bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxidation of hemoglobin: mechanisms of control in vitro and in vivo
Authors: BUEHLER PAUL W. , ALAYASH ABDU I. 
Published: February 2008

SUMMARYHemoglobin (Hb) within red blood cells (RBC) is protected from oxidative processes by enzymatic and small molecule antioxidants as well as the RBC membrane that provides a physical barrier against oxidation. When Hb is introduced into the circulation as a result of hemolysis or following infusion of Hb‐based oxygen carriers (HBOCs; ‘blood substitutes’), the control of oxidative processes becomes dependent on plasma oxidative status. In vitro studies clearly demonstrate that Hb and HBOCs undergo oxidative modification at the site of heme iron and at multiple amino acid sites as a result of autoxidation, nitrosylation and peroxidation. Recent findings from in vitro studies provide a strong basis for understanding of potential toxicity in vivo. The antioxidative status of both plasma and tissue becomes an important factor in the control of Hb and HBOC oxidation and nitrosylation in the circulation. Several studies that performed ex vivo and in vivo have demonstrated a critical role for plasma antioxidants such as ascorbic acid and uric acid in maintaining Hb and HBOCs in functional non‐oxidized states. In the present review we discuss mechanisms of Hb and HBOC autoxidation, nitrosylation and peroxidation in vitro and in vivo. Additionally, we explore the role(s) of plasma antioxidants in maintaining functional HBOC status that may potentially be exploited as part of protective strategies against Hb and HBOC oxidative toxicity.
The hemoglobin‐nitric oxide axis: implications for transfusion therapeutics
Authors: LANCASTER JACK , HUTCHINGS ANNE , KERBY JEFFREY D , PATEL RAKESH P 
Published: February 2008

SUMMARYUnderstanding mechanisms that regulate nitric oxide (•NO) function in the vascular compartment is critical in the context of transfusion‐based therapeutics. The role of hemoglobin (Hb), either cell‐free or encapsulated within the erythrocyte, has received much attention owing largely to the rapid rate of reactions between •NO and either oxy‐ or deoxyheme. In this review, we discuss the different mechanisms proposed by which •NO reactions with Hb are controlled under physiological conditions and which involve both preventing •NO‐scavenging by Hb and erythrocyte (and Hb)‐dependent stimulation of NO‐signaling. How these mechanisms may be utilized therapeutically in the design and application of Hb‐based oxygen carrier therapeutics is also discussed.
Pegylated hemoglobins mechanisms to avoid vasoconstriction and maintain perfusion
Authors: CABRALES PEDRO , FRIEDMAN JOEL M. 
Published: February 2008

SUMMARYDespite the advances in blood substitutes, the development of materials that are effective in maintaining blood volume and oxygen delivery remains the priority for emergency care and trauma. Vasoactivity, i.e. vasoconstriction, presumably caused by nitric oxide (NO) scavenging has been defined as the principal problem associated with acellular hemoglobin (Hb) with low hydrodynamic radius. Conversely, Hb‐based materials with very large hydrodynamic radius, achieved by surface decoration of the Hb tetramer with water‐trapping polymers such as polyethylene glycol (PEG) conjugation, have been found vasoinactive in spite of being effective NO scavengers. This article explores possible mechanisms for why PEGylated Hbs not only are not vasoconstrictive but also are actually facilitators for maintaining high perfusion levels in the microcirculation. The most promising mechanisms are based on relatively recent observations and models; they indicate that Hb can actively regulate availability of ‘bioactive’ NO forms. This regulation can occur via: (i) NO transport by Hb in an allosterically controlled reversible chemical reaction with the Cys beta 93 (S‐NO‐Hb); and (ii) production of bioactive forms of NO through nitrite reductase activity of deoxyHb. The principal issues associated with these proposed mechanisms are: (i) how these reactions generate bio‐available NO and (ii) how the generated NO is delivered to the site of action without being either degraded or sequestered. We present a promising hypothesis and preliminary supporting data that PEGylated Hbs through a nitrite‐mediated reaction are especially effective in generating nitrosothiols, creating a transportable source of bioactive NO.
A Numerical Simulation of Conjugate Heat Transfer in an Electronic Package Formed by Embedded Discrete Heat Sources in Contact With a Porous Heat Sink
Authors: Fedorov A. G. , Viskanta R. 
Published: February 2008

AbstractA physical/mathematical model has been developed to simulate the conjugate heat transfer in an actively cooled electronic package. The package consists of a highly conductive substrate with embedded discrete heat sources that are in intimate contact with a porous channel through which a gaseous coolant is circulated. The flow in the porous medium is analyzed using the extended Darcy model. The nonequilibrium, two-equation model which accounts for the near wall thermal dispersion effects was used for the heat transfer analysis. The concept of the general energy equation for the entire physical domain was employed as a method of solving numerically the conjugate system. The model has been validated by comparing the predictions with available experimental data for a similar system. A parametric study has been performed to examine the effects of some of the most important model parameters on the thermal performance of porous heat sink.
Role of Protein Tyrosine Kinase and Erk1/2 Activities in the Toll-Like Receptor 2-Induced Cellular Activation of Murine B Cells by Neisserial Porin
Authors: MacLeod Heather , Bhasin Navneet , Wetzler Lee M. 
Published: February 2008

ABSTRACTNeisserial porins are potent immune adjuvants and have been demonstrated to stimulate and induce the activation of human and murine B lymphocytes. Their immunopotentiating ability is due largely to the upregulation of the surface expression of the costimulatory ligand CD86 (B7-2) on B cells and other antigen-presenting cells. Porin-induced activation is dependent on the innate immune pattern recognition receptor Toll-like receptor 2 (TLR2). These data have led us to investigate the signal transduction events induced by PorB fromNeisseria meningitidisand then, using inhibitors of these pathways, to establish the mechanism by which this bacterial major outer membrane protein induces CD86 upregulation and the proliferation of murine B cells. PorB was able to induce (i) protein tyrosine kinase (PTK) activity, (ii) the phosphorylation of Erk1 and Erk2, and (iii) IκB-α phosphorylation, leading to NF-κB nuclear translocation in B cells in a TLR2-dependent manner. PorB-induced NF-κB nuclear translocation was not dependent on either PTK or Erk1/2 activities. However, B-cell proliferation and the induction of increased surface expression of CD86 by PorB were dependent on PTK activity and not Erk1/2 activation. In conclusion, PorB acts through TLR2 as a B-cell mitogen, triggering tyrosine phosphorylation of various cellular proteins that are involved in proliferation and CD86 expression, as well as the phosphorylation of Erk1/2, which is not necessary for CD86 upregulation or the proliferation of B cells.
Performance of the Cobas AmpliPrep/Cobas TaqMan Real-Time PCR Assay for Hepatitis B Virus DNA Quantification
Authors: Chevaliez Stéphane , Bouvier-Alias Magali , Laperche Syria , Pawlotsky Jean-Michel 
Published: February 2008

ABSTRACT

Hepatitis B virus (HBV) DNA quantification is used to establish the prognosis of chronic HBV-related liver disease, to identify those patients who need to be treated, and to monitor the virologic response and resistance to antiviral therapies. Real-time PCR-based assays are gradually replacing other technologies for routine quantification of HBV DNA in clinical practice. The goal of this study was to evaluate the intrinsic characteristics and clinical performance of the real-time PCR Cobas AmpliPrep/Cobas TaqMan (CAP/CTM) platform for HBV DNA quantification. Specificity was satisfactory (95% confidence interval, 98.1 to 100%). Intra-assay coefficients of variation ranged from 0.22% to 2.68%, and interassay coefficients of variation ranged from 1.31% to 4.13%. Quantification was linear over the full dynamic range of quantification of the assay (1.7 to 8.0 log
10
IU/ml) and was not affected by dilution. The assay was accurate regardless of the HBV genotype. Samples containing HBV DNA levels above 4.5 log
10
IU/ml were slightly underestimated relative to another accurate assay based on branched-DNA technology, but this is unlikely to have noteworthy clinical implications. Thus, the CAP/CTM HBV DNA assay is sensitive, specific, and reproducible, and it accurately quantifies HBV DNA levels in patients chronically infected by HBV genotypes A to F. Samples with HBV DNA concentrations above the upper limit of quantification need to be diluted and then retested. Broad use of fully automated real-time PCR assays should improve the management of patients with chronic HBV infection.
Relationship between
Mycobacterium tuberculosis
Genotype and the Clinical Phenotype of Pulmonary and Meningeal Tuberculosis
Authors: Thwaites Guy , Caws Maxine , Chau Tran Thi Hong , D'Sa Anthony , Lan Nguyen Thi Ngoc , Huyen Mai Nguyet Thu , Gagneux Sebastien , Anh Phan Thi Hoang , Tho Dau Quang , Torok Estee , Nhu Nguyen Thi Quynh , Duyen Nguyen Thi Hong , Duy Phan Minh , Richenberg Jonathan , Simmons Cameron , Hien Tran Tinh , Farrar Jeremy 
Published: February 2008

ABSTRACT

We used large sequence polymorphisms to determine the genotypes of 397 isolates of
Mycobacterium tuberculosis
from human immunodeficiency virus-uninfected Vietnamese adults with pulmonary (
n
= 235) or meningeal (
n
= 162) tuberculosis. We compared the pretreatment radiographic appearances of pulmonary tuberculosis and the presentation, response to treatment, and outcome of tuberculous meningitis between the genotypes. Multivariate analysis identified variables independently associated with genotype and outcome. A higher proportion of adults with pulmonary tuberculosis caused by the Euro-American genotype had consolidation on chest X-ray than was the case with disease caused by other genotypes (
P
= 0.006). Multivariate analysis revealed that meningitis caused by the East Asian/Beijing genotype was independently associated with a shorter duration of illness before presentation and fewer cerebrospinal fluid (CSF) leukocytes. Older age, fewer CSF leukocytes, and the presence of hemiplegia (but not strain lineage) were independently associated with death or severe disability, although the East Asian/Beijing genotype was strongly associated with drug-resistant tuberculosis. The genotype of
M. tuberculosis
influenced the presenting features of pulmonary and meningeal tuberculosis. The association between the East Asian/Beijing lineage and disease progression and CSF leukocyte count suggests the lineage may alter the presentation of meningitis by influencing the intracerebral inflammatory response. In addition, increased drug resistance among bacteria of the East Asian/Beijing lineage might influence the response to treatment. This study suggests the genetic diversity of
M. tuberculosis
has important clinical consequences.
NF-κB-Mediated Activation of the Chemokine CCL22 by the Product of the Human Cytomegalovirus Gene UL144 Escapes Regulation by Viral IE86
Authors: Poole Emma , Atkins Elizabeth , Nakayama Takashi , Yoshie Osamu , Groves Ian , Alcami Antonio , Sinclair John 
Published: February 2008

ABSTRACTThe product of the human cytomegalovirus (HCMV) gene UL144, expressed at early times postinfection, is located in the UL/b′ region of the viral genome and is related to members of the tumor necrosis factor receptor superfamily, but it does not bind tumor necrosis factor superfamily ligands. However, UL144 does activate NF-κB, resulting in NF-κB-mediated activation of the cellular chemokine CCL22. Consistent with this finding, isolates of HCMV lacking the UL/b′ region show no such activation of CCL22. Recently, it has been suggested that activation of NF-κB is repressed by the product of the viral gene IE86: IE86 appears to block NF-κB binding to DNA but not nuclear translocation of NF-κB. Intriguingly, IE86 is detectable throughout an infection with the virus, so how UL144 is able to activate NF-κB in the presence of continued IE86 expression is unclear. Here we show that although IE86 does repress the UL144-mediated activation of a synthetic NF-κB promoter, it is unable to block UL144-mediated activation of the CCL22 promoter, and this lack of responsiveness to IE86 appears to be regulated by binding of the CREB transcription factor.
Cytokine Responses in Porcine Respiratory Coronavirus-Infected Pigs Treated with Corticosteroids as a Model for Severe Acute Respiratory Syndrome
Authors: Zhang Xinsheng , Alekseev Konstantin , Jung Kwonil , Vlasova Anastasia , Hadya Nagesh , Saif Linda J. 
Published: February 2008

ABSTRACTThe effectiveness and potential immunosuppressive effects of anti-inflammatory glucocorticoids in the lungs of severe acute respiratory syndrome (SARS) patients are undefined. We treated porcine respiratory coronavirus (PRCV)-infected conventional pigs with the corticosteroid dexamethasone (DEX) as a model for SARS. Innate and Th1 cytokines in bronchoalveolar lavage (BAL) and serum were elevated in PRCV-infected pigs compared to controls, but were decreased after DEX treatment in the PRCV-infected, DEX-treated (PRCV/DEX) pigs. Although decreased in BAL, Th2 cytokine levels were higher in serum after DEX treatment. Levels of the proinflammatory cytokine interleukin-6 in BAL and serum were decreased in PRCV/DEX pigs early but increased later compared to those in phosphate-buffered saline-treated, PRCV-infected pigs, corresponding to a similar trend for lung lesions. PRCV infection increased T-cell frequencies in BAL, but DEX treatment of PRCV-infected pigs reduced frequencies of T cells; interestingly B and SWC3a+(monocytes/macrophages/granulocytes) cell frequencies were increased. DEX reduced numbers of PRCV-stimulated Th1 gamma interferon-secreting cells in spleen, tracheobroncheolar lymph nodes, and blood. Our findings suggest that future glucocorticoid treatment of SARS patients should be reconsidered in the context of potential local immunosuppression of immune responses in lung and systemic Th1 cytokine-biased suppression.
Calibration of Multiple Poliovirus Molecular Clocks Covering an Extended Evolutionary Range
Authors: Jorba Jaume , Campagnoli Ray , De Lina , Kew Olen 
Published: February 2008

ABSTRACTWe have calibrated five different molecular clocks for circulating poliovirus based upon the rates of fixation of total substitutions (Kt), synonymous substitutions (Ks), synonymous transitions (As), synonymous transversions (Bs), and nonsynonymous substitutions (Ka) into the P1/capsid region (2,643 nucleotides). Rates were determined over a 10-year period by analysis of sequences of 31 wild poliovirus type 1 isolates representing a well-defined phylogeny derived from a common imported ancestor. Similar rates were obtained by linear regression, the maximum likelihood/single-rate dated-tip method, and Bayesian inference. The very rapidKt[(1.03 ± 0.10) × 10−2substitutions/site/year] andKs[(1.00 ± 0.08) × 10−2] clocks were driven primarily by theAsclock [(0.96 ± 0.09) × 10−2], theBsclock was ∼10-fold slower [(0.10 ± 0.03) × 10−2], and the more stochasticKaclock was ∼30-fold slower [(0.03 ± 0.01) × 10−2]. Nonsynonymous substitutions at all P1/capsid sites, including the neutralizing antigenic sites, appeared to be constrained by purifying selection. Simulation of the evolution of third-codon positions suggested that saturation of synonymous transitions would be evident at 10 years and complete at ∼65 years of independent transmission. Saturation of synonymous transversions was predicted to be minimal at 20 years and incomplete at 100 years. The rapid evolution of theKt,Ks, andAsclocks can be used to estimate the dates of divergence of closely related viruses, whereas the slowerBsandKaclocks may be used to explore deeper evolutionary relationships within and across poliovirus genotypes.
Cell Surface Expression of the Vaccinia Virus Complement Control Protein Is Mediated by Interaction with the Viral A56 Protein and Protects Infected Cells from Complement Attack
Authors: Girgis Natasha M. , DeHaven Brian C. , Fan Xin , Viner Kendra M. , Shamim Mohammad , Isaacs Stuart N. 
Published: February 2008

ABSTRACTThe vaccinia virus (VACV) complement control protein (VCP) is the major protein secreted from VACV-infected cells. It has been reported that VCP binds to the surfaces of uninfected cells by interacting with heparan sulfate proteoglycans (HSPGs). In this study, we show that VCP is also expressed on the surfaces of infected cells and demonstrate that surface localization occurs independently of HSPGs. Since VCP does not contain a transmembrane domain, we hypothesized that VCP interacts with a membrane protein that localizes to the infected-cell surface. We show that the VACV A56 membrane protein is necessary for the cell surface expression of VCP and demonstrate that VCP and A56 interact in VACV-infected cells. Since the surface expression of VCP was abrogated by reducing agents, we examined the contribution of an unpaired cysteine residue on VCP to VCP surface expression and VCP's interaction with A56. To do this, we mutated the unpaired cysteine in VCP and generated a recombinant virus expressing the altered form of VCP. Following the infection of cells with the mutant virus, VCP was neither expressed on the cell surface nor able to interact with A56. Importantly, the cell surface expression of VCP was found to protect infected cells from complement-mediated lysis. Our findings suggest a new function for VCP that may be important for poxvirus pathogenesis and impact immune responses to VACV-based vaccines.
Deletion of Epstein-Barr Virus BFLF2 Leads to Impaired Viral DNA Packaging and Primary Egress as Well as to the Production of Defective Viral Particles
Authors: Granato Marisa , Feederle Regina , Farina Antonella , Gonnella Roberta , Santarelli Roberta , Hub Birgit , Faggioni Alberto , Delecluse Henri-Jacques 
Published: February 2008

ABSTRACT

Previous genetic and biochemical studies performed with several members of the
Alphaherpesvirus
subfamily have shown that the UL31 and UL34 proteins are essential components of the molecular machinery that mediates the primary egress of newly assembled capsids across the nuclear membrane. Further, there is substantial evidence that BFLF2 and BFRF1, the respective positional homologs of UL31 and UL34 in the Epstein-Barr virus (EBV) genome, are also their functional homologs, i.e., that the UL31/UL34 pathway is common to distant herpesviruses. However, the low degree of protein sequence identity between UL31 and BFLF2 would argue against such a hypothesis. To further clarify this issue, we have constructed a recombinant EBV strain devoid of BFLF2 (ΔBFLF2) and show that BFLF2 is crucial for efficient virus production but not for lytic DNA replication or B-cell transformation. This defective phenotype could be efficiently restored by
trans
complementation with a BFLF2 expression plasmid. Detailed analysis of replicating cells by electron microscopy revealed that, as expected, ΔBFLF2 viruses not only failed to egress from the nucleus but also showed defective DNA packaging. Nonfunctional primary egress did not, however, impair the production and extracellular release of enveloped but empty viral particles that comprised L particles containing tegument-like structures and a few virus-like particles carrying empty capsids. The ΔBFLF2 and ΔUL31 phenotypes therefore only partly overlap, from which we infer that BFLF2 and UL31 have substantially diverged during evolution to fulfil related but distinct functions.
Primer Binding Site-Dependent Restriction of Murine Leukemia Virus Requires HP1 Binding by TRIM28
Authors: Wolf Daniel , Cammas Florence , Losson Régine , Goff Stephen P. 
Published: February 2008

ABSTRACT
TRIM28 is a transcriptional corepressor which is required for primer binding site (PBS)-dependent restriction of murine leukemia virus (MLV) replication in embryonic stem and embryonic carcinoma (EC) cells. PBS-dependent restriction of MLV leads to transcriptional silencing of the integrated provirus and has been shown to correlate with TRIM28-mediated recruitment of HP1 to the silenced loci. Here we show, using a cell line with a point mutation in the HP1 binding domain of TRIM28, that interaction with HP1 is absolutely required for the PBS-dependent restriction of MLV in the F9 EC cell line.
Neural Processes Supporting Young and Older Adults' Emotional Memories
Authors: Kensinger Elizabeth A. , Schacter Daniel L. 
Published: February 2008

Abstract
Young and older adults are more likely to remember emotional information than neutral information. The present functional magnetic resonance imaging study examined the neural processes supporting young (ages 18–35) and older (ages 62–79) adults' successful encoding of positive, negative, and neutral objects (e.g., a sundae, a grenade, a canoe). The results revealed general preservation of the emotional memory network across the age groups. Both groups recruited the amygdala and the orbito-frontal cortex during the successful encoding of positive and negative information. Both ages also showed valence-specific recruitment: right fusiform activity was greatest during the successful encoding of negative information, whereas left prefrontal and temporal activity was greatest during the successful encoding of positive information. These valence-specific processes are consistent with behavioral evidence that negative information is processed with perceptual detail, whereas positive information is processed at a conceptual or schematic level. The only age differences in emotional memory emerged during the successful encoding of positive items: Older adults showed more activity in the medial prefrontal cortex and along the cingulate gyrus than young adults. Because these regions often are associated with self-referential processing, these results suggest that older adults' mnemonic boost for positive information may stem from an increased tendency to process this information in relation to themselves.