bluuebunny/crossref_metadata_2025 huggingface dataset:
Two Mesoarchaean terranes in the Reguibat shield of NW Mauritania
Authors: Key R. M. , Loughlin S. C. , Gillespie M. , Del Rio M. , Horstwood M. S. A. , Crowley Q. G. , Darbyshire D. P. F. , Pitfield P. E. J. , Henney P. J.
Published: May 2008

Two domains have previously been recognized in the Archaean Reguibat shield of NW Mauritania, based primarily on their gross lithological differences. New fieldwork has identified a major ductile shear zone (Tâçarât–Inemmaûdene Shear Zone) separating these domains and new geochronological studies show that the two domains record different Mesoarchaean histories. As such, the two domains are redefined as the Choum–Rag el Abiod Terrane and Tasiast–Tijirit Terrane. Previous isotopic studies of metamorphic lithologies of the eastern Choum–Rag el Abiod Terrane indicate a succession of crustal growth from about 3.5–3.45 Ga to between about 3.2 and 2.99 Ga. Isotopic data presented in this contribution from the Tasiast–Tijirit Terrane indicate that emplacement of major calc-alkaline plutons occurred at
c
. 2.93 Ga after volcanism (preserved as greenstone belts) that included late felsic eruptive centres dated at
c
. 2965 Ma. This Mesoarchaean intrusive and extrusive magmatism was confined to the Tasiast–Tijirit Terrane, where it was emplaced through migmatitic orthogneisses that are the oldest lithodemic unit of the Tasiast–Tijirit Terrane. Widespread bimodal, post-tectonic magmatism in both terranes included major granitic magmatism dated at
c
. 2730 Ma. The north–south- to NNE–SSW-trending curvilinear Tâçarât–Inemmaûdene Shear Zone that separates the two terranes records late intense transpressive ductile shearing. It has a flower structure over a horizontal distance of about 70 km across its southern portion with unquantifiable sinistral horizontal offset, and east-directed thrusting on its eastern side where it cuts into the Choum–Rag el Abiod Terrane. A new U–Pb zircon age of 2954±111 Ma is presented for a deformed granite confined within the central part of this shear zone. A minimum age for the shearing is provided by a previously determined
c
. 2.73 Ga age for a post-tectonic granite that cuts across the easternmost part of the shear zone in the Choum–Rag el Abiod Terrane.
Geological setting of the Guelb Moghrein Fe oxide-Cu-Au-Co mineralization, Akjoujt area, Mauritania
Authors: Kolb Jochen , Meyer F. Michael , Vennemann Torsten , Hoffbauer Radegund , Gerdes Axel , Sakellaris Gregori A.
Published: May 2008

The Guelb Moghrein Fe oxide–Cu–Au–Co deposit is located at the western boundary of the West African craton in NW Mauritania. The wall rocks to the mineralization represent a meta-volcanosedimentary succession typical of Archaean greenstone belts. Two types of meta-volcanic rocks are distinguished: (1) volcanoclastic rocks of rhyodacite–dacite composition (Sainte Barbe volcanic unit), which form the stratigraphic base; (2) tholeiitic andesites–basalts (Akjoujt meta-basalt unit). The trace element signature of both types is characteristic of a volcanic arc setting. A small meta-pelitic division belongs to the Sainte Barbe volcanic unit. A meta-carbonate body, which contains the mineralization, forms a tectonic lens in the Akjoujt meta-basalt unit. It can be defined by the high
X
Mg
(=36) of Fe–Mg carbonate, the REE pattern and the δ
13
C values of −18 to −17‰ as a marine precipitate similar to Archaean banded iron formation (BIF). Additionally, small slices of Fe–Mg clinoamphibole–chlorite schist in the meta-carbonate show characteristics of marine shale. This assemblage, therefore, does not represent an alteration product, but represents an iron formation unit deposited on a continental shelf, which probably belongs to the Lembeitih Formation. The hydrothermal mineralization at 2492 Ma was contemporaneous with regional D
2
thrusting of the Sainte Barbe volcanic unit and imbrications of the meta-carbonate in the upper greenschist facies. This resulted in the formation of an ore breccia in the meta-carbonate, which is enriched in Fe, Ni, Co, Cu, Bi, Mo, As and Au. Massive sulphide ore breccia contains up to 20 wt% Cu. The ore fluid was aqueous–carbonic in nature and either changed its composition from a Mg-rich oxidizing to an Fe-rich reducing fluid or the two fluid types mixed at the trap site. All lithologies at Guelb Moghrein were deformed by D
3
thrusting to the east in the lower greenschist facies. The mobility of REE in the retrogressed rocks explains the formation of a second generation of hydrothermal monazite, which was dated at
c
. 1742 Ma. Archaean rocks of the West African craton extend to the west to Guelb Moghrein. The active continental margin was deformed and mineralized in the Late Archaean–Early Proterozoic and again reactivated in the Mid-Proterozoic and Westphalian, showing that the western boundary of the craton was reactivated several times.
Role of caveolin-1 in the regulation of lipoprotein metabolism
Authors: Frank Philippe G. , Pavlides Stephanos , Cheung Michelle W.-C. , Daumer Kristin , Lisanti Michael P.
Published: May 2008

Lipoprotein metabolism plays an important role in the development of several human diseases, including coronary artery disease and the metabolic syndrome. A good comprehension of the factors that regulate the metabolism of the various lipoproteins is therefore key to better understanding the variables associated with the development of these diseases. Among the players identified are regulators such as caveolins and caveolae. Caveolae are small plasma membrane invaginations that are observed in terminally differentiated cells. Their most important protein marker, caveolin-1, has been shown to play a key role in the regulation of several cellular signaling pathways and in the regulation of plasma lipoprotein metabolism. In the present paper, we have examined the role of caveolin-1 in lipoprotein metabolism using caveolin-1-deficient (Cav-1−/−) mice. Our data show that, while Cav-1−/− mice show increased plasma triglyceride levels, they also display reduced hepatic very low-density lipoprotein (VLDL) secretion. Additionally, we also found that a caveolin-1 deficiency is associated with an increase in high-density lipoprotein (HDL), and these HDL particles are enriched in cholesteryl ester in Cav-1−/− mice when compared with HDL obtained from wild-type mice. Finally, our data suggest that a caveolin-1 deficiency prevents the transcytosis of LDL across endothelial cells, and therefore, that caveolin-1 may be implicated in the regulation of plasma LDL levels. Taken together, our studies suggest that caveolin-1 plays an important role in the regulation of lipoprotein metabolism by controlling their plasma levels as well as their lipid composition. Thus caveolin-1 may also play an important role in the development of atherosclerosis.
Influence of sedentary versus physically active conditions on regulation of plasma renin activity and vasopressin
Authors: Mueller Patrick J.
Published: May 2008

Physical inactivity is an independent risk factor for cardiovascular disease. Sedentary animals compared to physically active controls exhibit enhanced sympathoexcitatory responses, including arterial baroreflex-mediated sympathoexcitation. Hypotension-induced sympathoexcitation is also associated with the release of vasoactive hormones. We hypothesized that sedentary conditions may enhance release of the vasoactive hormones AVP and ANG II. To test this hypothesis, the humoral response to hypotension was examined in conscious rats after 9–12 wk of sedentary conditions or “normally active” conditions. Normally active conditions were produced by allowing rats access to running wheels in their home cages. Running distance peaked after 4 wk (4.5 ± 0.7 km/day), and the total distance run after 9 wk was 174 ± 23 km ( n = 25). Similar levels of hypotension were induced in conscious sedentary or physically active animals with the arterial vasodilator, diazoxide (25 mg/kg iv). Control experiments used a saline injection of equivalent volume. Plasma samples were collected and assayed for plasma AVP concentration and plasma renin activity (PRA). Sedentary conditions significantly enhanced resting and hypotension-induced PRA relative to normal physical activity. In contrast, resting and hypotension-induced AVP levels were not statistically different between groups. These data suggest that baroreflex-mediated activation of the renin-angiotensin system, but not AVP secretion, is enhanced by sedentary conditions. We speculate that augmented activation of the renin-angiotensin system may be related to enhanced sympathetic outflow observed in sedentary animals and may contribute to increased risk of cardiovascular disease in the sedentary population.
Ureter obstruction alters expression of renal acid-base transport proteins in rat kidney
Authors: Wang Guixian , Li Chunling , Kim Soo Wan , Ring Troels , Wen Jianguo , Djurhuus Jens Christian , Wang Weidong , Nielsen Søren , Frøkiær Jørgen
Published: May 2008

Urinary tract obstruction impairs renal function and is often associated with a urinary acidification defect caused by diminished net H+secretion and/or HCO3−reabsorption. To identify the molecular mechanisms of these defects, protein expression of key acid-base transporters were examined along the renal nephron and collecting duct of kidneys from rats subjected to 24-h bilateral ureteral obstruction (BUO), 4 days after release of BUO (BUO-R), or BUO-R rats with experimentally induced metabolic acidosis (BUO-A). Semiquantitative immunoblotting revealed that BUO caused a significant reduction in the expression of the type 3 Na+/H+exchanger (NHE3) in the cortex (21 ± 4%), electrogenic Na+/HCO3−cotransporter (NBC1; 71 ± 5%), type 1 bumetanide-sensitive Na+-K+-2Cl−cotransporter (NKCC2; 3 ± 1%), electroneutral Na+/HCO3−cotransporter (NBCn1; 46 ± 7%), and anion exchanger (pendrin; 87 ± 2%). The expression of H+-ATPase increased in the inner medullary collecting duct (152 ± 13%). These changes were confirmed by immunocytochemistry. In BUO-R rats, there was a persistent downregulation of all the acid-base transporters including H+-ATPase. Two days of NH4Cl loading reduced plasma pH and HCO3−levels in BUO-A rats. The results demonstrate that the expression of multiple renal acid-base transporters are markedly altered in response to BUO, which may be responsible for development of metabolic acidosis and contribute to the urinary acidification defect after release of the obstruction.
Influence of priming exercise on pulmonary O2 uptake kinetics during transitions to high-intensity exercise from an elevated baseline
Authors: DiMenna Fred J. , Wilkerson Daryl P. , Burnley Mark , Jones Andrew M.
Published: May 2008

It has been suggested that the slower O2 uptake (V̇o2) kinetics observed when exercise is initiated from an elevated baseline metabolic rate are linked to an impairment of muscle O2 delivery. We hypothesized that “priming” exercise would significantly reduce the phase II time constant (τ) during subsequent severe-intensity cycle exercise initiated from an elevated baseline metabolic rate. Seven healthy men completed exercise transitions to 70% of the difference between gas exchange threshold (GET) and peak V̇o2 from a moderate-intensity baseline (90% GET) on three occasions in each of the “unprimed” and “primed” conditions. Pulmonary gas exchange, heart rate, and the electromyogram of m. vastus lateralis were measured during all tests. The phase II V̇o2 kinetics were slower when severe exercise was initiated from a baseline of moderate exercise compared with unloaded pedaling (mean ± SD τ, 42 ± 15 vs. 33 ± 8 s; P < 0.05), but were not accelerated by priming exercise (42 ± 17 s; P > 0.05). The amplitude of the V̇o2 slow component and the change in electromyogram from minutes 2 to 6 were both significantly reduced following priming exercise (V̇o2 slow component: from 0.47 ± 0.09 to 0.27 ± 0.13 l/min; change in integrated electromyogram between 2 and 6 min: from 51 ± 35 to 26±43% of baseline; P < 0.05 for both comparisons). These results indicate that the slower phase II V̇o2 kinetics observed during transitions to severe exercise from an elevated baseline are not altered by priming exercise, but that the reduced V̇o2 slow component may be linked to changes in muscle fiber activation.
Trunk Sensorimotor Cortex Is Essential for Autonomous Weight-Supported Locomotion in Adult Rats Spinalized as P1/P2 Neonates
Authors: Giszter Simon , Davies Michelle R. , Ramakrishnan Arun , Udoekwere Ubong Ime , Kargo William J.
Published: May 2008

Unlike adult spinalized rats, approximately 20% of rats spinalized as postnatal day 1 or 2 (P1/P2) neonates achieve autonomous hindlimb weight support. Cortical representations of mid/low trunk occur only in such rats with high weight support. However, the importance of hindlimb/trunk motor cortex in function of spinalized rats remains unclear. We tested the importance of trunk sensorimotor cortex in their locomotion using lesions guided by cortical microstimulation in P1/P2 weight-supporting neonatal spinalized rats and controls. In four intact control rats, lesions of hindlimb/trunk cortex caused no treadmill deficits. All spinalized rats lesioned in trunk cortex ( n = 16: 4 transplant, 6 transect, 6 transect + fibrin glue) lost an average of about 40% of their weight support. Intact trunk cortex was essential to their level of function. Lesion of trunk cortex substantially increased roll of the hindquarters, which correlated to diminished weight support, but other kinematic stepping parameters showed little change. Embryonic day 14 (E14) transplants support development of the trunk motor representations in their normal location. We tested the role of novel relay circuits arising from the grafts in such cortical representations in E14 transplants using the rats that received (noncellular) fibrin glue grafting at P1/P2 (8 allografts and 32 xenografts). Fibrin-repaired rats with autonomous weight support also had trunk cortical representations similar to those of E14 transplant rats. Thus acellular repair and intrinsic plasticity were sufficient to support the observed features. Our data show that effective cortical mechanisms for trunk control are essential for autonomous weight support in P1/P2 spinalized rats and these can be achieved by intrinsic plasticity.
Active Learning: Learning a Motor Skill Without a Coach
Authors: Huang Vincent S. , Shadmehr Reza , Diedrichsen Jörn
Published: May 2008

When we learn a new skill (e.g., golf) without a coach, we are “active learners”: we have to choose the specific components of the task on which to train (e.g., iron, driver, putter, etc.). What guides our selection of the training sequence? How do choices that people make compare with choices made by machine learning algorithms that attempt to optimize performance? We asked subjects to learn the novel dynamics of a robotic tool while moving it in four directions. They were instructed to choose their practice directions to maximize their performance in subsequent tests. We found that their choices were strongly influenced by motor errors: subjects tended to immediately repeat an action if that action had produced a large error. This strategy was correlated with better performance on test trials. However, even when participants performed perfectly on a movement, they did not avoid repeating that movement. The probability of repeating an action did not drop below chance even when no errors were observed. This behavior led to suboptimal performance. It also violated a strong prediction of current machine learning algorithms, which solve the active learning problem by choosing a training sequence that will maximally reduce the learner's uncertainty about the task. While we show that these algorithms do not provide an adequate description of human behavior, our results suggest ways to improve human motor learning by helping people choose an optimal training sequence.
Dorsal Root Ganglion Neurons Innervating Skeletal Muscle Respond to Physiological Combinations of Protons, ATP, and Lactate Mediated by ASIC, P2X, and TRPV1
Authors: Light Alan R. , Hughen Ronald W. , Zhang Jie , Rainier Jon , Liu Zhuqing , Lee Jeewoo
Published: May 2008

The adequate stimuli and molecular receptors for muscle metaboreceptors and nociceptors are still under investigation. We used calcium imaging of cultured primary sensory dorsal root ganglion (DRG) neurons from C57Bl/6 mice to determine candidates for metabolites that could be the adequate stimuli and receptors that could detect these stimuli. Retrograde DiI labeling determined that some of these neurons innervated skeletal muscle. We found that combinations of protons, ATP, and lactate were much more effective than individually applied compounds for activating rapid calcium increases in muscle-innervating dorsal root ganglion neurons. Antagonists for P2X, ASIC, and TRPV1 receptors suggested that these three receptors act together to detect protons, ATP, and lactate when presented together in physiologically relevant concentrations. Two populations of muscle-innervating DRG neurons were found. One responded to low metabolite levels (likely nonnoxious) and used ASIC3, P2X5, and TRPV1 as molecular receptors to detect these metabolites. The other responded to high levels of metabolites (likely noxious) and used ASIC3, P2X4, and TRPV1 as their molecular receptors. We conclude that a combination of ASIC, P2X5 and/or P2X4, and TRPV1 are the molecular receptors used to detect metabolites by muscle-innervating sensory neurons. We further conclude that the adequate stimuli for muscle metaboreceptors and nociceptors are combinations of protons, ATP, and lactate.
The Activity of Spinal Commissural Interneurons During Fictive Locomotion in the Lamprey
Authors: Biró Zoltán , Hill Russell H. , Grillner Sten
Published: May 2008

Commissural interneurons in the lamprey coordinate activity of the hemisegmental oscillators to ensure proper left–right alternation during swimming. The activity of interneuronal axons at the ventral commissure was studied together with potential target motoneurons during fictive locomotion in the isolated lamprey spinal cord. To estimate the unperturbed activity of the interneurons, axonal recordings were chosen because soma recordings inevitably will affect the level of membrane depolarization and thereby spike initiation. Of 227 commissural axons recorded during locomotor activity, 14 produced inhibitory and 3 produced excitatory postsynaptic potentials (PSPs) in target motoneurons. The axons typically fired multiple spikes per locomotor cycle, with ∼10 Hz sustained frequency. The average shortest spike interval in a burst corresponded to an instantaneous frequency of ∼50 Hz for both the excitatory and inhibitory axons. The maximum number of spikes per locomotor cycle was inversely related to the locomotor frequency, in accordance with previous observations in the spinal hemicord preparation. In axons that fired multiple spikes per cycle, the mean interspike intervals were in the range in which the amplitude of the slow afterhyperpolarization (sAHP) is large, providing further support for the role of the sAHP in spike timing. One hundred ninety-five axons (86%) fired rhythmically during fictive locomotion, with preferred phase of firing distributed over either the segmental locomotor burst phase (40% of axons) or the transitional phase (between bursts; 60%). Thus in lamprey commissural interneurons, we found a broad distribution of firing rates and phases during fictive locomotion.
Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels in Mouse Vomeronasal Sensory Neurons
Authors: Dibattista Michele , Mazzatenta Andrea , Grassi Francesca , Tirindelli Roberto , Menini Anna
Published: May 2008

Hyperpolarization-activated currents ( Ih) are present in several neurons of the central and peripheral nervous system. However, Ihin neurons of the vomeronasal organ (VNO) is not well characterized. We studied the properties of Ihin sensory neurons from acute slices of mouse VNO. In voltage-clamp studies, Ihwas identified by the characteristic kinetics of activation, voltage dependence, and blockage by Cs+or ZD-7288, two blockers of the Ih. Forskolin, an activator of adenylyl cyclase, shifted the activation curve for Ihto less negative potentials. A comparison of Ihproperties in VNO neurons with those of heterologously expressed hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, together with RT-PCR experiments in VNO, indicate that Ihis caused by HCN2 and/or HCN4 subunits. In current-clamp recordings, blocking Ihwith ZD-7288 induced a hyperpolarization of 5.1 mV, an increase in input resistance, a decrease in the sensitivity to elicit action potentials in response to small current injections, and did not modify the frequency of action potentials elicited by a large current injection. It has been shown that in VNO neurons some pheromones induce a decrease in cAMP concentration, but the physiological role of cAMP is unknown. After application of blockers of adenylyl cyclase, we measured a hyperpolarization of 5.1 mV in 11 of 14 neurons, suggesting that basal levels of cAMP could modulate the resting potential. In conclusion, these results show that mouse VNO neurons express HCN2 and/or HCN4 subunits and that Ihcontributes to setting the resting membrane potential and to increase excitability at stimulus threshold.
Temporal Processing Across Multiple Topographic Maps in the Electrosensory System
Authors: Krahe Rüdiger , Bastian Joseph , Chacron Maurice J.
Published: May 2008

Multiple topographic representations of sensory space are common in the nervous system and presumably allow organisms to separately process particular features of incoming sensory stimuli that vary widely in their attributes. We compared the response properties of sensory neurons within three maps of the body surface that are arranged strictly in parallel to two classes of stimuli that mimic prey and conspecifics, respectively. We used information-theoretic approaches and measures of phase locking to quantify neuronal responses. Our results show that frequency tuning in one of the three maps does not depend on stimulus class. This map acts as a low-pass filter under both conditions. A previously described stimulus-class-dependent switch in frequency tuning is shown to occur in the other two maps. Only a fraction of the information encoded by all neurons could be recovered through a linear decoder. Particularly striking were low-pass neurons the information of which in the high-frequency range could not be decoded linearly. We then explored whether intrinsic cellular mechanisms could partially account for the differences in frequency tuning across maps. Injection of a Ca2+chelator had no effect in the map with low-pass characteristics. However, injection of the same Ca2+chelator in the other two maps switched the tuning of neurons from band-pass/high-pass to low-pass. These results show that Ca2+-dependent processes play an important part in determining the functional roles of different sensory maps and thus shed light on the evolution of this important feature of the vertebrate brain.
Noninvasive Stimulation of Human Corticospinal Axons Innervating Leg Muscles
Authors: Martin P. G. , Butler J. E. , Gandevia S. C. , Taylor J. L.
Published: May 2008

These studies investigated whether a single electrical stimulus over the thoracic spine activates corticospinal axons projecting to human leg muscles. Transcranial magnetic stimulation of the motor cortex and electrical stimulation over the thoracic spine were paired at seven interstimulus intervals, and surface electromyographic responses were recorded from rectus femoris, tibialis anterior, and soleus. The interstimulus intervals (ISIs) were set so that the first descending volley evoked by cortical stimulation had not arrived at (positive ISIs), was at the same level as (0 ISI) or had passed (negative ISIs) the site of activation of descending axons by the thoracic stimulation at the moment of its delivery. Compared with the responses to motor cortical stimulation alone, responses to paired stimuli were larger at negative ISIs but reduced at positive ISIs in all three leg muscles. This depression of responses at positive ISIs is consistent with an occlusive interaction in which an antidromic volley evoked by the thoracic stimulation collides with descending volleys evoked by cortical stimulation. The cortical and spinal stimuli activate some of the same corticospinal axons. Thus it is possible to examine the excitability of lower limb motoneuron pools to corticospinal inputs without the confounding effects of changes occurring within the motor cortex.
Evidence for Nonlinear Asymmetric Causality in US Inflation, Metal, and Stock Returns
Authors: Hristu-Varsakelis D. , Kyrtsou C.
Published: May 2008

The purpose of this paper is to propose a version of causality testing that focuses on
how the sign of the returns affects the causality results. We replace the traditional VAR
specification used in the Granger causality test by a discrete‐time bivariate noisy Mackey
glass model. Our test reveals interesting and previously unexplored relationships in US
economic series, including inflation, metal, and stock returns.
A Study of the Critical Uncertainty Contributions in the Analysis of PCBs in Ambient Air
Authors: Brown Andrew S. , Brown Richard J. C.
Published: May 2008

The measurement of polychlorinated biphenyls (PCBs) in ambient air requires a complex, multistep sample preparation procedure prior to analysis by gas chromatography—mass spectrometry (GC-MS). Although routine analytical laboratories regularly carry out these measurements, they are often undertaken with little regard to the accurate calculation of measurement uncertainty, or appreciation of the sensitivity of the accuracy of the measurement to each step of the analysis. A measurement equation is developed for this analysis, and the contributory sources to the overall uncertainty when preparing calibration standards and other solutions by gravimetric and volumetric approaches are discussed and compared. For the example analysis presented, it is found that the uncertainty of the measurement is dominated by the repeatability of the GC-MS analysis and suggested that volumetric (as opposed to gravimetric) preparation of solutions does not adversely affect the overall uncertainty. The methodology presented in this work can also be applied to analogous methods for similar analytes, for example, those used to measure polycyclic aromatic hydrocarbons (PAHs), pesticides, dioxins, or furans in ambient air.
Microwave Tomography for Brain Imaging: Feasibility Assessment for Stroke Detection
Authors: Semenov Serguei Y. , Corfield Douglas R.
Published: May 2008

There is a need for a medical imaging technology, that supplements current
clinical brain imaging techniques, for the near‐patient and mobile assessment of cerebral
vascular disease. Microwave tomography (MWT) is a novel imaging modality that has
this potential. The aim of the study was to assess the feasibility, and potential
performance characteristics, of MWT for brain imaging with particular focus on stroke
detection. The study was conducted using MWT computer simulations and 2D head
model with stroke. A nonlinear Newton reconstruction approach was used.
The MWT imaging of deep brain tissues presents a significant challenge, as the
brain is an object of interest that is located inside a high dielectric contrast shield,
comprising the skull and CSF. However, high performance, nonlinear MWT inversion
methods produced biologically meaningful images of the brain including images of
stroke. It is suggested that multifrequency MWT has the potential to significantly
improve imaging results.
A Hybrid PSO/ACO Algorithm for Discovering Classification Rules in Data Mining
Authors: Holden Nicholas , Freitas Alex A.
Published: May 2008

We have previously proposed a hybrid particle swarm optimisation/ant colony optimisation (PSO/ACO) algorithm for the discovery of classification rules. Unlike a conventional PSO algorithm, this hybrid algorithm can directly cope with nominal attributes, without converting nominal values into binary numbers in a preprocessing phase. PSO/ACO2 also directly deals with both continuous and nominal attribute values, a feature that current PSO and ACO rule induction algorithms lack. We evaluate the new version of the PSO/ACO algorithm (PSO/ACO2) in 27 public‐domain, real‐world data sets often used to benchmark the performance of classification algorithms. We compare the PSO/ACO2 algorithm to an industry standard algorithm PART and compare a reduced version of our PSO/ACO2 algorithm, coping only with continuous data, to our new classification algorithm for continuous data based on differential evolution. The results show that PSO/ACO2 is very competitive in terms of accuracy to PART and that PSO/ACO2 produces significantly simpler (smaller) rule sets, a desirable result in data mining—where the goal is to discover knowledge that is not only accurate but also comprehensible to the user. The results also show that the reduced PSO version for continuous attributes provides a slight increase in accuracy when compared to the differential evolution variant.
Dynamic Retransmission Limit Scheme in MAC Layer for Routing in Multihop Ad hoc Networks
Authors: El-Khoury Ralph , El-Azouzi Rachid
Published: May 2008

We consider a wireless ad hoc network with random
access channel. We present a model that takes into
account topology, routing, random access in MAC
layer, and forwarding probability. In this paper, we focus on drawing benefit from the interaction of the MAC (governed by IEEE 802.11 or slotted Aloha)
and routing by defining a new cross‐layer scheme
for routing based on the limit number of retransmission.
By adjusting dynamically and judiciously
this parameter in a saturated network, we have
realized that both stability of forwarding queues and
average throughput are significantly improved in
linear networks with symmetric traffic: a gain of 100% can be reached. While in asymmetric topology
network with asymmetric traffic, we achieve a better
average delay (resp., throughput) for each connection
without changing the average throughput (resp.,
delay). In addition, we show the efficiency of our
new scheme in case of multimedia applications with
delay constraint. A detailed performance study is
presented using analytical and simulation evaluation.
Influence of Multiscale Roughness Patterns in Cavitated Flows: Applications to Journal Bearings
Authors: Martin Sébastien
Published: May 2008

This paper deals with the coupling of two major problems in lubrication theory: cavitation phenomena and roughness of the surfaces in relative motion. Cavitation is defined as the rupture of the continuous film due to the formation of air bubbles, leading to the presence of a liquid‐gas mixture. For this, the Elrod‐Adams model (which is a pressure‐saturation model) is classically used to describe the behavior of a cavitated thin film flow. In addition, in practical situations, the surfaces of the devices are rough, due to manufacturing processes which induce defaults. Thus, we study the behavior of the solution, when highly oscillating roughness effects on the rigid surfaces occur. In particular, we deal with the reiterated homogenization of this Elrod‐Adams problem, using periodic unfolding methods. A numerical simulation illustrates the behavior of the solution. Although the pressure tends to a smooth one, the saturation oscillations are not damped. This does not prevent us from defining an equivalent homogenized saturation and highlights the anisotropic effects on the saturation function in cavitated areas.
The Effect of Infinitesimal Damping on the Dynamic Instability Mechanism of Conservative Systems
Authors: Sophianopoulos Dimitris S. , Michaltsos George T. , Kounadis Anthony N.
Published: May 2008

The local instability of 2 degrees of freedom (DOF) weakly damped systems is thoroughly discussed using the Liénard‐Chipart stability criterion. The individual and coupling effect of mass and stiffness distribution on the dynamic asymptotic stability due to mainly infinitesimal damping is examined. These systems may be as follows: (a) unloaded (free motion) and (b) subjected to a suddenly applied load of constant magnitude and direction with infinite duration (forced motion). The aforementioned parameters combined with the algebraic structure of the damping matrix (being either positive semidefinite or indefinite) may have under certain conditions a tremendous effect on the Jacobian eigenvalues and then on the local stability of these autonomous systems. It was found that such systems when unloaded may exhibit periodic motions or a divergent motion, while when subjected to the above step load may experience either a degenerate Hopf bifurcation or periodic attractors due to a generic Hopf bifurcation. Conditions for the existence of purely imaginary eigenvalues leading to global asymptotic stability are fully assessed. The validity of the theoretical findings presented herein is verified via a nonlinear dynamic analysis.
Syntheses of 5-Thio-D-Mannose from Petrochemicals and a Disaccharide Analog Containing It
Authors: Yuasa Hideya , Jouyabu Masatake , Mitsuhashi Nobuyuki , Hashimoto Hironobu
Published: May 2008

Per-O-acetyl-5-thio-DL-mannose was synthesized from petrochemicals in six steps and 9% overall yield. It was then derivatized into glycosyl trichloroacetimidate and subjected to glycosidation reaction with a mannosyl acceptor to give a separatable mixture of disaccharides with 5-thio-D- and L-mannosides. This is the first synthesis of an enantiomerically pure 5-thiosugar derivative from racemic chemicals. The D-glycoside was derivatized into methyl (5-thio-α-D-mannopyranosyl)-2-O-α-D-mannopyranoside 6-phosphate as a potential inhibitor of a golgiα-1,2-mannosidase.
PPARγ Inhibitors as Novel Tubulin‐Targeting Agents
Authors: Schaefer Katherine L.
Published: May 2008

The microtubule‐targeting agents (MTAs) are a very successful class of cancer drugs with therapeutic benefits in both hematopoietic and solid tumors. However, resistance to these drugs is a significant problem. Current MTAs bind to microtubules, and/or to their constituent tubulin heterodimers, and affect microtubule polymerization and dynamics. The PPARγ inhibitor T0070907 can reduce tubulin levels in colorectal cancer cell lines and suppress tumor growth in a murine xenograft model. T0070907 does not alter microtubule polymerization in vitro, and does not appear to work by triggering modulation of tubulin RNA levels subsequent to decreased polymerization. This observation suggests the possible development of antimicrotubule drugs that work by a novel mechanism, and implies the presence of cancer therapeutic targets that have not yet been exploited. This review summarizes what is known about PPARγ inhibitors and cancer cell death, with emphasis on the tubulin phenotype and PPAR‐dependence, and identifies potential mechanisms of action.
Gas‐Phase Photodegradation of Decane and Methanol on TiO2: Dynamic Surface Chemistry Characterized by Diffuse Reflectance FTIR
Authors: Balcerski William , Ryu Su Young , Hoffmann Michael R.
Published: May 2008

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to
study illuminated TiO2 surfaces under both vacuum conditions, and in the presence of organic molecules
(decane and methanol). In the presence of hole scavengers, electrons are trapped at Ti(III)–OH sites,
and free electrons are generated. These free electrons are seen to decay by exposure either to oxygen or to
heat; in the case of heating, reinjection of holes into the lattice by loss of sorbed hole scavenger leads to a
decrease in Ti(III)–OH centers. Decane adsorption experiments lend support to the theory that removal of
surficial hydrocarbon contaminants is responsible for superhydrophilic TiO2 surfaces. Oxidation of decane led to a mixture of surface‐bound organics, while oxidation of methanol leads to the formation of surface‐bound formic acid.
Nuclear architecture and chromosome dynamics in the search of the pairing partner in meiosis in plants
Authors: Naranjo T. , Corredor E.
Published: May 2008

The formation of haploid gametes in organisms with sexual reproduction requires regular bivalent chromosome pairing in meiosis. In many species, homologous chromosomes occupy separate territories at the onset of meiosis. To be paired at metaphase I, they need to be brought into a close proximity for interactions that include homology recognition and the establishment of some form of bonds. How homologues find each other is one of the least understood meiotic events. Plant species with large or medium sized genomes, such as wheat or maize, are excellent materials for the cytological analysis of chromosome dynamics at early meiosis, but genes that control meiosis have been identified mainly in small genome species such as Arabidopsis thaliana. This review is focused on the contribution studies on plants are providing to the knowledge of the initial steps of the meiotic process.
Pathways to doubled haploidy: chromosome doubling during androgenesis
Authors: Seguí-Simarro J.M. , Nuez F.
Published: May 2008

Production of doubled haploid (DH) plants through androgenesis induction is a promising and convenient alternative to conventional selfing techniques for the generation of pure lines for breeding programs. This process comprises two main steps: induction of androgenesis and duplication of the haploid genome. Such duplication is sometimes indirectly induced by the treatments used to promote androgenic development. But usually, an additional step of direct chromosome doubling must be included in the protocol. Duplication of the haploid genome of androgenic individuals has been thought to occur through three mechanisms: endoreduplication, nuclear fusion and c-mitosis. In this review we will revise and analyze the evidences supporting each of the proposed mechanisms and their relevance during androgenesis induction, embryo/callus development and plant regeneration. Special attention will be devoted to nuclear fusion, whose evidences are accumulating in the last years.
Downregulation of IL-13 Gene Transcription by T-bet in Human T Cells
Authors: Suzuki Kazuya , Kaminuma Osamu , Hiroi Takachika , Kitamura Fujiko , Miyatake Shoichiro , Takaiwa Fumio , Tatsumi Hideki , Nemoto Soichi , Kitamura Noriko , Mori Akio
Published: May 2008

Background: Downregulation of a Th2 cytokine, IL-4, by a Th1-specific transcription factor, T-bet, has been demonstrated. However, the regulatory role of T-bet in another Th2 cytokine, IL-13, is not fully delineated. Methods: IL-13 mRNA expression in Jurkat cells was examined by quantitative RT-PCR, while the transcriptional activity of 5′-flanking region in the IL-13 gene encompassing –1077 to +49 was investigated by fluorescence-based promoter reporter assay. The effect of T-bet was investigated by transfection of the cells with the T-bet expression vector. Results: Stimulation with phorbol ester plus Ca2+ ionophore clearly induced IL-13 gene transcription in Jurkat cells. Ectopically expressed T-bet significantly suppressed the inducible mRNA expression and promoter activity of IL-13. Conclusion: IL-13 expression was downregulated by T-bet at the level of gene transcription, independently of the modulation of Th1/Th2 balance. T-bet is the potential key factor in the development of Th1/Th2-related diseases.
Increase in Reactive Oxygen Metabolite Level in Acute Exacerbations of Asthma
Authors: Suzuki Shintaro , Matsukura Satoshi , Takeuchi Hiroko , Kawaguchi Mio , Ieki Koushi , Odaka Miho , Watanabe Shin , Homma Tetsuya , Dohi Kenji , Aruga Tohru , Sato Masayuki , Kurokawa Masatsugu , Kokubu Fumio , Adachi Mitsuru
Published: May 2008

Background: Oxidants including reactive oxygen species have been indicated to play an important role in the pathogenesis of asthma. Objective: We investigated oxidative status in patients with acute exacerbations of asthma and evaluated the therapeutic response using the D-ROM test which is simple to use and quick. Methods: We measured reactive oxygen metabolite (ROM) levels in the serum of 42 outpatients with acute exacerbations of asthma, 11 outpatients with stable asthma and 40 healthy subjects using the D-ROM test. Seven inpatients admitted due to acute exacerbations of asthma were also enrolled to evaluate the effects of treatment. Serum eosinophil cationic protein and plasma polymorphonuclear elastase were also measured by EIA or ELISA to evaluate the correlation between inflammation and oxidative status. Results: Serum ROM levels were significantly higher in patients with acute exacerbation of asthma than in patients with stable asthma or healthy subjects. Levels of serum eosinophil cationic protein and plasma polymorphonuclear elastase were increased in acute exacerbation and moderately correlated to ROM levels. Levels of ROM were significantly decreased after treatment with systemic steroids and bronchodilators. Conclusion: These findings suggest that acute exacerbation of asthma is associated with increased oxidative stress. Serum ROM levels would partly reflect the inflammation with eosinophils and neutrophils and may be useful as biomarkers of asthma.
Anti-Allergic Inflammatory Effects of Hepatocyte Growth Factor
Authors: Ito Wataru , Takeda Masahide , Tanabe Masako , Kihara Junko , Kato Hikari , Chiba Takahito , Yamaguchi Kazutoshi , Ueki Shigeharu , Kanehiro Arihiko , Kayaba Hiroyuki , Chihara Junichi
Published: May 2008

Hepatocyte growth factor (HGF) is known to influence a number of cell types and regulate various biological activities including cytokine production, cell migration, proliferation and survival. Thus, HGF is now recognized to be a key factor in the prevention and attenuation of disease progression. We have reported that HGF reduces allergic airway inflammation, airway hyperresponsiveness, remodeling and development of Th2 cytokines as well as growth factors such as transforming growth factor-β in vivo. In vitro, HGF directly attenuates chemotaxis of eosinophils in the absence of Th2 cytokines and modulates mitogen-activated protein kinases, which play an important role in eosinophil migration. In this review, we discuss the physiological role of HGF in allergic inflammation and its mechanism of anti-inflammatory effects, including the regulation of eosinophil functions.
Acute Appendagitis Presenting with Features of Appendicitis: Value of Abdominal CT Evaluation
Authors: Dubb Sukhpreet , Arnold Ahran , Banavali Shekar , Arnold Jayantha
Published: May 2008

We report a case of acute appendagitis in a patient who presented initially with typical features of acute appendicitis. The diagnosis of acute appendagitis was made on pathognomonic signs on computed tomography (CT) scan. Abdominal pain is a common surgical emergency. CT is not always done if there are clear features of acute appendicitis. The rare but important differential diagnosis of acute appendagitis must be borne in mind when dealing with patients with suspected acute appendicitis. A CT scan of the abdomen may avoid unnecessary surgery in these patients.
Concentration of Matrix Metalloproteinase-9 in the Jugular Bulb during Carotid Endarterectomy Correlates with Severity of Intraoperative Cerebral Ischemia
Authors: Ishigaki Daiya , Ogasawara Kuniaki , Suga Yasunori , Saito Hideo , Chida Kohei , Kobayashi Masakazu , Yoshida Kenji , Otawara Yasunari , Ogawa Akira
Published: May 2008

Background: Matrix metalloproteinase (MMP)-9 targets major components of the basal lamina of cerebral blood vessels and is a biochemical marker of blood-brain barrier disruption. The goal of this study was to determine whether plasma concentrations of MMP-9 in the jugular bulb during carotid endarterectomy (CEA) correlate with severity of intraoperative cerebral ischemia. Methods:In 41 patients undergoing CEA for ipsilateral internal carotid artery (ICA) stenosis, plasma samples for measurement of MMP-9 concentration were intraoperatively obtained from a venous catheter inserted into the ipsilateral jugular bulb. Transcranial cerebral oxygen saturation using near-infrared spectroscopy was also monitored intraoperatively to assess the severity of the ischemic insult during ICA clamping. Results: The MMP-9 concentrations were significantly higher after ICA declamping than before ICA clamping (p = 0.0023). A strong linear correlation was observed between the severity of the ischemic insult during carotid clamping and the increase in MMP-9 levels after ICA declamping (r = 0.776; p < 0.0001). At the postoperative neurological assessment, 3 patients showed transient minor neurological deficits. The MMP-9 level in the jugular bulb after ICA declamping was increased in patients with postoperative transient neurological deficits relative to those without. Conclusions: The concentration of MMP-9 in the jugular bulb during CEA correlates with the severity of intraoperative cerebral ischemia.
Long-Term Control with Etanercept (Enbrel®) of a Severe Acrodermatitis Continua of Hallopeau Refractory to Infliximab (Remicade®)
Authors: Thielen A.-M. , Barde C. , Marazza G. , Saurat J.-H.
Published: May 2008

Hallopeau’s acrodermatitis is characterized by the presence of aseptic pustules on an inflammatory basis of the periungual or subungual region. The cyclic recurrences induce important physical and psychological morbidity. By analogy to the efficacy of TNF-α antagonists in the treatment of generalized pustular psoriasis, our patient illustrates the long-term efficacy and safety of etanercept (Enbrel®) in the treatment of Hallopeau’s acrodermatitis refractory to infliximab (Remicade®). This treatment alternative should in consequence be considered in patients with a recalcitrant form of a potentially debilitating disease.
Effects of Seprafilm and Heparin in Combination on Intra-Abdominal Adhesions
Authors: Kaptanoglu L. , Kucuk H.F. , Yegenoglu A. , Uzun H. , Eser M. , Mentes C.V. , Kurt N.
Published: May 2008

Aim: Postoperative intra-abdominal adhesion formation is a significant cause of morbidity. The aim of this study was to assess the effects of heparin and Seprafilm, which is considered the gold standard, on the prevention of intra-abdominal adhesions. Method: Four groups consisting of 25 rats each were formed. Cecal abrasion was performed in all animals. Group 1 was the control group with no treatment; in group 2, heparin was applied intraperitoneally; in group 3, Seprafilm was used underneath the abdominal wall, and group 4 animals were treated with both heparin and Seprafilm. Two weeks after the surgical procedure, animals were sacrificed and specimens were removed for the measurement of the grade of adhesions, according to the Mazuji classification. Results:Formation of adhesions was prevented in the three study groups treated with heparin only, Seprafilm only and both heparin and Seprafilm (p < 0.001) compared with the control group. There was no statistical difference between the treatment groups. Autopsy results of the animals that died within the first week after the surgical procedure revealed intra-abdominal abscess formation and infections, which were considered as possible causes of death. Conclusion:Seprafilm seems to be more effective in the prevention of adhesions. In the combined application of Seprafilm and heparin, heparin showed no additive impact. Future studies are needed to detect the suitable dose and side effects of heparin for humans.
An Unusual Case of Aldosterone- and Norepinephrine-Secreting Retroperitoneal Leiomyosarcoma
Authors: Wu Y.-Y. , Wei Q. , Zeng H. , Chen H.-J. , Li H. , Lin H. , Li X.
Published: May 2008

A case of retroperitoneal leiomyosarcoma (LMS) in a 38-year-old woman who had a tumor in the retroperitoneum with severe hypertension and hypokalemia is presented. Further investigation revealed an elevated serum aldosterone and norepinephrine level. After tumorectomy, the levels of serum aldosterone and norepinephrine successfully normalized; hypertension and hypokalemia were also cured. The tumor was diagnosed as being a LMS by pathologic examination. We suggested that this was the first case of retroperitoneal LMS shown to be associated with increased levels of serum aldosterone and norepinephrine.