bluuebunny/crossref_metadata_2025 huggingface dataset:
Characteristics of night‐time sleeping places selected by golden monkeys (Rhinopithecus bieti) in the Samage Forest, Baima Snow Mountain Nature Reserve, China
Authors: LI Dayong , GRUETER Cyril C. , REN Baoping , ZHOU Qihai , LI Ming , PENG Zhengsong , WEI Fuwen
Published: January 2007

We examined the criteria for sleeping place selection in a social band of Rhinopithecus bieti (black‐and‐white snub‐nosed or golden monkeys) living in the mountainous Samage Forest, Baima Snow Mountain Nature Reserve, Yunnan, China. We performed principal component analysis and found that slope aspect, tree height and trunk diameter were likely key variables influencing selection of sleeping places. Sleeping sites were preferentially located in mixed deciduous/conifer forest. The monkeys slept exclusively in evergreen trees, of which 82% were conifers (mostly Picea likiangensis and Tsuga dumosa) and 18% evergreen oaks (Cyclobalanopsis oxyodon and Quercus spp.). Sleeping trees were tall (mean 30.5 m), had high boles (mean 18.4 m), large diameters (mean 62.6 cm) and large crown areas (mean 57.9 m2). A comparative analysis of phytological and architectural features between trees in “sleeping site plots” (n= 18) and trees in “non‐sleeping‐site plots” (n= 66) revealed that diameter, crown surface area and tree height were significantly (P < 0.01) larger in the former compared with the latter. All investigated roosting sites were situated on steep mountain slopes. Valleys and mountain ridges were avoided. We also detected re‐use of roosting sites on several occasions, but not on consecutive nights. It is most likely that a mix of factors (stability of trees, access to food, unit cohesion, monitoring potential) explains the pattern of sleeping site preference, but predation at night seems to be only slightly important. Climate appears to have a profound influence on patterns of sleeping site selection in the monkeys' harsh temperate habitat. This is demonstrated by the monkeys' preference for mixed forest at medium elevations over montane fir forest at high elevations and slopes instead of ridges, with reduced exposure to wind and precipitation inherent in the former. We also emphasize the possibly substantial role that non‐environmental factors (the nature of social organization and socio‐behavioral strategies) play in determining sleeping site use in R. bieti and other primates.
Calpain regulation of AMPA receptor channels in cortical pyramidal neurons
Authors: Yuen Eunice Y. , Gu Zhenglin , Yan Zhen
Published: January 2007

AMPA receptors (AMPARs) are the principal glutamate receptors mediating fast excitatory synaptic transmission in neurons. Aberrant extracellular glutamate has long been recognized as a hallmark phenomenon during neuronal excitotoxicity. Excessive glutamate triggers massive Ca2+ influx through NMDA receptors (NMDARs), which in turn can activate Ca2+‐dependent protease, calpain. In the present study, we found that prolonged NMDA treatment (100 μm, 10 min) caused a sustained and irreversible suppression of AMPAR‐mediated currents in cortical pyramidal neurons, which was largely blocked by selective calpain inhibitors. Biochemical and immunocytochemical studies demonstrated that in cortical cultures, prolonged glutamate or NMDA treatment reduced the level of surface and total GluR1, but not GluR2, subunits in a calpain‐dependent manner. Consistent with the in vitro data, in animals exposed to transient ischaemic insults, calpain was strongly activated, and the AMPAR current density and GluR1 expression level were substantially reduced. Moreover, calpain inhibitors blocked the ischaemia‐induced depression of AMPAR currents, and the NMDAR‐induced, calpain‐mediated depression of AMPA responses was occluded in ischaemic animals. Taken together, our studies show that overstimulation of NMDARs reduces AMPAR functions in cortical pyramidal neurons through activation of endogenous calpain, and calpain mediates the ischaemia‐induced synaptic depression. The down‐regulation of AMPARs by calpain provides a negative feedback to dampen neuronal excitability in excitotoxic conditions like ischaemia and epilepsy.
Signalling mechanisms in contraction‐mediated stimulation of intracellular NO production in cat ventricular myocytes
Authors: Dedkova E. N. , Wang Y. G. , Ji X. , Blatter L. A. , Samarel A. M. , Lipsius S. L.
Published: January 2007

In this study we sought to determine whether contractile activity has a role as a signalling mechanism in the activation of intracellular nitric oxide (NOi) production induced by electrical stimulation of cat ventricular myocytes. Field stimulation (FS) of single ventricular myocytes elicited frequency‐dependent increases in NOi that were blocked by the calmodulin (CaM) inhibitor 10 μm W‐7 and partially inhibited by the phosphatidylinositol 3′‐kinase (PI‐(3)K) inhibitor 10 μm LY294002. Increasing extracellular [Ca2+] caused a concentration‐dependent increase in FS‐induced NOi that was partially inhibited by LY294002. The negative inotropic agents BDM (5 mm) or blebbistatin (10 μm) decreased cell shortening and NOi production without concomitant changes in L‐type Ca2+ current (ICa,L) or [Ca2+]i transients. The positive inotropic agents EMD 57033 or CGP 48506 (1 μm) increased cell shortening and NOi production without concomitant changes in ICa,L or [Ca2+]i transients. FS‐induced NOi production was decreased in myocytes infected (100 multiplicity of viral infection (MOI); 24 h) with a replication‐deficient adenovirus expressing a dominant‐negative mutant of protein kinase B (Akt) compared with cells infected with a control adenovirus expressing β‐galactosidase. FS‐induced NOi was partially inhibited by either endothelial (eNOS) or neuronal nitric oxide synthase (nNOS) inhibitors and completely blocked by simultaneous exposure to both. FS‐induced [Ca2+]i transients were increased by the nNOS inhibitor nNOS‐I (0.24 μm), decreased by the eNOS inhibitor L‐NIO (1 μm) and unchanged by exposure to both inhibitors. We conclude that in cat ventricular myocytes, FS‐induced NOi production requires both Ca2+‐dependent CaM signalling and Ca2+‐independent PI‐(3)K–Akt signalling activated by contractile activity. FS activates NOi production from both eNOS and nNOS, and each source of NOi exerts opposing effects on [Ca2+]i transient amplitude. These findings are important for understanding the regulation of NOi signalling in the normal and mechanically failing heart.
The time, size, viscosity, and temperature dependence of the Brownian motion of polystyrene microspheres
Authors: Jia Dongdong , Hamilton Jonathan , Zaman Lenu M. , Goonewardene Anura
Published: January 2007

An upper division undergraduate laboratory module to study Brownian motion was developed using polystyrene microspheres suspended in a sample liquid cell that was isolated from its surroundings. The dependence of the Brownian motion of the microspheres on their radius, the time, the viscosity of the suspension liquid, and the temperature were measured using a CCD camera interfaced with a frame grabber and a computer. The motion of each particle was monitored for 5minutes and was found to be consistent with the Langevin formula for Brownian motion.
Tasting edge effects
Authors: Bocquet Lydéric
Published: January 2007

We show that the baking of potato wedges constitutes a crunchy example of edge effects, which are usually demonstrated in electrostatics. A simple model of the diffusive transport of water vapor around the potato wedges shows that the water vapor flux diverges at the sharp edges in analogy with its electrostatic counterpart. This increased evaporation at the edges leads to the crispy taste of these parts of the potatoes.
Measuring tongue motion from tagged cine-MRI using harmonic phase (HARP) processing
Authors: Parthasarathy Vijay , Prince Jerry L. , Stone Maureen , Murano Emi Z. , NessAiver Moriel
Published: January 2007

A cine series of tagged magnetic resonance (MR) images of the tongue is used to measure tongue motion and its internal deformation during speech. Tagged images are collected in three slice orientations (sagittal, coronal, and axial) during repetitions of the utterance “disouk” (/disuk/). A new technique called harmonic phase MRI (HARP-MRI) is used to process the tagged MR images to measure the internal deformation of the tongue. The measurements include displacement and velocity of tissue points, principal strains, and strain in the line-of-action of specific muscles. These measurements are not restricted to tag intersections, but can be calculated at every pixel in the image. The different motion measurements complement each other in understanding the tongue kinematics and in hypothesizing the internal muscle activity of the tongue.
Near-resonance scattering from arrays of artificial fish swimbladders
Authors: Nero R. W. , Feuillade C. , Thompson C. H. , Love R. H.
Published: January 2007

The air-filled swimbladders of fish resonate like damped air bubbles, and are very efficient acoustic scatterers at low to mid frequencies (typically <20kHz). Scattering experiments were performed on an artificial “fish school” constructed from polyethylene bubbles. A mathematical model, developed to describe near-resonance backscattering from schooling fish [J. Acoust. Soc. Am. 99, 196–208 (1996)], was used to analyze the physical behavior for three different arrays of these bubbles. The measurements gave excellent agreement with the model, showing that coupled-resonance and interference effects cause the frequency response of tightly packed arrays, with spacing corresponding to the order of a body length for fish, to differ significantly from those of more dispersed arrays. As the array spacing is increased to the equivalent of several body lengths, these effects rapidly diminish. The results of this comparison demonstrate that, at low to mid frequencies, coupled resonance and interference effects are likely in schooling fish, and need to be considered in applications of underwater acoustic methods to the study of fish populations.
Bio-inspired wideband sonar signals based on observations of the bottlenose dolphin (Tursiops truncatus)
Authors: Capus Chris , Pailhas Yan , Brown Keith , Lane David M. , Moore Patrick W. , Houser Dorian
Published: January 2007

This paper uses advanced time-frequency signal analysis techniques to generate new models for bio-inspired sonar signals. The inspiration comes from the analysis of bottlenose dolphin clicks. These pulses are very short duration, between 50 and 80μs, but for certain examples we can delineate a double down-chirp structure using fractional Fourier methods. The majority of clicks have energy distributed between two main frequency bands with the higher frequencies delayed in time by 5–20μs. Signal syntheses using a multiple chirp model based on these observations are able to reproduce much of the spectral variation seen in earlier studies on natural dolphin echolocation pulses. Six synthetic signals are generated and used to drive the dolphin based sonar (DBS) developed through the Biosonar Program office at the SPAWAR Systems Center, San Diego, CA. Analyses of the detailed echo structure for these pulses ensonifying two solid copper spherical targets indicate differences in discriminatory potential between the signals. It is suggested that target discrimination could be improved through the transmission of a signal packet in which the chirp structure is varied between pulses. Evidence that dolphins may use such a strategy themselves comes from observations of variations in the transmissions of dolphins carrying out target detection and identification tasks.
Spectral modulation detection as a function of modulation frequency, carrier bandwidth, and carrier frequency region
Authors: Eddins David A. , Bero Eva M.
Published: January 2007

The present study investigates the nature of spectral envelope perception using a spectral modulation detection task in which sinusoidal spectral modulation is superimposed upon a noise carrier. The principal goal of this study is to characterize spectral envelope perception in terms of the influence of modulation frequency (cycles/octave), carrier bandwidth (octaves), and carrier frequency region (defined by lower and upper cutoff frequencies in Hz). Spectral modulation detection thresholds measured as a function of spectral modulation frequency result in a spectral modulation transfer function (SMTF). The general form of the SMTF is bandpass in nature, with a minimum modulation detection threshold in the region between 2 to 4 cycles/octave. SMTFs are not strongly dependent on carrier bandwidth (ranging from 1 to 6 octaves) or carrier frequency region (ranging from 200 to 12800Hz), with the exception of carrier bands restricted to very low audio frequencies (e.g., 200–400Hz). Spectral modulation detection thresholds do not depend on the presence of random level variations or random modulation phase across intervals. The SMTFs reported here and associated excitation pattern computations are considered in terms of a linear systems approach to spectral envelope perception and potential underlying mechanisms for the perception of spectral features.
Scintillation index of high frequency acoustic signals forward scattered by the ocean surface
Authors: Cotté Benjamin , Culver R. Lee , Bradley David L.
Published: January 2007

Ocean measurements of the scintillation index (SI) of surface forward-scattered signals made in August 2002 are presented and compared with a model developed by Yang and McDaniel [Waves in Random Media 1, 419–439 (1991)]. The acoustic measurements employed continuous wave (CW) pulses and linear frequency modulated (LFM) sweeps with center frequencies of 20 and 40kHz. Simultaneously, measurements of wind speed, directional surface wave height spectrum, and ocean sound speed profile were made. The sea state was between 0 and 1 during the four days of the experiment, in part because the location is very much in the lee of San Clemente Island. The measured values of SI are found to agree with Yang and McDaniel model predictions, except for measurements with the largest signal bandwidth and/or the narrowest beamwidths, which violate model assumptions of continuous signals and omnidirectional projectors and hydrophones. In addition, the data show that SI decreases with increasing signal bandwidth (or decreasing temporal extent). An extension to the Yang and McDaniel model is developed that accounts for a reduction in signal temporal extent or ocean surface ensonification. The extended model is in qualitative agreement with the measurements, in that SI is predicted to decrease with increasing signal bandwidth.
An in vitro setup to test the relevance and the accuracy of low-order vocal folds models
Authors: Ruty Nicolas , Pelorson Xavier , Van Hirtum Annemie , Lopez-Arteaga Ines , Hirschberg Avraham
Published: January 2007

An experimental setup and human vocal folds replica able to produce self-sustained oscillations are presented. The aim of the setup is to assess the relevance and the accuracy of theoretical vocal folds models. The applied reduced mechanical models are a variation of the classical two-mass model, and a simplification inspired on the delayed mass model for which the coupling between the masses is expressed as a fixed time delay. The airflow is described as a laminar flow with flow separation. The influence of a downstream resonator is taken into account. The oscillation pressure threshold and fundamental frequency are predicted by applying a stability analysis to the mechanical models. The measured frequency response of the mechanical replica together with the initial (rest) area allows us to determine the model parameters (spring stiffness, damping, geometry, masses). Validation of theoretical model predictions to experimental data shows the relevance of low-order models in gaining a qualitative understanding of phonation. However, quantitative discrepancies remain large due to an inaccurate estimation of the model parameters and the crudeness in either flow or mechanical model description. As an illustration it is shown that significant improvements can be made by accounting for viscous flow effects.
Vocal tract resonances and the sound of the Australian didjeridu (yidaki). III. Determinants of playing quality
Authors: Smith John , Rey Guillaume , Dickens Paul , Fletcher Neville , Hollenberg Lloyd , Wolfe Joe
Published: January 2007

Traditional didjeridus have a broad range of bore geometries with many details not immediately apparent to a player, and are therefore suitable for examining the relationship between perceived quality and physical properties. Seven experienced players assessed the overall playing quality of 38 didjeridus that spanned a wide range of quality, pitch, and geometry, as well as 11 plastic cylindrical pipes. The ranking of these instruments was correlated with detailed measurements of their acoustic input impedance spectra. Most significantly, the ranked quality of a didjeridu was found to be negatively correlated with the magnitude of its acoustic input impedance, particularly in the frequency range from 1to2kHz. This is in accord with the fact that maxima in the impedance of the player’s vocal tract can inhibit acoustic flow, and consequently sound production, once the magnitude of these impedance maxima becomes comparable with or greater than those of the instrument. This produces the varying spectral peaks or formants in the sound envelope that characterize this instrument. Thus an instrument with low impedance and relatively weak impedance maxima in this frequency range would allow players greater control of the formants in the output sound and thus lead to a higher perceived playing quality.
Acoustic energy relations in Mudejar-Gothic churches
Authors: Zamarreño Teófilo , Girón Sara , Galindo Miguel
Published: January 2007

Extensive objective energy-based parameters have been measured in 12 Mudejar-Gothic churches in the south of Spain. Measurements took place in unoccupied churches according to the ISO-3382 standard. Monoaural objective measures in the 125–4000Hz frequency range and in their spatial distributions were obtained. Acoustic parameters: clarity C80, definition D50, sound strength G and center time TS have been deduced using impulse response analysis through a maximum length sequence measurement system in each church. These parameters spectrally averaged according to the most extended criteria in auditoria in order to consider acoustic quality were studied as a function of source-receiver distance. The experimental results were compared with predictions given by classical and other existing theoretical models proposed for concert halls and churches. An analytical semi-empirical model based on the measured values of the C80 parameter is proposed in this work for these spaces. The good agreement between predicted values and experimental data for definition, sound strength, and center time in the churches analyzed shows that the model can be used for design predictions and other purposes with reasonable accuracy.
Modeling the excitation of guided waves in generally anisotropic multilayered media
Authors: Velichko Alexander , Wilcox Paul D.
Published: January 2007

The design of transducers to excite and detect guided waves is a fundamental part of a nondestructive evaluation or structural health monitoring system and requires the ability to predict the radiated guided wave field of a transmitting transducer. For most transducers, this can be performed by making the assumption that the transducer is weakly coupled and then integrating the Green’s function of the structure over the area of the transducer. The majority of guided wave modeling is based on two-dimensional (2D) formulations where plane, straight-crested waves are modeled. Several techniques can be readily applied to obtain the solution to the forced 2D problem in terms of modal amplitudes. However, for transducer modeling it is desirable to obtain the complete three-dimensional (3D) field, which is particularly challenging in anisotropic materials. In this paper, a technique for obtaining a far-field asymptotic solution to the 3D Green’s function in terms of the modal solutions to the forced 2D problem is presented. Results are shown that illustrate the application of the technique to isotropic (aluminium) and anisotropic (cross-ply and unidirectional composite) plates. Where possible, results from the asymptotic model are compared to those from 3D time-marching finite element simulations and good agreement is demonstrated.
Review of field studies of aircraft noise-induced sleep disturbance
Authors: Michaud David S. , Fidell Sanford , Pearsons Karl , Campbell Kenneth C. , Keith Stephen E.
Published: January 2007

Aircraft noise-induced sleep disturbance (AN-ISD) is potentially among the more serious effects of aircraft noise on people. This literature review of recent field studies of AN-ISD finds that reliable generalization of findings to population-level effects is complicated by individual differences among subjects, methodological and analytic differences among studies, and predictive relationships that account for only a small fraction of the variance in the relationship between noise exposure and sleep disturbance. It is nonetheless apparent in the studied circumstances of residential exposure that sleep disturbance effects of nighttime aircraft noise intrusions are not dramatic on a per-event basis, and that linkages between outdoor aircraft noise exposure and sleep disturbance are tenuous. It is also apparent that AN-ISD occurs more often during later than earlier parts of the night; that indoor sound levels are more closely associated with sleep disturbance than outdoor measures; and that spontaneous awakenings, or awakenings attributable to nonaircraft indoor noises, occur more often than awakenings attributed to aircraft noise. Predictions of sleep disturbance due to aircraft noise should not be based on over-simplifications of the findings of the reviewed studies, and these reports should be treated with caution in developing regulatory policy for aircraft noise.
Convex optimization based time-domain broadband beamforming with sidelobe control
Authors: Yan Shefeng , Hou Chaohuan , Ma Xiaochuan , Ma Yuanliang
Published: January 2007

An approach to time-domain broadband beamforming with sidelobe control is proposed. The array response is expressed as a linear function of the finite impulse response filters tap weights. The filters are designed by minimizing beamformer output power while maintaining the distortionless response in the direction of the desired signal and guaranteeing the sidelobes to be below some given threshold values. Norm constraint on tap weights is also imposed to improve the robustness of the beamformer. Computationally efficient convex formulation for the beamformer design problem is derived using second-order cone programming. Simulation results demonstrate the satisfactory performance of the proposed approach.
A neural circuit transforming temporal periodicity information into a rate-based representation in the mammalian auditory system
Authors: Dicke Ulrike , Ewert Stephan D. , Dau Torsten , Kollmeier Birger
Published: January 2007

Periodic amplitude modulations (AMs) of an acoustic stimulus are presumed to be encoded in temporal activity patterns of neurons in the cochlear nucleus. Physiological recordings indicate that this temporal AM code is transformed into a rate-based periodicity code along the ascending auditory pathway. The present study suggests a neural circuit for the transformation from the temporal to the rate-based code. Due to the neural connectivity of the circuit, bandpass shaped rate modulation transfer functions are obtained that correspond to recorded functions of inferior colliculus (IC) neurons. In contrast to previous modeling studies, the present circuit does not employ a continuously changing temporal parameter to obtain different best modulation frequencies (BMFs) of the IC bandpass units. Instead, different BMFs are yielded from varying the number of input units projecting onto different bandpass units. In order to investigate the compatibility of the neural circuit with a linear modulation filterbank analysis as proposed in psychophysical studies, complex stimuli such as tones modulated by the sum of two sinusoids, narrowband noise, and iterated rippled noise were processed by the model. The model accounts for the encoding of AM depth over a large dynamic range and for modulation frequency selective processing of complex sounds.
Two-dimensional ultrasound detection with unfocused frequency-randomized signals
Authors: Clement Gregory T.
Published: January 2007

A method is described for detecting scattering in two-dimensions using an unfocused ultrasound field created from a continuously driven source array. The frequency of each element on the array is unique, resulting in a field that is highly variant as a function of both time and position. The scattered signal is then received by a single receiving line. The method, as currently written, is valid under the first order Born approximation. To demonstrate the approach, a series of simulations within the frequency range of 0.10–1.25MHz are performed and compared with a simulated B-Scan in the same frequency range. The method is found to be superior in resolving closely spaced objects, discerning 1.4mm separation in the radial and 0.5-mm separation in the axial direction. The method was also better able to determine object size, resolving scatters less than 10% of wavelength associated with the center frequency.
Staphylococcus aureus
Panton-Valentine Leukocidin Causes Necrotizing Pneumonia
Authors: Labandeira-Rey Maria , Couzon Florence , Boisset Sandrine , Brown Eric L. , Bes Michele , Benito Yvonne , Barbu Elena M. , Vazquez Vanessa , Höök Magnus , Etienne Jerome , Vandenesch François , Bowden M. Gabriela
Published: January 2007

The
Staphylococcus aureus
Panton-Valentine leukocidin (PVL) is a pore-forming toxin secreted by strains epidemiologically associated with the current outbreak of community-associated methicillin-resistant
Staphylococcus aureus
(CA-MRSA) and with the often-lethal necrotizing pneumonia. To investigate the role of PVL in pulmonary disease, we tested the pathogenicity of clinical isolates, isogenic PVL-negative and PVL-positive
S. aureus
strains, as well as purified PVL, in a mouse acute pneumonia model. Here we show that PVL is sufficient to cause pneumonia and that the expression of this leukotoxin induces global changes in transcriptional levels of genes encoding secreted and cell wall–anchored staphylococcal proteins, including the lung inflammatory factor staphylococcal protein A (Spa).
Plasma Amprenavir Pharmacokinetics and Tolerability following Administration of 1,400 Milligrams of Fosamprenavir Once Daily in Combination with either 100 or 200 Milligrams of Ritonavir in Healthy Volunteers
Authors: Ruane Peter J. , Luber Andrew D. , Wire Mary Beth , Lou Yu , Shelton Mark J. , Lancaster C. Tracey , Pappa Keith A.
Published: January 2007

Once-daily (QD) fosamprenavir (FPV) at 1,400 mg boosted with low-dose ritonavir (RTV) at 200 mg is effective when it is used in combination regimens for the initial treatment of human immunodeficiency virus infection. Whether a lower RTV boosting dose (i.e., 100 mg QD) could ensure sufficient amprenavir (APV) concentrations with improved safety/tolerability is unknown. This randomized, two 14-day-period, crossover pharmacokinetic study compared the steady-state plasma APV concentrations, safety, and tolerability of FPV at 1,400 mg QD boosted with either 100 mg or 200 mg of RTV QD in 36 healthy volunteers. Geometric least-square (GLS) mean ratios and the associated 90% confidence intervals (CIs) were estimated for plasma APV maximum plasma concentrations (
C
max
), the area under the plasma concentration-time curve over the dosing period (AUC
0-τ
), and trough concentrations (
C
τ
) during each dosing period. Equivalence between regimens (90% CIs of GLS mean ratios, 0.80 to 1.25) was observed for the plasma APV AUC
0-τ
(GLS mean ratio, 0.90 [90% CI, 0.84 to 0.96]) and
C
max
(0.97 [90% CI, 0.91 to 1.04]). The APV
C
τ
was 38% lower with RTV at 100 mg QD than with RTV at 200 mg QD (GLS mean ratio, 0.62 [90% CI, 0.55 to 0.69]) but remained sixfold higher than the protein-corrected 50% inhibitory concentration for wild-type virus, with the lowest APV
C
τ
observed during the 100-mg QD period being nearly threefold higher. The GLS mean APV
C
τ
was 2.5 times higher than the historical
C
τ
for unboosted FPV at 1,400 mg twice daily. Fewer clinical adverse drug events and smaller increases in triglyceride levels were observed with the RTV 100-mg QD regimen. Clinical trials evaluating the efficacy and safety of FPV at 1,400 mg QD boosted by RTV at 100 mg QD are now under way with antiretroviral therapy-naïve patients.
Synergistic Interactions of the Antiretroviral Protease Inhibitors Saquinavir and Ritonavir with Chloroquine and Mefloquine against
Plasmodium falciparum
In Vitro
Authors: Skinner-Adams T. S. , Andrews K. T. , Melville L. , McCarthy J. , Gardiner D. L.
Published: January 2007

The antimalarial activity of several antiretroviral protease inhibitor combinations was investigated. Data demonstrate that ritonavir and saquinavir behave synergistically with chloroquine and mefloquine. These data, and interactions with pepstatin-A, E-64, and bestatin, suggest that human immunodeficiency virus protease inhibitors do not target digestive-vacuole plasmepsins.
Umbilical cord milking reduces the need for red cell transfusions and improves neonatal adaptation in infants born at less than 29 weeks’ gestation: a randomised controlled trial
Authors: Hosono S , Mugishima H , Fujita H , Hosono A , Minato M , Okada T , Takahashi S , Harada K
Published: January 2007

Objective:

To investigate the effects of umbilical cord milking on the need for red blood cell (RBC) transfusion and morbidity in very preterm infants.

Patients and Methods:

40 singleton infants born between 24 and 28 weeks’ gestation were randomly assigned to receive umbilical cord clamped either immediately (control group, n = 20) or after umbilical cord milking (milked group, n = 20). Primary outcome measures were the probability of not needing transfusion, determined by Kaplan–Meier analysis, and the total number of RBC transfusions. Secondary outcome variables were haemoglobin value and blood pressure at admission.

Results:

There were no significant differences in gestational age and birth weight between the two groups. The milked group was more likely not to have needed red cell transfusion (p = 0.02) and had a decreased number (mean (SD)) of RBC transfusions (milked group 1.7 (3.0) vs controls 4.0 (4.2); p = 0.02). The initial mean (SD) haemoglobin value was higher in the milked group (165 (14) g/l) than in the controls (141 (16) g/l); p<0.01). Mean (SD) blood pressure at admission was significantly higher in the milked group (34 (9) mm Hg) than in the controls 28 (8) mm Hg; p = 0.03). There was no significant difference in mortality between the groups. The milked group had a shorter duration of ventilation or supplemental oxygen than the control group.

Conclusion:

Milking the umbilical cord is a safe procedure, reducing the need for RBC transfusions, and the need for circulatory and respiratory support in very preterm infants.
RAM ALLOCATION ALGORITHM FOR VIDEO PROCESSING APPLICATIONS ON FPGA
Authors: LAWAL NAJEEM , THÖRNBERG BENNY , O'NILS MATTIAS , NORELL HÅKAN
Published: January 2007

This paper presents an algorithm for the allocation of on-chip FPGA Block RAMs for the implementation of Real-Time Video Processing Systems. The effectiveness of the algorithm is shown through the implementation of realistic image processing systems. The algorithm, which is based on a heuristic, seeks the most cost-effective way of allocating memory objects to the FPGA Block RAMs. The experimental results obtained, show that this algorithm generates results which are close to the theoretical optimum for most design cases.
A SIC PAIR GENERATOR FOR A BILBO ENVIRONMENT
Authors: VOYIATZIS I. , KEHAGIAS D.
Published: January 2007

Built-In Self Test (BIST) techniques are commonly used as an efficient alternative to external testing in today's high-complexity VLSI chips since they provide on-chip test pattern generation and response verification. Among the BIST techniques, Built-In Logic Block Observation (BILBO) has been widely used in practice. Test patterns generated by BILBO structures target the detection of stuck-at faults.

It has been shown that most common failure mechanisms that appear into current CMOS VLSI circuits cannot be modeled as stuck-at faults. These mechanisms, modeled by sequential (i.e., stuck-open and delay) faults models, require the application of two-pattern tests (vector pairs) in the circuit-under-test inputs. Single Input Change (SIC) pairs are pairs of patterns where the second pattern differs from the first in only one bit and have been successfully used for two-pattern testing.

In this paper we present the BILBO-oriented SIC pair Generator technique that extends BILBO in order to generate SIC pairs; in this way, sequential faults are also detected.
Distinct modulation of Kv1.2 channel gating by wild type, but not open form, of syntaxin-1A
Authors: Neshatian Leila , Leung Yuk M. , Kang Youhou , Gao Xiaodong , Xie Huanli , Tsushima Robert G. , Gaisano Herbert Y. , Diamant Nicholas E.
Published: January 2007

SNARE proteins, syntaxin-1A (Syn-1A) and SNAP-25, inhibit delayed rectifier K+channels, Kv1.1 and Kv2.1, in secretory cells. We showed previously that the mutant open conformation of Syn-1A (Syn-1A L165A/E166A) inhibits Kv2.1 channels more optimally than wild-type Syn-1A. In this report we examined whether Syn-1A in its wild-type and open conformations would exhibit similar differential actions on the gating of Kv1.2, a major delayed rectifier K+channel in nonsecretory smooth muscle cells and some neuronal tissues. In coexpression and acute dialysis studies, wild-type Syn-1A inhibited Kv1.2 current magnitude. Of interest, wild-type Syn-1A caused a right shift in the activation curves of Kv1.2 without affecting its steady-state availability, an inhibition profile opposite to its effects on Kv2.1 (steady-state availability reduction without changes in voltage dependence of activation). Also, although both wild-type and open-form Syn-1A bound equally well to Kv1.2 in an expression system, open-form Syn-1A failed to reduce Kv1.2 current magnitude or affect its gating. This is in contrast to the reported more potent effect of open-form Syn-1A on Kv2.1 channels in secretory cells. This finding together with the absence of Munc18 and/or 13-1 in smooth muscles suggested that a change to an open conformation Syn-1A, normally facilitated by Munc18/13-1, is not required in nonsecretory smooth muscle cells. Taken together with previous reports, our results demonstrate the multiplicity of gating inhibition of different Kvchannels by Syn-1A and is compatible with versatility of Syn-1A modulation of repolarization in various secretory and nonsecretory (smooth muscle) cell types.
The impact of continuous positive airway pressure on the lower esophageal sphincter
Authors: Shepherd Kelly L. , Holloway Richard H. , Hillman David R. , Eastwood Peter R.
Published: January 2007

The lower esophageal sphincter (LES) is the primary barrier to gastroesophageal reflux. Reflux is associated with periods of LES relaxation, as occurs during swallowing. Continuous positive airway pressure (CPAP) has been shown to reduce reflux in individuals with and without sleep apnea, by an unknown mechanism. The aim of this study was to determine the effect of CPAP on swallow-induced LES relaxation. Measurements were made in 10 healthy, awake, supine individuals. Esophageal (Pes), LES (Ples), gastric (Pg), and barrier pressure to reflux (Pb = Ples − Pg) were recorded using a sleeve catheter during five swallows of 5 ml of water. This was repeated at four levels of CPAP (0, 5, 10, and 15 cmH2O). Pressures were measured during quiet breathing and during the LES relaxation associated with a swallow. Duration of LES relaxation was also recorded. During quiet breathing, CPAP significantly increased end-expiratory Pes, Ples, Pg, and Pb ( P < 0.05). The increase in Pb was due to a disproportionate increase in Ples compared with Pg ( P < 0.05). During a swallow, CPAP increased nadir Ples, Pg, and Pb and decreased the duration of LES relaxation (4.1 s with 0-cmH2O CPAP to 1.6 s on 15-cmH2O CPAP, P < 0.001). Pb increased with CPAP by virtue of a disproportionate increase in Ples compared with Pg. This may be due to either reflex activation of LES smooth muscle, or nonspecific transmission of pressure to the LES. The findings suggest CPAP may make the LES less susceptible to reflux by increasing Pb and decreasing the duration of LES relaxation.
Cyclic AMP-dependent protein kinase and Epac mediate cyclic AMP responses in pancreatic acini
Authors: Chaudhuri Anamika , Husain Sohail Z. , Kolodecik Thomas R. , Grant Wayne M. , Gorelick Fred S.
Published: January 2007

The pancreatic acinar cell has several phenotypic responses to cAMP agonists. At physiological concentrations of the muscarinic agonist carbachol (1 μM) or the CCK analog caerulein (100 pM), ligands that increase cytosolic Ca2+, cAMP acts synergistically to enhance secretion. Supraphysiological concentrations of carbachol (1 mM) or caerulein (100 nM) suppress secretion and cause intracellular zymogen activation; cAMP enhances both zymogen activation and reverses the suppression of secretion. In addition to stimulating cAMP-dependent protein kinase (PKA), recent studies using cAMP analogs that lack a PKA response have shown that cAMP can also act through the cAMP-binding protein, Epac (exchange protein directly activated by cyclic AMP). The roles of PKA and Epac in cAMP responses were examined in isolated pancreatic acini. The activation of both cAMP-dependent pathways or the selective activation of Epac was found to enhance amylase secretion induced by physiological and supraphysiological concentrations of the muscarinic agonist carbachol. Similarly, activation of both PKA or the specific activation of Epac enhanced carbachol-induced activation of trypsinogen and chymotrypsinogen. Disorganization of the apical actin cytoskeleton has been linked to the decreased secretion observed with supraphysiological concentrations of carbachol and caerulein. Although stimulation of PKA and Epac or Epac alone could largely overcome the decreased secretion observed with either supraphysiological carbachol or caerulein, stimulation of cAMP pathways did not reduce the disorganization of the apical cytoskeleton. These studies demonstrate that PKA and Epac pathways are coupled to both secretion and zymogen activation in the pancreatic acinar cell.
Determinants of contractile reserve in viable, chronically dysfunctional myocardium
Authors: Banas Michael D. , Baldwa Sunil , Suzuki Gen , Canty John M. , Fallavollita James A.
Published: January 2007

There is considerable variability in the sensitivity of inotropic reserve to identify viability in chronically dysfunctional myocardium. This is partially related to the underlying pathophysiology, with more frequent contractile reserve in chronically stunned (with normal resting perfusion) than hibernating myocardium (with reduced flow). This study was undertaken to determine the physiological responses to transient and graded stimulation in chronically stunned and hibernating myocardium to define the relative roles of acute catecholamine desensitization and biphasic responses. Pigs were chronically instrumented with a fixed left anterior descending artery stenosis that resulted in chronically stunned myocardium after 2 mo. One month later, hibernating myocardium was confirmed by regional dysfunction (wall thickening, 3.2 ± 0.3 vs. 5.5 ± 5 mm in remote, P = 0.01) with reduced resting flow (0.70 ± 0.07 vs. 0.92 ± 0.09 ml·min−1·g−1 in remote, P = 0.01) without infarction. Wall thickening in dysfunctional regions significantly increased during both graded and transient epinephrine stimulation in chronically stunned (from 3.6 ± 0.3 to 5.6 ± 0.5 and 4.9 ± 0.5 mm, respectively) and hibernating myocardium (from 3.3 ± 0.3 to 5.4 ± 0.6 and 5.0 ± 0.7 mm, respectively) and returned to baseline within 15 min. Although a biphasic response during graded stimulation was common, the subsequent decrement in function was small and similar in both groups (stunned, 0.7 ± 0.2 mm; hibernating, 1.1 ± 0.3 mm, P = 0.25). We conclude that 1) the extent of contractile reserve during β-adrenergic stimulation is similar in chronically stunned and hibernating myocardium, 2) there are no significant differences between the responses to transient compared with graded catecholamine stimulation, and 3) submaximal catecholamine stimulation does not induce additional stunning in either chronically stunned or hibernating myocardium.
Smooth muscle and neural mechanisms contributing to the downregulation of neonatal rat spontaneous bladder contractions during postnatal development
Authors: Ng Yuen-Keng , de Groat William C. , Wu Hsi-Yang
Published: January 2007

Spontaneous bladder contractions (SBCs) in the neonatal rat urinary bladder change from a high-amplitude, low-frequency pattern to a low-amplitude, high-frequency pattern during the first 6 wk of life. Understanding the mechanism of this developmental change may provide insights into the causes of bladder overactivity in adults. In vitro whole bladder preparations from Sprague-Dawley rats were used to study the modulation of SBCs by calcium-activated potassium channels (KCa) and electrical field stimulation from 3 days to 6 wk of life. SBCs in 3-day-old bladders were unmasked by treatment with iberiotoxin (100 nM), an inhibitor of large conductance KCa(BK) channels, or apamin (100 nM), an inhibitor of small conductance KCa(SK) channels. Iberiotoxin significantly increased the magnitude of SBCs at 2–3 wk, whereas apamin was only effective at 6 wk. In 1–2 wk bladders, exposure to room temperature Krebs solution decreased SBCs. This decrease was reversed by activating intramural nerves with electrical field stimulation. The effect of electrical field stimulation was inhibited by atropine (1 μM), suramin (10 μM), or pretreatment with tetrodotoxin (1 μM) but was not reversed by tetrodotoxin applied after electrical field stimulation. BK-α mRNA increased threefold, and BK-α protein increased fivefold from 3 days to 6 wk. These data suggest that BK channels play an important role in the regulation of SBCs in the neonatal bladder and that both increased BK channel activity, as well as changes in smooth muscle sensitivity to locally released neurotransmitters contribute to the downregulation of SBCs during early postnatal development.
Fat metabolism and acute resistance exercise in trained men
Authors: Ormsbee Michael J. , Thyfault John P. , Johnson Emily A. , Kraus Raymond M. , Choi Myung Dong , Hickner Robert C.
Published: January 2007

The purpose of this study was to investigate the effect of acute resistance exercise (RE) on lipolysis within adipose tissue and subsequent substrate oxidation to better understand how RE may contribute to improvements in body composition. Lipolysis and blood flow were measured in abdominal subcutaneous adipose tissue via microdialysis before, during, and for 5 h following whole body RE as well as on a nonexercise control day (C) in eight young (24 ± 0.7 yr), active (>3 RE session/wk for at least 2 yr) male participants. Fat oxidation was measured immediately before and after RE via indirect calorimetry for 45 min. Dialysate glycerol concentration (an index of lipolysis) was higher during (RE: 200.4 ± 38.6 vs. C: 112.4 ± 13.1 μmol/l, 78% difference; P = 0.02) and immediately following RE (RE: 184 ± 41 vs. C: 105 + 14.6 μmol/l, 75% difference; P = 0.03) compared with the same time period on the C day. Energy expenditure was elevated in the 45 min after RE compared with the same time period on the C day (RE: 104.4 ± 6.0 vs. C: 94.5 ± 4.0 kcal/h, 10.5% difference; P = 0.03). Respiratory exchange ratio was lower (RE: 0.71 ± 0.004 vs. C: 0.85 ± .03, 16.5% difference; P = 0.004) and fat oxidation was higher (RE: 10.2 ± 0.8 vs. C: 5.0 ± 1.0 g/h, 105% difference; P = 0.004) following RE compared with the same time period on the C day. Therefore, the mechanism behind RE contributing to improved body composition is in part due to enhanced abdominal subcutaneous adipose tissue lipolysis and improved whole body fat oxidation and energy expenditure in response to RE.
Cerebral angiogenic factors, angiogenesis, and physiological response to chronic hypoxia differ among four commonly used mouse strains
Authors: Ward Nicole L. , Moore Elizabeth , Noon Kristen , Spassil Nicholas , Keenan Erica , Ivanco Tammy L. , LaManna Joseph C.
Published: January 2007

Angiogenesis is a critical element for adaptation to low levels of oxygen and occurs following long-term exposure to mild hypoxia in rats. To test whether a similar response in mice occurs, CD1, 129/Sv, C57Bl/6, and Balb/c mice were exposed to 10% oxygen for up to 3 wk. All mice showed significant increases in the percentage of packed red blood cells, and CD1 and 129/Sv mice showed increased respiration frequency and minute volume, common physiological measures of hypoxia. Significant angiogenesis was observed in all strains except Balb/c following 3-wk exposure to chronic hypoxia. CD1 hypoxic mice had the largest increase (88%), followed by C57Bl/6 (48%), 129/Sv (41%), and Balb/c (12%), suggesting that some mice undergo more remodeling than others in response to hypoxia. Protein expression analysis of vascular endothelial growth factor (VEGF), angiopoietin (Ang)-1 and Ang2, and Tie2 were examined to determine whether regulation of different angiogenic proteins could account for the differences observed in hypoxia-induced angiogenesis. CD1 mice showed the strongest upregulation of VEGF, Ang2, Ang1, and Tie2, whereas Balb/c had only subtle increases in VEGF and no change in the other proteins. C57Bl/6 mice showed a regulatory response that fell between the CD1 and Balb/c mice, consistent with the intermediate increase in angiogenesis. Our results suggest that genetic heterogeneity plays a role in angiogenesis and regulation of angiogenic proteins and needs to be accounted for when designing and interpreting experiments using transgenic mice and when studying in vivo models of angiogenesis.
Modulation of motoneuronal firing behavior after spinal cord injury using intraspinal microstimulation current pulses: a modeling study
Authors: ElBasiouny Sherif M. , Mushahwar Vivian K.
Published: January 2007

We simulated the effects of delivering focal electrical stimuli to the central nervous system to modulate the firing rate of neurons and alleviate motor disorders. Application of these stimuli to the spinal cord to reduce the increased excitability of motoneurons and resulting spasticity after spinal cord injury (SCI) was examined by means of a morphologically detailed computer model of a spinal motoneuron. High-frequency sinusoidal and rectangular pulses as well as biphasic charge-balanced and charge-imbalanced pulses were examined. Our results suggest that suprathreshold high-frequency sinusoidal or rectangular current pulses could inactivate the Na+channels in the soma and initial segment, and block action potentials from propagating through the axon. Subthreshold biphasic charge-imbalanced pulses reduced the motoneuronal firing rate significantly (up to ∼25% reduction). The reduction in firing rate was achieved through stimulation-induced hyperpolarization generated in the first node of Ranvier. Because of their low net DC current, these pulses could be tolerated safely by the tissue. To deliver charge-imbalanced pulses with the lowest net DC current and induce the largest reduction in motoneuronal firing rate, we studied the effect of various charge-imbalanced pulse parameters. Short pulse durations were found to induce the largest reduction in firing rate for the same net DC level. Subthreshold high-frequency sinusoidal and rectangular current pulses and low-frequency biphasic charge-balanced pulses, on the other hand, were ineffective in reducing the motoneuronal firing rate. In conclusion, the proposed electrical stimulation paradigms could provide potential rehabilitation interventions for suppressing the excitability of neurons to reduce the severity of motor disorders after injury to the central nervous system.