bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vitro Activity of Tigecycline against Gram-Positive and Gram-Negative Pathogens as Evaluated by Broth Microdilution and Etest
Authors: Pillar Chris M. , Draghi Deborah C. , Dowzicky Michael J. , Sahm Daniel F.
Published: July 2008

The current surveillance establishes the activity profile of tigecycline against recent clinical U.S. isolates of target pathogens. Findings from a distributed surveillance that utilized Etest yielded a tigecycline activity profile that varied from that observed in a separate centralized broth microdilution (BMD) surveillance (D. C. Draghi et al., Poster D-0701, 46th Intersci. Conf. Antimicrob. Agents Chemother., San Francisco, CA). Differences were noted among
Acinetobacter
spp. and
Serratia marcescens
and, to a lesser extent, with
Streptococcus pyogenes
. To address whether these differences were due to discordance in testing methodology or to variations among the analyzed populations, isolates from the current surveillance were concurrently tested by BMD and Etest. In all, 1,800
Staphylococcus aureus
, 259
S. pyogenes
, 226
Streptococcus pneumoniae
, 93
Enterococcus faecalis
, 1,356
Enterobacteriaceae
, and 227
Acinetobacter baumannii
strains were evaluated. Tigecycline had potent activity by BMD, with >99.6% susceptibility (%S) observed for all pathogens with interpretive criteria, excluding
Enterobacter cloacae
(98.3% S) and
E. faecalis
(86.0% S), and MIC
90
s ranged from 0.03 μg/ml (
S. pyogenes
/
S. pneumoniae
) to 1 μg/ml (
Enterobacteriaceae
/
A. baumannii
). Similar profiles were observed by Etest, with the exception of
A. baumannii
, although for most evaluated pathogens Etest MICs trended one doubling-dilution higher than BMD MICs. Major or very major errors were infrequent, and a high degree of essential agreement was observed, excluding
A. baumannii, S. marcescens
, and
S. pneumoniae
, for which ≥4-fold differences in MICs were observed for 29, 27.1, and 34% of the isolates, respectively. Further analysis regarding the suitability of the tigecycline Etest for testing
S. marcescens, Acinetobacter
spp., and
S. pneumoniae
is warranted.
Salmonella
Infections in the Common Raccoon (
Procyon lotor
) in Western Pennsylvania
Authors: Compton Justin A. , Baney Jason A. , Donaldson Sarah C. , Houser Beth A. , San Julian Gary J. , Yahner Richard H. , Chmielecki Wayne , Reynolds Stanley , Jayarao Bhushan M.
Published: July 2008

Ten
Salmonella enterica
serotypes were isolated from fecal samples collected from anesthetized raccoons (
n
= 738) trapped in six Pennsylvania counties from 2003 to 2005. Comparison of raccoon pulsed-field gel electrophoresis (PFGE) pulse type data with the Pennsylvania Department of Health PFGE database revealed that the patterns of seven
Salmonella
serotypes matched those isolated from humans with salmonellosis.
Dermatitis Caused by
Neosartorya hiratsukae
Infection in a Hedgehog
Authors: Han Jae-Ik , Na Ki-Jeong
Published: July 2008

This case report describes the fungal dermatitis caused by
Neosartorya hiratsukae
infection in a household hedgehog confirmed by microscopic examination of conidiophores and DNA analyses including the internal transcribed spacer region, partial β-tubulin, and the calmodulin gene. It is the first report of a natural
N. hiratsukae
infection in animals.
Genetic Classification of Severe Early Childhood Caries by Use of Subtracted DNA Fragments from
Streptococcus mutans
Authors: Saxena Deepak , Caufield Page W. , Li Yihong , Brown Stuart , Song Jinmei , Norman Robert
Published: July 2008

Streptococcus mutans
is one of several members of the oral indigenous biota linked with severe early childhood caries (S-ECC). Because most humans harbor
S. mutans
, but not all manifest disease, it has been proposed that the strains of
S. mutans
associated with S-ECC are genetically distinct from those found in caries-free (CF) children. The objective of this study was to identify common DNA fragments from
S. mutans
present in S-ECC but not in CF children. Using suppressive subtractive hybridization, we found a number of DNA fragments (biomarkers) present in 88 to 95% of the S-ECC
S. mutans
strains but not in CF
S. mutans
strains. We then applied machine learning techniques including support vector machines and neural networks to identify the biomarkers with the most predictive power for disease status, achieving a 92% accurate classification of the strains as either S-ECC or CF associated. The presence of these gene fragments in 90 to 100% of the 26 S-ECC isolates tested suggested their possible functional role in the pathogenesis of
S. mutans
associated with dental caries.
Cost-Effectiveness of Detection of Intestinal Amebiasis by Using Serology and Specific-Amebic-Antigen Assays among Persons with or without Human Immunodeficiency Virus Infection
Authors: Chang Sui-Yuan , Sun Hsin-Yun , Ji Dar-Der , Lo Yi-Chun , Wu Cheng-Hsin , Wu Pei-Ying , Liu Wen-Chun , Hung Chien-Ching , Chang Shan-Chwen
Published: July 2008

Among 345 persons who underwent indirect hemagglutination (IHA) serological assays and assays of specific amebic antigens in their stool samples, 24 of 36 (66.7%) who were seropositive for
Entamoeba histolytica
had intestinal amebiasis as determined by antigen assays compared with 2 of 309 (0.2%) who were seronegative (odds ratio, 307; 95% confidence interval, 64.9 to 1,451). The estimated cost to detect a case of intestinal amebiasis by serology followed by antigen assays ($52) could be reduced by 74.3% and 69.9%, respectively, compared with the costs of the concurrent use of both assays ($202) and the antigen assays alone ($173). Our finding suggests that IHA assays followed by specific-amebic-antigen assays can be cost-effective in the diagnosis of intestinal amebiasis among persons with or without human immunodeficiency virus infection who are at risk for
E. histolytica
infection.
Performance of Three Commercial Viral Load Assays, Versant Human Immunodeficiency Virus Type 1 (HIV-1) RNA bDNA v3.0, Cobas AmpliPrep/Cobas TaqMan HIV-1, and NucliSens HIV-1 EasyQ v1.2, Testing HIV-1 Non-B Subtypes and Recombinant Variants
Authors: Holguín Africa , López Marisa , Molinero Mar , Soriano Vincent
Published: July 2008

Monitoring antiretroviral therapy requires that human immunodeficiency virus type 1 (HIV-1) viremia assays are applicable to all distinct variants. This study evaluates the performance of three commercial viral load assays—Versant HIV-1 RNA bDNA v3.0, Cobas AmpliPrep/Cobas TaqMan HIV-1, and NucliSens HIV-1 EasyQ v1.2—in testing 83 plasma specimens from patients carrying HIV-1 non-B subtypes and recombinants previously defined by phylogenetic analysis of the
pol
gene. All 28 specimens from patients under treatment presented viremia values below the detection limit with the three methods. In the remaining 55 specimens from naive individuals viremia could not be detected in 32.7, 20, and 14.6% using the NucliSens, Versant, or TaqMan tests, respectively, suggesting potential viral load underestimation of some samples by all techniques. Only 32 (58.2%) samples from naive subjects were quantified by the three methods; the NucliSens test provided the highest HIV RNA values (mean, 4.87 log copies/ml), and the Versant test provided the lowest (mean, 4.16 log copies/ml). Viremia differences of greater than 1 log were seen in 8 (14.5%) of 55 specimens, occurring in 10.9, 7.3, and 5.4%, respectively, of the specimens in comparisons of Versant versus NucliSens, Versant versus TaqMan, and TaqMan versus NucliSens. Differences greater than 0.5 log, considered significant for clinicians, occurred in 45.5, 27.3, and 29% when the same assays were compared. Some HIV-1 strains, such as subtype G and CRF02_AG, showed more discrepancies in distinct quantification methods than others. In summary, an adequate design of primers and probes is needed for optimal quantitation of plasma HIV-RNA in non-B subtypes. Our data emphasize the need to use the same method for monitoring patients on therapy and also the convenience of HIV-1 subtyping.
Human Immunodeficiency Virus Type 1 Nef Expression Prevents AP-2-Mediated Internalization of the Major Histocompatibility Complex Class II-Associated Invariant Chain
Authors: Toussaint Hélène , Gobert François-Xavier , Schindler Michael , Banning Carina , Kozik Patrycja , Jouve Mabel , Kirchhoff Frank , Benaroch Philippe
Published: July 2008

The lentiviral Nef protein has been studied extensively for its ability to induce the downregulation of several immunoreceptors on the surfaces of infected cells. However, Nef expression is unique in inducing highly effective upregulation of the major histocompatibility complex class II-associated chaperone invariant (Ii) chain complexes in different cell types. Under normal conditions, endocytosis of the Ii chain and other molecules, like the transferrin receptor and CD4, is rapid and AP-2 dependent. Human immunodeficiency virus type 1 (HIV-1) Nef expression strongly reduces the internalization of the Ii chain, enhances that of CD4, and does not modify transferrin uptake. The mutation of AP-2 binding motifs LL164 and DD174 in Nef leads to the inhibition of Ii chain upregulation. In AP-2-depleted cells, surface levels of the Ii chain are high and remain unmodified by Nef expression, further indicating that Nef regulates Ii chain internalization via the AP-2 pathway. Immunoprecipitation experiments revealed that the Ii chain can interact with Nef in a dileucine-dependent manner. Importantly, we have shown that Nef-induced CD4 downregulation and Ii chain upregulation are genetically distinguishable. We have identified natural
nef
alleles that have lost one of the two functions but not the other one. Moreover, we have characterized Nef mutant forms possessing a similar phenotype in the context of HIV-1 infection. Therefore, the Nef-induced accumulation of Ii chain complexes at the cell surface probably results from a complex mechanism leading to the impairment of AP-2-mediated endocytosis rather than from direct competition between Nef and the Ii chain for binding AP-2.
Viral Genome Methylation as an Epigenetic Defense against Geminiviruses
Authors: Raja Priya , Sanville Bradley C. , Buchmann R. Cody , Bisaro David M.
Published: July 2008

Geminiviruses encapsidate single-stranded DNA genomes that replicate in plant cell nuclei through double-stranded DNA intermediates that associate with cellular histone proteins to form minichromosomes. Like most plant viruses, geminiviruses are targeted by RNA silencing and encode suppressor proteins such as AL2 and L2 to counter this defense. These related proteins can suppress silencing by multiple mechanisms, one of which involves interacting with and inhibiting adenosine kinase (ADK), a cellular enzyme associated with the methyl cycle that generates
S
-adenosyl-methionine, an essential methyltransferase cofactor. Thus, we hypothesized that the viral genome is targeted by small-RNA-directed methylation. Here, we show that
Arabidopsis
plants with mutations in genes encoding cytosine or histone H3 lysine 9 (H3K9) methyltransferases, RNA-directed methylation pathway components, or ADK are hypersensitive to geminivirus infection. We also demonstrate that viral DNA and associated histone H3 are methylated in infected plants and that cytosine methylation levels are significantly reduced in viral DNA isolated from methylation-deficient mutants. Finally, we demonstrate that
Beet curly top virus L2
−
mutant DNA present in tissues that have recovered from infection is hypermethylated and that host recovery requires AGO4, a component of the RNA-directed methylation pathway. We propose that plants use chromatin methylation as a defense against DNA viruses, which geminiviruses counter by inhibiting global methylation. In addition, our results establish that geminiviruses can be useful models for genome methylation in plants and suggest that there are redundant pathways leading to cytosine methylation.
Differential Antigen Presentation Kinetics of CD8+T-Cell Epitopes Derived from the Same Viral Protein
Authors: Sacha Jonah B. , Reynolds Matthew R. , Buechler Matthew B. , Chung Chungwon , Jonas Anna K. , Wallace Lyle T. , Weiler Andrea M. , Lee Wonhee , Piaskowski Shari M. , Soma Taeko , Friedrich Thomas C. , Wilson Nancy A. , Watkins David I.
Published: July 2008

The kinetics of peptide presentation by major histocompatibility complex class I (MHC-I) molecules may contribute to the efficacy of CD8+T cells. Whether all CD8+T-cell epitopes from a protein are presented by the same MHC-I molecule with similar kinetics is unknown. Here we show that CD8+T-cell epitopes derived from SIVmac239 Gag are presented with markedly different kinetics. We demonstrate that this discrepancy in presentation is not related to immunodominance but instead is due to differential requirements for epitope generation. These results illustrate that significant differences in presentation kinetics can exist among CD8+T-cell epitopes derived from the same viral protein.
Preferential Cytolysis of Peripheral Memory CD4
+
T Cells by In Vitro X4-Tropic Human Immunodeficiency Virus Type 1 Infection before the Completion of Reverse Transcription
Authors: Zhou Yan , Shen Lin , Yang Hung-Chih , Siliciano Robert F.
Published: July 2008

CD4
+
T-cell depletion is the hallmark of AIDS pathogenesis. Multiple mechanisms may contribute to the death of productively infected CD4
+
T cells and innocent-bystander cells. In this study, we characterize a novel mechanism in which human immunodeficiency virus type 1 (HIV-1) infection preferentially depletes peripheral memory CD4
+
T cells before the completion of reverse transcription. Using a recombinant HIV-1 carrying the green fluorescent protein reporter gene, we demonstrate that memory CD4
+
T cells were susceptible to infection-induced cell death at a low multiplicity of infection. Infected memory CD4
+
T cells underwent rapid necrotic cell death. Killing of host cells was dependent on X4 envelope-mediated viral fusion, but not on virion-associated Vpr or Nef. In contrast to peripheral resting CD4
+
T cells, CD4
+
T cells stimulated by mitogen or certain cytokines were resistant to HIV-1-induced early cell death. These results demonstrate that early steps in HIV-1 infection have a detrimental effect on certain subsets of CD4
+
T cells. The early cell death may serve as a selective disadvantage for X4-tropic HIV-1 in acute infection but may play a role in accelerated disease progression, which is associated with the emergence of X4-tropic HIV-1 in the late stage of AIDS.
Vaccinia Virus L1 Protein Is Required for Cell Entry and Membrane Fusion
Authors: Bisht Himani , Weisberg Andrea S. , Moss Bernard
Published: July 2008

Genetic and biochemical studies have provided evidence for an entry/fusion complex (EFC) comprised of at least eight viral proteins (A16, A21, A28, G3, G9, H2, J5, and L5) that together with an associated protein (F9) participates in entry of vaccinia virus (VACV) into cells. The genes encoding these proteins are conserved in all poxviruses, are expressed late in infection, and are components of the mature virion membrane but are not required for viral morphogenesis. In addition, all but one component has intramolecular disulfides that are formed by the poxvirus cytoplasmic redox system. The L1 protein has each of the characteristics enumerated above except that it has been reported to be essential for virus assembly. To further investigate the role of L1, we constructed a recombinant VACV (vL1Ri) that inducibly expresses L1. In the absence of inducer, L1 synthesis was repressed and vL1Ri was unable to form plaques or produce infectious progeny. Unexpectedly, assembly and morphogenesis appeared normal and the noninfectious virus particles were indistinguishable from wild-type VACV as determined by transmission electron microscopy and analysis of the component polypeptides. Notably, the L1-deficient virions were able to attach to cells but the cores failed to penetrate into the cytoplasm. In addition, cells infected with vL1Ri in the absence of inducer did not form syncytia following brief low-pH treatment even though extracellular virus was produced. Coimmunoprecipitation experiments demonstrated that L1 interacted with the EFC and indirectly with F9, suggesting that L1 is an additional component of the viral entry apparatus.
Human Cytomegalovirus Infection Alters the Expression of Cellular MicroRNA Species That Affect Its Replication
Authors: Wang Fu-Zhang , Weber Frank , Croce Carlo , Liu Chang-Gong , Liao Xudong , Pellett Philip E.
Published: July 2008

The human genome encodes over 500 microRNAs (miRNAs), small RNAs (19 to 26 nucleotides [nt]) that regulate the expressions of diverse cellular genes. Many cellular processes are altered through a variety of mechanisms by human cytomegalovirus (HCMV) infection. We asked whether HCMV infection leads to changes in the expression of cellular miRNAs and whether HCMV-regulated miRNAs are important for HCMV replication. Levels of most miRNAs did not change markedly during infection, but some were positively or negatively regulated. Patterns of miRNA expression were linked to the time course of infection. Some similarly reregulated miRNAs share identical or similar seed sequences, suggesting coordinated regulation of miRNA species that have shared targets. miRNAs miR-100 and miR-101 were chosen for further analyses based on their reproducible changes in expression after infection and on the basis of having predicted targets in the 3′ untranslated regions (3′-UTR) of genes encoding components of the mammalian target of rapamycin (mTOR) pathway, which is important during HCMV infection. Reporter genes that contain the 3′-UTR of mTOR (predicted targets for miR-100 and miR-101) or raptor (a component of the mTOR pathway; predicted site for miR-100) were constructed. Mimics of miR-100 and miR-101 inhibited expression from the mTOR construct, while only miR-100 inhibited the raptor construct. Together, miR-100 and miR-101 reduced mTOR protein levels. While the miR-100 and miR-101 mimics individually modestly inhibited production of infectious progeny, much greater inhibition was achieved with a combination of both (33-fold). Our key finding is that HCMV selectively manipulates the expression of some cellular miRNAs to help its own replication.
Analysis of Natural Sequence Variation and Covariation in Human Immunodeficiency Virus Type 1 Integrase
Authors: Myers Richard E. , Pillay Deenan
Published: July 2008

Human immunodeficiency virus type 1 (HIV-1) integrase inhibitors are in clinical trials, and raltegravir and elvitegravir are likely to be the first licensed drugs of this novel class of HIV antivirals. Understanding resistance to these inhibitors is important to maximize their efficacy. It has been shown that natural variation and covariation provide valuable insights into the development of resistance for established HIV inhibitors. Therefore, we have undertaken a study to fully characterize natural polymorphisms and amino acid covariation within an inhibitor-naïve sequence set spanning all defined HIV-1 subtypes. Inter- and intrasubtype variation was greatest in a 50-amino-acid segment of HIV-1 integrase incorporating the catalytic aspartic acid codon 116, suggesting that polymorphisms affect inhibitor binding and pathways to resistance. The critical mutations that determine the resistance pathways to raltegravir and elvitegravir (N155H, Q148K/R/H, and E92Q) were either rare or absent from the 1,165-sequence data set. However, 25 out of 41 mutations associated with integrase inhibitor resistance were present. These mutations were not subtype associated and were more prevalent in the subtypes that had been sampled frequently within the database. A novel modification of the Jaccard index was used to analyze amino acid covariation within HIV-1 integrase. A network of 10 covarying resistance-associated mutations was elucidated, along with a further 15 previously undescribed mutations that covaried with at least two of the resistance positions. The validation of covariation as a predictive tool will be dependent on monitoring the evolution of HIV-1 integrase under drug selection pressure.
Protein Kinases: Starting a Molecular Systems View of Endocytosis
Authors: Liberali Prisca , Rämö Pauli , Pelkmans Lucas
Published: July 2008

The field of endocytosis is in strong need of formal biophysical modeling and mathematical analysis. At the same time, endocytosis must be much better integrated into cellular physiology to understand the former's complex behavior in such a wide range of phenotypic variations. Furthermore, the concept that endocytosis provides the space-time for signal transduction can now be experimentally addressed. In this review, we discuss these principles and argue for a systematic and top-down approach to study the endocytic membrane system. We provide a summary of published observations on protein kinases regulating endocytic machinery components and discuss global unbiased approaches to further map out kinase regulatory networks. In particular, protein phosphorylation is at the heart of controlling the physical properties of endocytosis and of integrating these physical properties into the signal transduction networks of the cell to allow a fine-tuned response to the continuously varying physiological conditions of a cell.
Regulation of APC/C Activators in Mitosis and Meiosis
Authors: Pesin Jillian A. , Orr-Weaver Terry L.
Published: July 2008

The anaphase-promoting complex/cyclosome (APC/C) is a multisubunit E3 ubiquitin ligase that triggers the degradation of multiple substrates during mitosis. Cdc20/Fizzy and Cdh1/Fizzy-related activate the APC/C and confer substrate specificity through complex interactions with both the core APC/C and substrate proteins. The regulation of Cdc20 and Cdh1 is critical for proper APC/C activity and occurs in multiple ways: targeted protein degradation, phosphorylation, and direct binding of inhibitory proteins. During the specialized divisions of meiosis, the activity of the APC/C must be modified to achieve proper chromosome segregation. Recent studies show that one way in which APC/C activity is modified is through the use of meiosis-specific APC/C activators. Furthermore, regulation of the APC/C during meiosis is carried out by both mitotic regulators of the APC/C as well as meiosis-specific regulators. Here, we review the regulation of APC/C activators during mitosis and the role and regulation of the APC/C during female meiosis.
Neurokinin A engages neurokinin-1 receptor to induce NF-κB-dependent gene expression in murine macrophages: implications of ERK1/2 and PI 3-kinase/Akt pathways
Authors: Sun Jia , Ramnath Raina Devi , Tamizhselvi Ramasamy , Bhatia Madhav
Published: July 2008

Neurokinin A (NKA) belongs to the tachykinin neuropeptide family. Its biological functions are primarily mediated by the neurokinin (NK)-2 receptor. NKA has been implicated in several inflammatory conditions. However, there are limited data about the mechanism of its pathogenetic action. Here, we investigated proinflammatory effects of NKA on peripheral immune cells using the mouse macrophage/monocyte cell line RAW 264.7 and primary peritoneal macrophages. The signaling mechanistic pathways involved were also studied. In mouse macrophages with no detectable NK-2 receptors, NKA induces the upregulation of NK-1 but not NK-2 receptor expression. Furthermore, NKA engages this NK-1 receptor, resulting in inflammatory-like responses involving activation of the transcription factor nuclear factor (NF)-κB and induction of NF-κB-responsive proinflammatory chemokine expression. NKA activates NF-κB as evidenced by induced phosphorylation (leading to degradation) of its inhibitory protein IκBα, increased cellular levels of the transactivation-active phospho(Ser276)-p65 and its nuclear translocation, as well as enhanced DNA-binding activity of NF-κB. These responses are specifically inhibited by selective NK-1 receptor antagonists but not NK-2 receptor antagonists, thereby excluding the role of NK-2 receptor. Further investigation on the upstream signaling mechanisms suggests that two NF-κB-activating pathways (extracellular signal-regulated kinase 1/2 and phosphatidylinositol 3-kinase/protein kinase B) are activated by NKA. Specific inhibitors of the two pathways block NF-κB-dependent chemokine expression. The inhibitory effects are mediated through regulation of nuclear translocation, DNA-binding activity, and/or transactivation activity of NF-κB. Together, we provide novel evidence that NKA engages NK-1 receptors on mouse macrophages to elicit NF-κB-dependent cellular responses. The findings reveal cellular mechanisms that may underlie NKA-mediated inflammatory and immunological conditions.
Cytoskeletal remodeling in differentiated vascular smooth muscle is actin isoform dependent and stimulus dependent
Authors: Kim Hak Rim , Gallant Cynthia , Leavis Paul C. , Gunst Susan J. , Morgan Kathleen G.
Published: July 2008

Dynamic remodeling of the actin cytoskeleton plays an essential role in the migration and proliferation of vascular smooth muscle cells. It has been suggested that actin remodeling may also play an important functional role in nonmigrating, nonproliferating differentiated vascular smooth muscle (dVSM). In the present study, we show that contractile agonists increase the net polymerization of actin in dVSM, as measured by the differential ultracentrifugation of vascular smooth muscle tissue and the costaining of single freshly dissociated cells with fluorescent probes specific for globular and filamentous actin. Furthermore, induced alterations of the actin polymerization state, as well as actin decoy peptides, inhibit contractility in a stimulus-dependent manner. Latrunculin pretreatment or actin decoy peptides significantly inhibit contractility induced by a phorbol ester or an α-agonist, but these procedures have no effect on contractions induced by KCl. Aorta dVSM expresses α-smooth muscle actin, β-actin, nonmuscle γ-actin, and smooth muscle γ-actin. The incorporation of isoform-specific cell-permeant synthetic actin decoy peptides, as well as isoform-specific probing of cell fractions and two-dimensional gels, demonstrates that actin remodeling during α-agonist contractions involves the remodeling of primarily γ-actin and, to a lesser extent, β-actin. Taken together, these results show that net isoform- and agonist-dependent increases in actin polymerization regulate vascular contractility.
Probenecid, a gout remedy, inhibits pannexin 1 channels
Authors: Silverman William , Locovei Silviu , Dahl Gerhard
Published: July 2008

Probenecid is a well-established drug for the treatment of gout and is thought to act on an organic anion transporter, thereby affecting uric acid excretion in the kidney by blocking urate reuptake. Probenecid also has been shown to affect ATP release, leading to the suggestion that ATP release involves an organic anion transporter. Other pharmacological evidence and the observation of dye uptake, however, suggest that the nonvesicular release of ATP is mediated by large membrane channels, with pannexin 1 being a prominent candidate. In the present study we show that probenecid inhibited currents mediated by pannexin 1 channels in the same concentration range as observed for inhibition of transport processes. Probenecid did not affect channels formed by connexins. Thus probenecid allows for discrimination between channels formed by connexins and pannexins.
Connective tissue growth factor inhibits adipocyte differentiation
Authors: Tan Joanne T. M. , McLennan Susan V. , Song William W. , Lo Lisa W.-Y. , Bonner James G. , Williams Paul F. , Twigg Stephen M.
Published: July 2008

Adipocyte differentiation is a key process implicated in the pathogenesis of obesity and insulin resistance. Its regulation is triggered by a cascade of transcription factors, including the CCAAT/enhancer binding proteins (C/EBPs) and peroxisome proliferator-activated receptor-γ (PPARγ). Growth factors such as transforming growth factor-β1 (TGF-β1) are known to inhibit adipocyte differentiation in vitro, via the C/EBP pathway, and in vivo, but whether a downstream mediator of TGF-β1, connective tissue growth factor (CTGF), also known as CCN2, has a similar role is unknown. Mouse 3T3-L1 cells were differentiated into adipocytes by using standard methods, and effects and regulation of CTGF were studied. Intervention with recombinant human CTGF during differing stages of differentiation caused an inhibition in the development of the adipocyte phenotype, according to the gene expression of the differentiation markers adiponectin and PPARγ, as well as suppression of lipid accumulation and expression of the lipogenic enzyme glycerol-3-phosphate dehydrogenase. Whereas CTGF gene expression promptly fell by 90% as 3T3-L1 preadipocytes differentiated into mature adipocytes, CTGF mRNA expression was induced by added TGF-β1. CTGF applied to cells early in the course of differentiation inhibited total cell protein levels and nuclear localization of the β-isoform of C/EBP (C/EBP-β) and, subsequently, total cell C/EBP-α levels. CTGF also inhibited the adipocyte differentiation program in primary cultures of mouse preadipocytes. Expression of CTGF mRNA was twofold higher in the central fat depots of mice compared with subcutaneous fat, suggesting a potential role for CTGF in vivo. In summary, these data show that CTGF inhibits the adipocyte differentiation program.
Insights into mechanisms of intestinal segmentation in guinea pigs: a combined computational modeling and in vitro study
Authors: Chambers Jordan D. , Bornstein Joel C. , Thomas Evan A.
Published: July 2008

Segmentation in the guinea pig small intestine consists of a number of discrete motor patterns including rhythmic stationary contractions that occur episodically at specific locations along the intestine. The enteric nervous system regulates segmentation, but the exact circuit is unknown. Using simple computer models, we investigated possible circuits. Our computational model simulated the mean neuron firing rate in the feedforward ascending and descending reflex pathways. A stimulus-evoked pacemaker was located in the afferent pathway or in a feedforward pathway. Output of the feedforward pathways was fed into a simple model to determine the response of the muscle. Predictions were verified in vitro by using guinea pig jejunum, in which segmentation was induced with luminal fatty acid. In the computational model, local stimuli produced an oral contraction and anal dilation, similar to in vitro responses to local distension, but did not produce segmentation. When the stimulus was distributed, representing a nutrient load, the result was either a tonic response or globally synchronized oscillations. However, when we introduced local variations in synaptic coupling, stationary contractions occurred around these locations. This predicts that severing the ascending and descending pathways will induce stationary contractions. An acute lesion in our in vitro model significantly increased the number of stationary contractions immediately oral and anal to the lesion. Our results suggest that spatially localized rhythmic contractions arise from a local imbalance between ascending excitatory and descending inhibitory muscle inputs and require a distributed stimulus and a rhythm generator in the afferent pathway.
NAD(P)H oxidase-derived peroxide mediates elevated basal and impaired flow-induced NO production in SHR mesenteric arteries in vivo
Authors: Zhou Xiaosun , Bohlen H. Glenn , Miller Steven J. , Unthank Joseph L.
Published: July 2008

Nitric oxide (NO) and reactive oxygen species (ROS) have fundamentally important roles in the regulation of vascular tone and remodeling. Although arterial disease and endothelial dysfunction alter NO and ROS levels to impact vasodilation and vascular structure, direct measurements of these reactive species under in vivo conditions with flow alterations are unavailable. In this study, in vivo measurements of NO and H2O2 were made on mesenteric arteries to determine whether antioxidant therapies could restore normal NO production in spontaneously hypertensive rats (SHR). Flow was altered from ∼50–200% of control in anesthetized Wistar-Kyoto rats (WKY) and SHR by selective placement of microvascular clamps on adjacent arteries while NO and H2O2 were directly measured with microelectrodes. Relative to WKY, SHR had significantly increased baseline NO and H2O2 concentrations (2,572 ± 241 vs. 1,059 ± 160 nM, P < 0.01; and 26 ± 7 vs. 7 ± 1 μM, P < 0.05, respectively). With flow elevation, H2O2 but not NO increased in SHR; NO but not H2O2 was elevated in WKY. Apocynin and polyethylene-glycolated catalase decreased baseline SHR NO and H2O2 to WKY levels and restored flow-mediated NO production. Suppression of NAD(P)H oxidase with gp91ds-tat decreased SHR H2O2 to WKY levels. Addition of topical H2O2 to increase peroxide to the basal concentration measured in SHR elevated WKY NO to levels observed in SHR. The results support the hypothesis that increased vascular peroxide in SHR is primarily derived from NAD(P)H oxidase and increases NO concentration to levels that cannot be further elevated with increased flow. Short-term and even acute administration of antioxidants are able to restore normal flow-mediated NO signaling in young SHR.
Inflammation and endothelial dysfunction during aging: role of NF-κB
Authors: Csiszar Anna , Wang Mingyi , Lakatta Edward G. , Ungvari Zoltan
Published: July 2008

One of the major conceptual advances in our understanding of the pathogenesis of age-associated cardiovascular diseases has been the insight that age-related oxidative stress may promote vascular inflammation even in the absence of traditional risk factors associated with atherogenesis (e.g., hypertension or metabolic diseases). In the present review we summarize recent experimental data suggesting that mitochondrial production of reactive oxygen species, innate immunity, the local TNF-α-converting enzyme (TACE)-TNF-α, and the renin-angiotensin system may underlie NF-κB induction and endothelial activation in aged arteries. The theme that emerges from this review is that multiple proinflammatory pathways converge on NF-κB in the aged arterial wall, and that the transcriptional activity of NF-κB is regulated by multiple nuclear factors during aging, including nuclear enzymes poly(ADP-ribose) polymerase (PARP-1) and SIRT-1. We also discuss the possibility that nucleophosmin (NPM or nuclear phosphoprotein B23), a known modulator of the cellular oxidative stress response, may also regulate NF-κB activity in endothelial cells.
Metamorphosis-Induced Changes in the Coupling of Spinal Thoraco-Lumbar Motor Outputs During Swimming inXenopus laevis
Authors: Beyeler Anna , Métais Charles , Combes Denis , Simmers John , Le Ray Didier
Published: July 2008

Anuran metamorphosis includes a complete remodeling of the animal's biomechanical apparatus, requiring a corresponding functional reorganization of underlying central neural circuitry. This involves changes that must occur in the coordination between the motor outputs of different spinal segments to harmonize locomotor and postural functions as the limbs grow and the tail regresses. In premetamorphic Xenopus laevis tadpoles, axial motor output drives rostrocaudally propagating segmental myotomal contractions that generate propulsive body undulations. During metamorphosis, the anterior axial musculature of the tadpole progressively evolves into dorsal muscles in the postmetamorphic froglet in which some of these back muscles lose their implicit locomotor function to serve exclusively in postural control in the adult. To understand how locomotor and postural systems interact during locomotion in juvenile Xenopus, we have investigated the coordination between postural back and hindlimb muscle activity during free forward swimming. Axial/dorsal muscles, which contract in bilateral alternation during undulatory swimming in premetamorphic tadpoles, change their left-right coordination to become activated in phase with bilaterally synchronous hindlimb extensions in locomoting juveniles. Based on in vitro electrophysiological experiments as well as specific spinal lesions in vivo, a spinal cord region was delimited in which propriospinal interactions are directly responsible for the coordination between leg and back muscle contractions. Our findings therefore indicate that dynamic postural adjustments during adult Xenopus locomotion are mediated by local intraspinal pathways through which the lumbar generator for hindlimb propulsive kicking provides caudorostral commands to thoracic spinal circuitry controlling the dorsal trunk musculature.
Activity and Neuromodulatory Input Contribute to the Recovery of Rhythmic Output After Decentralization in a Central Pattern Generator
Authors: Zhang Yili , Khorkova Olga , Rodriguez Rosa , Golowaschi Jorge
Published: July 2008

Central pattern generators (CPGs) are neuronal networks that control vitally important rhythmic behaviors including breathing, heartbeat, and digestion. Understanding how CPGs recover activity after their rhythmic activity is disrupted has important theoretical and practical implications. Previous experimental and modeling studies indicated that rhythm recovery after central neuromodulatory input loss (decentralization) could be based entirely on activity-dependent mechanisms, but recent evidence of long-term conductance regulation by neuromodulators suggest that neuromodulator-dependent mechanisms may also be involved. Here we examined the effects of altering activity and the neuromodulatory environment before decentralization of the pyloric CPG in Cancer borealis on the initial phase of rhythmic activity recovery after decentralization. We found that pretreatments altering the network activity through shifting the ionic balance or the membrane potential of pyloric pacemaker neurons reduced the delay of recovery initiation after decentralization, consistent with the recovery process being triggered already during the pretreatment period through an activity-dependent mechanism. However, we observed that pretreatment with neuromodulators GABA and proctolin, acting via metabotropic receptors, also affected the initial phase of the recovery of pyloric activity after decentralization. Their distinct effects appear to result from interactions of their metabotropic effects with their effects on neuronal activity. Thus we show that the initial phase of the recovery process can be accounted for by the existence of distinct activity-and neuromodulator-dependent pathways. We propose a computational model that includes activity- and neuromodulator-dependent mechanisms of the activity recovery process, which successfully explains the experimental observations and predicts the results of key biological experiments.
Early and Late Changes in the Distal Forelimb Representation of the Supplementary Motor Area After Injury to Frontal Motor Areas in the Squirrel Monkey
Authors: Eisner-Janowicz Ines , Barbay Scott , Hoover Erica , Stowe Ann M. , Frost Shawn B. , Plautz Erik J. , Nudo Randolph J.
Published: July 2008

Neuroimaging studies in stroke survivors have suggested that adaptive plasticity occurs following stroke. However, the complex temporal dynamics of neural reorganization after injury make the interpretation of functional imaging studies equivocal. In the present study in adult squirrel monkeys, intracortical microstimulation (ICMS) techniques were used to monitor changes in representational maps of the distal forelimb in the supplementary motor area (SMA) after a unilateral ischemic infarct of primary motor (M1) and premotor distal forelimb representations (DFLs). In each animal, ICMS maps were derived at early (3 wk) and late (13 wk) postinfarct stages. Lesions resulted in severe deficits in motor abilities on a reach and retrieval task. Limited behavioral recovery occurred and plateaued at 3 wk postinfarct. At both early and late postinfarct stages, distal forelimb movements could still be evoked by ICMS in SMA at low current levels. However, the size of the SMA DFL changed after the infarct. In particular, wrist-forearm representations enlarged significantly between early and late stages, attaining a size substantially larger than the preinfarct area. At the late postinfarct stage, the expansion in the SMA DFL area was directly proportional to the absolute size of the lesion. The motor performance scores were positively correlated to the absolute size of the SMA DFL at the late postinfarct stage. Together, these data suggest that, at least in squirrel monkeys, descending output from M1 and dorsal and ventral premotor cortices is not necessary for SMA representations to be maintained and that SMA motor output maps undergo delayed increases in representational area after damage to other motor areas. Finally, the role of SMA in recovery of function after such lesions remains unclear because behavioral recovery appears to precede neurophysiological map changes.
Macrophages, PPARs, and Cancer
Authors: Van Ginderachter Jo A. , Movahedi Kiavash , Van den Bossche Jan , De Baetselier Patrick
Published: July 2008

Mononuclear phagocytes often function as control switches of the immune system, securing the balance between pro‐ and anti‐inflammatory reactions. For this purpose and depending on the activating stimuli, these cells can develop into different subsets: proinflammatory classically activated (M1) or anti‐inflammatory alternatively activated (M2) macrophages. The expression of the nuclear peroxisome proliferator‐activated receptors (PPARs) is regulated by M1‐ or M2‐inducing stimuli, and these receptors are generally considered to counteract inflammatory M1 macrophages, while actively promoting M2 activation. This is of importance in a tumor context, where M1 are important initiators of inflammation‐driven cancers. As a consequence, PPAR agonists are potentially usefull for inhibiting the early phases of tumorigenesis through their antagonistic effect on M1. In more established tumors, the macrophage phenotype is more diverse, making it more difficult to predict the outcome of PPAR agonism. Overall, in our view current knowledge provides a sound basis for the clinical evaluation of PPAR ligands as chemopreventive agents in chronic inflammation‐associated cancer development, while cautioning against the unthoughtful application of these agents as cancer therapeutics.
The Role of PPAR‐γ and Its Interaction with COX‐2 in Pancreatic Cancer
Authors: Eibl Guido
Published: July 2008

In recent years, the study of the peroxisome proliferators activated receptor gamma (PPAR‐γ) as a potential target for cancer prevention and therapy has gained a strong interest. However, the overall biological significance of PPAR‐γin cancer development and progression is still controversial. While many reports documented antiproliferative effects in human cancer cell and animal models, several studies demonstrating potential tumor promoting actions of PPAR‐γligands raised considerable concerns about the role of PPAR‐γin human cancers. Controversy also exists about the role of PPAR‐γin human pancreatic cancers. The current review summarizes the data about PPAR‐γin pancreatic cancer and highlights the biologically relevant interactions between the cyclooxygenase and PPAR system.
An Extension of the Spectral Mapping Theorem
Authors: Medghalchi A. R. , Tabatabaie S. M.
Published: July 2008

We give an extension of the spectral mapping theorem
on hypergroups and prove that if K is a commutative strong hypergroup with and κ is a weakly continuous representation of M(K) on a W∗‐algebra such that for every t ∈ K, κt is an ∗‐automorphism, spκ is a synthesis
set for L1(K) and κ(L1(K)) is without order, then for any μ in a closed regular
subalgebra of M(K) containing L1(K), , where spκ is the
Arveson spectrum of κ.
Almost Periodic Solution of a Diffusive Mixed System with Time Delay and Type III Functional Response
Authors: Liu Qiong
Published: July 2008

A delayed predator‐prey model with diffusion and competition is
proposed. Some sufficient conditions on uniform persistence of the model have
been obtained. By applying Liapunov‐Razumikhin technique, we will point
out, under almost periodic circumstances, a set of sufficient conditions that
assure the existence and uniqueness of the positive almost periodic solution
which is globally asymptotically stable.
Differential Gain in InGaAsN/GaAs Double Quantum Well Structures by Numerical Simulations
Authors: Wartak M. S. , Weetman P. , Rusek P.
Published: July 2008

We performed numerical studies of differential gain in a coupled quantum well structures built from InGaAsN. Differential gain in In0.38Ga0.62As1_yNy/GaAs quantum well structures was determined and analyzed. A 10‐band k_p Hamiltonian matrix was used in the calculations and solved self‐consistently with Poisson′s equation. The effect of Nitrogen composition and barrier thickness on differential gain has been determined. The influence of Nitrogen composition on differential gain is significant whereas barrier effects are modest.
Bioinformatic Tools for Inferring Functional Information from Plant Microarray Data II: Analysis Beyond Single Gene
Authors: Coulibaly Issa , Page Grier P.
Published: July 2008

While it is possible to interpret microarray experiments a single gene at a time, most studies generate long lists of differentially expressed genes whose interpretation requires the integration of prior biological knowledge. This prior knowledge is stored in various public and private databases and covers several aspects of gene function and biological information. In this review, we will describe the tools and places where to find prior accurate biological information and how to process and incorporate them to interpret microarray data analyses. Here, we highlight selected tools and resources for gene class level ontology analysis (Section 2), gene coexpression analysis (Section 3), gene network analysis (Section 4), biological pathway analysis (Section 5), analysis of transcriptional regulation (Section 6), and omics data integration (Section 7). The overall goal of this review is to provide researchers with tools and information to facilitate the interpretation of microarray data.
Proteome Analysis of Chronically Inflamed Lungs in a Mouse Chronic Asthma Model
Authors: Wong W.S. Fred , Zhao Jing
Published: July 2008

Background: Asthma is a chronic airway inflammatory disease characterized by airway wall remodeling. The mechanisms underlying airway remodeling in asthma are not fully understood. There is an urgent need to investigate global protein profiling of chronically inflamed lungs to identify novel pathogenic molecules and biomarkers for chronic asthma. In this study, we described the first differentially expressed proteome of lung tissue and bronchoalveolar lavage fluid from a mouse chronic asthma model. Methods: BALB/c mice sensitized to ovalbumin were challenged with ovalbumin aerosol 3 times per week for 8 weeks. The lung tissue and lavage fluid proteins were resolved by 2-dimensional gel electrophoresis, and differentially expressed proteins were identified by matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry. Results: Airway goblet cell hyperplasia, smooth muscle hyperplasia, subepithelial fibrosis, airway hyperresponsiveness, pulmonary inflammatory cell infiltration and elevated serum ovalbumin-specific IgE level were observed in our chronic asthma model. We have identified at least 100 protein spots that were differentially expressed in chronically inflamed lungs, and the identity of 66 protein spots was confirmed. Conclusions: Many of these proteins, including cytoskeleton-related proteins, Ca2+-binding proteins and anti-oxidant proteins, may be related to the development of airway remodeling, and they should be evaluated further as potential therapeutic targets and biomarkers for chronic asthma.