bluuebunny/crossref_metadata_2025 huggingface dataset:
Incorporating Neural Network Material Models Within Finite Element Analysis for Rheological Behavior Prediction
Authors: Kessler B. Scott , El-Gizawy A. Sherif , Smith Douglas E.
Published: February 2007

The accuracy of a finite element model for design and analysis of a metal forging operation is limited by the incorporated material model’s ability to predict deformation behavior over a wide range of operating conditions. Current rheological models prove deficient in several respects due to the difficulty in establishing complicated relations between many parameters. More recently, artificial neural networks (ANN) have been suggested as an effective means to overcome these difficulties. To this end, a robust ANN with the ability to determine flow stresses based on strain, strain rate, and temperature is developed and linked with finite element code. Comparisons of this novel method with conventional means are carried out to demonstrate the advantages of this approach.
Asset Management Evaluation: A Pilot Case Study
Authors: Bauby C. E. , Charbonnier B. , Haik P. , Lacombe S. , Lonchampt J. , Remy E.
Published: February 2007

The long term management of a production asset raises several major issues, among which rank the technical management of the plant, its economics, and the fleet level perspective one has to adopt. Decision makers are therefore faced with the need to define long term policies (up to the end of asset operation) that take into account multiple criteria including safety (which is paramount) and performance. In this paper we first remind the reader of the EDF three-level methodology for asset management. As introduced in PVP 2003 and PVP 2004, this methodology addresses the component/technical level (how to safely operate daily and invest for the future), the plant level (how to translate technical decisions into plant-wide consequences including economic performance), and the fleet level (how to manage a large number of similar assets). We then focus on the software tool that implements this methodology in order to allow decision makers to define, evaluate, and analyze long term plant operation and maintenance policies. Lastly we show how the methodology and the software tool were used on a pilot case study. The technical and economic results obtained at the plant level are described as well as the conclusions one can draw from them in order to help decision makers evaluate and analyze long term asset management strategies.
A Single Technically Consistent Design Formula for the Thickness of Cylindrical Sections Under Internal Pressure
Authors: Fishburn John D.
Published: February 2007

Within the current design codes for boilers, piping, and pressure vessels, there are many different equations for the thickness of a cylindrical section under internal pressure. A reassessment of these various formulations, using the original data, is described together with more recent developments in the state of the art. A single formula, which can be demonstrated to retain the same design margin in both the time-dependent and time-independent regimes, is shown to give the best correlation with the experimental data and is proposed for consideration for inclusion in the design codes.
Selecting Suitable Probes Distances for Sizing Deep Surface Cracks Using the DCPD Technique
Authors: Takeo Fumio , Saka Masumi , Ahmed S. Reaz , Hamada Seiichi , Hayakawa Manabu
Published: February 2007

In this study, the way to enhance the sensitivity of evaluating deep surface cracks by DCPD technique using four probes is considered. The potential drops across two-dimensional cracks having different depths are analyzed by the three-dimensional finite-element method. The effect of the distance between current input and output probes and the distance between measuring probes on the change in potential drops are analyzed for a wide range of crack depths. By extending the distance between current input and output probes, the change in potential drop with the change in the depth of deeper crack becomes large. But the voltage of potential drop becomes small to measure. Finally, the way to select the appropriate distances between the probes for the measuring sensor is shown from the viewpoints of sensitivity and the required current.
Targeting of Diacylglycerol Degradation to M1 Muscarinic Receptors by ß-Arrestins
Authors: Nelson Christopher D. , Perry Stephen J. , Regier Debra S. , Prescott Stephen M. , Topham Matthew K. , Lefkowitz Robert J.
Published: February 2007

Seven-transmembrane receptor (7TMR) signaling is transduced by second messengers such as diacylglycerol (DAG) generated in response to the heterotrimeric guanine nucleotide–binding protein G
q
and is terminated by receptor desensitization and degradation of the second messengers. We show that β-arrestins coordinate both processes for the G
q
-coupled M1 muscarinic receptor. β-Arrestins physically interact with diacylglycerol kinases (DGKs), enzymes that degrade DAG. Moreover, β-arrestins are essential for conversion of DAG to phosphatidic acid after agonist stimulation, and this activity requires recruitment of the β-arrestin–DGK complex to activated 7TMRs. The dual function of β-arrestins, limiting production of diacylglycerol (by receptor desensitization) while enhancing its rate of degradation, is analogous to their ability to recruit adenosine 3′,5′-monophosphate phosphodiesterases to G
s
-coupled β
2
-adrenergic receptors. Thus, β-arrestins can serve similar regulatory functions for disparate classes of 7TMRs through structurally dissimilar enzymes that degrade chemically distinct second messengers.
Regulation of
Drosophila
Life Span by Olfaction and Food-Derived Odors
Authors: Libert Sergiy , Zwiener Jessica , Chu Xiaowen , VanVoorhies Wayne , Roman Gregg , Pletcher Scott D.
Published: February 2007

Smell is an ancient sensory system present in organisms from bacteria to humans. In the nematode
Caeonorhabditis elegans
, gustatory and olfactory neurons regulate aging and longevity. Using the fruit fly,
Drosophila melanogaster
, we showed that exposure to nutrient-derived odorants can modulate life span and partially reverse the longevity-extending effects of dietary restriction. Furthermore, mutation of odorant receptor
Or83b
resulted in severe olfactory defects, altered adult metabolism, enhanced stress resistance, and extended life span. Our findings indicate that olfaction affects adult physiology and aging in
Drosophila
, possibly through the perceived availability of nutritional resources, and that olfactory regulation of life span is evolutionarily conserved.
Response to Comment on "Rapid Advance of Spring Arrival Dates in Long-Distance Migratory Birds"
Authors: Jonzén Niclas , Lindén Andreas , Ergon Torbjørn , Knudsen Endre , Vik Jon Olav , Rubolini Diego , Piacentini Dario , Brinch Christian , Spina Fernando , Karlsson Lennart , Stervander Martin , Andersson Arne , Waldenström Jonas , Lehikoinen Aleksi , Edvardsen Erik , Solvang Rune , Stenseth Nils Chr.
Published: February 2007

Both's comment questions our suggestion that the advanced spring arrival time of long-distance migratory birds in Scandinavia and the Mediterranean may reflect a climate-driven evolutionary change. We present additional arguments to support our hypothesis but underscore the importance of additional studies involving direct tests of evolutionary change.
C-Terminal WxL Domain Mediates Cell Wall Binding in
Enterococcus faecalis
and Other Gram-Positive Bacteria
Authors: Brinster Sophie , Furlan Sylviane , Serror Pascale
Published: February 2007

Analysis of the genome sequence of
Enterococcus faecalis
clinical isolate V583 revealed novel genes encoding surface proteins. Twenty-seven of these proteins, annotated as having unknown functions, possess a putative N-terminal signal peptide and a conserved C-terminal region characterized by a novel conserved domain designated WxL. Proteins having similar characteristics were also detected in other low-G+C-content gram-positive bacteria. We hypothesized that the WxL region might be a determinant of bacterial cell location. This hypothesis was tested by generating protein fusions between the C-terminal regions of two WxL proteins in
E. faecalis
and a nuclease reporter protein. We demonstrated that the C-terminal regions of both proteins conferred a cell surface localization to the reporter fusions in
E. faecalis
. This localization was eliminated by introducing specific deletions into the domains. Interestingly, exogenously added protein fusions displayed binding to whole cells of various gram-positive bacteria. We also showed that the peptidoglycan was a binding ligand for WxL domain attachment to the cell surface and that neither proteins nor carbohydrates were necessary for binding. Based on our findings, we propose that the WxL region is a novel cell wall binding domain in
E. faecalis
and other gram-positive bacteria.
Population Genetics and Linkage Analysis of Loci within the FCT Region ofStreptococcus pyogenes
Authors: Kratovac Zerina , Manoharan Anand , Luo Feng , Lizano Sergio , Bessen Debra E.
Published: February 2007

The FCT regions ofStreptococcus pyogenesstrains encode a variety of cell wall-anchored surface proteins that bind the extracellular matrix of the human host and/or give rise to pilus-like appendages. Strong linkage is evident between transcription-regulatory loci positioned within the FCT andemmregions and theemmpattern genotype marker for preferred infection of the throat or skin. These findings provide a basis for the hypothesis that FCT region gene products contribute to tissue-specific infection. In an initial series of steps to address this possibility, the FCT regions of 13 strains underwent comparative sequence analysis, the gene content of the FCT region was characterized for 113 strains via PCR, and genetic linkage was assessed. A history of extensive recombination within FCT regions was evident. Theemmpattern D-defined skin specialist strains were highly homogenous in their FCT region gene contents, whereas theemmpattern A-C-defined throat specialist strains displayed a greater variety of forms. Most pattern A-C strains harboredprtF1(75%) but lackedcpa(75%). In contrast, the majority ofemmpattern D strains hadcpa(92%) but lackedprtF1(79%). Models based on FCT andemmregion genotypes revealed the most parsimonious pathways of evolution. Using niche-determining candidate genes to infer phylogeny,emmpattern E strains—the so-called generalists, which lack a strong tissue site preference—occupied a transition zone separating most throat specialists from skin specialists. Overall, population genetic analysis supports the possibility that the FCT region gives rise to surface proteins that are largely necessary, but not always sufficient, to confer tissue site preference for infection.
Systematic Survey of Nonspecific Agglutination by
Candida
spp. in Latex Assays
Authors: Becker Karsten , Almasri Ahmed S. , von Eiff Christof , Peters Georg , Heilmann Christine , Fegeler Wolfgang
Published: February 2007

In order to demonstrate that cells of
Candida
spp. may show considerable nonspecific agglutination in latex agglutination tests, 150 clinical and reference isolates of 12 yeast species were systematically studied by applying various test parameters. In fact, 40 (26.7%) of these isolates revealed nonspecific results, significantly associated with the time allowed for agglutination.
Discovery of a New Capsular Serotype (6C) within Serogroup 6 ofStreptococcus pneumoniae
Authors: Park In Ho , Pritchard David G. , Cartee Rob , Brandao Angela , Brandileone Maria Cristina C. , Nahm Moon H.
Published: February 2007

Using two monoclonal antibodies, we found subtypes among pneumococcal isolates that are typed as serotype 6A by the quellung reaction. The prevalent subtype bound to both monoclonal antibodies and was labeled here 6Aα, whereas the minor subtype bound to only one monoclonal antibody and was labeled 6Aβ. To determine the biochemical nature of the two serologically defined subtypes, we purified capsular polysaccharides (PSs) from the two subtypes and examined their chemical structures with gas-liquid chromatography and mass spectrometry. The study results for 6Aα PS are consistent with the previously published structure of 6A PS, which is →2) galactose (1→3) glucose (1→3) rhamnose (1→3) ribitol (5→phosphate. In contrast, the 6Aβ PS study results show that its repeating unit is →2) glucose 1 (1→3) glucose 2 (1→3) rhamnose (1→3) ribitol (5→phosphate. We propose to continue referring to 6Aα as serotype 6A but to refer to 6Aβ as serotype 6C. Serotype 6C would thus represent the 91st pneumococcal serotype, with 90 pneumococcal serotypes having previously been recognized. This study also demonstrates that a new serotype may exist within an established and well-characterized serogroup or serotype.
Structures of a Human Papillomavirus (HPV) E6 Polypeptide Bound to MAGUK Proteins: Mechanisms of Targeting Tumor Suppressors by a High-Risk HPV Oncoprotein
Authors: Zhang Yi , Dasgupta Jhimli , Ma Runlin Z. , Banks Lawrence , Thomas Miranda , Chen Xiaojiang S.
Published: February 2007

Human papillomavirus (HPV) E6 oncoprotein targets certain tumor suppressors such as MAGI-1 and SAP97/hDlg for degradation. A short peptide at the C terminus of E6 interacts specifically with the PDZ domains of these tumor suppressors, which is a property unique to high-risk HPVs that are associated with cervical cancer. The detailed recognition mechanisms between HPV E6 and PDZ proteins are unclear. To understand the specific binding of cellular PDZ substrates by HPV E6, we have solved the crystal structures of the complexes containing a peptide from HPV18 E6 bound to three PDZ domains from MAGI-1 and SAP97/Dlg. The complex crystal structures reveal novel features of PDZ peptide recognition that explain why high-risk HPV E6 can specifically target these cellular tumor suppressors for destruction. Moreover, a new peptide-binding loop on these PDZs is identified as interacting with the E6 peptide. Furthermore, we have identified an arginine residue, unique to high-risk HPV E6 but outside the canonical core PDZ recognition motif, that plays an important role in the binding of the PDZs of both MAGI-I and SAP97/Dlg, the mutation of which abolishes E6's ability to degrade the two proteins. Finally, we have identified a dimer form of MAGI-1 PDZ domain 1 in the cocrystal structure with E6 peptide, which may have functional relevance for MAGI-1 activity. In addition to its novel insights into the biochemistry of PDZ interactions, this study is important for understanding HPV-induced oncogenesis; this could provide a basis for developing antiviral and anticancer compounds.
Inhibition of Hepatitis B Virus Polymerase by Entecavir
Authors: Langley David R. , Walsh Ann W. , Baldick Carl J. , Eggers Betsy J. , Rose Ronald E. , Levine Steven M. , Kapur A. Jayne , Colonno Richard J. , Tenney Daniel J.
Published: February 2007

Entecavir (ETV; Baraclude) is a novel deoxyguanosine analog with activity against hepatitis B virus (HBV). ETV differs from the other nucleoside/tide reverse transcriptase inhibitors approved for HBV therapy, lamivudine (LVD) and adefovir (ADV), in several ways: ETV is >100-fold more potent against HBV in culture and, at concentrations below 1 μM, displays no significant activity against human immunodeficiency virus (HIV). Additionally, while LVD and ADV are obligate DNA chain terminators, ETV halts HBV DNA elongation after incorporating a few additional bases. Three-dimensional homology models of the catalytic center of the HBV reverse transcriptase (RT)-DNA-deoxynucleoside triphosphate (dNTP) complex, based on the HIV RT-DNA structure, were used with in vitro enzyme kinetic studies to examine the mechanism of action of ETV against HBV RT. A novel hydrophobic pocket in the rear of the RT dNTP binding site that accommodates the exocyclic alkene moiety of ETV was predicted, establishing a basis for the superior potency observed experimentally. HBV DNA chain termination by ETV was accomplished through disfavored energy requirements as well as steric constraints during subsequent nucleotide addition. Validation of the model was accomplished through modeling of LVD resistance substitutions, which caused an eightfold decrease in ETV susceptibility and were predicted to reduce, but not eliminate, the ETV-binding pocket, in agreement with experimental observations. ADV resistance changes did not affect the ETV docking model, also agreeing with experimental results. Overall, these studies explain the potency, mechanism, and cross-resistance profile of ETV against HBV and account for the successful treatment of naive and LVD- or ADV-experienced chronic HBV patients.
CTCF-Dependent Chromatin Boundary Element between the Latency-Associated Transcript and ICP0 Promoters in the Herpes Simplex Virus Type 1 Genome
Authors: Chen Qi , Lin Lan , Smith Sheryl , Huang Jing , Berger Shelley L. , Zhou Jumin
Published: February 2007

Cells latently infected with herpes simplex virus (HSV) contain nucleosomal DNA similar to that of host cell chromatin. Recent studies have demonstrated that histones in the latency-associated transcript (LAT) promoter and intron regions contain histone modifications permissive for transcription. However, those histones associated with the lytic-specific
ICP0
gene, which lies only 5 kb away, contain modifications typical of silenced chromatin. How this active chromatin is kept separate from the repressed chromatin in the nearby
ICP0
region remains crucial to the understanding of the HSV lytic cycle. In this study, we show that the LAT intron region contains an insulator. Specifically, we show that an 800-bp region from the LAT intron can block enhancers in both tissue culture cells and
Drosophila melanogaster
embryos. Importantly, the 800-bp HSV insulator protects a LAT transgene from positional effects in
Drosophila
eye tissue. The 800-bp region contains nine copies of 16-bp repeats. In vitro electrophoretic mobility shift assay revealed that CTCF interacts with the CTCCC sequence within the repeats. In vivo chromatin immunoprecipitation assay demonstrated that CTCF interacts with these repeats in latently infected trigeminal ganglion neurons. The deletion of these repeats impaired insulator activity in human K562 cells and
Drosophila
embryos. Finally, double-spaced RNA knockdown of CTCF disrupts enhancer-blocking activity of the LAT insulator in transfected
Drosophila
S3 cells. These results strongly support the hypothesis that the 800-bp DNA in the LAT intron region works as a chromatin boundary during latency to separate active chromatin associated with the LAT promoter region from repressed chromatin in the ICP0 gene.
A Mutation in Alpha Helix 3 of CA Renders Human Immunodeficiency Virus Type 1 Cyclosporin A Resistant and Dependent: Rescue by a Second-Site Substitution in a Distal Region of CA
Authors: Yang Ruifeng , Aiken Christopher
Published: February 2007

The replication of many isolates of human immunodeficiency virus type 1 (HIV-1) is enhanced by binding of the host cell protein cyclophilin A (CypA) to the viral capsid protein (CA). The immunosuppressive drug cyclosporine A (CsA) and its nonimmunosuppressive analogs bind with high affinity to CypA and inhibit HIV-1 replication. Previous studies have identified two mutations, A92E and G94D, in the CypA-binding loop of CA that confer the ability of HIV-1 to replicate in the presence of CsA. Interestingly, CsA stimulates the replication of HIV-1 mutants containing either the A92E or G94D substitution in some human cell lines. Here, we show that substitution of alanine for threonine at position 54 of CA (T54A) also confers HIV-1 resistance to and dependence on CsA. Like the previously identified CsA-resistant/dependent mutants, infection by the T54A mutant was stimulated by CsA in a target cell-specific manner. RNA interference-mediated reduction of CypA expression enhanced the permissiveness of HeLa cells to infection by the T54A mutant. A suppressor mutation, encoding a substitution of threonine for alanine at position 105 of CA (A105T), was identified through adaptation of the T54A mutant virus for growth in CEM cells. A105T rescued the impaired single-cycle infectivity and replication defects of both T54A and A92E mutants. These results indicate that CA determinants outside the CypA-binding loop can modulate the dependence of HIV-1 infection on CypA.
Cubital tunnel syndrome
Authors: Cutts Steven
Published: February 2007

Cubital tunnel syndrome is the second most common peripheral nerve entrapment syndrome in the human body. It is the cause of considerable pain and disability for patients. When appropriately diagnosed, this condition may be treated by both conservative and operative means. In this review, the current thinking on this important and common condition is discussed The recent literature on cubital tunnel syndrome was reviewed, and key papers on upper limb and hand surgery were discussed with colleagues.
SENTENCE ALIGNMENT USING FEED FORWARD NEURAL NETWORK
Authors: FATTAH MOHAMED ABDEL , REN FUJI , KUROIWA SHINGO
Published: February 2007

Parallel corpora have become an essential resource for work in multi lingual natural language processing. However, sentence aligned parallel corpora are more efficient than non-aligned parallel corpora for cross language information retrieval and machine translation applications. In this paper, we present a new approach to align sentences in bilingual parallel corpora based on feed forward neural network classifier. A feature parameter vector is extracted from the text pair under consideration. This vector contains text features such as length, punctuate score, and cognate score values. A set of manually prepared training data has been assigned to train the feed forward neural network. Another set of data was used for testing. Using this new approach, we could achieve an error reduction of 60% over length based approach when applied on English–Arabic parallel documents. Moreover this new approach is valid for any language pair and it is quite flexible approach since the feature parameter vector may contain more/less or different features than that we used in our system such as lexical match feature.
ROBUST EXPONENTIAL STABILIZATION OF A CLASS OF DELAYED NEURAL NETWORKS WITH REACTION-DIFFUSION TERMS
Authors: LOU XUYANG , CUI BAOTONG
Published: February 2007

In this paper, the problem of global robust exponential stabilization for a class of neural networks with reaction-diffusion terms and time-varying delays which covers the Hopfield neural networks and cellular neural networks is investigated. A feedback control gain matrix is derived to achieve the global robust exponential stabilization of the neural networks by using the Lyapunov stability theory, and the stabilization condition can be verified if a certain Hamiltonian matrix with no eigenvalues on the imaginary axis. This condition can avoid solving an algebraic Riccati equation. Finally, a numerical simulation illustrates the effectiveness of the results.
BIOLOGICAL SYSTEMS ANALYSIS BY A NETWORK PROTEOMICS APPROACH AND SUBCELLULAR PROTEIN PROFILING
Authors: FORST CHRISTIAN V. , CABUSORA LAWRENCE , MAWUENYEGA KWASI G. , CHEN XIAN
Published: February 2007

We provide a systematic analysis of a biological system, the microbial pathogen Mycobacterium tuberculosis (Mtb) by directly profiling its gene products. This analysis combines high-throughput proteomics and biocomputational approaches to elucidate the globally expressed complements of the three subcellular compartments (the cell wall, membrane and cytosol) of Mtb. We report the compartmentalization of 1,044 identified proteins using proteomics methods. Genome-based biological network analyses were performed and integrated with proteomics data to reconstruct response networks. From the reconstructed response networks for fatty acid degradation and lipid biosynthesis pathways in Mtb, we identified proteins whose involvements in these pathways were not previously suspected. Furthermore, the subcellular localizations of these expressed proteins provide interesting insights into the compartmentalization of these pathways, which appear to traverse from cell wall to cytoplasm. Results of this large-scale subcellular proteome profile of Mtb have confirmed and validated the computational network hypothesis that functionally related proteins work together in larger organizational structures.
Ca2+mobilization through dorsal root ganglion Ca2+-sensing receptor stably expressed in HEK293 cells
Authors: Awumey Emmanuel M. , Howlett Allyn C. , Putney James W. , Diz Debra I. , Bukoski Richard D.
Published: February 2007

The rat dorsal root ganglion (DRG) Ca2+-sensing receptor (CaR) was stably expressed in-frame as an enhanced green fluorescent protein (EGFP) fusion protein in human embryonic kidney (HEK)293 cells, and is functionally linked to changes in intracellular Ca2+concentration ([Ca2+]i). RT-PCR analysis indicated the presence of the message for the DRG CaR cDNA. Western blot analysis of membrane proteins showed a doublet of 168–175 and 185 kDa, consistent with immature and mature forms of the CaR.EGFP fusion protein, respectively. Increasing extracellular [Ca2+] ([Ca2+]e) from 0.5 to 1 mM resulted in increases in [Ca2+]ilevels, which were blocked by 30 μM 2-aminoethyldiphenyl borate. [Ca2+]e-response studies indicate a Ca2+sensitivity with an EC50of 1.75 ± 0.10 mM. NPS R-467 and Gd3+activated the CaR. When [Ca2+]ewas successively raised from 0.25 to 4 mM, peak [Ca2+]i, attained with 0.5 mM, was reduced by ∼50%. Similar reductions were observed with repeated applications of 10 mM Ca2+, 1 and 10 μM NPS R-467, or 50 and 100 μM Gd3+, indicating desensitization of the response. Furthermore, Ca2+mobilization increased phosphorylated protein kinase C (PKC)α levels in the cells. However, the PKC activator, phorbol myristate acetate did not inhibit CaR-mediated Ca2+signaling. Rather, a spectrum of PKC inhibitors partially reduced peak responses to Cae2+. Treatment of cells with 100 nM PMA for 24 h, to downregulate PKC, reduced [Ca2+]itransients by 49.9 ± 5.2% (at 1 mM Ca2+) and 40.5 ± 6.5% (at 2 mM Ca2+), compared with controls. The findings suggest involvement of PKC in the pathway for Ca2+mobilization following CaR activation.
Function of Kv1.5 channels and genetic variations ofKCNA5in patients with idiopathic pulmonary arterial hypertension
Authors: Remillard Carmelle V. , Tigno Donna D. , Platoshyn Oleksandr , Burg Elyssa D. , Brevnova Elena E. , Conger Diane , Nicholson Ann , Rana Brinda K. , Channick Richard N. , Rubin Lewis J. , O'Connor Daniel T. , Yuan Jason X.-J.
Published: February 2007

The pore-forming α-subunit, Kv1.5, forms functional voltage-gated K+(Kv) channels in human pulmonary artery smooth muscle cells (PASMC) and plays an important role in regulating membrane potential, vascular tone, and PASMC proliferation and apoptosis. Inhibited Kv channel expression and function have been implicated in PASMC from patients with idiopathic pulmonary arterial hypertension (IPAH). Here, we report that overexpression of the Kv1.5 channel gene ( KCNA5) in human PASMC and other cell lines produced a 15-pS single channel current and a large whole cell current that was sensitive to 4-aminopyridine. Extracellular application of nicotine, bepridil, correolide, and endothelin-1 (ET-1) all significantly and reversibly reduced the Kv1.5 currents, while nicotine and bepridil also accelerated the inactivation kinetics of the currents. Furthermore, we sequenced KCNA5 from IPAH patients and identified 17 single-nucleotide polymorphisms (SNPs); 7 are novel SNPs. There are 12 SNPs in the upstream 5′ region, 2 of which may alter transcription factor binding sites in the promoter, 2 nonsynonymous SNPs in the coding region, 2 SNPs in the 3′-untranslated region, and 1 SNP in the 3′-flanking region. Two SNPs may correlate with the nitric oxide-mediated decrease in pulmonary arterial pressure. Allele frequency of two other SNPs in patients with a history of fenfluramine and phentermine use was significantly different from patients who have never taken the anorexigens. These results suggest that 1) Kv1.5 channels are modulated by various agonists (e.g., nicotine and ET-1); 2) novel SNPs in KCNA5 are present in IPAH patients; and 3) SNPs in the promoter and translated regions of KCNA5 may underlie the altered expression and/or function of Kv1.5 channels in PASMC from IPAH patients.
Chronic intermittent hypoxia alters Ca2+handling in rat cardiomyocytes by augmented Na+/Ca2+exchange and ryanodine receptor activities in ischemia-reperfusion
Authors: Yeung Hang Mee , Kravtsov Gennadi M. , Ng Kwong Man , Wong Tak Ming , Fung Man Lung
Published: February 2007

This study examined Ca2+handling mechanisms involved in cardioprotection induced by chronic intermittent hypoxia (CIH) against ischemia-reperfusion (I/R) injury. Adult male Sprague-Dawley rats were exposed to 10% inspired O2continuously for 6 h daily from 3, 7, and 14 days. In isolated perfused hearts subjected to I/R, CIH-induced cardioprotection was most significant in the 7-day group with less infarct size and lactate dehydrogenase release, compared with the normoxic group. The I/R-induced alterations in diastolic Ca2+level, amplitude, time-to-peak, and the decay time of both electrically and caffeine-induced Ca2+transients measured by spectrofluorometry in isolated ventricular myocytes of the 7-day CIH group were less than that of the normoxic group, suggesting an involvement of altered Ca2+handling of the sarcoplasmic reticulum (SR) and sarcolemma. We further determined the protein expression and activity of45Ca2+flux of SR-Ca2+-ATPase, ryanodine receptor (RyR) and sarcolemmal Na+/Ca2+exchange (NCX) in ventricular myocytes from the CIH and normoxic groups before and during I/R. There were no changes in expression levels of the Ca2+-handling proteins but significant increases in the RyR and NCX activities were remarkable during I/R in the CIH but not the normoxic group. The augmented RyR and NCX activities were abolished, respectively, by PKA inhibitor (0.5 μM KT5720 or 0.5 μM PKI14-22) and PKC inhibitor (5 μM chelerythrine chloride or 0.2 μM calphostin C) but not by Ca2+/calmodulin-dependent protein kinase II inhibitor KN-93 (1 μM). Thus, CIH confers cardioprotection against I/R injury in rat cardiomyocytes by altered Ca2+handling with augmented RyR and NCX activities via protein kinase activation.
Cloning and characterization of an electrogenic Na/HCO3− cotransporter from the squid giant fiber lobe
Authors: Piermarini Peter M. , Choi Inyeong , Boron Walter F.
Published: February 2007

The squid giant axon is a classic model system for understanding both excitable membranes and ion transport. To date, a Na+-driven Cl-HCO3− exchanger, sqNDCBE—related to the SLC4 superfamily and cloned from giant fiber lobe cDNA—is the only HCO3−-transporting protein cloned and characterized from a squid. The goal of our study was to clone and characterize another SLC4-like cDNA. We used degenerate PCR to obtain a partial cDNA clone (squid fiber clone 3, SF3), which we extended in both the 5′ and 3′ directions to obtain the full-length open-reading frame. The predicted amino-acid sequence of SF3 is similar to sqNDCBE, and a phylogenetic analysis of the membrane domains indicates that SF3 clusters with electroneutral Na+-coupled SLC4 transporters. However, when we measure pHi and membrane potential—or use two-electrode voltage clamping to measure currents—on Xenopus oocytes expressing SF3, the oocytes exhibit the characteristics of an electrogenic Na/HCO3− cotransporter, NBCe. That is, exposure to extracellular CO2/HCO3− not only causes a fall in pHi, followed by a robust recovery, but also causes a rapid hyperpolarization. The current-voltage relationship is also characteristic of an electrogenic NBC. The pHi recovery and current require HCO3− and Na+, and are blocked by DIDS. Furthermore, neither K+ nor Li+ can fully replace Na+ in supporting the pHi recovery. Extracellular Cl− is not necessary for the transporter to operate. Therefore, SF3 is an NBCe, representing the first NBCe characterized from an invertebrate.
cFLIPL prevents TRAIL-induced apoptosis of hepatocellular carcinoma cells by inhibiting the lysosomal pathway of apoptosis
Authors: Guicciardi Maria Eugenia , Bronk Steven F. , Werneburg Nathan W. , Gores Gregory J.
Published: February 2007

Sensitivity to TNF-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis and the lysosomal pathway of cell death are features of cancer cells. However, it is unknown if TRAIL cytotoxic signaling engages the lysosomal pathway of cell death. Our aim, therefore, was to ascertain if TRAIL killing involves lysosomal permeabilization. TRAIL-induced apoptosis of hepatocellular carcinoma cells (HuH-7, Hep3B) was associated with lysosomal permeabilization, as demonstrated by redistribution of the lysosomal protease cathepsin B into the cytosol. Pharmacological and short hairpin RNA-targeted inhibition of cathepsin B reduced apoptosis. Because cellular FLICE-inhibitory protein (cFLIP) inhibits TRAIL-induced cell death and is frequently overexpressed by human cancers, the ability of cFLIP to prevent lysosomal permeabilization during TRAIL treatment was examined. Enforced long-form cFLIP (cFLIPL) expression reduced release of cathepsin B from lysosomes and attenuated apoptosis. cFLIPL overexpression was also associated with robust p42/44 MAPK activation following exposure to TRAIL. In contrast, cFLIPL overexpression attenuated p38 MAPK activation and had no significant effect on JNK and NF-κB activation. Inhibition of p42/44 MAPK by PD98059 restored TRAIL-mediated lysosomal permeabilization and apoptosis in cFLIP-overexpressing cells. In conclusion, these results demonstrate that lysosomal permeabilization contributes to TRAIL-induced apoptosis of hepatocellular carcinoma cells and suggest that cFLIPL cytoprotection is, in part, due to p42/44 MAPK-dependent inhibition of lysosomal breakdown.
Sex differences in the respiratory response to hemorrhage in the conscious, New Zealand white rabbit
Authors: Strittmatter Rachel R. , Schadt James C.
Published: February 2007

In conscious animals, the response to hemorrhage is biphasic. During phase 1, arterial pressure is maintained. Phase 2 is characterized by profound hypotension. Despite allied roles, less is known about the integrated cardiovascular and respiratory response to blood loss in conscious animals. We evaluated cardiorespiratory changes during hemorrhage to test the hypotheses that 1) respiratory rate (RR) and blood gases do not change during phase 1; 2) RR increases during phase 2; and 3) RR and blood gas changes during hemorrhage are similar in males and females. We measured mean arterial pressure, RR, and blood gases during hemorrhage in 16 conscious, chronically prepared, male and female New Zealand white rabbits. We removed venous blood until mean arterial pressure was ≤40 mmHg. Sex did not affect mean arterial pressure, heart rate, PaO2, PaCO2, or pH during hemorrhage or the blood loss required to induce phase 2. PaCO2 decreased significantly from 37 ± 1 to 33 ± 1 and 29 ± 1 mmHg ( P < 0.001) during phase 1 and 2, respectively. Before hemorrhage, PaO2 was 87 ± 2 mmHg. PaO2 was unchanged in phase 1 (92 ± 2 mmHg) but increased in phase 2 (101 ± 2 mmHg; P < 0.001). Body temperature, PvCO2 (thoracic vena cava), and ventilation-perfusion mismatch (A-a gradient) were unchanged during phases 1 and 2. Neither sex increased RR during phase 1. While males doubled RR during phase 2, RR in females did not change ( P < 0.001). Thus, while PaCO2 decreases in phase 1 and phase 2, the decreases are achieved in different ways across the two phases and in the two sexes.
Uteroplacental insufficiency alters nephrogenesis and downregulates cyclooxygenase-2 expression in a model of IUGR with adult-onset hypertension
Authors: Baserga Mariana , Hale Merica A. , Wang Zheng Ming , Yu Xing , Callaway Christopher W. , McKnight Robert A. , Lane Robert H.
Published: February 2007

Clinical and animal studies indicate that intrauterine growth restriction (IUGR) following uteroplacental insufficiency (UPI) reduces nephron number and predisposes toward renal insufficiency early in life and increased risk of adult-onset hypertension. In this study, we hypothesized that the inducible enzyme cyclooxygenase-2 (COX-2), a pivotal protein in nephrogenesis, constitutes a mechanism through which UPI and subsequent glucocorticoid overexposure can decrease nephron number. We further hypothesized that UPI downregulates the key enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), which converts corticosterone to inert 11-dehydrocorticosterone, thereby protecting both the glucocorticoid receptor (GR) and the mineralocorticoid receptor (MR) from the actions of corticosterone. Following bilateral uterine ligation on the pregnant rat, UPI significantly decreased renal COX-2, 11β-HSD2, and GR mRNA and protein levels, but upregulated expression of MR at birth. At day 21 of life, 11β-HSD2, GR, and also MR mRNA and protein levels were downregulated. UPI did not affect blood pressures (BP) at day 21 of life but significantly increased systolic BP in both genders at day 140. We conclude that in our animal model, UPI decreases fetal COX-2 expression during a period of active nephrogenesis in the IUGR rat, which is also characterized by decreased nephron number and adult-onset hypertension.
Knockdown of V-ATPase subunit A (atp6v1a) impairs acid secretion and ion balance in zebrafish (Danio rerio)
Authors: Horng Jiun-Lin , Lin Li-Yih , Huang Chang-Jen , Katoh Fumi , Kaneko Toyoji , Hwang Pung-Pung
Published: February 2007

In the skin of zebrafish embryo, the vacuolar H+-ATPase (V-ATPase, H+pump) distributed mainly in the apical membrane of H+-pump-rich cells, which pump internal acid out of the embryo and function similarly to acid-secreting intercalated cells in mammalian kidney. In addition to acid excretion, the electrogenic H+efflux via the H+-ATPases in the gill apical membrane of freshwater fish was proposed to act as a driving force for Na+entry through the apical Na+channels. However, convincing molecular physiological evidence in vivo for this model is still lacking. In this study, we used morpholino-modified antisense oligonucleotides to knockdown the gene product of H+-ATPase subunit A ( atp6v1a) and examined the phenotype of the mutants. The H+-ATPase knockdown embryos revealed several abnormalities, including suppression of acid-secretion from skin, growth retardation, trunk deformation, and loss of internal Ca2+and Na+. This finding reveals the critical role of H+-ATPase in embryonic acid -secretion and ion balance, as well.
Muscle glycogen oxidation during prolonged exercise measured with oral [13C]glucose: comparison with changes in muscle glycogen content
Authors: Harvey C. R. , Frew R. , Massicotte D. , Péronnet F. , Rehrer N. J.
Published: February 2007

Plasma glucose and muscle glycogen oxidation during prolonged exercise [75-min at 48 and 76% maximal O2 uptake (V̇o2 max)] were measured in eight well-trained male subjects [V̇o2 max = 4.50 l/min (SD 0.63)] using a simplified tracer technique in which a small amount of glucose highly enriched in 13C was ingested: plasma glucose oxidation was computed from 13C/12C in plasma glucose (which was stable beginning at minute 30 and minute 15 during exercise at 48 and 76% V̇o2 max, respectively) and 13CO2 production, and muscle glycogen oxidation was estimated by subtracting plasma glucose oxidation from total carbohydrate oxidation. Consistent data from the literature suggest that this small dose of exogenous glucose does not modify muscle glycogen oxidation and has little effect, if any, on plasma glucose oxidation. The percent contributions of plasma glucose and muscle glycogen oxidation to the energy yield at 48% V̇o2 max [15.1% (SD 3.8) and 45.9% (SD 5.8)] and at 76% V̇o2 max [15.4% (SD 3.6) and 59.8% (SD 9.2)] were well in line with data previously reported for similar work loads and exercise durations using conventional tracer techniques. The significant reduction in glycogen concentration measured from pre- and postexercise vastus lateralis muscle biopsies paralleled muscle glycogen oxidation calculated using the tracer technique and was larger at 76% than at 48% V̇o2 max. However, the correlation coefficients between these two estimates of muscle glycogen utilization were not different from zero at each of the two work loads. The simplified tracer technique used in the present experiment appears to be a valid alternative approach to the traditional tracer techniques for computing plasma glucose and muscle glycogen oxidation during prolonged exercise.
Effects of activation pattern on nonisometric human skeletal muscle performance
Authors: Maladen Ryan D. , Perumal Ramu , Wexler Anthony S. , Binder-Macleod Stuart A.
Published: February 2007

During volitional muscle activation, motor units often fire with varying discharge patterns that include brief, high-frequency bursts of activity. These variations in the activation rate allow the central nervous system to precisely control the forces produced by the muscle. The present study explores how varying the instantaneous frequency of stimulation pulses within a train affects nonisometric muscle performance. The peak excursion produced in response to each stimulation train was considered as the primary measure of muscle performance. The results showed that at each frequency tested between 10 and 50 Hz, variable-frequency trains that took advantage of the catchlike property of skeletal muscle produced greater excursions than constant-frequency trains. In addition, variable-frequency trains that could achieve targeted trajectories with fewer pulses than constant-frequency trains were identified. These findings suggest that similar to voluntary muscle activation patterns, varying the instantaneous frequency within a train of pulses can be used to improve muscle performance during functional electrical stimulation.
Microchambers and macrochambers in heel pads: are they functionally different?
Authors: Hsu Chih-Chin , Tsai Wen-Chung , Wang Chung-Li , Pao Sun-Hua , Shau Yio-Wha , Chuan Yu-Shuan
Published: February 2007

The heel pad consists of a superficial microchamber layer and a deep macrochamber layer. This study highlights the different biomechanical behaviors between the microchamber and macrochamber layers using ultrasonography. The heel pad in each left foot of six healthy volunteers aged ∼25 yr old was measured with a device consisting of a 10-MHz linear-array ultrasound transducer and a load cell. The testing heels were loaded on the ultrasound transducer with a loading velocity of ∼0.5 cm/s and were withdrawn when the specified maximum stress (158 kPa) was reached. Unloaded tissue thickness, end-loaded thickness, deformation proportion, average deformation, and rebound rates and elastic modulus of the microchamber and macrochamber layers were assessed. The unloaded thickness of the microchamber layer was ∼30% of the macrochamber layer. The microchamber layer also had significantly less unloaded thickness, end-loaded thickness, mean deformation rate, mean rebound rate, and deformation proportion than the macrochamber layer. A significant difference between the unloaded and end-loaded thickness in the macrochamber layer was observed. The average soft tissue deformation rate was significantly different from the rebound rate in the microchamber layer. A similar trend was detected in the macrochamber layer. The elastic modulus of the microchamber layer was 450 kPa (SD 240), which was nearly 10 times of that in the macrochamber layer. In conclusion, ultrasound can identify the heterogeneous tissue properties of the heel pad. The macrochamber layer responds to loading with large deformation, and the microchamber layer has a high degree of tissue stiffness.
Climbing Fiber Discharge Regulates Cerebellar Functions by Controlling the Intrinsic Characteristics of Purkinje Cell Output
Authors: McKay Bruce E. , Engbers Jordan D. T. , Mehaffey W. Hamish , Gordon Grant R. J. , Molineux Michael L. , Bains Jaideep S. , Turner Ray W.
Published: February 2007

The contribution of Purkinje cells to cerebellar motor coordination and learning is determined in part by the chronic and acute effects of climbing fiber (CF) afferents. Whereas the chronic effects of CF discharge, such as the depression of conjunctive parallel fiber (PF) inputs, are well established, the acute cellular functions of CF discharge remain incompletely understood. In rat cerebellar slices, we show that CF discharge presented at physiological frequencies substantially modifies the frequency and pattern of Purkinje cell spike output in vitro. Repetitive CF discharge converts a spontaneous trimodal pattern of output characteristic of Purkinje cells in vitro to a more naturalistic nonbursting pattern consisting of spike trains interrupted by short CF-evoked pauses or longer pauses associated with state transitions. All effects of CF discharge could be reproduced in the presence of synaptic blockers by using current injections to simulate complex spike depolarizations, revealing that CF-evoked changes in Purkinje cell output can occur independently of network activation. Rather postsynaptic changes are sufficient to account for the CF-evoked block of trimodal activity and include at least the activation of Ca2+-dependent K+ channels. Furthermore by controlling the frequency of Purkinje cell spike output over three discrete firing levels, CF discharge modulates the gain of Purkinje cell responsiveness to PF inputs in vitro through postsynaptic mechanisms triggered by the complex spike depolarization. The ability for CF discharge to acutely modulate diverse aspects of Purkinje cell output provides important insights into the probable cellular factors contributing to motor disturbances following CF denervation.
Characterization of Torque-Related Activity in Primary Motor Cortex During a Multijoint Postural Task
Authors: Herter Troy M. , Kurtzer Isaac , Cabel D. William , Haunts Kirk A. , Scott Stephen H.
Published: February 2007

The present study examined neural activity in the shoulder/elbow region of primary motor cortex (M1) during a whole-limb postural task. By selectively imposing torques at the shoulder, elbow, or both joints we addressed how neurons represent changes in torque at a single joint, multiple joints, and their interrelation. We observed that similar proportions of neurons reflected changes in torque at the shoulder, elbow, and both joints and these neurons were highly intermingled across the cortical surface. Most torque-related neurons were reciprocally excited and inhibited (relative to their unloaded baseline activity) by opposing flexor and extensor torques at a single joint. Although coexcitation/coinhibition was occasionally observed at a single joint, it was rarely observed at both joints. A second analysis assessed the relationship between single-joint and multijoint activity. In contrast to our previous observations, we found that neither linear nor vector summation of single-joint activities could capture the breadth of neural responses to multijoint torques. Finally, we studied the neurons' directional tuning across all the torque conditions, i.e., in joint-torque space. Our population of M1 neurons exhibited a strong bimodal distribution of preferred-torque directions (PTDs) that was biased toward shoulder-extensor/elbow-flexor (whole-limb flexor) and shoulder-flexor/elbow-extensor (whole-limb extensor) torques. Notably, we recently observed a similar bimodal distribution of PTDs in a sample of proximal arm muscles. This observation illustrates the intimate relationship between M1 and the motor periphery.