bluuebunny/crossref_metadata_2025 huggingface dataset:
Ophthalmic Regional Anesthesia
Authors: Nouvellon Emmanuel , L’Hermite Joel , Chaumeron Arnaud , Mahamat Aba , Mainemer Martine , Charavel Pierre , Mahiou Philippe , Dupeyron Gérard , Bassoul Bruno , Dareau Stephane , Eledjam Jean-Jacques , Ripart Jacques
Published: January 2004

Background

The purpose of this study was to evaluate the efficacy and safety of episcleral single-injection anesthesia in a large number of patients.

Methods

Over a period of 5 yr, in four institutions, anesthesiologists involved in this prospective study completed a standardized form to evaluate single-injection medial canthus high-volume episcleral anesthesia. The success rate of the block was rated according to an akinesia score. The study parameters included demographic data, surgical procedure, and anesthetic management. All patients were followed up at least until postoperative day 1, and all complications, pain, and discomfort were noted. Statistical analysis was done to assess the risk factors for complications.

Results

A total of 2,031 patients were included in the study. The most frequent surgical procedures performed were phacoemulsification and posterior chamber artificial lens implantation (91.0%). A total of 66 complications (3.3%) occurred in 60 patients. One patient had a retrobulbar hemorrhage, and 59 had one or two more minor incidents or pain/discomfort with the procedure. The complications consisted of subconjunctival hematoma (1.3%), ocular hypertonia (0.4%), and chemosis (0.30%). Statistical analysis revealed that inexperience in the technique represented a risk factor for complications.

Conclusions

This is the first survey of a large experience in episcleral single-injection anesthesia, a form of anesthesia that does not preclude sharp-needle complications and does require training. Only one complication occurred among 2,031 patients; however, a larger number of patients is needed to definitively evaluate the safety of episcleral single-injection anesthesia.
Epidural Neostigmine Produces Analgesia but Also Sedation in Women after Cesarean Delivery
Authors: Kaya F. Nur , Sahin Sukran , Owen Medge D. , Eisenach James C.
Published: January 2004

Background

Intrathecal neostigmine produces analgesia but also nausea, limiting its utility. In contrast, epidural administration of neostigmine has been suggested to produce postoperative analgesia without nausea in nonpregnant patients. The purpose of this study was to examine the dose range for efficacy and side effects of epidural neostigmine in women at cesarean delivery receiving combined spinal-epidural anesthesia.

Methods

After institutional approval and informed consent, 80 patients for elective cesarean delivery were given combined spinal-epidural anesthesia with 8 mg hyperbaric bupivacaine plus 10 microg fentanyl. Patients were randomized to receive either saline or 75, 150, or 300 microg neostigmine (n = 20 per group) in 10 ml saline after cord clamping. Pain, morphine consumption, and side effects were monitored for 24 h.

Results

Global pain assessment for the first 24 h was reduced from 5.4 +/- 0.2 in the saline group to 3.0-3.5 +/- 0.3 in the neostigmine groups, dose independently. Correspondingly, global satisfaction with neostigmine was also improved (P < 0.05). Nausea and morphine consumption were similar among groups. Intraoperative shivering and sedation were increased in the 300-microg neostigmine group only (P < 0.05), and postoperative sedation was increased by neostigmine in a dose-independent fashion (P < 0.05).

Conclusions

Epidural neostigmine produced modest analgesia in women after cesarean delivery. In contrast with previous reports, which focused primarily on nausea, these data suggest that epidural neostigmine can also produce mild sedation for several hours. These data suggest a limited role for single bolus-administration epidural neostigmine for analgesia after cesarean delivery. They also support future study of epidural neostigmine for obstetric analgesia.
Dose-dependent Effects of Propofol on the Central Processing of Thermal Pain
Authors: Hofbauer Robert K. , Fiset Pierre , Plourde Gilles , Backman Steven B. , Bushnell M. Catherine
Published: January 2004

Background

Anatomic and physiologic data show that multiple regions of the forebrain are activated by pain. However, the effect of anesthetic level on nociceptive input to these regions is not well understood.

Methods

The authors used positron emission tomography to measure the effect of various concentrations of propofol on pain-evoked changes in regional cerebral blood flow. Fifteen volunteers were scanned while warm and painful heat stimuli were presented to the volar forearm using a contact thermode during administration of target propofol concentrations of 0.0 microg/ml (alert control), 0.5 microg/ml (mild sedation), 1.5 microg/ml (moderate sedation), and 3.5 microg/ml (unconsciousness).

Results

During the 0.5-microg/ml target propofol concentration (mild sedation), the subjects' pain ratings increased relative to the alert control condition; correspondingly, pain-evoked regional cerebral blood flow increased in the thalamus and the anterior cingulate cortex. In contrast, when subjects lost consciousness (3.5 microg/ml), pain-evoked responses in the thalamus and the anterior cingulate cortex were no longer observed, whereas significant pain-evoked activation remained in the insular cortex.

Conclusion

These data show that propofol has a dose-dependent effect on thalamocortical transfer of nociceptive information but that some pain-evoked cortical activity remains after loss of consciousness.
Infraclavicular Perineural Local Anesthetic Infusion
Authors: Ilfeld Brian M. , Morey Timothy E. , Enneking F. Kayser
Published: January 2004

Background

In this randomized, double-blind study, the authors investigated the efficacy of continuous and patient-controlled ropivacaine infusions via an infraclavicular perineural catheter in ambulatory patients undergoing moderately painful orthopedic surgery at or distal to the elbow.

Methods

Preoperatively, patients (n = 30) received an infraclavicular perineural catheter and nerve block. Postoperatively, patients were discharged home with both oral analgesics and a portable infusion pump delivering 0.2% ropivacaine (500-ml reservoir) in one of three dosing regimens: the basal group (12 ml/h basal, 0.05-ml patient-controlled bolus dose), the basal-bolus group (8 ml/h basal, 4 ml bolus), or the bolus group (0.3 ml/h basal, 9.9 ml bolus). Investigators and patients were blinded to random group assignment.

Results

The basal group (n = 10) required more oral analgesics than the basal-bolus group (P = 0.002) and had a shorter median infusion duration than the other two groups (P < 0.001 for both). The bolus group had the longest median infusion duration (P < 0.001 for both) but experienced an increase in breakthrough pain incidence (P = 0.004) and intensity (P = 0.04 vs. basal-bolus group) as well as sleep disturbances (P < 0.001 for both) compared with the other groups. Overall satisfaction was greatest in the basal-bolus group (9.7 +/- 0.5 vs. 7.9 +/- 1.7 and 8.1 +/- 1.5; P < 0.05 for both).

Conclusions

After moderately painful orthopedic surgery at or distal to the elbow, 0.2% ropivacaine delivered as a continuous infusion combined with patient-controlled bolus doses via an infraclavicular perineural catheter optimizes analgesia while minimizing oral analgesic use compared with basal- or bolus-only dosing regimens.
Is Risk for Alcoholism Mediated by Individual Differences in Drinking Motivations?
Authors: Prescott Carol A. , Cross Rebecca J. , Kuhn Jonathan W. , Horn John L. , Kendler Kenneth S.
Published: January 2004

Abstract: Background: Individual differences in motivations to drink have been proposed as a mechanism that mediates risk for alcoholism. We investigated the genetic and environmental sources of variation in motivations for drinking, as assessed by four scales of the Alcohol Use Inventory (AUI), and then examined the extent to which genetic and environmental variations in risk for alcoholism are mediated by individual differences in drinking motives.

Methods: Data on four AUI scales (assessing drinking to manage mood states, to relieve social anxiety, in social situations, and to improve mental functioning) and lifetime DSM‐IV alcohol abuse and/or dependence (AAD) were obtained from 2529 female and 3709 male adult twins, including 2229 complete twin pairs, from the population‐based Virginia Twin Registry.

Results: Logistic regression analyses indicated that higher scores on each of the four AUI variables were significantly associated with AAD, with increases in risk for diagnosis of 40% to 141% per standard deviation increase in AUI score. Structural modeling analyses conducted using Mplus indicated that individual differences in AUI scores were in part due to genetic variation, particularly among women. Among males, genetic factors were substantial for drinking to alter mood but small for other measures. A substantial portion of the genetic variation in AAD overlapped with drinking to manage mood states. Results from bivariate twin models of AAD and the AUI scales were consistent with the mediation hypothesis for the social anxiety and social interaction scales but not drinking to manage mood or to enhance mental functioning.

Conclusions: Genetic contributions to variation in risk for alcoholism may be mediated in part by individual differences in motivations related to drinking in social settings. Drinking to manage mood indexes genetic risk for alcoholism but does not appear to act as a direct cause of alcoholism.
Ethanol Selectively Inhibits Enhanced Vesicular Release at Excitatory Synapses: Real‐Time Visualization in Intact Hippocampal Slices
Authors: Maldve Regina E. , Chen Xiaochun , Zhang Tao A. , Morrisett Richard A.
Published: January 2004

Abstract: Background: Conflicting information exists concerning the actions of ethanol on vesicular release at excitatory synapses. Because long‐term alterations in synaptic transmission are thought to underlie neuroadaptive responses to ethanol, we have directly measured the actions of ethanol on release dynamics at an intact central synapse.

Methods: Here we investigated the effects of ethanol on release dynamics in hippocampal slices using confocal microscopy with the lipophilic dye, FM1‐43, complemented by a patch clamp analysis of AMPA miniature excitatory postsynaptic currents (mEPSCs). After a pretreatment/loading paradigm with sulforhodamine (S‐Rhd) and FM1‐43, stable, dense punctate FM1‐43 staining in the CA1 stratum radiatum was evident.

Results: FM1‐43 fluorescence destaining was dose‐dependently induced by perfusion with elevated K+ (20–60 mM). Cadmium inhibited K+‐induced destaining, whereas nifedipine had no significant effect. Ethanol (25–75 mM) inhibited K+‐induced destaining with high efficacy and had no effect on basal destaining. Both ω‐Conotoxin GVIA and ω‐Agatoxin IVA inhibited K+‐induced destaining with high efficacy. The combination of ω‐Conotoxin GVIA and ω‐Agatoxin IVA occluded the inhibitory effect of ethanol, indicating that ethanol inhibition of release was dependent on inhibition of N/P/Q‐voltage‐gated calcium channels (VGCCs). Patch clamp studies of AMPA mEPSCs revealed similar findings in that vesicular release was enhanced with K+ depolarization in an ethanol‐sensitive manner.

Conclusions: These findings indicate that the FM1‐43/S‐Rhd method is a stable and powerful approach for direct real‐time measurement of vesicular release kinetics in intact brain slice preparations and that ethanol inhibits vesicular release induced by depolarization via inhibition of N/P/Q‐VGCCs.
Ethanol Interferes With the Measurement of Extracellular Ionized Calcium
Authors: Keiver Kathy
Published: January 2004

Abstract: Background: Maintenance of extracellular calcium (Ca) concentration within narrow limits is critical for normal cell function and optimization of bone health. Ionized Ca (iCa), the form of Ca that is regulated, has been reported to vary inversely with blood alcohol concentration (BAC). The mechanism by which ethanol decreases blood iCa levels is unknown. However, one possible explanation is that it is, at least partially, a methodological artifact due to an effect of ethanol on the function of the ion selective electrode used to measure iCa. The purpose of this study was to determine if ethanol interferes with the measurement of iCa and if this interference can account for the typically observed in vivo effects of ethanol consumption on blood iCa levels.

Methods: Ethanol (0–5 μl/ml) was added to blood or iCa standards and the iCa concentration measured using the ICA2 iCa analyzer (Radiometer) or the I‐Stat Clinical Analyzer (Abbott Laboratories). Both instruments use an ion selective electrode to measure iCa. The relationship between iCa and BAC determined from the ex vivo addition of ethanol to blood was compared with relationships obtained in vivo during chronic ethanol consumption.

Results: Addition of ethanol to blood or iCa standards resulted in a dose‐dependent decrease in iCa concentration when iCa was measured using the ICA2 analyzer but had no effect on iCa concentration when measured with the I‐Stat Clinical Analyzer. Ethanol's effect on iCa with the ICA2 analyzer did not differ between blood and standards, and ethanol had no effect on pH, suggesting that the ethanol‐induced decrease in iCa was due to a methodological artifact. However, the magnitude of ethanol's effect was small and does not account entirely for the relationship between iCa and BAC observed in vivo with chronic ethanol consumption.

Conclusion:: Ethanol can interfere with the measurement of iCa using ion selective electrodes, but this interference depends on the analyzer used. This is a significant methodological issue that has largely been unrecognized in the field of alcohol research. Although this interference does not explain entirely the relationship between iCa and BAC observed in vivo in studies on chronic ethanol consumption, it complicates investigations designed to assess the effect of ethanol on Ca homeostasis.
Association of GABRG3 With Alcohol Dependence
Authors: Dick Danielle M. , Edenberg Howard J. , Xuei Xiaoling , Goate Alison , Kuperman Sam , Schuckit Marc , Crowe Raymond , Smith Tom L. , Porjesz Bernice , Begleiter Henri , Foroud Tatiana
Published: January 2004

Abstract: Background: Evidence from human, animal, and in vitro cell models suggests that γ‐aminobutyric acid (GABA), the major inhibitory neurotransmitter in the human central nervous system, is involved in many of the neurochemical pathways that affect alcohol use, abuse, and dependence. Both linkage and association to the region on chromosome 15q that contains a cluster of GABAA receptor genes have previously been reported, but the role of these genes in alcoholism remains inconclusive.

Methods: We conducted family‐based association analyses by using a large sample of multiplex alcoholic families collected as part of the Collaborative Study on the Genetics of Alcoholism, to test for an association between alcohol dependence and the GABAA receptor genes clustered on chromosome 15q. Multiple single‐nucleotide polymorphisms were tested in each of the three chromosome 15q GABAA receptor genes:GABRA5, GABRB3, and GABRG3.

Results: Using both classic trio‐based analyses and extended‐family analyses, we found consistent evidence of association between alcohol dependence and GABRG3. Nearly all single‐nucleotide polymorphisms across the gene yielded evidence of association, and haplotype analyses were highly significant. No consistent evidence of association was observed with either GABRA5 or GABRB3, nor was there evidence for parent‐of‐origin effects with any of the genes.

Conclusions: These analyses suggest that GABRG3 may be involved in the risk for alcohol dependence. These findings support the theory that the predisposition to alcoholism may be inherited as a general state of central nervous system disinhibition/hyperexcitability that results from an altered responsiveness to GABA.
Rotary wing UAV potential applications: an analytical study through a matrix method
Authors: Saggiani G.M. , Teodorani B.
Published: January 2004

Industrial designers often need decision‐making methods to develop innovative solutions combining specified customer's requirements with project technical constraints. This paper describes a matrix approach as a technique to support system designer since the early stages of development, when many and important decisions must be taken. In this work, the matrix method has been used to analyze the civil unmanned aerial vehicle potential market and particularly for selecting the most promising applications of a multi‐role rotary wing unmanned aerial vehicle. According to the matrix results, two rotary wing multi‐role missions have been chosen as most promising customer attractive applications. This matrix method can also be improved for subsequent decision‐making in preliminary‐configuration analysis since it can be easily tailored to different specific engineering applications.
Development of high temperature resistant modified aluminide and titanium aluminide coatings on stainless steel 316
Authors: Quraishi M.A. , Sharma Hariom K.
Published: January 2004

Stainless steel 316 was coated with CeO2 and Y2O3 modified aluminide and titanium aluminide coatings. The coatings were prepared by the pack cementation method and the high temperature oxidation behaviour of the coatings was investigated in an atmosphere containing a limited supply of air. The performance of the coatings was studied by measuring oxidation kinetics, and by scanning electron microscopic techniques. The oxidation rates of these coatings were reduced in the presence of CeO2 and Y2O3 due to better adherence of their oxide scales.
“Money makes the world go around” – fee‐based services in Danish public libraries 2000‐2003
Authors: Gustav Johannsen Carl
Published: January 2004

This paper contains some of the main results of a recent 2003 Danish qualitative survey on opinions and experiences of fee‐based services among public libraries. Current considerations and reflections are reviewed, experiences with specific public library products and services and customers segments analysed and success factors and primary results identified. This study, among others, asserts that the discourse on fee‐based library services has fundamentally changed since the 1970s and that fee‐based services today are more likely to be seen as facilitators of organisational change, human resource development, learning, quality and the like than income and profit generation mechanisms. A balanced view on the effects on organisational culture and the traditional Danish cooperating library system suggests that fee‐based services in certain respects seem to stimulate knowledge sharing.
Metasearching in Boston College Libraries – a case study of user reactions
Authors: Tallent Ed
Published: January 2004

As the Boston College Libraries prepared to migrate to a new release of MetaLib, a metasearch and portal tool from Ex Libris, the library conducted some informal usability studies on its existing implementation. These studies combined conversations with undergraduate and graduate students about their research style and observations of students conducting searches using MetaQuest. This article reviews the main issues culled from this, focusing on student research style, asking if MetaLib, as an example of a metasearch engine, responds to this need, reviewing the existing MetaLib design issues, and finishes with pointers on where the Boston College Libraries are headed with this product.
Corrosion inhibition of iron in hydrochloric acid solution by jojoba oil
Authors: Chetouani A. , Hammouti B. , Benkaddour M.
Published: January 2004

The influence of addition of the natural material, jojoba oil, on the corrosion of iron in molar hydrochloric acid had been studied using weight loss measurement and electrochemical polarisation methods. It was found that the corrosion rate was significantly reduced in the presence of jojoba. It was also found that the corrosion inhibition efficiency increased with the concentration of the jojoba oil to attain a 100 per cent inhibition at 0.515 g/l of jojoba oil, indicating that jojoba oil was an excellent corrosion inhibitor. The effect of temperature on the corrosion behaviour of iron indicated that the inhibition efficiency of jojoba oil decreased very slightly with the rise of temperature. It was found that the adsorption of jojoba oil on the iron, which followed the Frumkin isotherm, was the main cause to the corrosion inhibition.
Molecular charge transfer complexes of metal ions thiazolylazo compounds with iodine
Authors: El‐Mossalamy E.H. , Ibrahim A.A.
Published: January 2004

Molecular charge transfer complexes of some thiazolazo compounds with Cu2+, Ni2+, Co2+, Zn2+, La3+ and Zr3+ complexes with iodine have been studied spectrophotometrically. The stoichiometry and formation constants of the complexes formed were determined. The effect of solvents, effect of buffer (pH 2‐11) and the energy of transition (E) were calculated. The optimum conditions favouring the formation of the coloured complexes were extensively studied by Beer's law and Ringbom method. Furthermore, the spectral characteristics, IR, UV‐Vis and 1H NMR of the complexes were investigated and discussed in terms of donor molecular structure.
Modeling and characterization of novel, low‐cost, direct‐write waveguide
Authors: Mignatti M.A. , Campbell M.I. , Ruizpalacios R. , Wood K.L. , Beaman J.J.
Published: January 2004

Both the current long term telecommunication trends toward optical networking and the recent growth in information bandwidth have pushed the necessity for improved optical communications. Our fabrication approach, which leverages our expertise in solid freeform fabrication in conjunction with sol‐gel technology, has advantages over these other methods because of the inherent benefits of using a direct‐write philosophy, such as design flexibility and minimal post‐processing. However, fabrication of such novel optical components requires extensive knowledge of their light guidance capabilities. This paper shows the technical issues involved in both modeling and characterizing small optical components fabricated by locally densifying sol‐gels in a modified direct‐write process.
Freeform fabrication of zinc‐air batteries and electromechanical assemblies
Authors: Malone Evan , Rasa Kian , Cohen Daniel , Isaacson Todd , Lashley Hilary , Lipson Hod
Published: January 2004

This paper reports on a fabrication platform and extensions to deposition‐based processes that permit freeform fabrication of three‐dimensional functional assemblies with embedded conductive wiring and power sources. Structure and joints are produced by fused deposition of thermoplastics and deposition of elastomers. Conductive wiring is achieved by deposition of various low‐melting‐point alloys and conductive pastes. Batteries based on zinc‐air chemistry are produced by the deposition of zinc, electrolyte, and catalysts, with separator media and electrodes. Details of the deposition processes are provided and several printed assemblies are demonstrated.
A real‐time workflow tracking system for a manufacturing environment
Authors: Ong N.S. , Foo W.C.
Published: January 2004

Introduces the concepts relating to workflow tracking systems designed to improve the performance and productivity of a production line by reducing non‐value added costs and activities within the manufacturing and assembly process. This results in lower cycle times and reduced manufacturing costs. Importantly, it also supports more effective decision making and adds flexibility to the forms of manufacturing strategy that can be adopted.
Customer centric business processing
Authors: Bolton Mike
Published: January 2004

The last decade has seen the emergence of customer relationship management (CRM) as a technique to underpin organisational performance improvement in improving customer retention, customer satisfaction and customer value. However, evidence suggests that many CRM initiatives fail. Suggests that CRM does not go far enough in changing the underlying culture and systems of an organisation. What is needed is complete customer‐centric business processing (CCBP), whereby all business processes and all individuals are focused on identifying and meeting the needs of customer. Explains the concepts behind CCBP and describes the key organisational changes that are needed to underpin CCBP.
Performance improvement
Authors: Grünberg Thomas
Published: January 2004

Many methodologies and techniques for improving operational performance have been developed over the years – these provide structured ways of improving company performance, but they do not explicitly tell us where to start. To be able to improve performance effectively, it is important to identify the particular factors of performance to work with. Furthermore, it is important to find those factors that have a high impact on performance. The paper presents a definition of performance, productivity and profitability and two main views of the relationships between the terms – a hierarchical view and a subset view. Each has its merits. Offers brief descriptions of some improvement techniques to show where the ideas for the suggested improvement method are taken from, i.e. a part of the analysis and synthesis process. Most of the techniques described are analysis tools, as the focus here is on identifying areas to improve – when it comes to the actual improvement, the actual solution is often quite easy. Finally, proposes a methodology for improvement work – this is to be evaluated in later research.
Solvent–amino acid interaction energies in three‐dimensional‐lattice Monte Carlo simulations of a model 27‐mer protein: Folding thermodynamics and kinetics
Authors: Leonhard Kai , Prausnitz John M. , Radke Clayton J.
Published: January 2004

Amino acid residue–solvent interactions are required for lattice Monte Carlo simulations of model proteins in water. In this study, we propose an interaction‐energy scale that is based on the interaction scale by Miyazawa and Jernigan. It permits systematic variation of the amino acid–solvent interactions by introducing a contrast parameter for the hydrophobicity, Cs, and a mean attraction parameter for the amino acids, ω. Changes in the interaction energies strongly affect many protein properties. We present an optimized energy parameter set for best representing realistic behavior typical for many proteins (fast folding and high cooperativity for single chains). Our optimal parameters feature a much weaker hydrophobicity contrast and mean attraction than does the original interaction scale. The proposed interaction scale is designed for calculating the behavior of proteins in bulk and at interfaces as a function of solvent characteristics, as well as protein size and sequence.
High‐temperature solution NMR structure of TmCsp
Authors: Jung Astrid , Bamann Christian , Kremer Werner , Kalbitzer Hans Robert , Brunner Eike
Published: January 2004

Cold shock proteins (Csps) are assumed to play a central role in the regulation of gene expression under cold shock conditions. Acting as single‐stranded nucleic acid‐binding proteins, they trigger the translation process and are therefore involved in the compensation of the influence of low temperatures (cold shock) upon the cell metabolism. However, it is unknown so far how Csps are switched on and off as a function of temperature. The aim of the present study is the study of possible structural changes responsible for this switching process. 1H‐15N HSQC spectra recorded at different temperatures and chemical‐shift analysis have indicated subtle conformational changes for the cold‐shock protein from the hyperthermophilic bacterium Thermotoga maritima (TmCsp) when the temperature is elevated from 303 K to its physiological temperature (343 K). The three‐dimensional structure of TmCsp was determined by nuclear magnetic resonance (NMR) spectroscopy at 343 K to obtain quantitative information concerning these structural changes. By use of residual dipolar couplings, the loss of NOE information at high temperature could be compensated successfully. Most pronounced conformational changes compared with room‐temperature conditions are observed for amino acid residues closely neighbored to two characteristic β‐bulges and a well‐defined loop region of the protein. Because the residues shown to be responsible for the interaction of TmCsp with single‐stranded nucleic acids can almost exclusively be found within these regions, nucleic acid‐binding activity might be down‐regulated with increasing temperature by the described conformational changes.
An automated in vitro protein folding screen applied to a human dynactin subunit
Authors: Scheich Christoph , Niesen Frank H. , Seckler Robert , Büssow Konrad
Published: January 2004

The preparation of proteins for structural and functional analysis using the Escherichia coli expression system is often hampered by the formation of insoluble intracellular protein aggregates (inclusion bodies). Transferring those proteins into their native states by in vitro protein folding requires screening for the best buffer conditions and suitable additives. However, it is difficult to assess the success of such a screen if no biological assay is available. We established a fully automated folding screen and a system to detect folded protein that is based on analytical hydrophobic interaction chromatography and tryptophan fluorescence spectroscopy. The system was evaluated with two model enzymes (carbonic anhydrase II and malate dehydrogenase), and was successfully applied to the folding of the p22 subunit of human dynactin, which is expressed in inclusion bodies in E. coli. The described screen allows for high‐throughput folding analysis of inclusion body proteins for structural and functional analyses.
A simple formalism on dynamics of proteins on potential energy landscapes
Authors: Murugan Rajamanickam , Mazumdar Shymalava
Published: January 2004

We present a simple formalism for the dynamics of proteins on a potential energy landscape, using connectedness of configurational domains as an order parameter. This formalism clearly shows that the energy bias required to form a unit correct contact toward the native configuration of a two‐state folder, to overcome Levinthal's paradox, is Ebias ≅ RT ln 2. This result agrees well with earlier studies and indicates that the bias is mainly due to hydrophobic interaction. Further investigations have shown that the landscape funnel could be experimentally mapped onto a two‐dimensional space formed by denaturant concentration and the connectedness of configurational domains. The theoretical value of the depth‐of‐folding funnel in terms of denaturant concentration has been calculated for a model protein (P450cam), which agrees well with the experimental value. Using our model, it is also possible to explain the turnover nature of heat‐capacity change upon unfolding of proteins and the existence of enthalpy and entropy convergence temperatures during unfolding without any strict assumptions as proposed in earlier studies.
An accurate, residue‐level, pair potential of mean force for folding and binding based on the distance‐scaled, ideal‐gas reference state
Authors: Zhang Chi , Liu Song , Zhou Hongyi , Zhou Yaoqi
Published: January 2004

Structure prediction on a genomic scale requires a simplified energy function that can efficiently sample the conformational space of polypeptide chains. A good energy function at minimum should discriminate native structures against decoys. Here, we show that a recently developed, residue‐specific, all‐atom knowledge‐based potential (167 atomic types) based on distance‐scaled, finite ideal‐gas reference state (DFIRE‐all‐atom) can be substantially simplified to 20 residue types located at side‐chain center of mass (DFIRE‐SCM) without a significant change in its capability of structure discrimination. Using 96 standard multiple decoy sets, we show that there is only a small reduction (from 80% to 78%) in success rate of ranking native structures as the top 1. The success rate is higher than two previously developed, all‐atom distance‐dependent statistical pair potentials. Applied to structure selections of 21 docking decoys without modification, the DFIRE‐SCM potential is 29% more successful in recognizing native complex structures than an all‐atom statistical potential trained by a database of dimeric interfaces. The potential also achieves 92% accuracy in distinguishing true dimeric interfaces from artificial crystal interfaces. In addition, the DFIRE potential with the Cα positions as the interaction centers recognizes 123 native structures out of a comprehensive 125‐protein TOUCHSTONE decoy set in which each protein has 24,000 decoys with only Cα positions. Furthermore, the performance by DFIRE‐SCM on newly established 25 monomeric and 31 docking Rosetta‐decoy sets is comparable to (or better than in the case of monomeric decoy sets) that of a recently developed, all‐atom Rosetta energy function enhanced with an orientation‐dependent hydrogen bonding potential.
The interface of a membrane‐spanning leucine zipper mapped by asparagine‐scanning mutagenesis
Authors: Ruan Weiming , Lindner Eric , Langosch Dieter
Published: January 2004

An oligo‐leucine sequence has previously been shown to function as an artificial transmembrane segment that efficiently self‐assembles in membranes and in detergent solution. Here, a novel technique, asparagine‐scanning mutagenesis, was applied to probe the interface of the self‐assembled oligo‐leucine domain. This novel approach identifies interfacial residues whose exchange to asparagine leads to enhanced self‐interaction of transmembrane helices by interhelical hydrogen bond formation. As analyzed by the ToxR system in membranes, the interface formed by the oligo‐leucine domain is based on a leucine‐zipper‐like heptad repeat pattern of amino acids. In general, the strongest impacts on self‐assembly were seen with asparagines located around the center of the sequence, indicating that interaction is be more efficient here than at the termini of the transmembrane domains.
The role of hydrogen bonding in the enzymatic reaction catalyzed by HIV‐1 protease
Authors: Trylska Joanna , Grochowski Paweł , McCammon J. Andrew
Published: January 2004

The hydrogen‐bond network in various stages of the enzymatic reaction catalyzed by HIV‐1 protease was studied through quantum‐classical molecular dynamics simulations. The approximate valence bond method was applied to the active site atoms participating directly in the rearrangement of chemical bonds. The rest of the protein with explicit solvent was treated with a classical molecular mechanics model. Two possible mechanisms were studied, general‐acid/general‐base (GA/GB) with Asp 25 protonated at the inner oxygen, and a direct nucleophilic attack by Asp 25. Strong hydrogen bonds leading to spontaneous proton transfers were observed in both reaction paths. A single‐well hydrogen bond was formed between the peptide nitrogen and outer oxygen of Asp 125. The proton was diffusely distributed with an average central position and transferred back and forth on a picosecond scale. In both mechanisms, this interaction helped change the peptide‐bond hybridization, increased the partial charge on peptidyl carbon, and in the GA/GB mechanism, helped deprotonate the water molecule. The inner oxygens of the aspartic dyad formed a low‐barrier, but asymmetric hydrogen bond; the proton was not positioned midway and made a slightly elongated covalent bond, transferring from one to the other aspartate. In the GA/GB mechanism both aspartates may help deprotonate the water molecule. We observed the breakage of the peptide bond and found that the protonation of the peptidyl amine group was essential for the peptide‐bond cleavage. In studies of the direct nucleophilic mechanism, the peptide carbon of the substrate and oxygen of Asp 25 approached as close as 2.3 Å.
Disabling the folding catalyst is the last critical step in α‐lytic protease folding
Authors: Cunningham Erin L. , Agard David A.
Published: January 2004

Alpha‐Lytic protease (αLP) is an extracellular bacterial pro‐protease marked by extraordinary conformational rigidity and a highly cooperative barrier to unfolding. Although these properties successfully limit its proteolytic destruction, thereby extending the functional lifetime of the protease, they come at the expense of foldability (t1/2 = 1800 yr) and thermodynamic stability (native αLP is less stable than the unfolded species). Efficient folding has required the coevolution of a large N‐terminal pro region (Pro) that rapidly catalyzes αLP folding (t1/2 = 23 sec) and shifts the thermodynamic equilibrium in favor of folded protease through tight native‐state binding. Release of active αLP from this stabilizing, but strongly inhibitory, complex requires the proteolytic destruction of Pro. αLP is capable of initiating Pro degradation via cleavage of a flexible loop within the Pro C‐terminal domain. This single cleavage event abolishes Pro catalysis while maintaining strong native‐state binding. Thus, the loop acts as an Achilles' heel by which the Pro foldase machinery can be safely dismantled, preventing Pro‐catalyzed unfolding, without compromising αLP native‐state stability. Once the loop is cleaved, Pro is rapidly degraded, releasing active αLP.
Crystal structure of a tetrameric GDP‐d‐mannose 4,6‐dehydratase from a bacterial GDP‐d‐rhamnose biosynthetic pathway
Authors: Webb Nicole A. , Mulichak Anne M. , Lam Joseph S. , Rocchetta Heather L. , Garavito R. Michael
Published: January 2004

d‐Rhamnose is a rare 6‐deoxy monosaccharide primarily found in the lipopolysaccharide of pathogenic bacteria, where it is involved in host–bacterium interactions and the establishment of infection. The biosynthesis of d‐rhamnose proceeds through the conversion of GDP‐d‐mannose by GDP‐d‐mannose 4,6‐dehydratase (GMD) to GDP‐4‐keto‐6‐deoxymannose, which is subsequently reduced to GDP‐d‐rhamnose by a reductase. We have determined the crystal structure of GMD from Pseudomonas aeruginosa in complex with NADPH and GDP. GMD belongs to the NDP‐sugar modifying subfamily of the short‐chain dehydrogenase/reductase (SDR) enzymes, all of which exhibit bidomain structures and a conserved catalytic triad (Tyr‐XXX‐Lys and Ser/Thr). Although most members of this enzyme subfamily display homodimeric structures, this bacterial GMD forms a tetramer in the same fashion as the plant MUR1 from Arabidopsis thaliana. The cofactor binding sites are adjoined across the tetramer interface, which brings the adenosyl phosphate moieties of the adjacent NADPH molecules to within 7 Å of each other. A short peptide segment (Arg35–Arg43) stretches into the neighboring monomer, making not only protein–protein interactions but also hydrogen bonding interactions with the neighboring cofactor. The interface hydrogen bonds made by the Arg35–Arg43 segment are generally conserved in GMD and MUR1, and the interacting residues are highly conserved among the sequences of bacterial and eukaryotic GMDs. Outside of the Arg35–Arg43 segment, residues involved in tetrameric contacts are also quite conserved across different species. These observations suggest that a tetramer is the preferred, and perhaps functionally relevant, oligomeric state for most bacterial and eukaryotic GMDs.
Zymogenic and enzymatic properties of the 70–80 loop mutants of factor X/Xa
Authors: Chen Lin , Manithody Chandrashekhara , Yang Likui , Rezaie Alireza R.
Published: January 2004

The Ca2+ binding 70–80 loop of factor X (fX) contains one basic (Arg71) and three acidic (Glu74, Glu76, and Glu77) residues whose contributions to the zymogenic and enzymatic properties of the protein have not been evaluated. We prepared four Ala substitution mutants of fX (R71A, E74A, E76A, and E77A) and characterized their activation kinetics by the factor VIIa and factor IXa in both the absence and presence of cofactors. Factor VIIa exhibited normal activity toward E74A and E76A and less than a twofold impaired activity toward R71A and E77A in both the absence and presence of tissue factor. Similarly, factor IXa in the absence of factor VIIIa exhibited normal activity toward both E74A and E76A; however, its activity toward R71A and E77A was impaired approximately two‐ to threefold. In the presence of factor VIIIa, factor IX activated all mutants with approximately two‐ to fivefold impaired catalytic efficiency. In contrast to changes in their zymogenic properties, all mutant enzymes exhibited normal affinities for factor Va, and catalyzed the conversion of prothrombin to thrombin with normal catalytic efficiencies. However, further studies revealed that the affinity of mutant enzymes for interaction with metal ions Na+ and Ca2+ was impaired. These results suggest that although charged residues of the 70–80 loop play an insignificant role in fX recognition by the factor VIIa‐tissue factor complex, they are critical for the substrate recognition by factor IXa in the intrinsic Xase complex. The results further suggest that mutant residues do not play a specific role in the catalytic function of fXa in the prothrombinase complex.
Accurate and efficient loop selections by the DFIRE‐based all‐atom statistical potential
Authors: Zhang Chi , Liu Song , Zhou Yaoqi
Published: January 2004

The conformations of loops are determined by the water‐mediated interactions between amino acid residues. Energy functions that describe the interactions can be derived either from physical principles (physical‐based energy function) or statistical analysis of known protein structures (knowledge‐based statistical potentials). It is commonly believed that statistical potentials are appropriate for coarse‐grained representation of proteins but are not as accurate as physical‐based potentials when atomic resolution is required. Several recent applications of physical‐based energy functions to loop selections appear to support this view. In this article, we apply a recently developed DFIRE‐based statistical potential to three different loop decoy sets (RAPPER, Jacobson, and Forrest‐Woolf sets). Together with a rotamer library for side‐chain optimization, the performance of DFIRE‐based potential in the RAPPER decoy set (385 loop targets) is comparable to that of AMBER/GBSA for short loops (two to eight residues). The DFIRE is more accurate for longer loops (9 to 12 residues). Similar trend is observed when comparing DFIRE with another physical‐based OPLS/SGB‐NP energy function in the large Jacobson decoy set (788 loop targets). In the Forrest‐Woolf decoy set for the loops of membrane proteins, the DFIRE potential performs substantially better than the combination of the CHARMM force field with several solvation models. The results suggest that a single‐term DFIRE‐statistical energy function can provide an accurate loop prediction at a fraction of computing cost required for more complicate physical‐based energy functions. A Web server for academic users is established for loop selection at the softwares/services section of the Web site http://theory.med.buffalo.edu/.
Blinded by the Enlightenment: Günter Grass in Calcutta
Authors: Reynolds Daniel
Published: January 2004

Günter Grass's 1988 Zunge zeigen has been criticised as an example of Eurocentricism, an especially harsh charge against this author known for his critique of globalisation. The claim that Grass writes about India as a colonising Westerner overlooks the ways in which he undermines the sovereignty of the Western subject through his polyphonic, self‐reflexive account. The result is a sincere attempt to destabilise the oppressive subject he has been accused of promoting. This attempt notwithstanding, Grass's critique does falter for two reasons that critics of Zunge zeigen have not addressed. The first concerns his use of Theodor Fontane both as a bridge to the history of colonialism and as a model for engaged literature. Fontane proves tenuous on both counts, and diverts Grass's attention both from India's colonial history and literary present. Second, Grass's prescription for overcoming the misery he documents in India and Bangladesh – the Enlightenment – ultimately reinscribes a discourse of domination that favours Europe. By choosing Kali, the Hindu goddess of destruction, to represent India, Grass reinforces the notion that rationality is a European invention that is alien to the mystical, chaotic East. Ultimately, Grass fails to account for the Enlightenment's own historical complicity in colonialism.
‘Phantomspuren’: Zu W.G. Sebalds Poetik der Erinnerung in Austerlitz
Authors: Fuchs Anne
Published: January 2004

Die vorliegende Lektüre von Sebalds Roman Austerlitz beschäftigt sich mit dem Entwurf eben jenes ethisch motivierten Erinnerungskonzepts, das für die Prosa Sebalds insgesamt konstitutiv ist. Es geht damit im Folgenden um die Frage, wie der Anspruch auf eine Platzhalterschaft für die Opfer der Geschichte erzählerisch umgesetzt wird, oder in Austerlitzens eigenen Worten, um die ‘Schmerzensspuren, die sich in unzähligen feinen Linien durch die Geschichte ziehen’. Hierbei zeigt die Analyse des Sebaldschen Umgangs mit den Themen Archiv, Historiographie, Namen, Intertextualität, bricolage und Film, dass Sebald Erinnerung grundsätzlich als eine von der Imagination geleitete Spurensuche in Szene setzt, die mit einem Benjaminschen Verfahren der ästhetischen Analogiebildung arbeitet. Sebalds oft diskutierter Enzyklopädismus resultiert daher auch in Austerlitz niemals in der rationalen Erledigung der Vergangenheit, sondern umgekehrt in der hyperbolischen Verrätselung der Geschichtserfahrung. Erinnern in der Sebaldschen Prosa wird damit beschreibbar als eine Phantomjagd, welche nicht‐rationale und halluzinatorische Korrespondenzen zwischen den Gegenständen freilegt, um so die epistemologische Unbegreiflichkeit eines katastrophalen Geschichtsverlaufs zum Vorschein zu bringen.
Recovery characteristics and post‐operative delirium after long‐duration laparoscope‐assisted surgery in elderly patients: propofol‐based vs. sevoflurane‐based anesthesia
Authors: Nishikawa K. , Nakayama M. , Omote K. , Namiki A.
Published: January 2004

Background:  Post‐operative mental dysfunction may be an important problem in elderly patients. This study was designed to compare the effects of propofol and sevoflurane anesthesia on recovery characteristics and the incidence of post‐operative delirium (POD) in long‐duration laparoscopic surgery for elderly patients.

Methods:  Fifty ASA physical status I–II patients over the age of 65 scheduled for laparoscopic surgery lasting 3 h or more randomly received propofol (group P, n = 25) or sevoflurane (group S, n = 25) for both induction and maintenance of general anesthesia. Both groups were combined with continuous perioperative epidural analgesia. The level of primary anesthetics was adjusted to maintain changes in mean arterial pressure within 20% of the pre‐anesthetic values. The emergence times from anesthesia (eye opening, extubation, response to command, and orientation) were recorded, and the occurrence of POD was assessed by the delirium rating scale (DRS) during the first 3 days after surgery. All patients received oxygen and continuous epidural analgesia postoperatively.

Results:  Immediate emergence, i.e. eye opening and extubation was significantly faster after sevoflurane (P < 0.05). There was no significant difference between the incidences of POD in the two groups during the first 3 days after surgery. The scores for DRS on day 2 and 3 after surgery, however, were significantly higher in group P than in group S (P < 0.01).

Conclusion:  Sevoflurane may be preferable to propofol for general anesthesia in combination with epidural analgesia with respect to less effect on mental function during the early postoperative period for long‐duration laparoscopic surgery in elderly patients.