bluuebunny/crossref_metadata_2025_split huggingface dataset:
Yield of Stool Culture with Isolate Toxin Testing versus a Two-Step Algorithm Including Stool Toxin Testing for Detection of Toxigenic
Clostridium difficile
Authors: Reller Megan E. , Lema Clara A. , Perl Trish M. , Cai Mian , Ross Tracy L. , Speck Kathleen A. , Carroll Karen C. 
Published: September 2007

ABSTRACT

We examined the incremental yield of stool culture (with toxin testing on isolates) versus our two-step algorithm for optimal detection of toxigenic
Clostridium difficile
. Per the two-step algorithm, stools were screened for
C. difficile
-associated glutamate dehydrogenase (GDH) antigen and, if positive, tested for toxin by a direct (stool) cell culture cytotoxicity neutralization assay (CCNA). In parallel, stools were cultured for
C. difficile
and tested for toxin by both indirect (isolate) CCNA and conventional PCR if the direct CCNA was negative. The “gold standard” for toxigenic
C. difficile
was detection of
C. difficile
by the GDH screen or by culture and toxin production by direct or indirect CCNA. We tested 439 specimens from 439 patients. GDH screening detected all culture-positive specimens. The sensitivity of the two-step algorithm was 77% (95% confidence interval [CI], 70 to 84%), and that of culture was 87% (95% CI, 80 to 92%). PCR results correlated completely with those of CCNA testing on isolates (29/29 positive and 32/32 negative, respectively). We conclude that GDH is an excellent screening test and that culture with isolate CCNA testing detects an additional 23% of toxigenic
C. difficile
missed by direct CCNA. Since culture is tedious and also detects nontoxigenic
C. difficile
, we conclude that culture is most useful (i) when the direct CCNA is negative but a high clinical suspicion of toxigenic
C. difficile
remains, (ii) in the evaluation of new diagnostic tests for toxigenic
C. difficile
(where the best reference standard is essential), and (iii) in epidemiologic studies (where the availability of an isolate allows for strain typing and antimicrobial susceptibility testing).
Modification of Cellular Autophagy Protein LC3 by Poliovirus
Authors: Taylor Matthew P. , Kirkegaard Karla 
Published: September 2007

ABSTRACT
Poliovirus infection remodels intracellular membranes, creating a large number of membranous vesicles on which viral RNA replication occurs. Poliovirus-induced vesicles display hallmarks of cellular autophagosomes, including delimiting double membranes surrounding the cytosolic lumen, acquisition of the endosomal marker LAMP-1, and recruitment of the 18-kDa host protein LC3. Autophagy results in the covalent lipidation of LC3, conferring the property of membrane association to this previously microtubule-associated protein and providing a biochemical marker for the induction of autophagy. Here, we report that a similar modification of LC3 occurs both during poliovirus infection and following expression of a single viral protein, a stable precursor termed 2BC. Therefore, one of the early steps in cellular autophagy, LC3 modification, can be genetically separated from the induction of double-membraned vesicles that contain the modified LC3, which requires both viral proteins 2BC and 3A. The existence of viral inducers that promote a distinct aspect of the formation of autophagosome-like membranes both facilitates the dissection of this cellular process and supports the hypothesis that this branch of the innate immune response is directly subverted by poliovirus.
Interaction of Decay-Accelerating Factor with Coxsackievirus B3
Authors: Hafenstein Susan , Bowman Valorie D. , Chipman Paul R. , Kelly Carol M. Bator , Lin Feng , Medof M. Edward , Rossmann Michael G. 
Published: September 2007

ABSTRACTMany entero-, parecho-, and rhinoviruses use immunoglobulin (Ig)-like receptors that bind into the viral canyon and are required to initiate viral uncoating during infection. However, some of these viruses use an alternative or additional receptor that binds outside the canyon. Both the coxsackievirus-adenovirus receptor (CAR), an Ig-like molecule that binds into the viral canyon, and decay-accelerating factor (DAF) have been identified as cellular receptors for coxsackievirus B3 (CVB3). A cryoelectron microscopy reconstruction of a variant of CVB3 complexed with DAF shows full occupancy of the DAF receptor in each of 60 binding sites. The DAF molecule bridges the canyon, blocking the CAR binding site and causing the two receptors to compete with one another. The binding site of DAF on CVB3 differs from the binding site of DAF on the surface of echoviruses, suggesting independent evolutionary processes.
Characterization of the Intracellular Deproteinized Relaxed Circular DNA of Hepatitis B Virus: an Intermediate of Covalently Closed Circular DNA Formation
Authors: Guo Haitao , Jiang Dong , Zhou Tianlun , Cuconati Andrea , Block Timothy M. , Guo Ju-Tao 
Published: September 2007

ABSTRACT
Covalently closed circular DNA (cccDNA) of hepatitis B virus (HBV) is formed by conversion of capsid-associated relaxed circular DNA (rcDNA) via unknown mechanisms and exists in the nucleus of the infected hepatocyte as a minichromosome that serves as the transcription template for viral RNAs. To study the molecular pathway of cccDNA formation and its regulation by viral and cellular factors, we have established a cell line that supports the replication of an envelope protein-deficient HBV genome in a tetracycline-inducible manner. Following induction of HBV replication, the cells accumulate higher levels of cccDNA as well as larger amounts of deproteinized rcDNA (DP-rcDNA) than cells that replicate wild-type HBV genomes. These results indicate that HBV envelope proteins negatively regulate cccDNA formation, and conversion of DP-rcDNA into cccDNA is a rate-limiting step of cccDNA formation in HepG2 cells. Detailed analyses reveal the following: (i) DP-rcDNA exists in both cytoplasm and nucleus; (ii) while nuclear DP-rcDNA is sensitive to DNase I digestion, a small fraction of cytoplasmic DP-rcDNA is DNase I resistant; (iii) both DNase I-sensitive and -resistant cytoplasmic DP-rcDNAs cosediment with capsids and can be immunoprecipitated with HBV core antibody; and (iv) a primer extension assay maps the 5′ end of the minus strand of DP-rcDNA at the authentic end of virion rcDNA. Hence, our results favor a hypothesis that the removal of viral polymerase protein covalently linked to the 5′ end of the minus-strand DNA occurs inside the capsid in the cytoplasm and most possibly via a reaction that cleaves the phosphodiester bond between the tyrosine of the polymerase and the 5′ phosphoryl group of minus-strand DNA.
Fas Ligand Interactions Contribute to CD8+T-Cell-Mediated Control of West Nile Virus Infection in the Central Nervous System
Authors: Shrestha Bimmi , Diamond Michael S. 
Published: September 2007

ABSTRACTWest Nile virus (WNV) is a neurotropic flavivirus that causes encephalitis, most frequently in elderly and immunocompromised humans. Previous studies demonstrated that CD8+T cells utilize perforin-dependent cytolytic mechanisms to limit WNV infection. Nonetheless, the phenotype of perforin-deficient CD8+T cells was not as severe as that of an absence of CD8+T cells, suggesting additional effector control mechanisms. In this study, we evaluated the contribution of Fas-Fas ligand (FasL) interactions to CD8+T-cell-mediated control of WNV infection. Notably, the cell death receptor Fas was strongly upregulated on neurons in culture and in vivo after WNV infection.gldmice that were functionally deficient in FasL expression showed increased susceptibility to lethal WNV infection. Although antigen-specific priming of CD8+T cells in peripheral lymphoid tissues was normal ingldmice, increased central nervous system (CNS) viral burdens and delayed clearance were observed. Moreover, the adoptive transfer of WNV-primed wild-type but notgldCD8+T cells to recipient CD8−/−orgldmice efficiently limited infection in the CNS and enhanced survival rates. Overall, our data suggest that CD8+T cells also utilize FasL effector mechanisms to contain WNV infection in Fas-expressing neurons in the CNS.
B7 Costimulation Molecules Expressed from the Herpes Simplex Virus 2 Genome Rescue Immune Induction in B7-Deficient Mice
Authors: Thebeau Lydia G. , Vagvala Sri P. , Wong Yee M. , Morrison Lynda A. 
Published: September 2007

ABSTRACTThe interaction between B7 costimulation molecules on antigen-presenting cells and CD28 on antigen-responsive T cells is essential for T-cell activation and maturation of immune responses to herpes simplex virus (HSV) infection. Vaccine-induced immune responses also depend upon adequate upregulation of B7 costimulation molecules, but this signal may be limiting for replication-defective virus vaccines. We investigated whether expression of B7 costimulation molecules by a prototypical replication-defective antiviral vaccine could enhance immune responses to the vaccine and whether B7-1 and B7-2 would be similarly effective. We altered an ICP8−replication-defective strain of HSV type 2 (HSV-2), 5BlacZ, to encode either murine B7-1 or B7-2. B7 molecule expression was detected on the surface of cells infected in vitro and at the RNA level in tissue of immunized mice. Immunization of B7-1/B7-2 knockout mice with B7-encoding virus modestly expanded the number of gamma interferon-producing T cells and significantly augmented class-switched HSV-specific antibody responses compared with the parental virus. Mice immunized with either B7-expressing virus showed less replication of challenge virus in the genital mucosa than mice immunized with 5BlacZ, markedly fewer signs of genital and neurological disease, and little weight loss. Virtually all mice immunized with B7-encoding virus survived challenge with a large dose of HSV-2, whereas most 5BlacZ-immunized mice succumbed to infection. These results indicate that protective immune responses can be enhanced by the inclusion of host B7 costimulation molecules in a prototypical replication-defective HSV vaccine against HSV-2 genital infection and that B7-1 and B7-2 induce immune responses with similar capacities to fight HSV-2 infection.
High Fidelity of Murine Hepatitis Virus Replication Is Decreased in nsp14 Exoribonuclease Mutants
Authors: Eckerle Lance D. , Lu Xiaotao , Sperry Steven M. , Choi Leena , Denison Mark R. 
Published: September 2007

ABSTRACT
Replication fidelity of RNA virus genomes is constrained by the opposing necessities of generating sufficient diversity for adaptation and maintaining genetic stability, but it is unclear how the largest viral RNA genomes have evolved and are maintained under these constraints. A coronavirus (CoV) nonstructural protein, nsp14, contains conserved active-site motifs of cellular exonucleases, including DNA proofreading enzymes, and the severe acute respiratory syndrome CoV (SARS-CoV) nsp14 has 3′-to-5′ exoribonuclease (ExoN) activity in vitro. Here, we show that nsp14 ExoN remarkably increases replication fidelity of the CoV murine hepatitis virus (MHV). Replacement of conserved MHV ExoN active-site residues with alanines resulted in viable mutant viruses with growth and RNA synthesis defects that during passage accumulated 15-fold more mutations than wild-type virus without changes in growth fitness. The estimated mutation rate for ExoN mutants was similar to that reported for other RNA viruses, whereas that of wild-type MHV was less than the established rates for RNA viruses in general, suggesting that CoVs with intact ExoN replicate with unusually high fidelity. Our results indicate that nsp14 ExoN plays a critical role in prevention or repair of nucleotide incorporation errors during genome replication. The established mutants are unique tools to test the hypothesis that high replication fidelity is required for the evolution and stability of large RNA genomes.
Affinity Thresholds for Membrane Fusion Triggering by Viral Glycoproteins
Authors: Hasegawa Kosei , Hu Chunling , Nakamura Takafumi , Marks James D. , Russell Stephen J. , Peng Kah-Whye 
Published: September 2007

ABSTRACT

Enveloped viruses trigger membrane fusion to gain entry into cells. The receptor affinities of their attachment proteins vary greatly, from 10
−4
M to 10
−9
M, but the significance of this is unknown. Using six retargeted measles viruses that bind to Her-2/neu with a 5-log range in affinity, we show that receptor affinity has little impact on viral attachment but is nevertheless a key determinant of infectivity and intercellular fusion. For a given cell surface receptor density, there is an affinity threshold above which cell-cell fusion proceeds efficiently. Suprathreshold affinities do not further enhance the efficiency of membrane fusion.
Random T-Cell Receptor Recruitment in Human Immunodeficiency Virus Type 1 (HIV-1)-Specific CD8
+
T Cells from Genetically Identical Twins Infected with the Same HIV-1 Strain
Authors: Yu Xu G. , Lichterfeld Mathias , Williams Katie L. , Martinez-Picado Javier , Walker Bruce D. 
Published: September 2007

ABSTRACT

Human immunodeficiency virus type 1 (HIV-1) cytotoxic T-lymphocyte escape mutations represent both a major reason for loss of HIV immune control and a considerable challenge for HIV-1 vaccine design. Previous data suggest that initial HIV-1-specific CD8
+
T-cell responses are determined largely by viral and host genetics, but the mechanisms influencing the subsequent viral evolution are unclear. Here, we show a random recruitment of T-cell receptor (TCR) alpha and beta clonotypes of the initial HIV-1-specific CD8
+
T cells during primary infection in two genetically identical twins infected simultaneously with the same virus, suggesting that stochastic TCR recruitment of HIV-1-specific CD8
+
T cells contributes to the diverse and unpredictable HIV-1 sequence evolution.
Novel TRIM5 Isoforms Expressed byMacaca nemestrina
Authors: Brennan Greg , Kozyrev Yury , Kodama Toshiaki , Hu Shiu-Lok 
Published: September 2007

ABSTRACTThe TRIM5 family of proteins contains a RING domain, one or two B boxes, and a coiled-coil domain. TheTRIM5α isoform also encodes a C-terminal B30.2(SPRY) domain, differences within which define the breadth and potency of TRIM5α-mediated retroviral restriction. BecauseMacaca nemestrinaanimals are susceptible to some human immunodeficiency virus (HIV) isolates, we sought to determine if differences exist in theTRIM5gene and transcripts of these animals. We identified a two-nucleotide deletion (Δ2) in the transcript at the 5′ terminus of exon 7 in allM. nemestrinaTRIM5 cDNA clones examined. This frameshift results in a truncated protein of 300 amino acids lacking the B30.2(SPRY) domain, which we have named TRIM5θ. This deletion is likely due to a single nucleotide polymorphism that alters the 3′ splice site between intron 6 and exon 7. In some clones, a deletion of the entire 27-nucleotide exon 7 (Δexon7) resulted in the restoration of the TRIM5 open reading frame and the generation of another novel isoform,TRIM5η. There are 18 amino acid differences betweenM. nemestrinaTRIM5η andMacaca mulattaTRIM5α, some of which are at or near locations previously shown to affect the breadth and potency of TRIM5α-mediated restriction. Infectivity assays performed on permissive CrFK cells stably transduced with TRIM5η or TRIM5θ show that these isoforms are incapable of restricting either HIV type 1 (HIV-1) or simian immunodeficiency virus infection. The expression of TRIM5 alleles incapable of restricting HIV-1 infection may contribute to the previously reported increased susceptibility ofM. nemestrinato HIV-1 infection in vivo.
The design and application of effective written instructional material: a review of published work
Authors: Mayberry John F 
Published: September 2007

Abstract
This review will consider the evidence base for the format of educational material drawing on academic papers and the practice of the design industry. The core issues identified from the review are drawn together in guidelines for educational posters, text and web based material. The review deals with the design of written material both for use in leaflets and books as well as the impact of factors such as font type and size as well as colour on poster design. It sets these aspects of educational material within a research framework, which looks at impact on learning and subsequent change in practice. These issues are examined through a practical example of a poster designed for a regional gastroenterology meeting.
Environmental influences on the high mortality from colorectal cancer in African Americans
Authors: Sharma Sumit , O'Keefe Stephen J D 
Published: September 2007

Abstract
Colon cancer is the second leading cause of cancer related death in American adults. The incidence and mortality are highest in African Americans (AAs) (incidence: 52 per 100 000) and lowest in American Hispanics (37 per 100 000). Comparative studies with Native Africans (&lt;5 per 100 000) suggest that genetic susceptibility is an unlikely explanation and that environmental influences are to blame. Studies have suggested that risk is high because of excessive intakes of animal meat and fat products and differences in colonic bacterial metabolism, and that preventative and therapeutic management of colon cancer is compromised by the development of greater tumour virulence possibly resulting from disparities in educational and insurance status, screening behaviour, treatment patterns, social support, and access to and use of health care facilities. It should be possible to reduce the unacceptably higher rates of morbidity and mortality from colon cancer in AAs by dietary and lifestyle changes aimed at suppressing excessive intakes of animal meat and fat products, increasing the consumption of fresh fruit and vegetables, controlling energy balance, and by developing strategies to improve the availability, use and accessibility to health care resources.
Survey of the use of epinephrine (adrenaline) for anaphylaxis by junior hospital doctors
Authors: Jose Ricardo , Clesham Gerald J 
Published: September 2007

Abstract

Background
Anaphylaxis is a life threatening reaction where prompt and appropriate management can save lives. Epinephrine (adrenaline) is the treatment of choice; however, the recommended dose and route of administration of epinephrine used in the management of anaphylaxis is different from that used in the management of cardiac arrest.

Objective
To investigate how junior doctors would administer epinephrine in a case of anaphylactic shock in an adult patient.

Methods
Junior medical staff in two district general hospitals were assessed with a short questionnaire.

Results
95 junior hospital doctors were assessed. The majority (94%) would administer epinephrine as the life saving drug of choice, but only 16.8% would administer it as recommended by the UK Resuscitation Council Guidelines.

Conclusion
Junior doctors may be called to make immediate management decisions in patients with anaphylaxis; however, widespread confusion exists regarding the dose and route of administration of epinephrine. Strategies to improve education and access to appropriate drugs are needed. A labelled “anaphylaxis box” on every resuscitation trolley, containing the dose of epinephrine with clear labelling for intramuscular use, may be one solution.
Muscle metabolic responses during 16 hours of intermittent heavy exercise
Authors: Green H.J. , Duhamel T.A. , Holloway G.P. , Moule J. , Ouyang J. , Ranney D. , Tupling A.R. 
Published: September 2007

The alterations in muscle metabolism were investigated in response to repeated sessions of heavy intermittent exercise performed over 16 h. Tissue samples were extracted from the vastus lateralis muscle before (B) and after (A) 6 min of cycling at approximately 91% peak aerobic power at repetitions one (R1), two (R2), nine (R9), and sixteen (R16) in 13 untrained volunteers (peak aerobic power = 44.3 ± 0.66 mL·kg–1·min–1, mean ± SE). Metabolite content (mmol·(kg dry mass)–1) in homogenates at R1 indicated decreases (p < 0.05) in ATP (21.9 ± 0.62 vs. 17.7 ± 0.68) and phosphocreatine (80.3 ± 2.0 vs. 8.56 ± 1.5) and increases (p < 0.05) in inosine monophosphate (IMP, 0.077 ± 0.12 vs. 3.63 ± 0.85) and lactate (3.80 ± 0.57 vs. 84.6 ± 10.3). The content (µmol·(kg dry mass)–1) of calculated free ADP ([ADPf], 86.4 ± 5.5 vs. 1014 ± 237) and free AMP ([AMPf], 0.32 ± 0.03 vs. 78.4 ± 31) also increased (p < 0.05). No differences were observed between R1 and R2. By R9 and continuing to R16, pronounced reductions (p < 0.05) at A were observed in IMP (72.2%), [ADPf] (58.7%), [AMPf] (85.5%), and lactate (41.3%). The 16-hour protocol resulted in an 89.7% depletion (p < 0.05) of muscle glycogen. Repetition-dependent increases were also observed in oxygen consumption during exercise. It is concluded that repetitive heavy exercise results in less of a disturbance in phosphorylation potential, possibly as a result of increased mitochondrial respiration during the rest-to-work non-steady-state transition.
The time course of inflammatory cytokine secretion in a rat model of postoperative pain does not coincide with the onset of mechanical hyperalgesia
Authors: Loram Lisa C. , Themistocleous Andreas C. , Fick Linda G. , Kamerman Peter R. 
Published: September 2007

We characterized the time course of inflammatory cytokine release at the site of injury and in plasma after surgery on the rat tail. Anesthetized Sprague–Dawley rats had a 20 mm long incision made through the skin and fascia of their tails. Control rats were anesthetized, but no incision was made. Blood and tissue samples were taken 2 h and 1, 2, 4, and 8 days after surgery and analysed by ELISA for interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and cytokine-induced neutrophil chemoattractant-1 (CINC-1). In another group of rats, daily behavioral measurements were made of the rats’ responses to a blunt noxious mechanical stimulus (4 Newtons) applied to their tails. Primary hyperalgesia developed within 2 h of surgery and lasted for 6 days. The tissue concentrations of IL-1β, IL-6, and CINC-1 increased within 24 h of surgery, and TNF-α concentration increased within 48 h of surgery. Thereafter, cytokine concentrations remained elevated for 4 (IL-1β and IL-6) to 8 days (CINC-1, TNF-α) after surgery. Control animals did not develop hyperalgesia and no changes in cytokines concentrations were detected. Thus, in our model of postoperative pain, secretion of inflammatory cytokines IL-1β, IL-6, TNF-α, and CINC-1 was not essential for the initiation of postoperative hyperalgesia.
Glutathione Peroxidase 3, Deleted or Methylated in Prostate Cancer, Suppresses Prostate Cancer Growth and Metastasis
Authors: Yu Yan P. , Yu Guoying , Tseng George , Cieply Kathleen , Nelson Joel , Defrances Marie , Zarnegar Reza , Michalopoulos George , Luo Jian-Hua 
Published: September 2007

Abstract
Glutathione peroxidase 3 is a selenium-dependent enzyme playing a critical role in detoxifying reactive oxidative species and maintaining the genetic integrity of mammalian cells. In this report, we found that the expression of glutathione peroxidase 3 (GPx3) was widely inactivated in prostate cancers. Complete inactivation of GPx3 correlates with a poor clinical outcome. Deletions (hemizygous and homozygous) of GPx3 gene are frequent in prostate cancer samples, occurring in 39% of the samples studied. The rate of methylation of the GPx3 exon 1 region in prostate cancer samples reaches 90%. Overexpression of GPx3 in prostate cancer cell lines induced the suppression of colony formation and anchorage-independent growth of PC3, LNCaP, and Du145 cells. PC3 cells overexpressing GPx3 reduced invasiveness in Matrigel transmigration analysis by an average of 2.7-fold. Xenografted PC3 cells expressing GPx3 showed reduction in tumor volume by 4.8-fold, elimination of metastasis (0/16 versus 7/16), and reduction of animal death (3/16 versus 16/16). The tumor suppressor activity of GPx3 seems to relate to its ability to suppress the expression of c-met. The present findings suggest that GPx3 is a novel tumor suppressor gene. [Cancer Res 2007;67(17):8043–50]