bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical Switches for Remote and Noninvasive Control of Cell Signaling
Authors: Gorostiza Pau , Isacoff Ehud Y.
Published: October 2008

Although the identity and interactions of signaling proteins have been studied in great detail, the complexity of signaling networks cannot be fully understood without elucidating the timing and location of activity of individual proteins. To do this, one needs a means for detecting and controlling specific signaling events. An attractive approach is to use light, both to report on and control signaling proteins in cells, because light can probe cells in real time with minimal damage. Although optical detection of signaling events has been successful for some time, the development of the means for optical control has accelerated only recently. Of particular interest is the development of chemically engineered proteins that are directly sensitive to light.
Validation, Performance under Field Conditions, and Cost-Effectiveness of Capillus HIV-1/HIV-2 and Determine HIV-1/2 Rapid Human Immunodeficiency Virus Antibody Assays Using Sequential and Parallel Testing Algorithms in Tanzania
Authors: Mayhood Meghan K. , Afwamba Isaac A. , Odhiambo Christopher O. , Ndanu Epimack , Thielman Nathan M. , Morrissey Anne B. , Shao John F. , Wells Pence Brian , Crump John A.
Published: October 2008

Rapid human immunodeficiency virus (HIV) antibody tests support the effort to expand access to HIV testing and counseling services in remote, rural, and poor parts of the world. We validated the Capillus HIV-1/HIV-2 (Trinity Biotech PLC, Bray, County Wicklow, Ireland) and Determine HIV-1/2 (Abbott Laboratories, Abbott Park, IL) rapid tests in a reference laboratory using patient samples from Tanzania and evaluated the performance of the tests under field conditions in northern Tanzania. We used the resulting data to study sequential and parallel testing algorithms. In the validation study, sensitivity, specificity, the predictive value of a positive test (PV
+
), and the predictive value of a negative test (PV
−
) were all 100% for Capillus and Determine. In the field evaluation among 12,737 clients, sensitivity, specificity, PV
+
, and PV
−
were 99.7%, 99.8%, 98.7%, and 99.9%, respectively, for Capillus and 99.6%, 99.9%, 99.5%, and 99.9%, respectively, for Determine. A sequential testing algorithm that did not confirm a negative initial Capillus result with a Determine result cost $7.77 per HIV diagnosis but missed 0.3% of HIV infections. A sequential testing algorithm that did not confirm a negative initial Determine result with a Capillus result cost $7.64 per HIV diagnosis but missed 0.4% of HIV infections. A parallel testing algorithm cost $13.46 per HIV diagnosis but detected more HIV-infected clients.
Tuberculosis Drug Resistance in an Area of Low Endemicity in 2004 to 2006: Semiquantitative Drug Susceptibility Testing and Genotyping
Authors: Springer Burkhard , Calligaris-Maibach Romana C. , Ritter Claudia , Böttger Erik C.
Published: October 2008

We determined the quantitative levels and the genetic mechanisms of resistance in drug-resistant clinical isolates of
Mycobacterium tuberculosis
sampled over a period of 3 years (
n
= 45; 17 of the isolate were multidrug resistant). Our results led us to hypothesize that some strains categorized as resistant to isoniazid, ethambutol, or streptomycin by standard laboratory procedures of in vitro drug susceptibility testing may still respond to a treatment regimen that includes these agents.
Optimization of Human Immunodeficiency Virus Type 1 Envelope Glycoproteins with V1/V2 Deleted, Using Virus Evolution
Authors: Bontjer Ilja , Land Aafke , Eggink Dirk , Verkade Erwin , Tuin Kiki , Baldwin Chris , Pollakis Georgios , Paxton William A. , Braakman Ineke , Berkhout Ben , Sanders Rogier W.
Published: October 2008

The human immunodeficiency virus type 1 envelope glycoprotein (Env) complex is the principal focus of neutralizing antibody-based vaccines. The functional Env complex is a trimer consisting of six individual subunits: three gp120 molecules and three gp41 molecules. The individual subunits have proven unsuccessful as vaccines presumably because they do not resemble the functional Env complex. Variable domains and carbohydrates shield vulnerable neutralization epitopes on the functional Env complex. The deletion of variable loops has been shown to improve gp120's immunogenicity; however, problems have been encountered when introducing such modifications in stabilized Env trimer constructs. To address these issues, we have created a set of V1/V2 and V3 loop deletion variants in the context of complete virus to allow optimization by forced virus evolution. Compensatory second-site substitutions included the addition and/or removal of specific carbohydrates, changes in the disulfide-bonded architecture of the V1/V2 stem, the replacement of hydrophobic residues by hydrophilic and charged residues, and changes in distal parts of gp120 and gp41. These viruses displayed increased sensitivity to neutralizing antibodies, demonstrating the improved exposure of conserved domains. The results show that we can select for functionally improved Env variants with loop deletions through forced virus evolution. Selected evolved Env variants were transferred to stabilized Env trimer constructs and were shown to improve trimer expression and secretion. Based on these findings, we can make recommendations on how to delete the V1/V2 domain from recombinant Env trimers for vaccine and X-ray crystallography studies. In general, virus evolution may provide a powerful tool to optimize Env vaccine antigens.
Role of Thiol/Disulfide Exchange in Newcastle Disease Virus Entry
Authors: Jain Surbhi , McGinnes Lori W. , Morrison Trudy G.
Published: October 2008

Newcastle disease virus (NDV) entry into host cells is mediated by the hemagglutinin-neuraminidase (HN) and fusion (F) glycoproteins. We previously showed that production of free thiols in F protein is required for membrane fusion directed by F protein (S. Jain et al., J. Virol. 81:2328-2339, 2007). In the present study we evaluated the oxidation state of F protein in virions and virus-like particles and its relationship to activation of F protein by HN protein, F protein conformational intermediates, and virus-cell fusion. F protein, in particles, does not have free thiols, but free thiols were produced upon binding of particles to target cells. Free thiols were produced at 16°C in F protein in virions bound to the target cells. They also appeared in different fusion defective mutant F proteins. Free thiols were produced in the presence of mutant HN proteins that are defective in F protein activation but are attachment competent. These results suggest that free thiols appear prior to any of the proposed major conformational changes in F protein which accompany fusion activation. These results also indicate that HN protein binding to its receptor likely facilitates the interaction between F protein and host cell isomerases, leading to reduction of disulfide bonds in F protein. Taken together, these results show that free thiols are produced in F protein at a very early stage during the onset of fusion and that the production of free thiols is required for fusion in addition to activation by HN protein.
Exploring the Nuclear Envelope of Herpes Simplex Virus 1-Infected Cells by High-Resolution Microscopy
Authors: Wild Peter , Senn Claudia , Manera Céline L. , Sutter Esther , Schraner Elisabeth M. , Tobler Kurt , Ackermann Mathias , Ziegler Urs , Lucas Miriam S. , Kaech Andres
Published: October 2008

Herpesviruses are composed of capsid, tegument, and envelope. Capsids assemble in the nucleus and exit the nucleus by budding at the inner nuclear membrane, acquiring tegument and the envelope. This study focuses on the changes of the nuclear envelope during herpes simplex virus 1 (HSV-1) infection in HeLa and Vero cells by employing preparation techniques at ambient and low temperatures for high-resolution scanning and transmission electron microscopy and confocal laser scanning microscopy. Cryo-field emission scanning electron microscopy of freeze-fractured cells showed for the first time budding of capsids at the nuclear envelope at the third dimension with high activity at 10 h and low activity at 15 h of incubation. The mean number of pores was significantly lower, and the mean interpore distance and the mean interpore area were significantly larger than those for mock-infected cells 15 h after inoculation. Forty-five percent of nuclear pores in HSV-1-infected cells were dilated to more than 140 nm. Nuclear material containing capsids protrude through them into the cytoplasm. Examination of in situ preparations after dry fracturing revealed significant enlargements of the nuclear pore diameter and of the nuclear pore central channel in HSV-1-infected cells compared to mock-infected cells. The demonstration of nucleoporins by confocal microscopy also revealed fewer pores but focal enhancement of fluorescence signals in HSV-1-infected cells, whereas Western blots showed no loss of nucleoporins from cells. The data suggest that infection with HSV-1 alters the number, size, and architecture of nuclear pores without a loss of nucleoporins from altered nuclear pore complexes.
Frequency and Phenotype of Human Immunodeficiency Virus Envelope-Specific B Cells from Patients with Broadly Cross-Neutralizing Antibodies
Authors: Doria-Rose Nicole A. , Klein Rachel M. , Manion Maura M. , O'Dell Sijy , Phogat Adhuna , Chakrabarti Bimal , Hallahan Claire W. , Migueles Stephen A. , Wrammert Jens , Ahmed Rafi , Nason Martha , Wyatt Richard T. , Mascola John R. , Connors Mark
Published: October 2008

Induction of broadly cross-reactive neutralizing antibodies (NAb) is an important goal for a prophylactic human immunodeficiency virus type 1 (HIV-1) vaccine. Some HIV-infected patients make a NAb response that reacts with diverse strains of HIV-1, but most candidate vaccines have induced NAb only against a subset of highly sensitive isolates. To better understand the nature of broad NAb responses that arise during natural infection, we screened patients for sera able to neutralize diverse HIV strains and explored the frequency and phenotype of their peripheral Envelope-specific B cells. We screened 113 HIV-infected patients of various clinical statuses for the prevalence of broad NAb. Sera able to neutralize at least four of five viral isolates were found in over one-third of progressors and slow progressors, but much less frequently in aviremic long-term nonprogressors. Most Env-specific antibody-secreting B cells were CD27
hi
CD38
hi
plasmablasts, and the total plasmablast frequency was higher in HIV-infected patients than in uninfected donors. We found that 0.0031% of B cells and 0.047% of plasmablasts secreted Env-specific immunoglobulin G (IgG) in an enzyme-linked immunospot (ELISPOT) assay. We developed a novel staining protocol to label HIV-specific B cells with Env gp140 protein. A total of 0.09% of B cells were found to be Env-specific by this method, a frequency far higher than that indicated by ELISPOT assay. gp140-labeled B cells were predominantly CD27
+
and surface IgG
+
. These data describe the breadth and titer of serum NAb and the frequency and phenotype of HIV-specific B cells in a cohort of patients with broad cross-neutralizing antibody responses that are potential goals for vaccines for HIV.
The EBNA1 Protein of Epstein-Barr Virus Functionally Interacts with Brd4
Authors: Lin Ammy , Wang Shan , Nguyen Tin , Shire Kathy , Frappier Lori
Published: October 2008

The EBNA1 protein of Epstein-Barr virus (EBV) is essential for EBV latent infection in ensuring the replication and stable segregation of the EBV genomes and in activating the transcription of other EBV latency genes. We have tested the ability of four host proteins (Brd2, Brd4, DEK, and MeCP2) implicated in the segregation of papillomavirus and Kaposi's sarcoma-associated herpesvirus to support EBNA1-mediated segregation of EBV-based plasmids in
Saccharomyces cerevisiae
. We found that Brd4 enabled EBNA1-mediated segregation while Brd2 and MeCP2 had a general stimulatory effect on plasmid maintenance. EBNA1 interacted with Brd4 in both yeast and human cells through N-terminal sequences previously shown to mediate transcriptional activation but not segregation. In keeping with this interaction site, silencing of Brd4 in human cells decreased transcriptional activation by EBNA1 but not the mitotic chromosome attachment of EBNA1 that is required for segregation. In addition, Brd4 was found to be preferentially localized to the FR enhancer element regulated by EBNA1, over other EBV sequences, in latently EBV-infected cells. The results indicate that EBNA1 can functionally interact with Brd4 in native and heterologous systems and that this interaction facilitates transcriptional activation by EBNA1 from the FR element.
Mouse Hepatitis Virus Liver Pathology Is Dependent on ADP-Ribose-1″-Phosphatase, a Viral Function Conserved in the Alpha-Like Supergroup
Authors: Eriksson Klara Kristin , Cervantes-Barragán Luisa , Ludewig Burkhard , Thiel Volker
Published: October 2008

Viral infection of the liver can lead to severe tissue damage when high levels of viral replication and spread in the organ are coupled with strong induction of inflammatory responses. Here we report an unexpected correlation between the expression of a functional X domain encoded by the hepatotropic mouse hepatitis virus strain A59 (MHV-A59), the high-level production of inflammatory cytokines, and the induction of acute viral hepatitis in mice. X-domain (also called macro domain) proteins possess poly-ADP-ribose binding and/or ADP-ribose-1′′-phosphatase (ADRP) activity. They are conserved in coronaviruses and in members of the “alpha-like supergroup” of phylogenetically related positive-strand RNA viruses that includes viruses of medical importance, such as rubella virus and hepatitis E virus. By using reverse genetics, we constructed a recombinant murine coronavirus MHV-A59 mutant encoding a single-amino-acid substitution of a strictly conserved residue that is essential for coronaviral ADRP activity. We found that the mutant virus replicated to slightly reduced titers in livers but, strikingly, did not induce liver disease. In vitro, the mutant virus induced only low levels of the inflammatory cytokines tumor necrosis factor alpha and interleukin-6 (IL-6). In vivo, we found that IL-6 production, in particular, was reduced in the spleens and livers of mutant virus-infected mice. Collectively, our data demonstrate that the MHV X domain exacerbates MHV-induced liver pathology, most likely through the induction of excessive inflammatory cytokine expression.
DISPERSITY AND STABILITY MEASUREMENT OF FUNCTIONALIZED MULTIWALLED CARBON NANOTUBES IN ALCOHOLS
Authors: KIM HUN-SIK , KANG MINSUNG , PARK WON-IL , KIM DON-YOUNG , JIN HYOUNG-JOON
Published: October 2008

Multiwalled carbon nanotubes (MWCNTs) were dispersed in various alcohols such as methanol, ethanol and isopropanol using ultrasonication. In order to disperse the MWCNTs in the alcohols, they were treated using a mixture of H 2 SO 4 and HNO 3 (3 : 1, vol/vol). The concentration of MWCNTs was approximately 0.03 wt.% and they formed a homogeneous dispersion in the alcohol solutions. The functional groups introduced on the surface of the MWCNTs during the acid treatment were characterized by Fourier transform-infrared spectroscopy and X-ray photoelectron spectroscopy. The dispersibility of the MWCNTs in the alcohols was characterized using atomic force microscopy, scanning electron microscopy and transmission electron microscopy. The stability of the MWCNT dispersions was also measured using a recently developed optical analyzer (Turbiscan).
CENTRALITY EVOLUTION OF pt AND yt SPECTRA FROM Au–Au COLLISIONS AT $\sqrt{s_{NN}} = 200\, {\rm GeV}$
Authors: TRAINOR THOMAS A.
Published: October 2008

A two-component analysis of spectra to pt = 12 GeV/c for identified pions and protons from 200 GeV Au – Au collisions is presented. The method is similar to an analysis of the nch dependence of pt spectra from p–p collisions at 200 GeV, but applied to Au – Au centrality dependence. The soft-component reference is a Lévy distribution on transverse mass mt. The hard-component reference is a Gaussian on transverse rapidity yt with exponential (pt power-law) tail. Deviations of data from the reference are described by hard-component ratio rAA, which generalizes nuclear modification factor RAA. The analysis suggests that centrality evolution of pion and proton spectra is dominated by changes in parton fragmentation. The structure of rAA suggests that parton energy loss produces a negative boost Δyt of a large fraction (but not all) of the minimum-bias fragment distribution, and that lower-energy partons suffer relatively less energy loss, possibly due to color screening. The analysis also suggests that the anomalous p/π ratio may be due to differences in the parton energy-loss process experienced by the two hadron species. This analysis provides no evidence for radial flow.
IS IT POSSIBLE TO CONSERVE ELECTRIC CHARGE WITHOUT SEPARATELY CONSERVING BARYONIC NUMBER AND LEPTONIC NUMBER?
Authors: TSAN UNG CHAN
Published: October 2008

Charges that are sources of fields must be universally conserved. Any quantity which is proved to be violated in certain circumstance cannot be a source of field. To account for the asymmetry of our Universe baryon number A has to be violated; thus A cannot be a charge. We postulate a new interaction, matter creation, with (A–L) as charge and Z * as messenger. Conservation of (A–L) instead of (3A–L) suggested by Sakharov is deduced on the one hand from observational facts (our Universe is both material and neutral) and on the other hand from the generalized Gell-Mann and Nishijima formula. Conservation of (A–L) forbids neutrinoless double beta decay and neutron antineutron oscillations. The union of four interactions — electromagnetism, the MC interaction, the weak interaction and the strong interaction — considered as the product U(1) × U(1) × SU(2) × SU(3) would account for available experimental and observational data. Observation of processes violating baryon number conservation would be of great interest in falsifying this suggestion.
A Rough Guide to Environmental Art
Authors: Thornes John E.
Published: October 2008

To appreciate the beauty or the fragility of our environment and our cultural responses to it, we need to understand how artists have portrayed the environment in the past and how they are continuing to portray it in the present. Environmental art is presented in this paper as a new genre to describe works of art that are not only directly representational of the environment (e.g., Constable's Cloud Series or Monet's London Series) but also works of art that are clearly nonrepresentational and performative, such as Long's A Line Made by Walking or Turrell's Skyspaces. The need for an overarching new genre to describe nonrepresentational performative environmental art is more obvious because there has been a host of labels given to this type of art since the late 1960s, such as land art, earthworks, site-specific art, destination art, ecological art, eco-art, and environmental sculpture. The review is also concerned with the potential of environmental art for communicating climate change.
Coalescence Models for Hadron Formation from Quark-Gluon Plasma
Authors: Fries Rainer , Greco Vincenzo , Sorensen Paul
Published: October 2008

We review hadron formation from a deconfined quark-gluon plasma (QGP) via coalescence or recombination of quarks and gluons. We discuss the abundant experimental evidence for coalescence from the Relativistic Heavy Ion Collider (RHIC) and compare the various coalescence models advocated in the literature. We comment on the underlying assumptions and remaining challenges as well as the merits of the models. We conclude with a discussion of some recent developments in the field.
Health Effects of Combat: A Life-Course Perspective
Authors: Levy Barry S. , Sidel Victor W.
Published: October 2008

Armed combat (also termed war or armed conflict) has profound direct and indirect impacts on the long-term physical and mental health of both military personnel and noncombatant civilians. Although most research has focused on immediate and short-term health consequences of war, an increasing number of studies have focused on the long-term health consequences for both veterans of military service and noncombatant civilians. However, these long-term studies focus almost entirely on posttraumatic stress disorder and other mental health problems; relatively few long-term studies have focused on physical injuries due to war and the impact of those injuries on relationships, work, and other aspects of life. This article reviews illustrative examples of the existing literature on these long-term health consequences of war, focusing not only on military veterans of several different armed conflicts but also on noncombatant civilian populations, including spouses and children of military veterans as well as refugees and internally displaced persons. Public health professionals can help address these problems.
Expression of active p21-activated kinase-1 induces Ca2+ flux modification with altered regulatory protein phosphorylation in cardiac myocytes
Authors: Sheehan Katherine A. , Ke Yunbo , Wolska Beata M. , Solaro R. John
Published: October 2008

p21-Activated kinase-1 (Pak1) is a serine-threonine kinase that associates with and activates protein phosphatase 2A in adult ventricular myocytes and, thereby, induces increased Ca2+ sensitivity of skinned-fiber tension development mediated by dephosphorylation of myofilament proteins (Ke Y, Wang L, Pyle WG, de Tombe PP, Solaro RJ. Circ Res 94: 194–200, 2004). We test the hypothesis that activation of Pak1 also moderates cardiac contractility through regulation of intracellular Ca2+ fluxes. We found no difference in field-stimulated intracellular Ca2+ concentration ([Ca2+]i) transient amplitude and extent of cell shortening between myocytes expressing constitutively active Pak1 (CA-Pak1) and controls expressing LacZ; however, time to peak shortening was significantly faster and rate of [Ca2+]i decay and time of relengthening were slower. Neither caffeine-releasable sarcoplasmic reticulum (SR) Ca2+ content nor fractional release was different in CA-Pak1 myocytes compared with controls. Isoproterenol application revealed a significantly blunted increase in [Ca2+]i transient amplitude, as well as a slowed rate of [Ca2+]i decay, increased SR Ca2+ content, and increased cell shortening, in CA-Pak1 myocytes. We found no significant change in phospholamban phosphorylation at Ser16 or Thr17 in CA-Pak1 myocytes. Analysis of cardiac troponin I revealed a significant reduction in phosphorylated species that are primarily attributable to Ser23/24 in CA-Pak1 myocytes. Nonstimulated, spontaneous SR Ca2+ release sparks were significantly smaller in amplitude in CA-Pak1 than LacZ myocytes. Propagation of spontaneous Ca2+ waves resulting from SR Ca2+ overload was significantly slower in CA-Pak1 myocytes. Our data indicate that CA-Pak1 expression has significant effects on ventricular myocyte contractility through altered myofilament Ca2+ sensitivity and modification of the [Ca2+]i transient.
NADPH oxidase contributes to renal damage and dysfunction in Dahl salt-sensitive hypertension
Authors: Tian Niu , Moore Rebecca S. , Phillips William E. , Lin Lin , Braddy Sharkeshia , Pryor Janelle S. , Stockstill Rachel L. , Hughson Michael D. , Manning R. Davis
Published: October 2008

The goal of this study was to test the hypothesis that NADPH oxidase contributes importantly to renal cortical oxidative stress and inflammation, as well as renal damage and dysfunction, and increases in arterial pressure. Fifty-four 7- to 8-wk-old Dahl salt-sensitive (S) or R/Rapp strain rats were maintained for 5 wk on a high sodium (8%) or high sodium + apocynin (1.5 mmol/l in drinking water). Arterial and venous catheters were implanted on day 21. By day 35 in the high-Na S rats, mRNA expression of renal cortical gp91phox, p22phox, p47phox, and p67phox NADPH subunits in S rats increased markedly, and treatment of high-Na S rats with the NADPH oxidase inhibitor apocynin resulted in significant decreases in mRNA expression of these NADPH oxidase subunits. At the same time, in apocynin-treated S rats 1) renal cortical GSH/GSSG ratio increased, 2) renal cortical O2•− release and NADPH oxidase activity decreased, and 3) renal glomerular and interstitial damage markedly fell. Apocynin also decreased renal cortical monocyte/macrophage infiltration, and apocynin, but not the xanthine oxidase inhibitor allopurinol, attenuated decreases in renal hemodynamics and lowered arterial pressure. These data suggest that NADPH oxidase plays an important role in causing renal cortical oxidative stress and inflammation, which lead to decreases in renal hemodynamics, renal cortical damage, and increases in arterial pressure.
Retinoic acid-dependent activation of the polycystic kidney disease-1 (PKD1) promoter
Authors: Islam M. Rafiq , Puri Sanjeev , Rodova Marianna , Magenheimer Brenda S. , Maser Robin L. , Calvet James P.
Published: October 2008

The retinoic acids all- trans retinoic acid (AT-RA) and 9- cis retinoic acid (9C-RA) and the retinoic acid receptors RAR and RXR significantly induce transcriptional activity from a 200-bp PKD1 proximal promoter in transfected mammalian cells. This PKD1 promoter region contains Ets, p53, and GC box motifs, but lacks a canonical RAR/RXR motif. Mutagenesis of the Ets sites did not affect RA induction. In contrast, GC box mutations completely blocked stimulation by AT-RA and by RXRβ or RARβ. Mithramycin A, which prevents Sp1 binding, significantly reduced basal promoter activity and suppressed upregulation by AT-RA and RXR. The 200-bp proximal promoter could not be induced by AT-RA in Drosophila SL2 cells, which lack Sp1, but could be activated in these cells transfected with exogenous Sp1. Small interfering RNA knockdown of Sp1 in mammalian cells completely blocked RXRβ upregulation of the promoter. These data indicate that induction of the PKD1 promoter by retinoic acid is mediated through Sp1 elements. RT-PCR showed that AT-RA treatment of HEK293T cells increased the levels of endogenous PKD1 RNA, and chromatin immunoprecipitation showed the presence of both RXR and Sp1 at the PKD1 proximal promoter. These results suggest that retinoids and their receptors may play a role in PKD1 gene regulation.
Myogenic origin of the hypotension induced by rapid changes in posture in awake dogs following autonomic blockade
Authors: Wong Brett J. , Sheriff Don D.
Published: October 2008

The “push-pull” effect denotes the reduced tolerance to +Gz (hypergravity) when +Gz stress is preceded by exposure to hypogravity, i.e., fractional, zero, or negative Gz. The purpose of this study was to test the hypothesis that an exaggerated, myogenically mediated rise in leg vascular conductance contributes to the push-pull effect, using heart level arterial blood pressure as a measure of G tolerance. The approach was to impose control (30 s of 30° head-up tilt) and push-pull (30 s of 30° head-up tilt immediately preceded by 10 s of −15° head-down tilt) gravitational stress after administration of hexamethonium (5 mg/kg) to inhibit autonomic ganglionic neurotransmission in seven dogs. Cardiac output or thigh level arterial pressure (myogenic stimulus) was maintained constant by computer-controlled ventricular pacing. The animals were sedated with acepromazine and lightly restrained in lateral recumbency on a tilt table. Following the onset of head-up tilt, the magnitude of the fall in heart level arterial pressure from baseline was −11.6 ± 2.9 and −17.1 ± 2.2 mmHg for the control and push-pull trials, respectively ( P < 0.05), when cardiac output was maintained constant. Over 40% of the exaggerated fall in heart level arterial pressure was attributable to an exaggerated rise in hindlimb vascular conductance ( P < 0.05). Maintaining thigh level arterial pressure constant abolished the exaggerated rise in hindlimb blood flow. Thus a push-pull effect largely attributable to a myogenically induced rise in leg vascular conductance occurs when autonomic function is inhibited.
Postactivation Depression of the Soleus H Reflex Measured Using Threshold Tracking
Authors: McNulty Penelope A. , Jankelowitz Stacey K. , Wiendels Tanya M. , Burke David
Published: October 2008

The interpretation of changes in the soleus H reflex is problematic in the face of reflex gain changes, a nonlinear input/output relationship for the motoneuron pool, and a nonhomogeneous response of different motoneurons to afferent inputs. By altering the stimulus intensity to maintain a constant reflex output, threshold tracking allows a relatively constant population of α-motoneurons to be studied. This approach was used to examine postactivation (“homosynaptic”) depression of the H reflex (HD) in 23 neurologically healthy subjects. The H reflex was elicited by tibial nerve stimulation at 0.05, 0.1, 0.3, 1, and 2 Hz at rest and during voluntary plantar flexion at 2.5, 5, and 10% of maximum. A computerized threshold tracking procedure was used to set the current needed to generate a target H reflex 10% of Mmax. The current needed to produce the target reflex increased with stimulus rate but not significantly beyond 1 Hz. In three subjects, the current needed to produce H reflexes of 5, 10, 15, and 20% Mmax at 0.3, 1, and 2 Hz increased with rate and with the size of the test H reflex. HD was significantly reduced during voluntary contractions. Using threshold tracking, HD was maximal at lower frequencies than previously emphasized, probably because HD is greater the larger the test H reflex. This would reinforce the greater sensitivity of small motoneurons to reflex inputs.
Differential Inhibition of Ca2+ Channels by α2-Adrenoceptors in Three Functional Subclasses of Rat Sympathetic Neurons
Authors: Li Chen , Horn John P.
Published: October 2008

A comparison of identified sympathetic neurons in the isolated intact superior cervical ganglion revealed that secretomotor, pilomotor, and vasoconstrictor cells differ in their action potential mechanisms and in their postsynaptic α2-adrenergic responses to 10 μM norepinephrine (NE). In normal saline, the half-width of the spike afterhyperpolarization (AHP) in secretomotor neurons (103.5 ± 6.2 ms) was twofold that recorded in vasoconstrictor neurons (47.7 ± 2.9 ms) and 1.5-fold that in pilomotor neurons (71.4 ± 10.3 ms). Bath-applied NE reversibly inhibited the action potential repolarization shoulder, AHP amplitude, and AHP duration in secretomotor and pilomotor neurons to a similar extent, but had no effect on vasoconstrictor neurons. The insensitivity of vasomotor neurons to NE was not an artifact produced by microelectrode recording because all three cell groups were similar in terms of resting potential and input resistance. Moreover, NE insensitivity was not a natural consequence of briefer AHP duration in vasoconstrictor cells. Adding 10 mM TEA+ caused marked accentuation of the shoulder and AHP duration in vasoconstrictor neurons and comparable changes in the other two cell types, but did not unmask any sign of NE sensitivity in the vasoconstrictors. However, the spike shoulder and AHP in vasoconstrictors were Cd2+ sensitive, blocked by ω-conotoxin, an N-type calcium channel antagonist, and inhibited by oxotremorine-M, a muscarinic receptor agonist. These data show that NE can differentially modulate functional subsets of mammalian sympathetic neurons and that NE insensitivity can serve as a practical experimental criterion for identification of vasomotor neurons in the isolated ganglion.
Auditory Selective Attention Modulates Activation of Human Inferior Colliculus
Authors: Rinne Teemu , Balk Marja H. , Koistinen Sonja , Autti Taina , Alho Kimmo , Sams Mikko
Published: October 2008

Selective auditory attention powerfully modulates neural activity in the human auditory cortex (AC). In contrast, the role of attention in subcortical auditory processing is not well established. Here, we used functional MRI (fMRI) to examine activation of the human inferior colliculus (IC) during strictly controlled auditory attention tasks. The IC is an obligatory midbrain nucleus of the ascending auditory pathway with diverse internal and external connections. The IC also receives a massive descending projection from the AC, suggesting that cortical processes affect IC operations. In this study, 21 subjects selectively attended to left-ear or right-ear sounds and ignored sounds delivered to the other ear. IC activations depended on the direction of attention, indicating that auditory processing in the human IC is not only determined by acoustic input but also by the current behavioral goals.
Presynaptic and Postsynaptic NMDA Receptors Mediate Distinct Effects of Brain-Derived Neurotrophic Factor on Synaptic Transmission
Authors: Madara Joseph C. , Levine Eric S.
Published: October 2008

In addition to its effects on neuronal survival and differentiation, brain-derived neurotrophic factor (BDNF) plays an important role in modulating synaptic transmission and plasticity in many brain areas, most notably the neocortex and hippocampus. These effects may underlie a role for BDNF in learning and memory as well as developmental plasticity. Consistent with localization of the tropomyosin-related kinase B receptor to both sides of the synapse, BDNF appears to have pre- and postsynaptic effects, but the underlying cellular mechanisms are unclear and it is not known whether pre- and postsynaptic modulations by BDNF occur simultaneously. To address these issues, we recorded dual-component (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid [AMPA] and N-methyl-d-aspartate [NMDA]) miniature excitatory postsynaptic currents (mEPSCs) from cortical and hippocampal pyramidal neurons and dentate gyrus granule cells from acute brain slices. BDNF had no effect on the fast component of mEPSC decay or on the peak amplitude, suggesting that BDNF did not modulate postsynaptic AMPA receptors, although BDNF rapidly modulated NMDA receptors, as seen by an enhancement of the slow component of mEPSC decay that was prevented by blocking postsynaptic NMDA receptors. At the same time, BDNF acted presynaptically to enhance mEPSC frequency. Surprisingly, the effect on frequency was also NMDA receptor dependent, but required activation of presynaptic, not postsynaptic, NMDA receptors. BDNF also enhanced action potential–dependent glutamate release via presynaptic NMDA receptors, an effect that was unmasked when voltage-gated calcium channels were partially inhibited. Our results indicate that BDNF acutely modulates presynaptic release and postsynaptic responsiveness through simultaneous effects on pre- and postsynaptic NMDA receptors.
Effects of Temperature Acclimation on a Central Neural Circuit and Its Behavioral Output
Authors: Szabo Theresa M. , Brookings Ted , Preuss Thomas , Faber Donald S.
Published: October 2008

In this study, we address the impact of temperature acclimation on neuronal properties in the Mauthner (M-) system, a brain stem network that initiates the startle-escape behavior in goldfish. The M-cell can be studied at cellular and behavioral levels, since it is uniquely identifiable physiologically within the intact vertebrate brain, and a single action potential in this neuron determines not only whether a startle response will occur but also the direction of the escape. Using animals acclimated to 15°C as a control, 25°C-acclimated fish showed a significant increase in escape probability and a decrease in the ability to discriminate escape directionality. Intracellular recordings demonstrated that M-cells in this population possessed decreased input resistance and reduced strength and duration of inhibitory inputs. In contrast, fish acclimated to 5°C were behaviorally similar to 15°C fish and had increased input resistance, increased strength of inhibitory transmission, and reduced excitatory transmission. We show here that alterations in the balance between excitatory and inhibitory synaptic transmission in the M-cell circuit underlie differences in behavioral responsiveness in acclimated populations. Specifically, during warm acclimation, synaptic inputs are weighted on the side of excitation and fish demonstrate hyperexcitability and reduced left–right discrimination during rapid escapes. In contrast, cold acclimation results in transmission weighted on the side of inhibition and these fish are less excitable and show improved directional discrimination.
How to Live Long and Prosper: Autophagy, Mitochondria, and Aging
Authors: Yen Wei-Lien , Klionsky Daniel J.
Published: October 2008

Autophagy is a process of cellular self-degradation in which portions of the cytoplasm are sequestered within cytosolic double-membrane vesicles and delivered to the lysosome/vacuole. This process occurs in all eukaryotic cells and is partly a stress response; autophagy is induced during starvation and hypoxia. However, autophagy also plays a role during development and is associated with a range of diseases. Accumulating data also suggest the involvement of autophagy in aging. For example, the role of various hormones and nutrient sensing pathways in life span extension may involve autophagy. Similarly, autophagy is the primary mechanism for removing damaged organelles, such as mitochondria, which may have a direct impact on aging. Here, we review the role of autophagy, with an emphasis on the signaling pathways that are involved in regulation, and the consequences of autophagy induction with regard to aging.
Brain Protection by Erythropoietin: A Manifold Task
Authors: Rabie Tamer , Marti Hugo H.
Published: October 2008

Many hematopoietic growth factors are produced locally in the brain. Among these, erythropoietin (Epo), has a dominant role for neuroprotection, neurogenesis, and acting as a neurotrophic factor in the central nervous system. These functions make erythropoietin a good candidate for treating diseases associated with neuronal cell death.
Endogenous Neural Progenitor Cells as Therapeutic Target After Spinal Cord Injury
Authors: Obermair Franz-Josef , Schröter Aileen , Thallmair Michaela
Published: October 2008

Growing knowledge about the role of neural progenitor cells supports the hope that stem cell-based therapeutic approaches aimed at restoring function in the lesioned central nervous system can be established. Possible therapies for promoting recovery after spinal cord injury include stimulating the formation of neurons and glial cells by endogenous progenitor cells. This article reviews the current knowledge about the nature of adult progenitor cells in the intact and injured spinal cord and summarizes possibilities and limitations of cellular replacement strategies based on manipulations of endogenous spinal cord progenitor cells and their environment.
Nanoengineering Ion Channels for Optical Control
Authors: Gorostiza Pau , Isacoff Ehud Y.
Published: October 2008

Chemical modification with photoisomerizable tethered ligands endows proteins with sensitivity to light. These optically actuated proteins are revolutionizing research in biology by making it possible to manipulate biological processes noninvasively and with unprecedented spatiotemporal resolution.
Two‐Dimensional Free Energy Surfaces for Electron Transfer Reactions in Solution
Authors: Murata Shigeo , El-Kemary Maged , Tachiya M.
Published: October 2008

Change in intermolecular distance between electron donor (D) and acceptor (A) can induce intermolecular electron transfer (ET) even in nonpolar solvent, where solvent orientational polarization is absent. This was shown by making simple calculations of the energies of the initial and final states of ET. In the case of polar solvent, the free energies are functions of both D‐A distance and solvent orientational polarization. On the basis of 2‐dimensional free energy surfaces, the relation of Marcus ET and exciplex formation is discussed. The transient effect in fluorescence quenching was measured for several D‐A pairs in a nonpolar solvent. The results were analyzed by assuming a distance dependence of the ET rate that is consistent with the above model.
Nonviral Production of Human Interleukin-7 in Spodoptera Frugiperda Insect Cells as a Soluble Recombinant Protein
Authors: Mirzaei Maryam , Xu Yan , Elias Cynthia B. , Prakash Satya
Published: October 2008

Human interleukin-7 (hIL-7) is a cytokine secreted by the stromal cells of the red marrow. It is important for proliferation during certain stages of B-cell maturation and for T and NK cell survival, development, and homeostasis. It is a critical growth factor for enhancement and recovery of the immune T-cell. Because of its strong immunomodulatory effects, hIL-7 may become a valuable supplementary agent for immunotherapeutical treatments in patients with HIV infection or immunodeficiency. Human IL-7 has previously been produced in various protein expression systems. In this paper, we present an alternative expression system, inSpodoptera frugiperdacells, for the production of hIL-7 using nonlytic vector systems. This system allows generation of correctly translated and accurately processed heterologous proteins as soluble recombinant proteins. Here we report plasmid construction, transfection, and consequent expression of hIL-7 using this nonlytic insect cell expression system. The levels of secreted hIL-7 in a small scale experiment reached a level of 1.7 μg·1−1under serum-free cell culture conditions.
Early Changes in Functional Dynamic Magnetic Resonance Imaging Predict for Pathologic Response to Neoadjuvant Chemotherapy in Primary Breast Cancer
Authors: Ah-See Mei-Lin W. , Makris Andreas , Taylor N. Jane , Harrison Mark , Richman Paul I. , Burcombe Russell J. , Stirling J. James , d'Arcy James A. , Collins David J. , Pittam Michael R. , Ravichandran Duraisamy , Padhani Anwar R.
Published: October 2008

Purpose: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) allows noninvasive, in vivo measurements of tissue microvessel perfusion and permeability. We examined whether DCE-MRI done after two cycles of neoadjuvant chemotherapy could predict final clinical and pathologic response in primary breast cancers.

Experimental Design: Thirty-seven patients with primary breast cancer, due to receive six cycles of neoadjuvant 5-fluorouracil, epirubicin and cyclophosphamide chemotherapy, were examined using DCE-MRI before neoadjuvant chemotherapy and after two cycles of treatment. Changes in DCE-MRI kinetic parameters (Ktrans, kep, ve, MaxGd, rBV, rBF, MTT) were correlated with the final clinical and pathologic response to neoadjuvant chemotherapy. Test-retest variability was used to determine individual patient response.

Results: Twenty-eight patients were evaluable for response (19 clinical responders and 9 nonresponders; 11 pathologic responders and 17 nonresponders). Changes in the DCE-MRI kinetic parameters Ktrans, kep, MaxGd, rBV, and rBF were significantly correlated with both final clinical and pathologic response (P < 0.01). Change in Ktrans was the best predictor of pathologic nonresponse (area under the receiver operating characteristic curve, 0.93; sensitivity, 94%; specificity, 82%), correctly identifying 94% of nonresponders and 73% of responders. Change in MRI-derived tumor size did not predict for pathologic response.

Conclusion: Changes in breast tumor microvessel functionality as depicted by DCE-MRI early on after starting anthracycline-based neoadjuvant chemotherapy can predict final clinical and pathologic response. The ability to identify nonresponders early may allow the selection of patients who may benefit from a therapy change.
Subclassification and Individual Survival Time Prediction from Gene Expression Data of Neuroblastoma Patients by Using CASPAR
Authors: Oberthuer André , Kaderali Lars , Kahlert Yvonne , Hero Barbara , Westermann Frank , Berthold Frank , Brors Benedikt , Eils Roland , Fischer Matthias
Published: October 2008

Purpose: To predict individual survival times for neuroblastoma patients from gene expression data using the cancer survival prediction using automatic relevance determination (CASPAR) algorithm.

Experimental Design: A first set of oligonucleotide microarray gene expression profiles comprising 256 neuroblastoma patients was generated. Then, CASPAR was combined with a leave-one-out cross-validation to predict individual times for both the whole cohort and subgroups of patients with unfavorable markers, including stage 4 disease (n = 67), unfavorable genetic alterations, intermediate-risk or high-risk stratification by the German neuroblastoma trial, and patients predicted as unfavorable by a recently described gene expression classifier (n = 83). Prediction accuracy of individual survival times was assessed by Kaplan-Meier analyses and time-dependent receiver operator characteristics curve analyses. Subsequently, classification results were validated in an independent cohort (n = 120).

Results: CASPAR separated patients with divergent outcome in both the initial and the validation cohort [initial set, 5y-OS 0.94 ± 0.04 (predicted long survival) versus 0.38 ± 0.17 (predicted short survival), P < 0.0001; validation cohort, 5y-OS 0.94 ± 0.07 (long) versus 0.40 ± 0.13 (short), P < 0.0001]. Time-dependent receiver operator characteristics analyses showed that CASPAR-predicted individual survival times were highly accurate (initial set, mean area under the curve for first 10 years of overall survival prediction 0.92 ± 0.04; validation set, 0.81 ± 0.05). Furthermore, CASPAR significantly discriminated short (<5 years) from long survivors (>5 years) in subgroups of patients with unfavorable markers with the exception of MYCN-amplified patients (initial set). Confirmatory results with high significance were observed in the validation cohort [stage 4 disease (P = 0.0049), NB2004 intermediate-risk or high-risk stratification (P = 0.0017), and unfavorable gene expression prediction (P = 0.0017)].

Conclusions: CASPAR accurately forecasts individual survival times for neuroblastoma patients from gene expression data.
Antibody-Mediated Delivery of Interleukin-2 to the Stroma of Breast Cancer Strongly Enhances the Potency of Chemotherapy
Authors: Mårlind Jessica , Kaspar Manuela , Trachsel Eveline , Sommavilla Roberto , Hindle Stuart , Bacci Camilla , Giovannoni Leonardo , Neri Dario
Published: October 2008

Purpose: There is an interest in the discovery of biopharmaceuticals, which are well tolerated and which potentiate the action of anthracyclines and taxanes in breast cancer therapy.

Experimental Design: We have produced a recombinant fusion protein, composed of the human antibody fragment scFv(F16) fused to human interleukin-2 (F16-IL2), and tested its therapeutic performance in the MDA-MB-231 xenograft model of human breast cancer. The F16 antibody is specific to the alternatively spliced A1 domain of tenascin-C, which is virtually undetectable in normal tissues but is strongly expressed in the neovasculature and stroma of breast cancer.

Results: When used as monotherapy, F16-IL2 displayed a strikingly superior therapeutic benefit compared with unconjugated recombinant IL-2. The administration of doxorubicin either before (8 days, 24 h, or 2 h) or simultaneously with the injection of F16-IL2 did not decrease the accumulation of immunocytokine in the tumor as measured by quantitative biodistribution analysis. Therapy experiments, featuring five once per week coadministrations of 20 μg F16-IL2 and doxorubicin, showed a statistically significant reduction of tumor growth rate and prolongation of survival at a 4 mg/kg doxorubicin dose but not at a 1 mg/kg dose. By contrast, combination of F16-IL2 with paclitaxel (5 and 1 mg/kg) exhibited a significant therapeutic benefit compared with paclitaxel alone at both dose levels. F16-IL2, alone or in combination with doxorubicin, was well tolerated in cynomolgus monkeys at doses equivalent to the ones now used in clinical studies.

Conclusions: F16-IL2 may represent a new useful biopharmaceutical for the treatment of breast cancer.