bluuebunny/crossref_metadata_2025 huggingface dataset:
Photon Counters for the Far Ultraviolet
Authors: Chubb T. A. , Friedman H.
Published: February 2005

Photosensitive Geiger counters are useful for detection of ultraviolet radiation between 1050 A and 2500 A. The spectral sensitivities of such photon counters are determined by the photoelectric characteristics of the cathodes and the absorption and photo-ionization properties of the filling gases. Electronegative gases increase the cathode work function and greatly reduce by negative ion formation the probability that a photoelectron will initiate a count. By proper combinations of gases to fix the long wavelength limit of counter sensitivity and filters to limit the short wavelength responses, it is possible to construct relatively narrow band detectors for the extreme ultraviolet. Such tubes have been used to study the solar spectrum from rockets and have been applied in the laboratory to absorption measurements of concentrations of gases such as H2O in air and O2 in the presence of H2, N2, and the rare gases. Characteristics of solid and gaseous materials useful in vacuum ultraviolet work are listed.
Automatic Electronic Polarimeter
Authors: Landegren G. F.
Published: February 2005

An electronic device for measuring the angle of rotation produced by optically active substances is described. Light, after passing through a continuously rotating polarizing element, is divided into two beams, one of which passes through the solution being tested. Each beam then passes through respective stationary polarizing elements and falls, as sinusoidally modulated light, upon respective phototubes, the output of each thereby being pulsating dc and passed as sinusoidal ac by its respective audio amplifier. Outputs of each channel are then fed to an electronic phasemeter which indicates the angular phase displacement produced by the optically active sample. A scheme for increased sensitivity involving a frequency multiplier in each electrical channel is proposed, and the possibility of adapting the arrangement to speed-of-light measurements is suggested.
Identification of Charged Particles with a Crystal Telescope
Authors: Wolfe B. , Silverman A. , DeWire J. W.
Published: February 2005

An electronic technique is described for identifying nonrelativistic charged particles. The ionization and energy of the particle are measured in a two-crystal telescope, and the product E(dE/dx) is obtained electronically. Since E(dE/dx)∼M0.8Z2 particles of different mass and/or charge can be separated.
Calibration and Use of Germanium Resistance Thermometers for Precise Heat Capacity Measurements from 1 to 25°K. High Purity Copper for Interlaboratory Heat Capacity Comparisons
Authors: Osborne Darrell W. , Flotow Howard E. , Schreiner Felix
Published: February 2005

The cryogenic apparatus and techniques used to calibrate 3 platinum-encapsulated 4-lead germanium resistance thermometers for use in precision calorimetry from 1 to 25°K are described. The calibration data for each thermometer were fitted with the aid of a digital computer by a polynomial expressing logR in terms of powers of logT. The sensitivity and temperature-cycling stability of these thermometers were adequate to recommend this type of temperature sensor for accurate low temperature calorimetry. A test of the temperature scale and of an isothermal type calorimeter was made by measuring the heat capacity of a sample of 99.99+% copper from the 1965 Calorimetry Conference Copper Standard and comparing the results with those obtained by other investigators. An equation to represent the heat capacity of pure copper from 1 to 25°K, based upon appropriate literature results and the present data, is offered as a convenient copper reference equation for intercomparison of heat capacity results from various laboratories.
Single-Electron Response of a Porous KCl Transmission Dynode and Application of Polya Statistics to Particle Counting in an Electron Multiplier
Authors: Dietz L. A. , Hanrahan L. R. , Hance A. B.
Published: February 2005

The single electron statistics of a porous KCl transmission dynode are studied experimentally. Pulse amplification for subsequent analysis in a multichannel analyzer is obtained by coupling the output of the transmission dynode to a 14 stage electron multiplier. The observed pulse height distribution is quasiexponential. Single primary electrons, emitted thermionically from a hairpin filament and accelerated to 8–9 kV impact energy, produce stable secondary electron yields of 30–40 electrons at pulse counting rates up to 2×106 cps. In a second experiment, the KCl transmission dynode is preceded by an Al2O3 target surface, which is bombarded by single ions and produces a peaked secondary electron distribution from this surface. In this case, the anode pulse height distribution of the electron multiplier also is peaked, but has a relative variance greater than that expected from Poisson statistics. The two physical arrangements cover a wide range of shapes of pulse height distributions, and the resulting compound distributions are in good agreement with theoretical shapes calculated from a Polya statistical model, which includes Poisson and exponential distributions as limiting cases.
Thermostating High Power Coils
Authors: Freedman M. S. , Porter F. T. , Wagner F.
Published: February 2005

Internal turbulent water cooling is used to limit electrical conductor peak temperature rise to 8°C, only 2°C above the outlet water temperature, and average temperature rise to 2°C, at a current density of 6750 A/cm2, and a power transfer of 13 W/cm2. The water is continuously purified to maintain a resistivity ≈107 Ω-cm, to keep electrical leakage through 200 water junctions to less than 10−5 of the current in the conductors. A thermostating system using transient-limiting ``anticipator'' thermocouples keeps temperature excursions associated with large power steps (1–80 kW) to 1°C, a sevenfold improvement over the system without anticipators.
Rotating Disk Thermocell. II. Experimental
Authors: Sundheim B. R. , Sauerwein W.
Published: February 2005

A thermocell consisting of a rotating disk electrode and another wire electrode in an electrolytic solution is described. The temperature difference is produced by mounting a heater inside the rotating disk electrode while the temperature of the bulk solution is kept constant at a mean temperature of 21°C. The change of the thermoelectric power ε for 0.1 and 1.0 N aqueous KCl solution with Ag/AgCl electrodes was independent of the speed of rotation below 375–400 rpm (laminar flow range). At speeds >400 rpm, the ε values became dependent on the rotation speed, presumably because of increasing turbulence of the liquid. In the laminar flow range, the mean ε values were 185 μV/deg and 250 μV/deg for 1.0 N and 0.1 N aqueous KCl solutions, respectively.
Method for Measuring Pressure Dependence of Thermal Conductivity of Gases
Authors: Freud P. J. , Rothberg G. M.
Published: February 2005

A simple and sensitive method has been devised for measuring the pressure dependence of the thermal conductivity of gases. The method uses the high thermoelectric power of a semiconductor for the accurate measurement of a temperature difference. Data at 25°C for argon, nitrogen, and helium to 3000 atm and carbon dioxide to 1300 atm are given. The results are compared with those of other investigators and agreement is generally better than 10%, using a two point calibration, and better than 3% using a multipoint calibration.
Identification and analysis of alternative splicing events conserved in human and mouse
Authors: Yeo Gene W. , Van Nostrand Eric , Holste Dirk , Poggio Tomaso , Burge Christopher B.
Published: February 2005

Alternative pre-mRNA splicing affects a majority of human genes and plays important roles in development and disease. Alternative splicing (AS) events conserved since the divergence of human and mouse are likely of primary biological importance, but relatively few of such events are known. Here we describe sequence features that distinguish exons subject to evolutionarily conserved AS, which we call alternative conserved exons (ACEs), from other orthologous human/mouse exons and integrate these features into an exon classification algorithm,
acescan
. Genome-wide analysis of annotated orthologous human–mouse exon pairs identified ≈2,000 predicted ACEs. Alternative splicing was verified in both human and mouse tissues by using an RT-PCR-sequencing protocol for 21 of 30 (70%) predicted ACEs tested, supporting the validity of a majority of
acescan
predictions. By contrast, AS was observed in mouse tissues for only 2 of 15 (13%) tested exons that had EST or cDNA evidence of AS in human but were not predicted ACEs, and AS was never observed for 11 negative control exons in human or mouse tissues. Predicted ACEs were much more likely to preserve the reading frame and less likely to disrupt protein domains than other AS events and were enriched in genes expressed in the brain and in genes involved in transcriptional regulation, RNA processing, and development. Our results also imply that the vast majority of AS events represented in the human EST database are not conserved in mouse.
T cells from epicutaneously immunized mice are prone to T cell receptor revision
Authors: Bynoe Margaret S. , Viret Christophe , Flavell Richard A. , Janeway Charles A.
Published: February 2005

Epicutaneous immunization of T cell receptor (TCR) transgenic (Tg) mice whose CD4
+
T cells are specific for the Ac1-11 fragment of myelin basic protein (MBP) with Ac1-11 elicits T cells with dominant suppressor/regulatory activity that confers protection against Ac1-11-induced experimental autoimmune encephalomyelitis. We now report that such disease-resistant MBP TCR Tg mice also harbor a sizeable fraction of peripheral CD4
+
T cells lacking surface expression of the Tg TCR β chain and expressing diverse, endogenously rearranged TCR β chains.
Ex vivo
incubation at physiological temperature caused the loss of neo-β-chain expression and reversion to the MBP αβ TCR
+
phenotype. The presence of recombination activating gene 1 and 2 proteins in CD4
+
T cells with revised TCRs was consistent with effective V(D)J recombination activity. The emergence of these cells did not depend on the thymic compartment. We conclude that in mice epicutaneously immunized with an autoantigen, peripheral specific T cells are susceptible to multiple mechanisms of tolerance.
Crystal structure of the tandem GAF domains from a cyanobacterial adenylyl cyclase: Modes of ligand binding and dimerization
Authors: Martinez Sergio E. , Bruder Sandra , Schultz Anita , Zheng Ning , Schultz Joachim E. , Beavo Joseph A. , Linder Jürgen U.
Published: February 2005

In several species, GAF domains, which are widely expressed small-molecule-binding domains that regulate enzyme activity, are known to bind cyclic nucleotides. However, the molecular mechanism by which cyclic nucleotide binding affects enzyme activity is not known for any GAF domain. In the cyanobacterium,
Anabaena
, the
cyaB1
and
cyaB2
genes encode adenylyl cyclases that are stimulated by binding of cAMP to their N-terminal GAF domains. Replacement of the tandem GAF-A/B domains in
cyaB1
with the mammalian phosphodiesterase 2A GAF-A/B tandem domains allows regulation of the chimeric protein by cGMP, suggesting a highly conserved mechanism of activation. Here, we describe the 1.9-Å crystal structure of the tandem GAF-A/B domains of
cyaB2
with bound cAMP and compare it to the previously reported structure of the PDE2A GAF-A/B. Unexpectedly, the
cyaB2
GAF-A/B dimer is antiparallel, unlike the parallel dimer of PDE2A. Moreover, there is clear electron density for cAMP in both GAF-A and -B, whereas in PDE2A, cGMP is found only in GAF-B. Phosphate and ribose group contacts are similar to those in PDE2A. However, the purine-binding pockets appear very different from that in PDE2A GAF-B. Differences in the β2–β3 loop suggest that this loop confers much of the ligand specificity in this and perhaps in many other GAF domains. Finally, a conserved asparagine appears to be a new addition to the signature NKFDE motif, and a mechanism for this motif to stabilize the cNMP-binding pocket is proposed.
The cyanobacterial tandem GAF domains from the cyaB2 adenylyl cyclase signal via both cAMP-binding sites
Authors: Bruder Sandra , Linder Jürgen U. , Martinez Sergio E. , Zheng Ning , Beavo Joseph A. , Schultz Joachim E.
Published: February 2005

The tandem GAF domains from the cyanobacterium
Anabaena
PCC7120 cyaB2 adenylyl cyclase form an antiparallel dimer with cAMP bound to all four binding sites. cAMP binding causes highly cooperative allosteric enzyme activation (>500-fold; EC
50
= 1 μM; Hill coefficient >2.0). The cyaB2 GAF domains, like those of the cyclic nucleotide phosphodiesterases (PDEs), contain conserved NKFDE motifs that when mutated in the PDEs abrogate cyclic nucleotide binding. We mutated the aspartic acids within this motif in cyaB2 to determine which domains were required for signaling. Constructs containing an Asp/Ala mutation in either GAF domain still showed positive cooperative cAMP stimulation but with reduced Hill coefficients. The cyaB2 GAF domain NKFDE motifs contain inserts of 14 (GAF-A) and 19 (GAF-B) amino acids not present in PDE2 or cyaB1. Constructs having these inserts deleted could still be activated by cAMP (23- to 100-fold) but lost all positive cooperative activation, suggesting that the inserts play an important role in domain interaction and/or stabilization of the cAMP-binding pockets. In the shortened constructs, even those with a single Asp/Ala mutation in the NKFDE motifs could still be activated by cAMP. However, in a double Asp/Ala mutant of the shortened construct, stimulation by cAMP was almost completely lost, and the EC
50
shifted far to the right. Overall, the data suggest that in GAF domains without these inserts, only the canonical lysine:aspartate salt bridge keeps the α4-helix and the α4-β5 linker that close over the cyclic nucleotide properly oriented, thereby stabilizing the binding pocket. The cyaB2 GAF ensemble appears to be an evolutionary intermediate where both GAF domains still participate in allosteric activation by cAMP.
Tailored catalysts for plant cell-wall degradation: Redesigning the exo/endo preference of
Cellvibrio japonicus
arabinanase 43A
Authors: Proctor Mark R. , Taylor Edward J. , Nurizzo Didier , Turkenburg Johan P. , Lloyd Ruth M. , Vardakou Maria , Davies Gideon J. , Gilbert Harry J.
Published: February 2005

Enzymes acting on polymeric substrates are frequently classified as exo or endo, reflecting their preference for, or ignorance of, polymer chain ends. Most biotechnological applications, especially in the field of polysaccharide degradation, require either endo- or exo-acting hydrolases, or they harness the essential synergy between these two modes of action. Here, we have used genomic data in tandem with structure to modify, radically, the chain-end specificity of the
Cellvibrio japonicus exo
-arabinanase
Cj
Arb43A. The structure of
Bacillus subtilis endo
-arabinanase 43A (
Bs
Arb43A) in harness with chain-end recognition kinetics of
Cj
Arb43A directed a rational design approach that led to the conversion of the
Cellvibrio
enzyme from an exo to an endo mode of action. One of the exo-acting mutants, D35L/Q316A, displays similar activity to WT
Cj
Arb43A and the removal of the steric block mediated by the side chains of Gln-316 and Asp-53 at the –3 subsite confers its capacity to attack internal glycoside bonds. This study provides a template for the production of tailored industrial catalysts. The introduction of subtle changes informed by comparative 3D structural and genomic data can lead to fundamental changes in the mode of action of these enzymes.
TNF receptor (TNFR)-associated factor (TRAF) 3 serves as an inhibitor of TRAF2/5-mediated activation of the noncanonical NF-κB pathway by TRAF-binding TNFRs
Authors: Hauer Julia , Püschner Stephanie , Ramakrishnan Parameswaran , Simon Ute , Bongers Martina , Federle Christine , Engelmann Hartmut
Published: February 2005

TNF family members and their receptors contribute to increased gene expression for inflammatory processes and intracellular cascades leading to programmed cell death, both via activation of NF-κB. TNF receptor (TNFR)-associated factors (TRAFs) are cytoplasmic adaptor proteins binding to various receptors of the TNFR family. In an attempt to delineate the role of individual TRAFs, we compared NF-κB activation by CD40wtand CD40 mutants with different TRAF recruitment patterns. Recognized only recently, NF-κB signaling occurs at least via two different pathways. Each pathway results in nuclear translocation of two different Reldimers, the canonical p50/RelA and the noncanonical p52/RelB. Here, we show that via TRAF6, CD40 mediates only the activation of the canonical NF-κB pathway. Via TRAF2/5, CD40 activates both the canonical and the noncanonical NF-κB pathways. We observed that TRAF3 specifically blocked the NF-κB activation via TRAF2/5. This inhibitory effect of TRAF3 depends on the presence of an intact zinc finger domain. Paradoxically, suppression of TRAF2/5-mediated NF-κB activation by TRAF3 resulted in enhanced transcriptional activity of TRAF6-mediated canonical NF-κB emanating from CD40. We also observed that 12 TNFR family members (p75TNFR, LTβR, RANK, HVEM, CD40, CD30, CD27, 4-1BB, GITR, BCMA, OX40, and TACI) are each capable of activating the alternative NF-κB pathway and conclude that TRAF3 serves as a negative regulator of this pathway for all tested receptors.
Shared and specific muscle synergies in natural motor behaviors
Authors: d'Avella Andrea , Bizzi Emilio
Published: February 2005

Selecting the appropriate muscle pattern to achieve a given goal is an extremely complex task because of the dimensionality of the search space and because of the nonlinear and dynamical nature of the transformation between muscle activity and movement. To investigate whether the central nervous system uses a modular architecture to achieve motor coordination we characterized the motor output over a large set of movements. We recorded electromyographic activity from 13 muscles of the hind limb of intact and freely moving frogs during jumping, swimming, and walking in naturalistic conditions. We used multidimensional factorization techniques to extract invariant amplitude and timing relationships among the muscle activations. A decomposition of the instantaneous muscle activations as combinations of nonnegative vectors, synchronous muscle synergies, revealed a spatial organization in the muscle patterns. A decomposition of the same activations as a combination of temporal sequences of nonnegative vectors, time-varying muscle synergies, further uncovered specific characteristics in the muscle activation waveforms. A mixture of synergies shared across behaviors and synergies for specific behaviors captured the invariances across the entire dataset. These results support the hypothesis that the motor controller has a modular organization.
Decreased muscle sympathetic nerve activity does not explain increased vascular conductance during contralateral isometric exercise in humans
Authors: Fisher James P. , Sander Mikael , MacDonald Ian , White Michael J.
Published: February 2005

At the onset of both electrically evoked (STIM) and voluntary (VOL) isometric calf exercise there is an increase in vascular conductance of the contralateral lower limb, suggesting withdrawal of muscle sympathetic nerve activity (MSNA). Seven subjects performed STIM or VOL ischaemic calf exercise at 30% maximum voluntary contraction in a seated position. Blood pressure, heart rate and peroneal MSNA in the resting contralateral lower limb were recorded. During both STIM and VOL exercise blood pressure increased (P < 0.05). Blood flow increased by 40 ± 3 and 35 ± 3% and conductance increased by 37 ± 3 and 31 ± 4% (P < 0.05) after 10 s of STIM and VOL, respectively, and thereafter declined. The time course and direction of these changes persisted with subjects in a semisupine position, confirming that the transient conductance changes were not an artefact of the dependent leg position. Thigh cuff inflation for 1 min without exercise caused a 47 ± 7.5% (P < 0.05) reduction in MSNA, which recovered when the circulation was restored. However, when cuff inflation was followed by STIM or VOL exercise, MSNA did not fall further. These data suggest that the transient increase in vascular conductance at the onset of contralateral electrically evoked or voluntary lower limb exercise is unrelated to MSNA.
Effects of ischaemia‐mimetic factors on isolated rat ventricular myocytes
Authors: Lu Jun , Zang Wei‐Jin , Yu Xiao‐Jiang , Chen Li‐Na , Zhang Chun‐Hong , Jia Bing
Published: February 2005

Conventional ischaemia‐mimetic solutions contain several key components for inducing hypoxia, glucose deficiency, acidosis, lactate accumulation and hyperosmosis. The effect of each component on myocyte contractility during cardiac ischaemia was investigated in this study. A video‐based edge‐detection system was used to monitor single ventricular myocytes isolated from the rat. The effect of each factor was compared by preparing the following ischaemia‐mimetic solutions: solution A, containing all of the above‐mentioned factors; and solutions B, C, D, E and F, each with one of the factors excluded. The solutions that contained lactate severely reduced the contractility of the cardiomyocytes, but cell contraction did not differ significantly between the cardiomyocytes in these solutions. The effect of the solution without the acidosis‐inducing component was weaker than that of the conventional ischaemia‐mimetic solution. The solution lacking lactate produced the least depression of cell contractility. Lactate impaired cardiomyocyte contractility in a concentration‐dependent manner. Our observations suggest that lactate is the main contributor to cardiac ischaemic injury and that its effects are attributable to acidosis and are concentration dependent. Imposition of hypoxia, glucose deficiency and hyperosmosis had little impact on the cardiomyocytes.
Capillary supply and gene expression of angiogenesis‐related factors in murine skeletal muscle following denervation
Authors: Wagatsuma A. , Tamaki H. , Ogita F.
Published: February 2005

Capillary supply of skeletal muscle decreases during denervation. To gain insight into the regulation of this process, we investigated capillary supply and gene expression of angiogenesis‐related factors in mouse gastrocnemius muscle following denervation for 4 months. Frozen transverse sections were stained for alkaline phosphatase to detect endogenous enzyme in the capillary endothelium. The mRNA for angiogenesis‐related factors, including hypoxia inducible factor‐1α (HIF‐1α), vascular endothelial growth factor (VEGF), kinase insert domain‐containing receptor/fetal liver kinase‐1 (KDR/Flk‐1), fms‐like tyrosine kinase (Flt‐1), angiopoietin‐1 and tyrosine kinase with Ig and epidermal growth factor(EGF) homology domain 2 (Tie‐2), was analysed using a semi‐quantitative reverse transcriptase‐polymerase chain reaction (RT‐PCR). The fibre cross‐sectional area after denervation was about 20% of the control value, and the capillary to fibre ratio was significantly lower in denervated than in control muscles. The number of capillaries around each fibre also decreased to about 40% of the control value. These observations suggest that muscle capillarity decreases in response to chronic denervation. RT‐PCR analysis showed that the expression of VEGF mRNA was lower in denervated than in control muscles, while the expression of HIF‐1α mRNA remained unchanged. The expression levels of the KDR/Flk‐1 and Flt‐1 genes were decreased in the denervated muscle. The expression levels of angiopoietin‐1 but not Tie‐2 genes were decreased in the denervated muscle. These findings indicate that reduction in the expression of mRNAs in the VEGF/KDR/Flk‐1 and Flt‐1 as well as angiopoietin‐1/Tie‐2 signal pathways might be one of the reasons for the capillary regression during chronic denervation.
THE INSULIN RESISTANCE SYNDROME: Definition and Dietary Approaches to Treatment
Authors: Reaven Gerald M.
Published: February 2005

▪ Abstract  The ability of insulin to stimulate glucose disposal varies at least sixfold in apparently healthy individuals, and approximately one-third of the population that is most resistant to this action of insulin is at greatly increased risk to develop a number of adverse clinical outcomes. Type 2 diabetes occurs when insulin resistant individuals are unable to secrete enough insulin to compensate for the defect in insulin action, and this was the first clinical syndrome identified as being related to insulin resistance. Although the majority of insulin-resistant individuals are able to maintain the level of compensatory hyperinsulinemia needed to prevent the development of a significant degree of hyperglycemia, the combination of insulin resistance and hyperinsulinemia greatly increases the likelihood of developing a cluster of closely related abnormalities and the resultant clinical diagnoses that can be considered to make up the insulin resistance syndrome (IRS). Since being overweight/obese and sedentary decreases insulin sensitivity, it is not surprising that the prevalence of the manifestations of the IRS is increasing at a rapid rate. From a dietary standpoint, there are two approaches to attenuating the manifestations of the IRS: (a) weight loss to enhance insulin sensitivity in those overweight/obese individuals who are insulin resistant/hyperinsulinemic; and (b) changes in macronutrient content of diets to avoid the adverse effects of the compensatory hyperinsulinemia. This chapter will focus on defining the abnormalities and clinical syndromes that compose the IRS and evaluating the dietary changes that can ameliorate its adverse consequences.
Agency Theory
Authors: Shapiro Susan P.
Published: February 2005

In an agency relationship, one party acts on behalf of another. It is curious that a concept that could not be more profoundly sociological does not have a niche in the sociological literature. This essay begins with the economics paradigm of agency theory, which casts a very long shadow over the social sciences, and then traces how these ideas diffuse to and are transformed (if at all) in the scholarship produced in business schools, political science, law, and sociology. I cut a swathe through the social fabric where agency relationships are especially prevalent and examine some of the institutions, roles, forms of social organization, deviance, and strategies of social control that deliver agency and respond to its vulnerabilities, and I consider their impact. Finally, I suggest how sociology might make better use of and contribute to agency theory.
An ionic model for rhythmic activity in small clusters of embryonic chick ventricular cells
Authors: Krogh-Madsen Trine , Schaffer Peter , Skriver Anne D. , Taylor Louise Kold , Pelzmann Brigitte , Koidl Bernd , Guevara Michael R.
Published: February 2005

We recorded transmembrane potential in whole cell recording mode from small clusters (2–4 cells) of spontaneously beating 7-day embryonic chick ventricular cells after 1–3 days in culture and investigated effects of the blockers D-600, diltiazem, almokalant, and Ba2+. Electrical activity in small clusters is very different from that in reaggregates of several hundred embryonic chick ventricular cells, e.g., TTX-sensitive fast upstrokes in reaggregates vs. TTX-insensitive slow upstrokes in small clusters (maximum upstroke velocity ∼100 V/s vs. ∼10 V/s). On the basis of our voltage- and current-clamp results and data from the literature, we formulated a Hodgkin-Huxley-type ionic model for the electrical activity in these small clusters. The model contains a Ca2+current ( ICa), three K+currents ( IKs, IKr, and IK1), a background current, and a seal-leak current. ICagenerates the slow upstroke, whereas IKs, IKr, and IK1contribute to repolarization. All the currents contribute to spontaneous diastolic depolarization, e.g., removal of the seal-leak current increases the interbeat interval from 392 to 535 ms. The model replicates the spontaneous activity in the clusters as well as the experimental results of application of blockers. Bifurcation analysis and simulations with the model predict that annihilation and single-pulse triggering should occur with partial block of ICa. Embryonic chick ventricular cells have been used as an experimental model to investigate various aspects of spontaneous beating of cardiac cells, e.g., mutual synchronization, regularity of beating, and spontaneous initiation and termination of reentrant rhythms; our model allows investigation of these topics through numerical simulation.
Cardioprotection with palm tocotrienol: antioxidant activity of tocotrienol is linked with its ability to stabilize proteasomes
Authors: Das Samarjit , Powell Saul R. , Wang Ping , Divald Andras , Nesaretnam Kalanithi , Tosaki Arpad , Cordis Gerald A. , Maulik Nilanjana , Das Dipak K.
Published: February 2005

Tocotrienols, isomers of vitamin E, have been found to possess many health benefits. The present study was designed to determine whether tocotrienol has a direct cardioprotective role. Isolated rat hearts were perfused for 15 min with Krebs-Ringer bicarbonate buffer in the absence or presence of palm tocotrienol derived from the tocotrienol-rich fraction (0.035%) of palm oil (TRF). In another group of studies, the hearts were preperfused for 15 min in the presence of a c-Src inhibitor, 4-amino-5-(4-methylphenyl)-7-( t-butyl)-pyrazolo-3,4- d-pyrimidine (PPI). The hearts were then subjected to 30 min of global ischemia followed by 2 h of reperfusion. As expected, ischemia-reperfusion caused ventricular dysfunction, electrical rhythm disturbances, and increased myocardial infarct size. PPI or TRF could reverse the ischemia-reperfusion-mediated cardiac dysfunction. Ischemia-reperfusion also upregulated c-Src expression and phosphorylation. Although TRF only minimally affected c-Src expression, it significantly inhibited the phosphorylation of c-Src. Ischemia-reperfusion reduced 20S and 26S proteasome activities, an effect prevented by TRF pretreatment. PPI exerted a cardioprotective effect that is not mediated by the proteasome but, rather, through direct inhibition of c-Src. The results of this study support a role for c-Src in postischemic cardiac injury and dysfunction and demonstrate direct cardioprotective effects of TRF. The cardioprotective properties of TRF appear to be due to inhibition of c-Src activation and proteasome stabilization.
Catullus 63: A 'Hellenistic Poem'?
Authors: Harder Annette
Published: February 2005

This article gives a survey and analysis of the Hellenistic elements in Catullus 63. After a description of the poem's Hellenistic background it is argued that in this poem Catullus makes a selective, but careful and creative use of Hellenistic elements, with a certain focus on the means of allusion and Kreuzung der Gattungen. In doing so he alerts the reader to the poem's position within the literary tradition and within his own corpus. The meta-poetic aspects of his treatment of Hellenistic elements may require further exploration.
Attis: A Greek God in Anatolian Pessinous and Catullan Rome
Authors: Bremmer Jan
Published: February 2005

In my contribution I attempt a new analysis of the myth and ritual of Attis and its reception in Catullan Rome. I argue (1) that the attempts to identify Attis with the Herodotean Atys are unconvincing, as they are based on Hermesianax's poem, which intended to provide an aetiology for a taboo on the pig in Pessinous; (2) that Attis starts to appear in the Greek world in the middle to the third quarter of the fourth century BC; the mention in Demosthenes should be taken as referring to his own time, not to that of Aeschines' mother; (3) that a careful comparison of Timotheus' account with that of Pausanias enables us to reconstruct the Phrygian myth and ritual of Pessinous as well as its gradual development, whereby special attention is given to Kybele, Agdistis, Attis and his festival, and the eunuch Galli; (4) that the religious aspects of Catullus 63 show a close identification of the cult of Kybele with that of Dionysus.
Altering Attis: Ethnicity, Gender and Genre in Catullus 63
Authors: Harrison Stephen
Published: February 2005

Catullus 63 is one of the most unusual of Latin poems, and also one of the most difficult for literary interpreters. In this paper I would like to discuss it from three angles, connected by the common factor of change or alteration: ethnicity, the poem's alteration of Attis' previous ethnic identity to make him Greek and to stress the contrast with the poem's Asiatic setting; gender, its transsexual use of previous female literary characters as models for Attis' two speeches;2) and genre, the literary form of the poem and its alteration and mixture of various types of generic antecedent.
Chronic pneumonia with Pseudomonas aeruginosa and impaired alveolar fluid clearance
Authors: Boyer Sophie , Faure Karine , Ader Florence , Husson Odile Marie , Kipnis Eric , Prangere Thierry , Leroy Xavier , Guery Benoit P
Published: February 2005

Background

While the functional consequences of acute pulmonary infections are widely documented, few studies focused on chronic pneumonia. We evaluated the consequences of chronic Pseudomonas lung infection on alveolar function.

Methods

P. aeruginosa, included in agar beads, was instilled intratracheally in Sprague Dawley rats. Analysis was performed from day 2 to 21, a control group received only sterile agar beads. Alveolar-capillary barrier permeability, lung liquid clearance (LLC) and distal alveolar fluid clearance (DAFC) were measured using a vascular (131I-Albumin) and an alveolar tracer (125I-Albumin).

Results

The increase in permeability and LLC peaked on the second day, to return to baseline on the fifth. DAFC increased independently of TNF-α or endogenous catecholamine production. Despite the persistence of the pathogen within the alveoli, DAFC returned to baseline on the 5th day. Stimulation with terbutaline failed to increase DAFC. Eradication of the pathogen with ceftazidime did not restore DAFC response.

Conclusions

From these results, we observe an adequate initial alveolar response to increased permeability with an increase of DAFC. However, DAFC increase does not persist after the 5th day and remains unresponsive to stimulation. This impairment of DAFC may partly explain the higher susceptibility of chronically infected patients to subsequent lung injury.
An adaptive method for cDNA microarray normalization
Authors: Zhao Yingdong , Li Ming-Chung , Simon Richard
Published: February 2005

Background

Normalization is a critical step in analysis of gene expression profiles. For dual-labeled arrays, global normalization assumes that the majority of the genes on the array are non-differentially expressed between the two channels and that the number of over-expressed genes approximately equals the number of under-expressed genes. These assumptions can be inappropriate for custom arrays or arrays in which the reference RNA is very different from the experimental samples.

Results

We propose a mixture model based normalization method that adaptively identifies non-differentially expressed genes and thereby substantially improves normalization for dual-labeled arrays in settings where the assumptions of global normalization are problematic. The new method is evaluated using both simulated and real data.

Conclusions

The new normalization method is effective for general microarray platforms when samples with very different expression profile are co-hybridized and for custom arrays where the majority of genes are likely to be differentially expressed.
Nine-year comparison of presentation and management of acute coronary syndromes in Ireland: a national cross-sectional survey
Authors: Doyle Frank , De La Harpe Davida , McGee Hannah , Shelley Emer , Conroy Ronán
Published: February 2005

Background

Shorter time to treatment is associated with lower mortality in acute coronary syndromes (ACS). A previous (1994) survey showed substantial delays for acute myocardial infarction (AMI) in Ireland. The present study compared current practice with 1994 and surveyed acute coronary syndromes as a more complete contemporary evaluation of critical cardiac care than assessing AMI alone.

Methods

Following ethics committee approval, all centres (N = 39) admitting acute cardiac patients to intensive/coronary care unit provided information on 1365 episodes. A cross-sectional survey design was employed.

Results

Since 1994, median hospital arrival to thrombolysis time was reduced by 41% (76 to 45 minutes). Thrombolysis was delivered more often in the emergency department in 2003 (48% vs 2%). Thrombolysis when delivered in the emergency department was achieved faster than thrombolysis delivered in intensive/coronary care (35 mins v 60 mins; z = 5.62, p < .0001). Suspected AMI patients who did not subsequently receive thrombolysis took longer to present to hospital (5 h vs 2 h 34 mins; z = 7.33, p < .0001) and had longer transfer times to the intensive/coronary care unit following arrival (2 h 17 mins vs 1 h 10 mins; z = 8.92, p < .0001). Fewer confirmed AMI cases received thrombolysis in 2003 (43% vs 58%). There was an increase in confirmed cases of AMI from 1994 (70% to 87%).

Conclusions

Substantial improvements in time to thrombolysis have occurred since 1994, probably relating to treatment provision in emergency departments. Patient delay pre-hospital is still the principal impediment to effective treatment of ACS. A recent change of definition of AMI may have precluded an exact comparison between 1994 and 2003 data.
Prolonged conservative treatment or 'early' surgery in sciatica caused by a lumbar disc herniation: rationale and design of a randomized trial [ISRCT 26872154]
Authors: Peul Wilco C , van Houwelingen Hans C , van der Hout Wilbert B , Brand Ronald , Eekhof Just AH , Tans Joseph ThJ , Thomeer Ralph TWM , Koes Bart W
Published: February 2005

Background

The design of a randomized multicenter trial is presented on the effectiveness of a prolonged conservative treatment strategy compared with surgery in patients with persisting intense sciatica (lumbosacral radicular syndrome).

Methods/design

Patients presenting themselves to their general practitioner with disabling sciatica lasting less than twelve weeks are referred to the neurology outpatient department of one of the participating hospitals. After confirmation of the diagnosis and surgical indication MRI scanning is performed. If a distinct disc herniation is discerned which in addition covers the clinically expected site the patient is eligible for randomization. Depending on the outcome of the randomization scheme the patient will either be submitted to prolonged conservative care or surgery. Surgery will be carried out according to the guidelines and between six and twelve weeks after onset of complaints. The experimental therapy consists of a prolonged conservative treatment under supervision of the general practitioner, which may be followed by surgical intervention in case of persisting or progressive disability. The main primary outcome measure is the disease specific disability of daily functioning. Other primary outcome measures are perceived recovery and intensity of legpain. Secondary outcome measures encompass severity of complaints, quality of life, medical consumption, absenteeism, costs and preference. The main research question will be answered at 12 months after randomization. The total follow-up period covers two years.

Discussion

Evidence is lacking concerning the optimal treatment of lumbar disc induced sciatica. This pragmatic randomized trial, focusses on the 'timing' of intervention, and will contribute to the decision of the general practictioner and neurologist, regarding referral of patients for surgery.
A new example of viral intein in Mimivirus
Authors: Ogata Hiroyuki , Raoult Didier , Claverie Jean-Michel
Published: February 2005

Background

Inteins are "protein introns" that remove themselves from their host proteins through an autocatalytic protein-splicing. After their discovery, inteins have been quickly identified in all domains of life, but only once to date in the genome of a eukaryote-infecting virus.

Results

Here we report the identification and bioinformatics characterization of an intein in the DNA polymerase PolB gene of amoeba infecting Mimivirus, the largest known double-stranded DNA virus, the origin of which has been proposed to predate the emergence of eukaryotes. Mimivirus intein exhibits canonical sequence motifs and clearly belongs to a subclass of archaeal inteins always found in the same location of PolB genes. On the other hand, the Mimivirus PolB is most similar to eukaryotic Polδ sequences.

Conclusions

The intriguing association of an extremophilic archaeal-type intein with a mesophilic eukaryotic-like PolB in Mimivirus is consistent with the hypothesis that DNA viruses might have been the central reservoir of inteins throughout the course of evolution.
Pulmonary capillary pressure in pulmonary hypertension
Authors: Souza Rogerio , Amato Marcelo Britto Passos , Demarzo Sergio Eduardo , Deheinzelin Daniel , Barbas Carmen Silvia Valente , Schettino Guilherme Paula Pinto , Carvalho Carlos Roberto Ribeiro
Published: February 2005

Introduction

Pulmonary capillary pressure (PCP), together with the time constants of the various vascular compartments, define the dynamics of the pulmonary vascular system. Our objective in the present study was to estimate PCPs and time constants of the vascular system in patients with idiopathic pulmonary arterial hypertension (IPAH), and compare them with these measures in patients with acute respiratory distress syndrome (ARDS).

Methods

We conducted the study in two groups of patients with pulmonary hypertension: 12 patients with IPAH and 11 with ARDS. Four methods were used to estimate the PCP based on monoexponential and biexponential fitting of pulmonary artery pressure decay curves.

Results

PCPs in the IPAH group were considerably greater than those in the ARDS group. The PCPs measured using the four methods also differed significantly, suggesting that each method measures the pressure at a different site in the pulmonary circulation. The time constant for the slow component of the biexponential fit in the IPAH group was significantly longer than that in the ARDS group.

Conclusion

The PCP in IPAH patients is greater than normal but methodological limitations related to the occlusion technique may limit interpretation of these data in isolation. Different disease processes may result in different times for arterial emptying, with resulting implications for the methods available for estimating PCP.
Initial distribution volume of glucose can be approximated using a conventional glucose analyzer in the intensive care unit
Authors: Ishihara Hironori , Nakamura Hitomi , Okawa Hirobumi , Takase Hajime , Tsubo Toshihito , Hirota Kazuyoshi
Published: February 2005

Introduction

We previously reported that initial distribution volume of glucose (IDVG) reflects central extracellular fluid volume, and that IDVG may represent an indirect measure of cardiac preload that is independent of the plasma glucose values present before glucose injection or infusion of insulin and/or vasoactive drugs. The original IDVG measurement requires an accurate glucose analyzer and repeated arterial blood sampling over a period of 7 min after glucose injection. The purpose of the present study was to compare approximated IDVG, derived from just two blood samples, versus original IDVG, and to test whether approximated IDVG is an acceptable alternative measure of IDVG in the intensive care unit.

Methods

A total of 50 consecutive intensive care unit patients were included, and the first IDVG determination in each patient was analyzed. Glucose (5 g) was injected through the central venous line to calculate IDVG. Original IDVG was calculated using a one-compartment model from serial incremental arterial plasma glucose concentrations above preinjection using a reference glucose analyzer. Approximated IDVG was calculated from glucose concentrations in both plasma and whole blood, using a combined blood gas and glucose analyzer, drawn at two time points: immediately before glucose injection and 3 min after injection. Subsequently, each approximated IDVG was calculated using a formula we proposed previously.

Results

The difference (mean ± standard deviation) between approximated IDVG calculated from plasma samples and original IDVG was -0.05 ± 0.54 l, and the difference between approximated IDVG calculated from whole blood samples and original IDVG was -0.04 ± 0.61 l. There was a linear correlation between approximated and original IDVG (r2 = 0.92 for plasma samples, and r2 = 0.89 for whole blood samples).

Conclusion

Our findings demonstrate that there was good correlation between each approximated IDVG and original IDVG, although the two measures are not interchangeable. This suggests that approximated IDVG is clinically acceptable as an alternative calculation of IDVG, although approximated and original IDVGs are not equivalent; plasma rather than whole blood measurements are preferable.
Adherence to antiretroviral therapy among HIV-infected prison inmates (Spain)
Authors: Soto Blanco José M , Pérez Isabel Ruiz , March Joan C
Published: February 2005

This cross-sectional study was carried out in two Spanish prisons. A group of 177 HIV-infected prison inmates were interviewed. Standardized personal interviews using a structured questionnaire were conducted to assess sociodemographic features and prison setting characteristics, clinical variables, social support and drug consumption. A simplified four-item questionnaire for self-reported adherence was used. A total of 24.3% were non-adherent. Predictors of non-adherence in the multivariate analysis included poor or lack of ability to follow the prescribed treatment regimen, no visits in a month, anxious and/or depressed mood, difficulty in taking medication, receiving methadone treatment, cannabis consumption and robbery as the reason for imprisonment. Adherence to antiretroviral therapy was higher than in the wider community. However, other variables related to the correctional setting, such as assignments within the facility, adaptability of the prison system to authorize the cell being opened in the event of missed medication, or legal situation had no effect on adherence for inmates with HIV disease.
Associations between pornography consumption and sexual practices among adolescents in Sweden
Authors: Häggström-Nordin E , Hanson U , Tydén T
Published: February 2005

Pornography consumption and sexual behaviour were studied, with an aim to investigate any associations. Participants were 718 students from 47 high school classes, mean age 18 years, in a medium-sized Swedish city. More men (98%) than women (72%) had ever consumed pornography. More male high consumers than low consumers or women got sexually aroused by, fantasized about, or tried to perform acts seen in a pornographic film ( P<0.001). Three-quarters of the sample had had sexual intercourse, of which 71% reported contraceptive use at first intercourse. Anal intercourse was reported by 16%, with infrequent condom use (39%). Intercourse with a friend (adjusted odds ratio (adj. OR) 2.29; 95% confidence interval (CI) 1.27–4.12) was significantly associated with high consumption of pornography among men, while anal intercourse (adj. OR 1.99; 95% CI 0.95-4.16) and group sex (adj. OR 1.95; 95% CI 0.70-5.47) tended to be associated. A significant confounder was early age of sexual debut (adj. OR 1.49; 95% CI 1.18-1.88).