprofen. The process was followed by displacement chromatography using increasing concentrations of the competitor, i.e., lithocholate, in the mobile phase. The inhibition of rac‐ketoprofen binding resulting was enantioselective and greater displacement was observed for the (S) enantiomer. The displacement process resulting was competitive in nature, the two enantiomers of ketoprofen binding to the same binding site as the modifier. The investigation was extended to other nonsteroidal antiinflammatory drugs. The enantioselective binding inhibition was larger in the case of rac‐naproxen and rac‐suprofen with respect to the phenomenon observed in the case of rac‐ketoprofen. The difference in circular dichroism spectroscopy was also used to characterize the binding of lithocholate to human serum albumin. This bile acid was proven to bind to site II on human serum albumin. The results, as obtained by displacement chromatography and difference circular dichroism spectroscopy, strongly support the hypothesized role of bile acids in inducing the enantioselective inhibition of ketoprofen binding to human serum albumin in patients suffering from liver diseases. Chirality 13:372–378, 2001. © 2001 Wiley‐Liss, Inc.
Polar ejection forces are operative in crane‐fly spermatocytes, but their action is limited to the spindle periphery
Authors: LaFountain James R. , Cole Richard W. , Rieder Conly L.
Published: August 2002

Laser microsurgery was employed to reveal kinetochore‐independent forces acting on chromosome arms in crane‐fly spermatocytes. When a portion of an arm situated along the interpolar axis between the equator and a pole was cut off, the resultant acentric fragment was transported poleward and outward into the peripheral domain of the spindle. If the fragment was generated well in advance of the onset of anaphase, then at the spindle periphery, it changed direction and moved away from the pole and back toward the equator. That domain‐specific movement—poleward in the central spindle and away from the pole at the spindle periphery—not only provides the first evidence for polar ejection forces acting on acentric fragments in a meiotic system, but it is the first example of kinetochore‐independent forces in both directions at the same stage of division. Sniglets generated by laser pulses directed at specific sites in the spindle revealed that the mechanism underlying ejection forces was specific to chromosomes. At anaphase onset, polar ejection forces ceased, and pole‐directed forces took over. At that time, chromosome fragments that had been ejected to the equator moved poleward again, providing clear evidence for kinetochore‐independent forces on chromosome arms during anaphase. Cell Motil. Cytoskeleton 51:16–26, 2002. © 2002 Wiley‐Liss, Inc.
The Chlamydomonas MBO2 locus encodes a conserved coiled‐coil protein important for flagellar waveform conversion
Authors: Tam Lai‐Wa , Lefebvre Paul A.
Published: August 2002

Chlamydomonas flagella can undergo a calcium‐dependent conversion between an asymmetric ciliary waveform and a symmetric flagellar waveform. Mutations at three MBO loci abolish the predominant ciliary waveform and result in cells that move backward only with the flagellar waveform. We have cloned and characterized the MBO2 gene. It encodes a novel protein with extensive alpha‐helical coiled‐coils and two leucine zippers. Sequences highly similar to MBO2p were found in a variety of organisms with cilia and flagella, suggesting that the MBO2 gene function may be conserved in many diverse taxa. Antibodies to MBO2p recognized an axonemal protein of 110 kDa, which appeared to be tightly associated with doublet microtubules. The protein was present in flagella of a variety of paralyzed flagellar mutants that lacked different axonemal structures, indicating that MBO2p is a component of a previously uncharacterized flagellar protein complex. In contrast to the earlier suggestion that the MBO2 gene may encode a component of an intramicrotubular beak‐like structure present only proximally in flagella, we localized an epitope‐tagged MBO2p along the entire length of the flagella. Moreover, the insertion of a hemagglutinin (HA) epitope in the conserved C‐terminal domain of MBO2p reduced the swimming velocity of cells transformed with the epitope‐tagged gene. These results indicate that MBO2p may play a role both in the assembly of the beak‐like structure and the regulation of the force‐generation machinery during the ciliary beat. Cell Motil. Cytoskeleton 51:197–212, 2002. © 2002 Wiley‐Liss, Inc.