bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanical properties of the domains of titin in a Go-like model
Authors: Cieplak Marek , Pastore Annalisa , Hoang Trinh Xuan
Published: January 2005

Comparison of properties of three domains of titin, I1, I27, and I28, in a simple geometry-based model shows that despite a high structural homology between their native states different domains show similar but distinguishable mechanical properties. Folding properties of the separate domains are predicted to be diversified which reflects sensitivity of the kinetics to the details of native structures. The Go-like model corresponding to the experimentally resolved native structure of the I1 domain is found to provide the biggest thermodynamic and mechanical stability compared to the other domains studied here. We analyze elastic, thermodynamic, and kinetic properties of several structures corresponding to the I28 domain as obtained through homology-based modeling. We discuss the ability of the models of the I28 domain to reproduce experimental results qualitatively. A strengthening of contacts that involve hydrophobic amino acids does not affect theoretical comparisons of the domains. Tandem linkages of up to five identical or different domains unravel in a serial fashion at low temperatures. We study the nature of the intermediate state that arises in the early stages of the serial unraveling and find it to qualitatively agree with the results of Marszalek et al.
Electronic effect on protonated hydrogen-bonded imidazole trimer and corresponding derivatives cationized by alkali metals (Li+, Na+, and K+)
Authors: Yan Shihai , Bu Yuxiang , Li Ping
Published: January 2005

The electronic effects on the protonated hydrogen-bonded imidazole trimer (Im)3H+ and the derivatives cationized by alkali metals (Li+, Na+, and K+) are investigated using B3LYP method in conjunction with the 6-311+G* basis set. The prominent characteristics of (Im)3H+ on reduction are the backflow of the transferred proton to its original fragment and the remoteness of the H atom from the attached side bare N atom. The proton transfer occurs on both reduction and oxidation for the corresponding hydrogen-bonded imidazole trimer. For the derivatives cationized by Li+, (Im)3Li+, the backflow of the transferred proton occurs on reduction. The electron detachment from respective highest occupied molecular orbital of (Im)3Na+ and (Im)3K+ causes the proton transferring from the fragment attached by the alkali metal cation to the middle one. The order of the adiabatic ionization potentials of (Im)3M+ is (Im)3H+>(Im)3Li+>(Im)3Na+>(Im)3K+; the order of (Im)3M indicates that (Im)3H is the easicst complex to be ionized. The polarity of (Im)3M+ (M denotes H, Li, Na, and K) increases on both oxidation and reduction. The (Im)3M+ complexes dissociate into (Im)3 and M+ except (Im)3H+, which dissociates preferably into (Im)3+ and H atom, while the neutral complexes [(Im)3M] dissociate into (Im)3 and M. The stabilization energy of (Im)3Li2+, (Im)3Na2+, and (Im)3K2+ indicate that their energies are higher as compared to those of the monomers.
Unipolar space-charge limited current through layers with a disparate concentration of shallow traps: Experiment and model
Authors: Fleissner Arne , Weise Wieland , von Seggern Heinz
Published: January 2005

The influence of the spatial distribution of trap states on unipolar space-charge limited current (SCLC) is investigated experimentally and theoretically. Thin-layered films of the small molecule organic semiconductor N,N′-di(1-naphtyl)-N,N′-diphenylbenzidine(α-NPD) are vapor deposited on indium tin oxide, with aluminum as the counter electrode. The small molecule 4,4′,4″-tris-[N-(1-naphtyl)-N-(phenylamino)]-triphenylamine(1-NaphDATA), which creates well-known shallow traps for holes, is used as dopant. The realized organic films consist of three layers, one of which is homogeneously doped. The influence of the spatial position of the doped layer on the current–voltage characteristics of the diodes is examined. Compared to an undoped device, the current density is strongly decreased and varies over orders of magnitude for the different spatial positions of the doped layer. It is shown that traps near the injecting electrode have the most pronounced effect on SCLC. A model for unipolar SCLC through a system of homogeneous layers with different trapping parameters for shallow traps is presented. The model quantitatively describes the experimental data and is used to calculate the spatial distributions of the charge-carrier density and the electric-field strength in the differently doped devices.
A virtual dynamic atomic force microscope for image calculations
Authors: Polesel-Maris Jérôme , Gauthier Sébastien
Published: January 2005

Calculations of frequency modulation-atomic force microscopy (FM-AFM) images are presented. A virtual FM-AFM, which realistically simulates the experiment by including the control system of the microscope, is implemented in order to go beyond the usual static approximation. It is shown that the results obtained within the static approach can be recovered in the limit of small scanning speed, while images at realistic scanning speed are distorted. The influence of the experimental noise on the images is investigated, allowing us to evaluate the sensitivity of the instrument.
Effect of ion streaming on particle–particle interactions in a dusty plasma
Authors: Vyas Vivek , Kushner Mark J.
Published: January 2005

Dust particles in low-temperature, low-pressure plasmas form Coulomb crystals and display collective behavior under select conditions. The trajectories of ions can be perturbed as they pass by negatively charged dust particles and, in some cases, will converge beyond the particle. This process, called ion streaming, produces a positive potential in the wakefield of the particle that can be large enough to perturb interparticle dynamics. In this paper, we discuss results from a three-dimensional model for dust particle transport in plasma processing reactors with which we investigated the effects of ion streaming on particle–particle interactions. When including the wakefield potential produced by ion streaming, dust particles can form vertically correlated pairs when trapped in electrical potential wells. The ion-streaming force was found to be significant only over a select range of pressures and for given combinations of particle sizes and mass densities. The formation of vertically correlated pairs critically depends on the shape of the potential well. Wakefield forces can also affect the order of multilayer lattices by producing vertical correlations between particles in adjacent layers.
Near-field microwave microscopy on nanometer length scales
Authors: Imtiaz Atif , Pollak Marc , Anlage Steven M. , Barry John D. , Melngailis John
Published: January 2005

The Near-field scanning microwave microscope (NSMM) can be used to measure ohmic losses of metallic thin films. We report on the presence of an interesting length scale in the probe-to-sample interaction for the NSMM. We observe that this length scale plays an important role when the tip-to-sample separation is less than about 10 nm. Its origin can be modeled as a tiny protrusion at the end of the tip. The protrusion causes deviation from a logarithmic increase of capacitance versus a decrease in the height of the probe above the sample. We model this protrusion as a cone at the end of a sphere above an infinite plane. By fitting the frequency shift of the resonator versus height data (which is directly related to capacitance versus height) for our experimental setup, we find the protrusion size to be 3–5 nm. For one particular tip, the frequency shift of the NSMM relative to 2 μm away saturates at a value of about −1150 kHz at a height of 1 nm above the sample, where the nominal range of sheet resistance values of the sample is 15–150 Ω. Without the protrusion, the frequency shift would have followed the logarithmic dependence and reached a value of about −1500 kHz.
Sn-mediated Ge∕Ge(001) growth by low-temperature molecular-beam epitaxy: Surface smoothening and enhanced epitaxial thickness
Authors: Bratland K. A. , Foo Y. L. , Spila T. , Seo H.-S. , Haasch R. T. , Desjardins P. , Greene J. E.
Published: January 2005

Fully strained single-crystal metastable Ge1−xSnx layers were grown on Ge(001) in order to probe the role of Sn dopant and alloy concentrations (CSn=1×1018cm−3to6.1at.%) on surface roughening pathways leading to epitaxial breakdown during low-temperature (155°C) molecular-beam epitaxy of compressively strained films. The addition of Sn was found to mediate Ge(001) surface morphological evolution through two competing pathways. At very low Sn concentrations (x≲0.02), the dominant effect is a Sn-induced enhancement in both the Ge surface diffusivity and the probability of interlayer mass transport. This, in turn, results in more efficient filling of interisland trenches, and thus delays epitaxial breakdown. In fact, breakdown is not observed at all for Sn concentrations in the doping regime, 1×1018⩽CSn<4.4×1020cm−3 (2.3×10−5⩽x<0.010)! At higher concentrations, there is a change in Ge1−xSnx(001) growth kinetics due to a rapid increase in the amount of compressive strain. This leads to a gradual reduction in the film thickness h1(x) corresponding to the onset of breakdown as strain-induced roughening overcomes the surface smoothening effects, and results in an increase in the overall roughening rate. We show that by varying the Sn concentration through the dopant to dilute alloy concentration range during low-temperature Ge(001) growth, we can controllably manipulate the surface roughening pathway, and hence the epitaxial thickness, over a very wide range.
Gliding arc in tornado using a reverse vortex flow
Authors: Kalra Chiranjeev S. , Cho Young I. , Gutsol Alexànder , Fridman Alexander , Rufael Tecle S.
Published: January 2005

The present article reports a new gliding arc (GA) system using a reverse vortex flow (“tornado”) in a cylindrical reactor (gliding arc in tornado, or GAT), as used to preserve the main advantages of traditional GA systems and overcome their main drawbacks. The primary advantages of traditional GA systems retained in the present GAT are the possibility to generate transitional plasma and to avoid considerable electrode erosion. In contrast to a traditional GA, the new GAT system ensures much more uniform gas treatment and has a significantly larger gas residence time in the reactor. The present article also describes the design of the new reactor and its stable operation regime when the variation of GAT current is very small. These features are understood to be very important for most viable applications. Additionally the GAT provides near-perfect thermal insulation from the reactor wall, indicating that the present GAT does not require the reactor wall to be constructed of high-temperature materials. The new GAT system, with its unique properties such as a high level of nonequilibrium and a large residence time, looks very promising for many industrial applications including fuel conversion, carbon dioxide conversion to carbon monoxide and oxygen, surface treatment, waste treatment, flame stabilization, hydrogen sulfide treatment, etc.
Synthesis, Characterization, and Non-Linear Optical Properties of Two New Symmetrical Two-Photon Photopolymerization Initiators
Authors: Yan Yunxing , Tao Xutang , Xu Guibao , Zhao Huaping , Sun Yuanhong , Wang Chuankui , Yang Jiaxiang , Yu Xiaoqiang , Zhao Xian , Jiang Minhua
Published: January 2005

Two new symmetrical two-photon free-radical photopolymerization initiators, 1,4-bis-{2-[4-(2-pyridin-4-ylvinyl)phenyl]vinyl}-2,5-bisdimethoxybenzene 6 and 1,4-bis-{2-[4-(2-pyridin-4-ylvinyl)phenyl]vinyl}-2,5-bisdodecyloxybenzene 7, were synthesized using an efficient Wittig and Pd-catalyzed Heck coupling methodology. One-photon fluorescence, one-photon fluorescence quantum yields, one-photon fluorescence lifetimes, and two-photon fluorescence have been investigated. Experimental results show that both compounds were good two-photon absorbing chromophores and effective two-photon photopolymerization initiators. Two-photon polymerization microfabrication experiments have been studied and the possible photopolymerization mechanism is discussed.
Enhanced Anti-Fungal Activity of the Organo-Soluble Borate Ester, Tetra-n-butylammonium Bis(ortho-hydroxymethylphenolato)borate
Authors: Carr Jenny M. , Duggan Peter J. , Humphrey David G. , Tyndall Edward M.
Published: January 2005

The borate ester, tetra-n-butylammonium bis(ortho-hydroxymethylphenolato)borate, NBu4[B(o-hmp)2], was synthesized and characterized by NMR spectroscopy (1H, 13C, 11B), ES-MS, and X-ray crystallography. The anti-fungal activity of this compound, as well as its sodium salt, the parent phenol, tetra-n-butylammonium bromide, and boric acid were evaluated against two wood decay fungi. The tetraalkylammonium borate NBu4[B(o-hmp)2] shows the highest activity out of the compounds examined. This finding suggests that the formation of lipophilic borate esters is a promising approach for the development of leach-resistant, borate-based wood preservatives.
Development and evaluation of a microdevice for amino acid biomarker detection and analysis on Mars
Authors: Skelley Alison M. , Scherer James R. , Aubrey Andrew D. , Grover William H. , Ivester Robin H. C. , Ehrenfreund Pascale , Grunthaner Frank J. , Bada Jeffrey L. , Mathies Richard A.
Published: January 2005

The Mars Organic Analyzer (MOA), a microfabricated capillary electrophoresis (CE) instrument for sensitive amino acid biomarker analysis, has been developed and evaluated. The microdevice consists of a four-wafer sandwich combining glass CE separation channels, microfabricated pneumatic membrane valves and pumps, and a nanoliter fluidic network. The portable MOA instrument integrates high voltage CE power supplies, pneumatic controls, and fluorescence detection optics necessary for field operation. The amino acid concentration sensitivities range from micromolar to 0.1 nM, corresponding to part-per-trillion sensitivity. The MOA was first used in the lab to analyze soil extracts from the Atacama Desert, Chile, detecting amino acids ranging from 10–600 parts per billion. Field tests of the MOA in the Panoche Valley, CA, successfully detected amino acids at 70 parts per trillion to 100 parts per billion in jarosite, a sulfate-rich mineral associated with liquid water that was recently detected on Mars. These results demonstrate the feasibility of using the MOA to perform sensitive
in situ
amino acid biomarker analysis on soil samples representative of a Mars-like environment.
Human maintenance DNA (cytosine-5)-methyltransferase and p53 modulate expression of p53-repressed promoters
Authors: Estève Pierre-Olivier , Chin Hang Gyeong , Pradhan Sriharsa
Published: January 2005

DNA (cytosine-5)-methyltransferase (DNMT) 1 participates in transcriptional repression of genes by methylation-dependent and -independent mechanisms. Here, DNMT1 is shown to bind p53 and colocalize in the nucleus. DNMT1-mediated methylation is stimulated by p53
in vitro
. Upon p53 induction, a reporter construct containing the antiapoptotic gene
survivin
promoter, which contains a natural p53 binding site, was methylated in WT HCT116 cells but not in DNMT1 null or p53 null cells. Endogenous
survivin
gene repression involves cooperation between DNMT1 and p53 and is relieved by introduction of DNMT1- or p53-specific small inhibitory RNA. DNMT1 null cells did not exhibit a significant repressive effect for p53 responsive
survivin
and
cdc25C
gene expression compared with the parental cells. Normal human fibroblasts also exhibited similar DNMT1- and p53-mediated methylation of the
survivin
promoter, suggesting cooperation between p53 and DNMT1 in gene silencing.
The landscape of genetic complexity across 5,700 gene expression traits in yeast
Authors: Brem Rachel B. , Kruglyak Leonid
Published: January 2005

Many studies have identified quantitative trait loci (QTLs) that contribute to continuous variation in heritable traits of interest. However, general principles regarding the distribution of QTL numbers, effect sizes, and combined effects of multiple QTLs remain to be elucidated. Here, we characterize complex genetics underlying inheritance of thousands of transcript levels in a cross between two strains ofSaccharomyces cerevisiae. Most detected QTLs have weak effects, with a median variance explained of 27% for highly heritable transcripts. Despite the high statistical power of the study, no QTLs were detected for 40% of highly heritable transcripts, indicating extensive genetic complexity. Modeling of QTL detection showed that only 3% of highly heritable transcripts are consistent with single-locus inheritance, 17–18% are consistent with control by one or two loci, and half require more than five loci under additive models. Strikingly, analysis of parent and progeny trait distributions showed that a majority of transcripts exhibit transgressive segregation. Sixteen percent of highly heritable transcripts exhibit evidence of interacting loci. Our results will aid design of future QTL mapping studies and may shed light on the evolution of quantitative traits.
Statistical coevolution analysis and molecular dynamics: Identification of amino acid pairs essential for catalysis
Authors: Estabrook R. August , Luo Jia , Purdy Matthew M. , Sharma Vyas , Weakliem Paul , Bruice Thomas C. , Reich Norbert O.
Published: January 2005

Molecular dynamics (MD) simulations of HhaI DNA methyltransferase and statistical coupling analysis (SCA) data on the DNA cytosine methyltransferase family were combined to identify residues that are coupled by coevolution and motion. The highest ranking correlated pairs from the data matrix product (SCA·MD) are colocalized and form stabilizing interactions; the anticorrelated pairs are separated on average by 30 Å and form a clear focal point centered near the active site. We suggest that these distal anti-correlated pairs are involved in mediating active-site compressions that may be important for catalysis. Mutants that disrupt the implicated interactions support the validity of our combined SCA·MD approach.
The Müller-Lyer illusion explained by the statistics of image–source relationships
Authors: Howe Catherine Q. , Purves Dale
Published: January 2005

The Müller-Lyer effect, the apparent difference in the length of a line as the result of its adornment with arrowheads or arrow tails, is the best known and most controversial of the classical geometrical illusions. By sampling a range-image database of natural scenes, we show that the perceptual effects elicited by the MüllerLyer stimulus and its major variants are correctly predicted by the probability distributions of the possible physical sources underlying the relevant retinal images. These results support the conclusion that the Müller-Lyer illusion is a manifestation of the probabilistic strategy of visual processing that has evolved to contend with the uncertain provenance of retinal stimuli.
Reversible Silencing of CFTR Chloride Channels by Glutathionylation
Authors: Wang Wei , Oliva Claudia , Li Ge , Holmgren Arne , Lillig Christopher Horst , Kirk Kevin L.
Published: January 2005

The cystic fibrosis transmembrane conductance regulator (CFTR) is a phosphorylation- and ATP-dependent chloride channel that modulates salt and water transport across lung and gut epithelia. The relationship between CFTR and oxidized forms of glutathione is of potential interest because reactive glutathione species are produced in inflamed epithelia where they may be modulators or substrates of CFTR. Here we show that CFTR channel activity in excised membrane patches is markedly inhibited by several oxidized forms of glutathione (i.e., GSSG, GSNO, and glutathione treated with diamide, a strong thiol oxidizer). Three lines of evidence indicate that the likely mechanism for this inhibitory effect is glutathionylation of a CFTR cysteine (i.e., formation of a mixed disulfide with glutathione): (a) channels could be protected from inhibition by pretreating the patch with NEM (a thiol alkylating agent) or by lowering the bath pH; (b) inhibited channels could be rescued by reducing agents (e.g., DTT) or by purified glutaredoxins (Grxs; thiol disulfide oxidoreductases) including a mutant Grx that specifically reduces mixed disulfides between glutathione and cysteines within proteins; and (c) reversible glutathionylation of CFTR polypeptides in microsomes could be detected biochemically under the same conditions. At the single channel level, the primary effect of reactive glutathione species was to markedly inhibit the opening rates of individual CFTR channels. CFTR channel inhibition was not obviously dependent on phosphorylation state but was markedly slowed when channels were first “locked open” by a poorly hydrolyzable ATP analogue (AMP-PNP). Consistent with the latter finding, we show that the major site of inhibition is cys-1344, a poorly conserved cysteine that lies proximal to the signature sequence in the second nucleotide binding domain (NBD2) of human CFTR. This region is predicted to participate in ATP-dependent channel opening and to be occluded in the nucleotide-bound state of the channel based on structural comparisons to related ATP binding cassette transporters. Our results demonstrate that human CFTR channels are reversibly inhibited by reactive glutathione species, and support an important role of the region proximal to the NBD2 signature sequence in ATP-dependent channel opening.
Isoform-specific Subcellular Localization among 14-3-3 Proteins inArabidopsisSeems to be Driven by Client Interactions
Authors: Paul Anna-Lisa , Sehnke Paul C. , Ferl Robert J.
Published: January 2005

In most higher eukaryotes, the predominantly phosphoprotein-binding 14-3-3 proteins are the products of a multigene family, with many organisms having 10 or more family members. However, current models for 14-3-3/phosphopeptide interactions suggest that there is little specificity among 14-3-3s for diverse phosphopeptide clients. Therefore, the existence of sequence diversity among 14-3-3s within a single organism begs questions regarding the in vivo specificities of the interactions between the various 14-3-3s and their clients. Chief among those questions is, Do the different 14-3-3 isoforms interact with different clients within the same cell? Although the members of the Arabidopsis 14-3-3 family of proteins typically contain highly conserved regions of sequence, they also display distinctive variability with deep evolutionary roots. In the current study, a survey of several Arabidopsis 14-3-3/GFP fusions revealed that 14-3-3s demonstrate distinct and differential patterns of subcellular distribution, by using trichomes and stomate guard cells as in vivo experimental cellular contexts. The effects of client interaction on 14-3-3 localization were further analyzed by disrupting the partnering with peptide and chemical agents. Results indicate that 14-3-3 localization is both isoform specific and highly dependent upon interaction with cellular clients.
A Phase III, Double-blind, Placebo-controlled, Multicenter Study on the Efficacy of Recombinant Human Antithrombin in Heparin-resistant Patients Scheduled to Undergo Cardiac Surgery Necessitating Cardiopulmonary Bypass
Authors: Avidan Michael S. , Levy Jerrold H. , Scholz Jens , Delphin Elise , Rosseel Peter M. J. , Howie Michael B. , Gratz Irwin , Bush Charles R. , Skubas Nikolaos , Aldea Gabriel S. , Licina Michael , Bonfiglio Laura J. , Kajdasz Daniel K. , Ott Elizabeth , Despotis George J.
Published: January 2005

Background

The study evaluated the efficacy of recombinant human antithrombin (rhAT) for restoring heparin responsiveness in heparin resistant patients undergoing cardiac surgery.

Methods

This was a multicenter, randomized, double-blind, placebo-controlled study in heparin-resistant patients undergoing cardiac surgery with cardiopulmonary bypass. Heparin resistance was diagnosed when the activated clotting time was less than 480 s after 400 U/kg heparin. Fifty-four heparin-resistant patients were randomized. One cohort received 75 U/kg rhAT, and the other received normal saline. If the activated clotting time remained less than 480 s, this was considered treatment failure, and 2 units fresh frozen plasma was transfused. Patients were monitored for adverse events.

Results

Only 19% of patients in the rhAT group received fresh frozen plasma, compared with 81% of patients in the placebo group (P < 0.001). During their hospitalization, 48% of patients in the rhAT group received fresh frozen plasma, compared with 85% of patients in the placebo group (P = 0.009). Patients in the placebo group required higher heparin doses (P < 0.005) for anticoagulation. There was no increase in serious adverse events associated with rhAT. There was increased blood loss 12 h postoperatively (P = 0.05) with a trend toward increased 24-h bleeding in the rhAT group (P = 0.06). There was no difference between the groups in blood and platelet transfusions.

Conclusion

Treatment with 75 U/kg rhAT is effective in restoring heparin responsiveness and promoting therapeutic anticoagulation in the majority of heparin-resistant patients. Treating heparin-resistant patients with rhAT may decrease the requirement for heparin and fresh frozen plasma.
Cricoid Pressure Does Not Increase the Rate of Failed Intubation by Direct Laryngoscopy in Adults
Authors: Turgeon Alexis F. , Nicole Pierre C. , Trépanier Claude A. , Marcoux Sylvie , Lessard Martin R.
Published: January 2005

Background

Cricoid pressure (CP) is applied during induction of anesthesia to prevent regurgitation of gastric content and pulmonary aspiration. However, it has been suggested that CP makes tracheal intubation more difficult. This double-blind randomized study evaluated the effect of CP on orotracheal intubation by direct laryngoscopy in adults.

Methods

Seven hundred adult patients undergoing general anesthesia for elective surgery were randomly assigned to have a standardized CP (n = 344) or a sham CP (n = 356) during laryngoscopy and intubation. After anesthesia induction and complete muscle relaxation, a 30-s period was allowed to complete intubation with a Macintosh No. 3 laryngoscope blade. The primary endpoint was the rate of failed intubation at 30 s. The secondary endpoints included the intubation time, the Cormack and Lehane grade of laryngoscopic view, and the Intubation Difficulty Scale score.

Results

Groups were similar for demographic data and risk factors for difficult intubation. The rates of failed intubation at 30 s were comparable for the two groups: 15 of 344 (4.4%) and 13 of 356 (3.7%) in the CP and sham CP groups, respectively (P = 0.70). The grades of laryngoscopic view and the Intubation Difficulty Scale score were also comparable. Median intubation time was slightly longer in the CP group than in the sham CP group (11.3 and 10.4 s, respectively, P = 0.001).

Conclusions

CP applied by trained personnel does not increase the rate of failed intubation. Hence CP should not be avoided for fear of increasing the difficulty of intubation when its use is indicated.
Type 2 Diabetes Mellitus and the Catabolic Response to Surgery
Authors: Schricker Thomas , Gougeon Rejeanne , Eberhart Leopold , Wykes Linda , Mazza Louise , Carvalho George , Carli Franco
Published: January 2005

Background

The authors tested the hypothesis that the catabolic responses to colorectal surgery are amplified in the presence of type 2 diabetes mellitus.

Methods

Seven nondiabetic and seven diabetic patients underwent a 6-h stable isotope infusion study (3 h fasted, 3-h glucose infusion at 4 mg . kg . min) on the second postoperative day. Leucine rate of appearance (Ra), leucine oxidation, nonoxidative leucine disposal, and glucose Ra were assessed by L-[1-C]leucine and [6,6-H2]glucose. Circulating concentrations of glucose, lactate, insulin, glucagon, and cortisol also were determined.

Results

Diabetic patients had a higher leucine oxidation than nondiabetic patients (P = 0.0003), whereas leucine Ra and nonoxidative leucine disposal were not different. Administration of glucose did not affect leucine kinetics regardless of whether patients were diabetic. In diabetic patients, glucose Ra was greater than in the nondiabetic group (P = 0.0032). Glucose infusion suppressed the endogenous glucose Ra to a lesser extent in diabetic than in nondiabetic patients (P = 0.0048). Plasma glucose concentrations were higher in diabetic than in nondiabetic patients (P = 0.0203), both in the postabsorptive and the fed state. Circulating concentrations of glucagon were higher (P = 0.0065) and concentrations of insulin were lower (P = 0.0146) in the presence of diabetes, resulting in a lower insulin/glucagon ratio (P = 0.0002). In diabetic patients, the insulin/glucagon ratio increased during glucose infusion to a lesser extent than in the nondiabetic group (P = 0.0014).

Conclusion

Protein catabolism after colorectal surgery is increased in patients with type 2 diabetes mellitus as reflected by an increased oxidative protein loss.
Human Kidneys Play an Important Role in the Elimination of Propofol
Authors: Takizawa Daisuke , Hiraoka Haruhiko , Goto Fumio , Yamamoto Koujirou , Horiuchi Ryuya
Published: January 2005

Background

Extrahepatic clearance of propofol has been suggested because its total body clearance exceeds hepatic blood flow. However, it remains uncertain which organs are involved in the extrahepatic clearance of propofol. In vitro studies suggest that the kidneys contribute to the clearance of this drug. The purpose of this study was to confirm whether human kidneys participate in propofol disposition in vivo.

Methods

Ten patients scheduled to undergo nephrectomy were enrolled in this study. Renal blood flow was measured using para-aminohippurate. Anesthesia was induced with vecuronium (0.1 mg/kg) and propofol (2 mg/kg) and then maintained with nitrous oxide (60%), sevoflurane (1 approximately 2%) in oxygen, and an infusion of propofol (2 mg . kg . h). Radial arterial blood for propofol and para-aminohippurate analysis was collected from a cannula inserted in the radial artery. The renal venous sample and the radial arterial sample were obtained at the same time after the steady state of propofol was established.

Results

The renal extraction ratio of propofol was 0.58 +/- 0.15 (mean +/- SD). The renal clearance of propofol was 0.41 +/- 0.15 l/min (mean +/- SD), or 27 +/- 9.9% (mean +/- SD) of total body clearance.

Conclusion

Human kidneys play an important role in the elimination of propofol.
Halothane and Isoflurane Do Not Directly Interact with Cardiac Cross-bridge Function
Authors: Vivien Benoît , Lecarpentier Yves , Riou Bruno , Coirault Catherine
Published: January 2005

Background

Halogenated anesthetics depress myocardial contractility by altering a number of specific mechanisms. These alterations include decreases in inward calcium current and sarcoplasmic reticulum function and reduced calcium myofilament sensitivity. However, the direct effects of volatile anesthetics on cross-bridge function have yet to be precisely determined.

Methods

Myosin monomers and actin filaments were isolated from fresh rat left ventricles and rabbit skeletal muscles, respectively. Halothane or isoflurane was added at concentrations equivalent to 1 and 2 minimum alveolar concentration (MAC). Motility of actin filaments over myosin was initiated by adding 2 mm adenosine triphosphate and was analyzed at 30 degrees C. Maximum actomyosin adenosine triphosphatase activity and the association constant of myosin for actin were determined from a double-reciprocal Lineweaver-Burk plot of the adenosine triphosphatase rate versus actin concentration. A known inhibitor of actomyosin function, 2,3-butanedione 2-monoxime (2 mm), was used in positive control experiments. Data are presented as mean +/- SD.

Results

Motility velocities driven by myosin were not significantly different between baseline and 1 and 2 MAC halothane (2.70 +/- 0.33, 2.72 +/- 0.36, and 2.70 +/- 0.40 microm/s, respectively). Similarly, motility velocities driven by myosin were not significantly different between baseline and 1 and 2 MAC isoflurane (2.73 +/- 0.33, 2.72 +/- 0.37, and 2.72 +/- 0.40 microm/s, respectively). Neither of the two halogenated anesthetics, at any concentration tested, significantly modified the maximum actomyosin adenosine triphosphatase activity or the association constant of myosin for actin as compared with baseline. 2,3-Butanedione 2-monoxime induced a drastic reduction in both motility velocity and maximum actomyosin adenosine triphosphatase activity.

Conclusion

These results indicate that isoflurane and halothane do not directly depress the mechanical or enzymatic properties of cross-bridges in the heart.
Continuous Peripheral Nerve Blocks at Home for Treatment of Recurrent Complex Regional Pain Syndrome I in Children
Authors: Dadure Christophe , Motais Frederic , Ricard Christine , Raux Olivier , Troncin Rachel , Capdevila Xavier
Published: January 2005

Background

Recurrent complex regional pain syndrome I is not rare in the pediatric population. The authors conducted this study to evaluate the efficacy of continuous peripheral nerve blocks with elastomeric disposable pumps associated with initial Bier blocks for the treatment of recurrent complex regional pain syndrome I in children.

Methods

After parental informed consent, 13 children who did not respond to conventional complex regional pain syndrome treatment were included (mean age, 13 yr; range, 9-16 yr). After general anesthesia, peripheral nerve block was performed using 0.5 ml/kg lidocaine, 1%, with epinephrine and 0.5% ropivacaine injected in the peripheral nerve block catheter. Then, a 20-min Bier block was performed using a tourniquet and 0.2 ml/kg lidocaine, 1%; 3 ml/kg hydroxyethyl starch 130/06; and 5 mg/kg buflomedil injected intravenously. A solution of 0.1 ml . kg . h continuous ropivacaine, 0.2%, was infused through the catheter using an elastomeric pump for 96 h. Need for rescue analgesia, occurrence of side effects, and status of motor and sensory block were recorded at hours 1, 6, 12, 24, 48, 72, and 96. Children and parents completed a satisfaction assessment. All of the children had follow-up visits after 2 months.

Results

Postoperative analgesia was excellent. The median pain score was 0 for each period studied. Motor blockade was minimal before 12 h (median, 1) and absent thereafter. One child needed rescue analgesia. All children were able to walk easily after the initial 24-h period (walking score, > 4). Children and parents were all satisfied. Children returned home under parental surveillance beginning in the 24th hour. Neither peripheral nerve block nor Bier block caused side effects. After 2 months, none of the children exhibited any clinical symptom of recurrent complex regional pain syndrome.

Conclusion

Ambulatory continuous peripheral nerve block associated with an initial Bier block seems to be a significant and novel contribution to treat recurrent pediatric complex regional pain syndrome I. It allows complete pain relief, early mobilization, and rapid return home, representing a psychological advantage for these children.
Intraoperative Remifentanil Infusion Does Not Increase Postoperative Opioid Consumption Compared with 70% Nitrous Oxide
Authors: Lee Libby H. Y. , Irwin Michael G. , Lui Siu-kuen
Published: January 2005

Background

Remifentanil is commonly used to replace nitrous oxide in general anesthesia to avoid the side effects of the latter. However, there are reports that intraoperative remifentanil infusion can lead to acute opioid tolerance. In this study, the authors tried to determine the dose of remifentanil comparable in efficacy to 70% nitrous oxide and to evaluate its effect on postoperative pain and morphine consumption after colorectal surgery using isoflurane anesthesia.

Methods

Sixty adult patients undergoing open colorectal surgery were randomly assigned to receive either remifentanil or 70% nitrous oxide along with isoflurane anesthesia. After morphine analgesia titration in the postanesthesia care unit, patient-controlled analgesia was commenced. Morphine consumption and pain were scored at rest and during cough or movement for 24 h.

Results

The mean remifentanil infusion rate was 0.17 mug . kg . min. The median visual analog pain score on arrival in the postanesthesia care unit was 1 (0-10) in the nitrous oxide group and 3 (0-9) in the remifentanil group (P < 0.05). Otherwise, there was no difference in pain scores at 5, 10, and 15 min and no difference in the total morphine consumption during the stay in the postanesthesia care unit. The two groups had similar total morphine consumption in the first 24 h and pain scores at rest and during movement. The incidence of postoperative nausea and vomiting was 10% in both groups. There was no difference in the sedation scores.

Conclusion

The substitution of 70% nitrous oxide with remifentanil at a mean infusion rate of 0.17 mug . kg . minute for colorectal surgery did not affect postoperative opioid consumption.
Antlers honestly advertise sperm production and quality
Authors: Malo Aurelio F. , Roldan Eduardo R. S. , Garde Julian , Soler Ana J. , Gomendio Montserrat
Published: January 2005

Evolutionary theory proposes that exaggerated male traits have evolved via sexual selection, either through female mate choice or male–male competition. While female preferences for ornamented males have been amply demonstrated in other taxa, among mammals sexual characters are commonly regarded as weapons whose main function is to enhance male competitiveness in agonistic encounters. One particularly controversial hypothesis to explain the function of male sexual characters proposes that they advertise male fertility. We test this hypothesis in red deer (Cervus elaphus), a species where sexual characters (antlers) reach an extreme degree of elaboration. We find that a global measure of relative antler size and complexity is associated with relative testes size and sperm velocity. Our results exclude the possibility that condition dependence, age or time of culling, drive these associations. Red deer antlers could signal male fertility to females, the ability to avoid sperm depletion throughout the reproductive season and/or the competitive ability of ejaculates. By contrast, male antlers could also signal to other males not only their competitive ability at the behavioural level (fighting ability) but also at the physiological level (sperm competition).
The distribution of radio plasma in time and space
Authors: Blundell Katherine M.
Published: January 2005

The influence of jet–ejected plasma has been an important theme of this meeting; I draw attention to the prevalence of jet–ejected plasma, in particular that which has not been properly accounted for in the past. There are three strands to this paper: important emission which is prominent only at the lowest radio frequencies; relic radio plasma which must exist if even the most basic aspects of radio source evolutionary models are correct; and evidence that some ‘radio–quiet’ quasars could be FR–I radio sources.
Frequent infection of Hylobates pileatus (pileated gibbon) with species-associated variants of hepatitis B virus in Cambodia
Authors: Sall A. A. , Starkman S. , Reynes J. M. , Lay S. , Nhim T. , Hunt M. , Marx N. , Simmonds P.
Published: January 2005

As well as being distributed widely in human populations, hepatitis B virus (HBV) infections occur frequently in chimpanzee, gibbon and other ape populations in sub-Saharan Africa and South-East Asia. To investigate the frequency and genetic relationships of HBV infecting gibbons in Cambodia, pileated gibbons (Hylobates pileatus) that were originally wild-caught were screened for surface antigen. Twelve of 26 (46 %) were positive, of which 11 were positive for HBV DNA. Phylogenetic analysis of complete genome sequences revealed two distinct genetic groups in the gibbon/orangutan clade. Three were similar to previously described variants infecting H. pileatus in Thailand and eight formed a distinct clade, potentially representing distinct strains of HBV circulating in geographically separated populations in South-East Asia. Because of the ability of HBV to cross species barriers, large reservoirs of infection in gibbons may hamper ongoing attempts at permanent eradication of HBV infection from human populations in South-East Asia through immunization.
NF-κB activation can mediate inhibition of human cytomegalovirus replication
Authors: Eickhoff Jan Eike , Cotten Matt
Published: January 2005

The activation of NF-κB has long been considered a positive factor for human cytomegalovirus (HCMV) replication. The HCMV immediate-early promoter, the initial transcriptional element in the HCMV replication cycle, is activated by the transcription factor NF-κB, and several HCMV gene products have been demonstrated to activate this transcription factor. However, the role of NF-κB in the full replication cycle of the virus has not been carefully examined. A series of experiments that demonstrate an important inhibitory role of NF-κB for HCMV replication in fibroblasts is presented here. Using both genetic and pharmaceutical methods, it was shown that blocking NF-κB activation in cell culture does not inhibit HCMV replication, but rather leads to a modest increase in replication. Two cytokines inhibitory for HCMV, tumour necrosis factor-αand interferon-γ, no longer inhibit HCMV when NF-κB activation is blocked. Furthermore, forced expression of the NF-κB activating IκB kinaseβ(IKKβ), but not a kinase inactive mutant, also inhibits HCMV replication. In addition, it was shown that NF-κB signalling is essential for the production of an anti-viral factor in the supernatant of HCMV-infected fibroblasts, and identified interferon-βas this factor. Thus, the role of NF-κB in fibroblasts is to activate a host defence against HCMV.
The English strain of rat cytomegalovirus (CMV) contains a novel captured CD200 (vOX2) gene and a spliced CC chemokine upstream from the major immediate-early region: further evidence for a separate evolutionary lineage from that of rat CMV Maastricht
Authors: Voigt Sebastian , Sandford Gordon R. , Hayward Gary S. , Burns William H.
Published: January 2005

Sequence data for eight genes, together with time-course Northern blotting and 3′- and 5′-RACE (rapid amplification of cDNA ends) analysis for some mRNAs from a 12 kb region upstream from the major immediate-early (MIE) genes of the English isolate of rat cytomegalovirus (RCMV), are presented. The results identified important differences compared to both murine cytomegalovirus (MCMV) and the Maastricht isolate of RCMV. A striking finding is the presence of a highly conserved, rightwards-oriented homologue of the rat cellular CD200 (OX2) gene immediately to the right of the MIE region, which replaces either the leftwards-oriented AAV REP gene of RCMV (Maastricht) or the upstream spliced portions of the immediate-early 2 gene (ie2) in MCMV. From the presence of other homologues of MCMV- and RCMV-specific genes, such as theβ-chemokine MCK-2, SGG1 and an Fcγreceptor gene, as reported here, the basic architecture of the MIE region (reported previously) and the level of IE2 and DNA polymerase (POL) protein conservation in phylogenetic analyses, it is clear that the English strain of RCMV is also a member of the genusMuromegalovirus, but is aβ-herpesvirus species that is very distinct from both MCMV and RCMV (Maastricht). Both the lack of a CD200 homologue in the other two rodent viruses and the depth of sequence divergence of the rodent CMV IE2 and POL proteins suggest that these three viruses have evolved as separate species in the genusMuromegalovirussince very early in the host rodent lineage.
Predictive value of anti-cell and anti-human immunodeficiency virus (HIV) humoral responses in HIV-1-exposed seronegative cohorts of European and Asian origin
Authors: Lopalco L. , Barassi C. , Paolucci C. , Breda D. , Brunelli D. , Nguyen M. , Nouhin J. , Luong T. T. , Truong L. X. , Clerici M. , Calori G. , Lazzarin A. , Pancino G. , Burastero S. E.
Published: January 2005

Unconventional immune responses have been demonstrated in individuals who, despite repeated exposure to human immunodeficiency virus (HIV) infection, remain seronegative. As environmental exposure to pathogens and genetic background may modulate immune responses differentially, one Italian and two Asian populations of HIV-1-exposed seronegative individuals were studied. In serum samples from each group, IgG to CCR5, IgG to CD4 and IgA to gp41 were measured, which were previously described as markers of unconventional immunity in HIV-exposed seronegative Caucasians. Given the importance of conformational epitopes in virus–cell interactions, IgG to CD4–gp120 complex was also measured. It was found that markers of HIV exposure were present in all populations studied. HIV-specific humoral responses (IgA to gp41 and IgG to CD4–gp120 complex) were extremely significant predictors of HIV exposure (P<0·0001 in both cases), whereas the predictive values of anti-cell antibodies (anti-CCR5 and anti-CD4) varied between populations. Evidence is provided for the correlation of these differences with route of exposure to HIV and level of natural antibodies to cross-reactive microbial antigens. In conclusion, exposed seronegative individuals of ethnically different origins display similar signs of HIV-dependent unconventional immunity. A specific relevance must be attributed to different innate and acquired factors.
Type-specific reactivity of anti-glycoprotein G antibodies from herpes simplex virus-infected individuals is maintained by single or dual type-specific residues
Authors: Tunbäck Petra , Bergström Tomas , Löwhagen Gun-Britt , Hoebeke Johan , Liljeqvist Jan-Åke
Published: January 2005

Glycoprotein G-1 (gG-1) of herpes simplex virus type 1 (HSV-1) and gG-2 of HSV-2 are the only known HSV proteins that induce type-specific human antibody responses. Recently, it was shown that purified human anti-gG-1 and anti-gG-2 antibodies presented a type-specific reactivity to immunogenic stretches with high similarity between gG-1 and gG-2. In this study, the molecular basis for this type-specific recognition was investigated employing synthetic peptides covering the indicated regions, including substitutions of the type-specific residues. The results revealed that single or dual type-specific residues localized within regions of high similarity could induce significant structural differences, explaining the type-specific recognition of the human antibody response to the gG proteins.