bluuebunny/crossref_metadata_2025 huggingface dataset:
Acoustics and behavioral contexts of “gecker” vocalizations in young rhesus macaques (Macaca mulatta)
Authors: Patel Erik R. , Owren Michael J.
Published: January 2007

Loud, pulsed “gecker” vocalizations are commonly produced by young rhesus macaques in distressful circumstances. The acoustics, usage, and responses associated with these calls were examined using audio recordings and observational data from captive, socially living rhesus up to 24 months old. One-hundred-eleven gecker bouts were recorded from ten individuals (six males, four females), with most geckers produced during the first 6 months of age. A gecker call consisted of a bout of up to 28 pulses of spectrally structured noise with a single prominent frequency peak. Nine contexts of calling were identified, but little evidence of context-specific acoustic variation was found. While geckering often triggered responses by the vocalizer’s mother, the most common outcome was the absence of any reaction. Females geckered longer and at higher rates than did males, while also showing acoustic evidence of greater vocal effort. Mothers nonetheless responded more often and more positively to males. Overall, results show that gecker acoustics vary somewhat with vocalizer sex, age, and likely arousal level, but do not reflect detailed aspects of behavioral context. Circumstances of production suggest that geckers function primarily to draw the attention of mothers, who in turn are selective in responding.
Microbubble spectroscopy of ultrasound contrast agents
Authors: van der Meer Sander M. , Dollet Benjamin , Voormolen Marco M. , Chin Chien T. , Bouakaz Ayache , de Jong Nico , Versluis Michel , Lohse Detlef
Published: January 2007

A new optical characterization of the behavior of single ultrasound contrast bubbles is presented. The method consists of insonifying individual bubbles several times successively sweeping the applied frequency, and to record movies of the bubble response up to 25 million frames/s with an ultrahigh speed camera operated in a segmented mode. The method, termed microbubble spectroscopy, enables to reconstruct a resonance curve in a single run. The data is analyzed through a linearized model for coated bubbles. The results confirm the significant influence of the shell on the bubble dynamics: shell elasticity increases the resonance frequency by about 50%, and shell viscosity is responsible for about 70% of the total damping. The obtained value for shell elasticity is in quantative agreement with previously reported values. The shell viscosity increases significantly with the radius, revealing a new nonlinear behavior of the phospholipid coating.
Voicing and silence periods in daily and weekly vocalizations of teachers
Authors: Titze Ingo R. , Hunter Eric J. , Švec Jan G.
Published: January 2007

The National Center for Voice and Speech (NCVS) data bank on voice dosimetry was used to study the distributions of continuous voicing periods and silence periods in 31 teachers over the duration of two weeks. Recordings were made during all awake hours of the day. Voicing periods were grouped into half decades, ranging from 0.0316to0.10s for the shortest periods of phonation to 31.6–100s for the longest periods of phonation. Silence periods were grouped into similar half decades, but ranged up to periods of several hours. On average, the teachers had 1800 occurrences of voicing (onset followed by offset) per hour at work and 1200 occurrences per hour while not at work. Voicing occurred 23% of the total time at work, dropping to 13% during off-work hours and 12% on weekends. The greatest accumulation of voicing occurred in the 0.316–1.0s voicing periods, whereas the greatest accumulation of silence occurred in the 3–10s silence periods. The study begins to lay the groundwork for understanding vocal fatigue in terms of repetitive motion and collision of tissue, as well as recovery from such mechanical stress.
Sea surface effect on shallow-water reverberation
Authors: Zhou Ji-Xun , Zhang Xue-Zhen , Peng Zhaohui , Martin James S.
Published: January 2007

Wideband reverberation measurements were made at a fixed location in the East China Sea on 3 and 5 June 2001 using the same measurement system. Sound-speed profiles were similar during both measurements. Wind speed (W) and rms surface-wave height (σ) changed from 2.74m∕s and 0.10m on 3 June to 7.45m∕s and 0.33m on 5 June. Thus, these measurements offer an opportunity to evaluate sea-surface effects on reverberation vertical coherence (RVC), RVC-inverted bottom acoustic parameters, and reverberation level (RL) in shallow water. The two sets of RVC and RL data, in a frequency range of 100–2500Hz, show differences that are the apparent effects of the surface roughness. With increasing sea state, the RVC increases and the RL decreases. The effective bottom losses, inverted from the RVC data, correspond to the variation of sea state. This additional loss gives a physical explanation of the characteristics of both the measured RVC and RL. These preliminary findings show the importance of surface effects in shallow-water reverberation and propagation models. These effects would be pronounced for high frequencies and sea states. For the conditions reported here, the effects were most apparent for f>500Hz when W=7.45m∕s.
Sentence recognition in native- and foreign-language multi-talker background noise
Authors: Van Engen Kristin J. , Bradlow Ann R.
Published: January 2007

Studies of speech perception in various types of background noise have shown that noise with linguistic content affects listeners differently than nonlinguistic noise [e.g., Simpson, S. A., and Cooke, M. (2005). “Consonant identification in N-talker babble is a nonmonotonic function of N,” J. Acoust. Soc. Am. 118, 2775–2778; Sperry, J. L., Wiley, T. L., and Chial, M. R. (1997). “Word recognition performance in various background competitors,” J. Am. Acad. Audiol. 8, 71–80] but few studies of multi-talker babble have employed background babble in languages other than the target speech language. To determine whether the adverse effect of background speech is due to the linguistic content or to the acoustic characteristics of the speech masker, this study assessed speech-in-noise recognition when the language of the background noise was either the same or different from the language of the target speech. Replicating previous findings, results showed poorer English sentence recognition by native English listeners in six-talker babble than in two-talker babble, regardless of the language of the babble. In addition, our results showed that in two-talker babble, native English listeners were more adversely affected by English babble than by Mandarin Chinese babble. These findings demonstrate informational masking on sentence-in-noise recognition in the form of “linguistic interference.” Whether this interference is at the lexical, sublexical, and/or prosodic levels of linguistic structure and whether it is modulated by the phonetic similarity between the target and noise languages remains to be determined.
Bayesian estimation of the underlying bone properties from mixed fast and slow mode ultrasonic signals
Authors: Marutyan Karen R. , Bretthorst G. Larry , Miller James G.
Published: January 2007

We recently proposed that the observed apparent negative dispersion in bone can arise from the interference between fast wave and slow wave modes, each exhibiting positive dispersion [Marutyan et al., J. Acoust. Soc. Am. 120, EL55–EL61 (2006)]. In the current study, we applied Bayesian probability theory to solve the inverse problem: extracting the underlying properties of bone. Simulated mixed mode signals were analyzed using Bayesian probability. The calculations were implemented using the Markov chain Monte Carlo with simulated annealing to draw samples from the marginal posterior probability for each parameter.
Excitation of polymer-shelled contrast agents with high-frequency ultrasound
Authors: Ketterling Jeffrey A. , Mamou Jonathan , Allen John S. , Aristizábal Orlando , Williamson Rene G. , Turnbull Daniel H.
Published: January 2007

Few experimental and complementary theoretical studies have investigated high-frequency (>20MHz) nonlinear responses from polymer-shelled ultrasound contrast agents. Three polymer agents with different shell properties were examined for their single-bubble backscatter when excited with a 40MHz tone burst. Higher-order harmonic responses were observed for the three agents; however, their occurrence was at least partly due to nonlinear propagation. Only one of the agents (1.1μm mean diameter) showed a subharmonic response for longer excitations (≈10–15cycles) and midlevel pressure excitations (≈2.5MPa). Theoretical calculations of the backscattered spectrum revealed behavior similar to the experimental results in specific parameter regimes.
A Molecule Carrier
Authors: Wong K. L. , Pawin G. , Kwon K.-Y. , Lin X. , Jiao T. , Solanki U. , Fawcett R. H. J. , Bartels L. , Stolbov S. , Rahman T. S.
Published: January 2007

We found that anthraquinone diffuses along a straight line across a flat, highly symmetric Cu(111) surface. It can also reversibly attach one or two CO
2
molecules as “cargo” and act as a “molecule carrier,” thereby transforming the diffusive behavior of the CO
2
molecules from isotropic to linear. Density functional theory calculations indicated a substrate-mediated attraction of ∼0.12 electron volt (eV). Scanning tunneling microscopy revealed individual steps of the molecular complex on its diffusion pathway, with increases of ∼0.03 and ∼0.02 eV in the diffusion barrier upon attachment of the first and second CO
2
molecule, respectively.
Integration of TGF-ß and Ras/MAPK Signaling Through p53 Phosphorylation
Authors: Cordenonsi Michelangelo , Montagner Marco , Adorno Maddalena , Zacchigna Luca , Martello Graziano , Mamidi Anant , Soligo Sandra , Dupont Sirio , Piccolo Stefano
Published: January 2007

During development and tissue homeostasis, cells must integrate different signals. We investigated how cell behavior is controlled by the combined activity of transforming growth factor–β (TGF-β) and receptor tyrosine kinase (RTK) signaling, whose integration mechanism is unknown. We find that RTK/Ras/MAPK (mitogen-activated protein kinase) activity induces p53 N-terminal phosphorylation, enabling the interaction of p53 with the TGF-β–activated Smads. This mechanism confines mesoderm specification in
Xenopus
embryos and promotes TGF-β cytostasis in human cells. These data indicate a mechanism to allow extracellular cues to specify the TGF-β gene-expression program.
Contribution of Target Gene Mutations and Efflux to Decreased Susceptibility of
Salmonella enterica
Serovar Typhimurium to Fluoroquinolones and Other Antimicrobials
Authors: Chen Sheng , Cui Shenghui , McDermott Patrick F. , Zhao Shaohua , White David G. , Paulsen Ian , Meng Jianghong
Published: January 2007

The mechanisms involved in fluoroquinolone resistance in
Salmonella enterica
include target alterations and overexpression of efflux pumps. The present study evaluated the role of known and putative multidrug resistance efflux pumps and mutations in topoisomerase genes among laboratory-selected and naturally occurring fluoroquinolone-resistant
Salmonella enterica
serovar Typhimurium strains. Strains with ciprofloxacin MICs of 0.25, 4, 32, and 256 μg/ml were derived in vitro using serovar Typhimurium S21. These mutants also showed decreased susceptibility or resistance to many nonfluoroquinolone antimicrobials, including tetracycline, chloramphenicol, and several β-lactams. The expression of efflux pump genes
acrA
,
acrB
,
acrE
,
acrF
,
emrB
,
emrD
, and
mdlB
were substantially increased (≥2-fold) among the fluoroquinolone-resistant mutants. Increased expression was also observed, but to a lesser extent, with three other putative efflux pumps:
mdtB
(
yegN
),
mdtC
(
yegO
), and
emrA
among mutants with ciprofloxacin MICs of ≥32 μg/ml. Deletion of
acrAB
or
tolC
in S21 and its fluoroquinolone-resistant mutants resulted in increased susceptibility to fluoroquinolones and other tested antimicrobials. In naturally occurring fluoroquinolone-resistant serovar Typhimurium strains, deletion of
acrAB
or
tolC
increased fluoroquinolone susceptibility 4-fold, whereas replacement of
gyrA
double mutations (S83F D87N) with wild-type
gyrA
increased susceptibility >500-fold. These results indicate that a combination of topoisomerase gene mutations, as well as enhanced antimicrobial efflux, plays a critical role in the development of fluoroquinolone resistance in both laboratory-derived and naturally occurring quinolone-resistant serovar Typhimurium strains.
Overexpression and Initial Characterization of the Chromosomal Aminoglycoside 3′-
O
-Phosphotransferase APH(3′)-IIb from
Pseudomonas aeruginosa
Authors: Hainrichson Mariana , Yaniv Orit , Cherniavsky Marina , Nudelman Igor , Shallom-Shezifi Dalia , Yaron Sima , Baasov Timor
Published: January 2007

The chromosomal gene
aph(3
′
)-IIb
, encoding an aminoglycoside 3′-phosphotransferase in
Pseudomonas aeruginosa
, was cloned and overexpressed in
Escherichia coli
. The APH(3′)-IIb enzyme was purified as a monomer in a two-step procedure and was shown to phosphorylate its substrates at the C-3′-OH position, with
k
cat
/

K
m

values of 0.4 × 10
4
to 36 × 10
4
M
−1
s
−1
.
AN ALGORITHM FOR MINIMUM SPACE QUANTUM BOOLEAN CIRCUITS CONSTRUCTION
Authors: TSAI I-MING , KUO SY-YEN
Published: January 2007

Implementing a quantum computer at the circuit level has emerged as an important field of research recently. An important topic of building a general-purpose quantum computer is to implement classical Boolean logic using quantum gates and devices. Since the Toffoli gate is universal in classical Boolean logic, any classical combinational circuit can be implemented by the straightforward replacement algorithm with auxiliary qubits as intermediate storage. However, this inefficient implementation causes a large number of auxiliary qubits to be used. In this paper, a systematic procedure is proposed to derive a minimum space quantum circuit for a given classical combinational logic. We first formulate the problem of transforming an m-to-n bit classical Boolean logic into a t-bit unitary quantum operation. The eligible solution set is then constructed such that a solution can be found simply by selecting any member from this set. Finally, we show that the algorithm is optimal in terms of the space consumption.
BLIND IMAGE RESTORATION BY COMBINING WAVELET TRANSFORM AND RBF NEURAL NETWORK
Authors: GUO PING , LI HONGZHAI , LYU MICHAEL R.
Published: January 2007

In this paper, we present a novel technique for restoring a blurred noisy image without any prior knowledge of the blurring function and the statistics of noise. The technique combines wavelet transform with radial basis function (RBF) neural network to restore the given image which is degraded by Gaussian blur and additive noise. In the proposed technique, the wavelet transform is adopted to decompose the degraded image into high frequency parts and low frequency part. Then the RBF neural network based technique is used to restore the underlying image from the given image. The inverse principal element method (IPEM) is applied to speed up the computation. Experimental results show that the proposed technique inherited the advantages of wavelet transform and IPEM, and the algorithm is efficient in computation and robust to the noise.
ON DIRECT METHODS FOR TIME-LIMITED SIGNAL AND IMAGE RECONSTRUCTION AND ENHANCEMENT
Authors: WANG YANFEI , WEN ZAIWEN , NASHED ZUHAIR , SUN QIYU
Published: January 2007

The discrete Fourier transform (DFT) can be considered as an observing system, which has an input f, an output F, and a response with additive noise E. In many applications, part of the frequency spectrum/frequency information is missing or unavailable due to the passage of the time-limited signal through a band-limited system, for example, the discrete Fourier system. We suggest improving the resolution of the reconstruction of signals and images using a novel approach for the solution of the discrete Fourier system and by image enhancement. We note that the reconstruction of a time-limited signal can be simply realized by only using either the real part or the imaginary part of the DFT matrix. Therefore, based on the study of the special structure of the real and imaginary parts of the discrete Fourier matrix, a fast direct computational method is developed that utilizes explicit formulas for the truncated singular value decomposition (TSVD) obtained recently by the authors. For improving the resolution of the reconstructions, enhancement by logarithm transform is applied. This fast direct computational method is superior to other direct methods such as LU decomposition, QR decomposition, classical SVD and classical TSVD. The explicit TSVD along with the enhancement can be considered as a useful tool for signal and image reconstructions. Numerical tests for signal and image reconstructions and enhancements are given as well.
SUPPORT VECTOR MACHINE SOLVING FREEFORM CURVE AND SURFACE RECONSTRUCTION PROBLEM
Authors: YANG ZHIXIA , JING LING
Published: January 2007

Reconstruction of mathematically unknown freeform curve and surface is of paramount importance for reverse engineering. This problem belongs to a regression problem, but there is a particular requirement, namely the curve and surface have to be smooth. Support vector machine (SVM) is a new and powerful method for the regression problem. However, the fitting results of SVM are usually not smooth enough due to its sensitivity to outliers or noises. In this paper, a modified version, called as smooth support vector machine (S-SVM), is proposed. The new version treats the training points differently by constructing their penalty factors based on the smooth degree, so smooth regression curve and surface can be obtained. In order to compare this new version with SVM, numerical experiments on both curve and surface fitting are given, which show clearly the improvements.
MATCHING ALGORITHM USING WAVELET THINNING FEATURES FOR OFFLINE SIGNATURE VERIFICATION
Authors: FANG BIN , YOU XINGE , CHEN WEN-SHENG , TANG YUAN YAN
Published: January 2007

Structure distortion evaluation allows us to directly measure the similarity between signature patterns without classification using feature vectors, which usually suffers from limited training samples. In this paper, we incorporate the merits of both global and local alignment algorithms to define structure distortion using signature skeletons identified by a robust wavelet thinning technique. A weak affine model is employed to globally register two signature skeletons and structure distortion between two signature patterns, which are determined by applying an elastic local alignment algorithm. Similarity measurement is evaluated in the form of Euclidean distance of all found corresponding feature points. Experimental results showed that the proposed similarity measurement was able to provide sufficient discriminatory information in terms of equal error rate being 18.6% with four training samples.
MULTIRESOLUTION IMAGE PERCEPTUAL GROUPING USING TOPOLOGICAL STRUCTURE EMBEDDED IN MANIFOLD
Authors: ZOU QI , HUANG XIANG-LIN , LUO SI-WEI
Published: January 2007

Contour grouping is the precondition for high-level visual tasks such as region-of-interest detection and object recognition. Those methods adopting local geometric features and simple photometric attributes always lead to unreliable result or bad robustness. In this paper, we propose a grouping method using multiresolution analysis and one-dimensional manifold. By using multiresolution analysis, grouping seeds and initial clusters are detected as precondition for describing topological structure. Then one-dimensional manifold is applied to discovering intrinsic order of topological structure, which corresponds to coordinates of edges in a closed contour. These two improvements enhance our method's robustness relative to those using local features or linear combinations of them. Experiments on different classes of real images show competence of our method.
PRECISE EYE LOCATION USING DEMPSTER–SHAFER THEORY
Authors: GAO YONG , WANG YANGSHENG
Published: January 2007

Eye location is an important step in automatic visual interpretation and face recognition. In this paper, we present a novel eye location algorithm based on Dempster–Shafer's evidential reasoning. Four eye detectors are trained by AdaBoost with different combinations of feature spaces and samples. They detect face region respectively and produce an eye candidate set, then two of the four eye detectors calculate the confidence of every eye candidate. The confidence is converted to belief and plausibility. We use the combining rule to obtain combined belief and plausibility of each eye candidate, which represent the fusion information of the two eye detectors. The centers of eye candidates with great plausibility are considered as actual eye centers. Experimental results on several open face databases demonstrate that our method is precise, robust and has less computational complexity than other newly proposed ones.
ADAPTIVE WATERMARKING AND PERFORMANCE ANALYSIS BASED ON IMAGE CONTENT
Authors: NI RONGRONG , RUAN QIUQI , LU JUN
Published: January 2007

This paper presents a novel adaptive watermarking based on iteration mapping and image content. An original image is divided into non-overlapped blocks, which are analyzed by means of fractal dimension, and the feature blocks which contain edges and textures are further classified by variance characteristics into three different parts: edges, weak textures, and strong textures. The original watermark is a distinguishable gray image, which is scrambled and amended to form a watermark signal to be embedded. DCT is applied to all the original image blocks and the formed watermark is embedded into their middle-frequency coefficients with different strength. Performance analysis of adaptive watermark extraction is presented in details. Experimental results show that this algorithm is able to achieve a watermarked image with good perceptual invisibility, high security and strong robustness.
A NOVEL MODEL FOR EXCITATION OF PERIPHERAL NERVES STIMULATED BY A TRANSVERSE ELECTRIC FIELD
Authors: YU HUI , LIU XUELIANG , ZHENG CHONGXUN , WANG YI
Published: January 2007

The disadvantage of the classical cable model is that it cannot describe the excitation of peripheral nerves stimulated by a perpendicular electric field. To address this problem, a novel model is studied and presented to describe peripheral nerves stimulated by a transverse-field in this paper. With this model, the responses of the Ranvier nodes by a transverse-field are investigated. The simulation demonstrates that under perpendicular electric field stimulation, the responses of Ranvier nodes evoke a two-stage process including an initial polarization and the actual change of the transmembrane potential. The peripheral nerve excitation results from the net inward current along a radial direction of the Ranvier node driven with an external field.
GAIT SYNTHESIS BASED ON FWN FOR A FIVE-LINK BIPED ROBOT
Authors: LIU PENGFEI , HAN JIUQIANG , MA JIANMEI , WANG DONGLIN
Published: January 2007

This paper presents a new reference trajectory and a fuzzy wavelet neural network controller to synthesize the gait of a five-link biped robot when walking on the level ground. Both the single support phase (SSP) and the double support phase (DSP) are considered. The gait of the biped can be determined when the trajectories of the hip and the swing limb are designed. The trajectories of the hip and the swing limb are approximated with the time polynomial functions. The coefficients of the functions are determined by the constraint equations cast in terms of coherent physical characteristics, such as repeatability, continuity, stability, and minimization of the effect of impact. The fuzzy wavelet neural network controller is trained by error back-propagation algorithm. Given the certain gait parameters such as the step length, maximum step height, walking speed, and so on, the control scheme can generate the smooth gait profiles. The simulation results show that the designed controller can follow the reference trajectories well.
Morphological and biochemical characterization of remodeling in aorta and vena cava of DOCA-salt hypertensive rats
Authors: Watts Stephanie W. , Rondelli Catherine , Thakali Keshari , Li Xiaopeng , Uhal Bruce , Pervaiz Mohammad H. , Watson Ralph E. , Fink Gregory D.
Published: January 2007

Arterial remodeling occurs in response to mechanical and neurohumoral stimuli. We hypothesized that veins, which are not exposed to higher pressures in hypertension, would demonstrate less active remodeling than arteries. We assessed remodeling with two standard measures of arterial remodeling: vessel morphometry and the expression/function of matrix metalloproteinases (MMPs). Thoracic aorta and vena cava from sham normotensive and DOCA-salt hypertensive rats (110 ± 4 and 188 ± 8 mmHg systolic blood pressure, respectively) were used. Wall thickness was increased in DOCA-salt vs. sham aorta (301 ± 23 vs. 218 ± 14 μm, P < 0.05), as was medial area, but neither measure was altered in the vena cava. The aorta and vena cava expressed the gelatinases MMP-2, MMP-9, transmembrane proteinase MT1-MMP, and tissue inhibitor of metalloproteinase-2 (TIMP-2). Immunohistochemically, MMP-2 localized to smooth muscle in the aorta and densely in endothelium/smooth muscle of the vena cava. Western and zymographic analyses verified that MMP-2 was active in all vessels and less active in the vena cava than aorta. In hypertension, MMP-2 expression and activity in the aorta were increased (59.1 ± 3.7 and 74.5 ± 6.1 units in sham and DOCA, respectively, P < 0.05); similar elevations were not observed in the vena cava. MMP-9 was weakly expressed in all vessels. MT1-MMP was expressed by the aorta and vena cava and elevated in the vena cava from DOCA-salt rats. TIMP-2 expression was significantly increased in the aorta of DOCA rats compared with sham but was barely detectable in the vena cava of sham or DOCA-salt hypertensive rats. These findings suggest that large veins may not undergo vascular remodeling in DOCA-salt hypertension.
Comparative changes in the blood-brain barrier and cerebral infarction of SHR and WKY rats
Authors: Hom Sharon , Fleegal Melissa A. , Egleton Richard D. , Campos Christopher R. , Hawkins Brian T. , Davis Thomas P.
Published: January 2007

Hypertension is involved in the exacerbation of stroke. It is unclear how blood-brain barrier (BBB) tight-junction (TJ) and ion transporter proteins critical for maintaining brain homeostasis contribute to cerebral infarction during hypertension development. In the present study, we investigated cerebral infarct volume following permanent 4-h middle cerebral artery occlusion (MCAO) and characterized the expression of BBB TJ and ion transporter proteins in brain microvessels of spontaneously hypertensive rats (SHR) compared with age-matched Wistar-Kyoto (WKY) rats at 5 wk (prehypertension), 10 wk (early-stage hypertension), and 15 wk (later-stage hypertension) of age. Hypertensive SHR show increased infarct volume following MCAO compared with WKY control rats. BBB TJ and ion transporter proteins, known to contribute to edema and fluid volume changes in the brain, show differential protein expression patterns during hypertension development. Western blot analysis of TJ protein zonula occludens-2 (ZO-2) showed decreased expression, while ion transporter, Na+/H+exchanger 1 (NHE-1), was markedly increased in hypertensive SHR. Expression of TJ proteins ZO-1, occludin, actin, claudin-5, and Na+-K+-2Cl−cotransporter remain unaffected in SHR compared with control. Selective inhibition of NHE-1 using dimethylamiloride significantly attenuated ischemia-induced infarct volume in hypertensive SHR following MCAO, suggesting a novel role for NHE-1 in the brain in the regulation of ischemia-induced infarct volume in SHR.
Cutaneous blood flow and sweat rate responses to exogenous administration of acetylcholine and methacholine
Authors: Kimura Kenichi , Low David A. , Keller David M. , Davis Scott L. , Crandall Craig G.
Published: January 2007

The aim of this study was to evaluate cutaneous vasodilation and sweating responses to exogenous administration of acetylcholine (ACh) and methacholine (MCh), which have different sensitivities to endogenous cholinesterase. Four intradermal microdialysis probes were placed in dorsal forearm skin: two sites were perfused with ACh (1 × 10−7–1 M) and the other two with the same molar concentrations of MCh. Sweat rate (SR) and cutaneous blood flow were simultaneously assessed directly over each microdialysis membrane. Dose-response curves were constructed, and the effective concentration of the drug resulting in 50% of the maximal response (EC50) was identified. For SR and cutaneous vascular conductance (CVC), there were no significant differences in EC50between sites receiving the same drug: −1.52 ± 0.18 and −1.19 ± 0.09 log-molar concentration of ACh at distal and proximal sites, respectively, and −2.35 ± 0.24 and −2.42 ± 0.23 log-molar concentration of MCh at distal and proximal sites, respectively, for SR ( P > 0.05) and −3.87 ± 0.32 and −3.97 ± 0.27 log-molar concentration of ACh at distal and proximal sites, respectively, and −4.78 ± 0.17 and −4.46 ± 0.16 log-molar concentration of MCh at distal and proximal sites, respectively, for CVC ( P > 0.05). However, the EC50for CVC and SR was significantly lower at the MCh than at the ACh sites. A second procedure was performed to confirm that differences in responses between ACh and MCh could be attributed to different cholinesterase sensitivities. Similarly, four microdialysis membranes were placed in dorsal forearm skin: two sites were perfused with ACh and other two with MCh. However, one of each of the ACh and MCh sites was also perfused with 10 μM neostigmine (an acetylcholinesterase inhibitor). Neostigmine at the ACh site induced a leftward shift (i.e., lower EC50) of the SR and CVC dose-response curves compared with the site treated with ACh alone, resulting in no difference in the EC50for SR and CVC between the ACh + neostigmine and the MCh site. These results suggest that elevations in SR and CVC occur earlier with MCh than with ACh treatment because of differences in cholinesterase susceptibility between these drugs.
Reduced efficiency, but increased fat oxidation, in mitochondria from human skeletal muscle after 24-h ultraendurance exercise
Authors: Fernström Maria , Bakkman Linda , Tonkonogi Michail , Shabalina Irina G. , Rozhdestvenskaya Zinaida , Mattsson C. Mikael , Enqvist Jonas K. , Ekblom Björn , Sahlin Kent
Published: January 2007

The hypothesis that ultraendurance exercise influences muscle mitochondrial function has been investigated. Athletes in ultraendurance performance performed running, kayaking, and cycling at 60% of their peak O2consumption for 24 h. Muscle biopsies were taken preexercise (Pre-Ex), postexercise (Post-Ex), and after 28 h of recovery (Rec). Respiration was analyzed in isolated mitochondria during state 3 (coupled to ATP synthesis) and state 4 (noncoupled respiration), with fatty acids alone [palmitoyl carnitine (PC)] or together with pyruvate (Pyr). Electron transport chain activity was measured with NADH in permeabilized mitochondria. State 3 respiration with PC increased Post-Ex by 39 and 41% ( P < 0.05) when related to mitochondrial protein and to electron transport chain activity, respectively. State 3 respiration with Pyr was not changed ( P > 0.05). State 4 respiration with PC increased Post-Ex but was lower than Pre-Ex at Rec ( P < 0.05 vs. Pre-Ex). Mitochondrial efficiency [amount of added ADP divided by oxygen consumed during state 3 (P/O ratio)] decreased Post-Ex by 9 and 6% ( P < 0.05) with PC and PC + Pyr, respectively. P/O ratio remained reduced at Rec. Muscle uncoupling protein 3, measured with Western blotting, was not changed Post-Ex but tended to decrease at Rec ( P = 0.07 vs. Pre-Ex). In conclusion, extreme endurance exercise decreases mitochondrial efficiency. This will increase oxygen demand and may partly explain the observed elevation in whole body oxygen consumption during standardized exercise (+13%). The increased mitochondrial capacity for PC oxidation indicates plasticity in substrate oxidation at the mitochondrial level, which may be of advantage during prolonged exercise.
Mitochondrial Transporters as Novel Targets for Intracellular Calcium Signaling
Authors: Satrústegui Jorgina , Pardo Beatriz , del Arco Araceli
Published: January 2007

Ca2+signaling in mitochondria is important to tune mitochondrial function to a variety of extracellular stimuli. The main mechanism is Ca2+entry in mitochondria via the Ca2+uniporter followed by Ca2+activation of three dehydrogenases in the mitochondrial matrix. This results in increases in mitochondrial NADH/NAD ratios and ATP levels and increased substrate uptake by mitochondria. We review evidence gathered more than 20 years ago and recent work indicating that substrate uptake, mitochondrial NADH/NAD ratios, and ATP levels may be also activated in response to cytosolic Ca2+signals via a mechanism that does not require the entry of Ca2+in mitochondria, a mechanism depending on the activity of Ca2+-dependent mitochondrial carriers (CaMC). CaMCs fall into two groups, the aspartate-glutamate carriers (AGC) and the ATP-Mg/Picarriers, also named SCaMC (for short CaMC). The two mammalian AGCs, aralar and citrin, are members of the malate-aspartate NADH shuttle, and citrin, the liver AGC, is also a member of the urea cycle. Both types of CaMCs are activated by Ca2+in the intermembrane space and function together with the Ca2+uniporter in decoding the Ca2+signal into a mitochondrial response.
Matrix Metalloproteinases in Lung: Multiple, Multifarious, and Multifaceted
Authors: Greenlee Kendra J. , Werb Zena , Kheradmand Farrah
Published: January 2007

The matrix metalloproteinases (MMPs), a family of 25 secreted and cell surface-bound neutral proteinases, process a large array of extracellular and cell surface proteins under normal and pathological conditions. MMPs play critical roles in lung organogenesis, but their expression, for the most part, is downregulated after generation of the alveoli. Our knowledge about the resurgence of the MMPs that occurs in most inflammatory diseases of the lung is rapidly expanding. Although not all members of the MMP family are found within the lung tissue, many are upregulated during the acute and chronic phases of these diseases. Furthermore, potential MMP targets in the lung include all structural proteins in the extracellular matrix (ECM), cell adhesion molecules, growth factors, cytokines, and chemokines. However, what is less known is the role of MMP proteolysis in modulating the function of these substrates in vivo. Because of their multiplicity and substantial substrate overlap, MMPs are thought to have redundant functions. However, as we explore in this review, such redundancy most likely evolved as a necessary compensatory mechanism given the critical regulatory importance of MMPs. While inhibition of MMPs has been proposed as a therapeutic option in a variety of inflammatory lung conditions, a complete understanding of the biology of these complex enzymes is needed before we can reasonably consider them as therapeutic targets.
Preclinical evaluation of 213Bi-labeled plasminogen activator inhibitor type 2 in an orthotopic murine xenogenic model of human breast carcinoma
Authors: Stutchbury Tamantha K. , Al-ejeh Fares , Stillfried Gillian E. , Croucher David R. , Andrews John , Irving David , Links Matthew , Ranson Marie
Published: January 2007

Tumor-associated urokinase plasminogen activator (uPA) is a critical marker of invasion and metastasis, has strong prognostic relevance, and is thus a potential therapeutic target. Experimental data published to date has established the proof-of-principle of uPA targeting by 213Bi-labeled plasminogen activator inhibitor type 2 (α-PAI-2) in multiple carcinoma models. Here, we present preclinical toxicologic and efficacy assessment of α-PAI-2 in mice, using both single and multiple-dose schedules, administered by an i.p. route. We also present novel data showing that human PAI-2 inhibited murine uPA and was specifically endocytosed by murine fibroblast cells. This diminishes potential problems associated with species specificity of the targeting reagent in toxicologic assessments as human α-PAI-2 should interact with any uPA-expressing host cells. In this model, single bolus doses up to 36 mCi/kg α-PAI-2 did not reach the maximum tolerated dose (MTD). The MTD for a multiple fractionated (once daily for 5 days) administration schedule was determined to lie between 4.8 and 6.0 mCi/kg/d × 5. Comparison of the tumor growth rates and survival using sub-MTD single and multiple-dose schedules in an orthotopic human breast carcinoma xenograft murine model indicated that 4.8 mCi/kg/d × 5 was the most efficacious schedule. In conclusion, we have determined a safe dose and schedule of α-PAI-2 administration in mice, thus confirming that it is an efficacious therapeutic modality against tumor growth. This will allow detailed safety evaluation in a second species and for the initiation of human studies. [Mol Cancer Ther 2007;6(1):203–11]
A phase I trial of hyperthermia-induced interleukin-12 gene therapy in spontaneously arising feline soft tissue sarcomas
Authors: Siddiqui Farzan , Li Chuan-Yuan , LaRue Susan M. , Poulson Jean M. , Avery Paul R. , Pruitt Amy F. , Zhang Xiuwu , Ullrich Robert L. , Thrall Donald E. , Dewhirst Mark W. , Hauck Marlene L.
Published: January 2007

Interleukin-12 (IL-12), a proinflammatory cytokine, shows anticancer properties. Systemically administered IL-12 causes dose-dependent toxicity. To achieve localized intratumoral gene expression, an adenoviral gene therapy vector with IL-12 controlled by a heat-inducible promoter (heat shock promoter 70B) was developed and tested in a phase I clinical trial in cats with spontaneously arising soft tissue sarcoma. A feasibility study was done in 16 cats with soft tissue sarcoma using murine IL-12 and/or enhanced green fluorescent protein adenoviral vectors under cytomegalovirus or heat shock promoter 70 control. Subsequently, we conducted a phase I clinical trial using an adenoviral feline IL-12 construct in 13 cats with soft tissue sarcoma. The soft tissue sarcomas were irradiated (48 Gy/16 fractions) followed by intratumoral injection of adenovirus. Twenty-four hours postinjection, tumors were heated (41°C, 60 min). Tumor expression of feline IL-12 and IFN-γ was determined. Cats were monitored for systemic toxicity. For the murine IL-12 construct, an association was noted between viral dose and murine IL-12 levels within tumor, whereas serum levels were minimal. Mild toxicity was noted at 1011 plaque-forming units (pfu). With the feline IL-12 construct, high levels of feline IL-12 mRNA were detected in tumor biopsies with low or absent IFN-γ mRNA following gene therapy. Hematologic and hepatic toxicities were noted at the highest viral doses and were associated with detection of IFN-γ mRNA in tumor. It is possible to localize gene expression and limit systemic toxicity of IL-12 using the hyperthermia-induced gene therapy approach. The maximum tolerated dose of the feline IL-12 adenoviral vector was 1010 pfu/tumor as dose-limiting toxicities were noted at the 4 × 1010 pfu dose. [Mol Cancer Ther 2007;6(1):380–9]
The human IgM antibody SAM-6 induces tumor-specific apoptosis with oxidized low-density lipoprotein
Authors: Brändlein Stephanie , Rauschert Nicole , Rasche Leo , Dreykluft Angela , Hensel Frank , Conzelmann Ernst , Müller-Hermelink Hans-Konrad , Vollmers H. Peter
Published: January 2007

Lipids are essential for normal and malignant cells during growth and differentiation. The turnover is strictly regulated because an uncontrolled uptake and accumulation is cytotoxic and can lead to lipoapoptosis: lipoptosis. The human monoclonal antibody SAM-6 binds to a cell surface receptor on malignant cells and to oxidized low-density lipoprotein (LDL). SAM-6 induces an excess of intracellular lipids, by overfeeding malignant cells with oxidized LDL, via a receptor-mediated endocytosis. The treated cells overaccumulate depots of cholesteryl esters and triglycerides. This lipid overaccumulation is tumor specific; nonmalignant cells neither bind the antibody nor harvest lipids after incubation. Because for both forms of apoptosis, the death domain dependent (“extrinsic”) and independent (“intrinsic”), the activation of proteases is crucial, we also investigated this pathway in more detail. It was found that shortly after internalization of antibody/oxidized LDL/receptor complex and formation of lipid depots, cytochrome c is released by mitochondria. Followed by this, initiator caspase-8 and caspase-9 and effector caspase-3 and caspase-6 are activated. The mechanism of mitochondrial trigger (e.g., by free fatty acids) is under investigation. However, the present data indicate that the SAM-6 antibody induces an intrinsic-like form of apoptosis by overfeeding malignant cells with lipoproteins. [Mol Cancer Ther 2007;6(1):326–33]
Eupalmerin acetate, a novel anticancer agent from Caribbean gorgonian octocorals, induces apoptosis in malignant glioma cells via the c-Jun NH2-terminal kinase pathway
Authors: Iwamaru Arifumi , Iwado Eiji , Kondo Seiji , Newman Robert A. , Vera Burnilda , Rodríguez Abimael D. , Kondo Yasuko
Published: January 2007

The marine ecosystem is a vast but largely untapped resource for potential naturally based medicines. We tested 15 compounds derived from organisms found in the Caribbean Sea (14 gorgonian octocoral–derived compounds and one sponge-derived compound) for their anticancer effects on human malignant glioma U87-MG and U373-MG cells. Eupalmerin acetate (EPA) was chosen as the lead compound based on its longer-term stability and greater cytotoxicity than those of the other compounds we tested in these cell types. EPA induced G2-M cell cycle arrest and apoptosis via the mitochondrial pathway; it translocated Bax from the cytoplasm to the mitochondria and dissipated the mitochondrial transmembrane potential in both cell types. EPA was found to increase phosphorylated c-Jun NH2-terminal kinase (JNK) by >50% in both U87-MG and U373-MG cells. A specific JNK inhibitor, SP600125, inhibited EPA-induced apoptosis, confirming the involvement of the JNK pathway in EPA-induced apoptotic cell death. Furthermore, 7 days of daily intratumoral injections of EPA significantly suppressed the growth of s.c. malignant glioma xenografts (P < 0.01, on day 19). These results indicate that EPA is therapeutically effective against malignant glioma cells in vitro and in vivo and that it, or a similar marine-based compound, may hold promise as a clinical anticancer agent. [Mol Cancer Ther 2007;6(1):184–92]
MRP8/ABCC11 directly confers resistance to 5-fluorouracil
Authors: Oguri Tetsuya , Bessho Yuji , Achiwa Hiroyuki , Ozasa Hiroaki , Maeno Ken , Maeda Hiroyoshi , Sato Shigeki , Ueda Ryuzo
Published: January 2007

Multidrug-resistance–associated protein, MRP8/ABCC11 (ABCC11), is an efflux pump for nucleotide analogues and 5-fluoro-2′-deoxyuridine 5′-monophosphate (FdUMP). To test whether ABCC11 directly confers 5-fluorouracil (5-FU) resistance, we used the 5-FU–resistant subline PC-6/FU23-26 selected from PC-6 human small-cell lung cancer cells by 5-FU and found that it increases the resistance by ∼25-fold. The intracellular FdUMP accumulation was reduced in PC-6/FU23-26 cells concomitant with the overexpression of the ABCC11 gene. These findings suggest that ABCC11 confers 5-FU resistance in the sublines by enhancing the efflux for the active metabolite FdUMP. Previously, methotrexate also increased the efflux by ABCC11, and we found cross-resistance to methotrexate in PC-6/FU23-26 cells. To confirm our hypothesis, we examined whether decreasing the expression of ABCC11 in PC-6/FU23-26 cells by small interfering RNA altered the cytotoxicity to 5-FU and methotrexate and found that this enhanced 5-FU and methotrexate cytotoxicity in PC-6/FU23-26 cells. These data indicate that expression of the ABCC11 gene is induced by 5-FU, and that ABCC11 is directly involved in 5-FU resistance by the efflux transport of the active metabolite FdUMP. [Mol Cancer Ther 2007;6(1):122–7]
The JAMM motif of human deubiquitinase Poh1 is essential for cell viability
Authors: Gallery Melissa , Blank Jonathan L. , Lin Yinghui , Gutierrez Juan A. , Pulido Jacqueline C. , Rappoli David , Badola Sunita , Rolfe Mark , MacBeth Kyle J.
Published: January 2007

Poh1 deubiquitinase activity is required for proteolytic processing of polyubiquitinated substrates by the 26S proteasome, linking deubiquitination to complete substrate degradation. Poh1 RNA interference (RNAi) in HeLa cells resulted in a reduction in cell viability and an increase in polyubiquitinated protein levels, supporting the link between Poh1 and the ubiquitin proteasome pathway. To more specifically test for any requirement of the zinc metalloproteinase motif of Poh1 to support cell viability and proteasome function, we developed a RNAi complementation strategy. Effects on cell viability and proteasome activity were assessed in cells with RNAi of endogenous Poh1 and induced expression of wild-type Poh1 or a mutant form of Poh1, in which two conserved histidines of the proposed catalytic site were replaced with alanines. We show that an intact zinc metalloproteinase motif is essential for cell viability and 26S proteasome function. As a required enzymatic component of the proteasome, Poh1 is an intriguing therapeutic drug target for cancer. [Mol Cancer Ther 2007;6(1):262–8]
Survivin depletion preferentially reduces the survival of activated K-Ras-transformed cells
Authors: Sarthy Aparna V. , Morgan-Lappe Susan E. , Zakula Dorothy , Vernetti Lawrence , Schurdak Mark , Packer Jeremy C.L. , Anderson Mark G. , Shirasawa Senji , Sasazuki Takehiko , Fesik Stephen W.
Published: January 2007

To identify cancer-specific targets, we have conducted a synthetic lethal screen using a small interfering RNA (siRNA) library targeting ∼4,000 individual genes for enhanced killing in the DLD-1 colon carcinoma cell line that expresses an activated copy of the K-Ras oncogene. We found that siRNAs targeting baculoviral inhibitor of apoptosis repeat-containing 5 (survivin) significantly reduced the survival of activated K-Ras-transformed cells compared with its normal isogenic counterpart in which the mutant K-Ras gene had been disrupted (DKS-8). In addition, survivin siRNA induced a transient G2-M arrest and marked polyploidy that was associated with increased caspase-3 activation in the activated K-Ras cells. These results indicate that tumors expressing the activated K-Ras oncogene may be particularly sensitive to inhibitors of the survivin protein. [Mol Cancer Ther 2007;6(1):269–76]