bluuebunny/crossref_metadata_2025_split huggingface dataset:
INX-08189, a Phosphoramidate Prodrug of 6-
O
-Methyl-2′-
C
-Methyl Guanosine, Is a Potent Inhibitor of Hepatitis C Virus Replication with Excellent Pharmacokinetic and Pharmacodynamic Properties
Authors: Vernachio John H. , Bleiman Blair , Bryant K. Dawn , Chamberlain Stanley , Hunley Damound , Hutchins Jeff , Ames Brenda , Gorovits Elena , Ganguly Babita , Hall Andrea , Kolykhalov Alexander , Liu Yule , Muhammad Jerry , Raja Nicholas , Walters C. Robin , Wang Jin , Williams Karen , Patti Joseph M. , Henson Geoffrey , Madela Karolina , Aljarah Mohamed , Gilles Arnaud , McGuigan Christopher 
Published: March 2011

ABSTRACT

INX-08189 is an aryl-phosphoramidate of 6-
O
-methyl-2′-
C
-methyl guanosine. INX-08189 was highly potent in replicon assays, with a 50% effective concentration of 10 ± 6 nM against hepatitis C genotype 1b at 72 h. The inhibitory effect on viral replication was rapid, with a 50% effective concentration (EC
50
) of 35 ± 8 nM at 24 h. An intracellular 2′-
C
-methyl guanosine triphosphate (2′-
C
-MeGTP) concentration of 2.43 ± 0.42 pmol/10
6
cells was sufficient to achieve 90% inhibition of viral replication.
In vitro
resistance studies confirmed that the S282T mutation in the NS5b gene conferred an approximately 10-fold reduction in sensitivity to INX-08189. However, the complete inhibition of S282T mutant replicons still could be achieved with an EC
90
of 344 ± 170 nM. Drug combination studies of INX-08189 and ribavirin indicated significant synergy in antiviral potency both in wild-type and S282T-expressing replicons. Genotype 1b replicons could be cleared after 14 days of culture when exposed to as little as 20 nM INX-08189. No evidence of mitochondrial toxicity was observed after 14 days of INX-08189 exposure in both HepG2 and CEM human cell lines.
In vivo
studies of rats and cynomolgus monkeys demonstrated that 2′-
C
-MeGTP concentrations in liver equivalent to the EC
90
could be attained after a single oral dose of INX-08189. Rat liver 2′-
C
-MeGTP concentrations were proportional to dose, sustained for greater than 24 h, and correlated with plasma concentrations of the nucleoside metabolite 2′-
C
-methyl guanosine. The characteristics displayed by INX-08189 support its continued development as a clinical candidate for the treatment of chronic HCV infection.
Ligand-Dependent Disorder of the Ω Loop Observed in Extended-Spectrum SHV-Type β-Lactamase
Authors: Sampson Jared M. , Ke Wei , Bethel Christopher R. , Pagadala S. R. R. , Nottingham Michael D. , Bonomo Robert A. , Buynak John D. , van den Akker Focco 
Published: March 2011

ABSTRACT

Among Gram-negative bacteria, resistance to β-lactams is mediated primarily by β-lactamases (EC 3.2.6.5), periplasmic enzymes that inactivate β-lactam antibiotics. Substitutions at critical amino acid positions in the class A β-lactamase families result in enzymes that can hydrolyze extended-spectrum cephalosporins, thus demonstrating an “extended-spectrum” β-lactamase (ESBL) phenotype. Using SHV ESBLs with substitutions in the Ω loop (R164H and R164S) as target enzymes to understand this enhanced biochemical capability and to serve as a basis for novel β-lactamase inhibitor development, we determined the spectra of activity and crystal structures of these variants. We also studied the inactivation of the R164H and R164S mutants with tazobactam and SA2-13, a unique β-lactamase inhibitor that undergoes a distinctive reaction chemistry in the active site. We noted that the reduced

K
i

values for the R164H and R164S mutants with SA2-13 are comparable to those with tazobactam (submicromolar). The apo enzyme crystal structures of the R164H and R164S SHV variants revealed an ordered Ω loop architecture that became disordered when SA2-13 was bound. Important structural alterations that result from the binding of SA2-13 explain the enhanced susceptibility of these ESBL enzymes to this inhibitor and highlight ligand-dependent Ω loop flexibility as a mechanism for accommodating and hydrolyzing β-lactam substrates.
Evaluation of CLSI M44-A2 Disk Diffusion and Associated Breakpoint Testing of Caspofungin and Micafungin Using a Well-Characterized Panel of Wild-Type and
fks
Hot Spot Mutant Candida Isolates
Authors: Arendrup Maiken Cavling , Park Steven , Brown Steven , Pfaller Michael , Perlin David S. 
Published: March 2011

ABSTRACT

Disk diffusion testing has recently been standardized by the CLSI, and susceptibility breakpoints have been established for several antifungal compounds. For caspofungin, 5-μg disks are approved, and for micafungin, 10-μg disks are under evaluation. We evaluated the performances of caspofungin and micafungin disk testing using a panel of
Candida
isolates with and without known
FKS
echinocandin resistance mechanisms. Disk diffusion and microdilution assays were performed strictly according to CLSI documents M44-A2 and M27-A3. Eighty-nine clinical
Candida
isolates were included:
Candida albicans
(20 isolates/10 mutants),
C. glabrata
(19 isolates/10 mutants),
C. dubliniensis
(2 isolates/1 mutant),
C. krusei
(16 isolates/3 mutants),
C. parapsilosis
(14 isolates/0 mutants), and
C. tropicalis
(18 isolates/4 mutants). Quality control strains were
C. parapsilosis
ATCC 22019 and
C. krusei
ATCC 6258. The correlations between zone diameters and MIC results were good for both compounds, with identical susceptibility classifications for 93.3% of the isolates by applying the current CLSI breakpoints. However, the numbers of
fks
hot spot mutant isolates misclassified as being susceptible (S) (very major errors [VMEs]) were high (61% for caspofungin [S, ≥11 mm] and 93% for micafungin [S, ≥14 mm]). Changing the disk diffusion breakpoint to S at ≥22 mm significantly improved the discrimination. For caspofungin, 1 VME was detected (a
C. tropicalis
isolate with an F76S substitution) (3.5%), and for micafungin, 10 VMEs were detected, the majority of which were for
C. glabrata
(8/10). The broadest separation between zone diameter ranges for wild-type (WT) and mutant isolates was seen for caspofungin (6 to 12 mm versus −4 to 7 mm). In conclusion, caspofungin disk diffusion testing with a modified breakpoint led to excellent separation between WT and mutant isolates for all
Candida
species.
Selection of Clinically Relevant Protease Inhibitor-Resistant Viruses Using the Genotype 2a Hepatitis C Virus Infection System
Authors: Cheng Guofeng , Chan Katie , Yang Huiling , Corsa Amy , Pokrovskii Maria , Paulson Matthew , Bahador Gina , Zhong Weidong , Delaney William 
Published: March 2011

ABSTRACT

Treatment of patients infected with hepatitis C virus (HCV) with direct acting antivirals can lead to the emergence of drug-resistant variants that may pose a long-term threat to viral eradication. HCV replicons have been used to select resistance mutations; however, genotype 2a JFH-1-based viruses provide the opportunity to perform resistance selection in a
bona fide
infection system. In this study, we used a tissue culture-adapted J6/JFH-1 virus to select resistance to the NS3 protease inhibitors BILN-2061 and VX-950. Lunet-CD81 cells were infected with J6/JFH-1 virus and maintained in the presence of inhibitors until high-titer viral supernatant was produced. Viral supernatants were passaged over naive cells at escalating drug concentrations, and the resulting viruses were then characterized. Three NS3 resistance mutations were identified in BILN-2061-resistant viruses: A156G, D168A, and D168V. Interestingly, D168A, D168V, and A156T/V, but not A156G, were selected in parallel using a genotype 2a replicon. For VX-950, the T54A and A156S NS3 resistance mutations were identified in the virus selections, whereas only A156T/V emerged in genotype 2a replicon selections. Of note, VX-950 resistance mutations selected using the 2a virus (T54A and A156S) were also observed during VX-950 clinical studies in genotype 2 patients. We also performed viral fitness evaluations and determined that the mutations selected in the viral system did not confer marked reductions in virus production kinetics or peak titers. Overall, the HCV infection system is an efficient tool for drug resistance selections and has advantages for the rapid identification and characterization of clinically relevant resistance mutations.
Overexpression of AmpC and Efflux Pumps in Pseudomonas aeruginosa Isolates from Bloodstream Infections: Prevalence and Impact on Resistance in a Spanish Multicenter Study
Authors: Cabot Gabriel , Ocampo-Sosa Alain A. , Tubau Fe , Macia María D. , Rodríguez Cristina , Moya Bartolomé , Zamorano Laura , Suárez Cristina , Peña Carmen , Martínez-Martínez Luis , Oliver Antonio ,   the Spanish Network for Research in Infectious Diseases (REIPI)
Published: March 2011

ABSTRACT

The prevalence and impact of the overexpression of AmpC and efflux pumps were evaluated with a collection of 190
Pseudomonas aeruginosa
isolates recovered from bloodstream infections in a 2008 multicenter study (10 hospitals) in Spain. The MICs of a panel of 13 antipseudomonal agents were determined by microdilution, and the expressions of
ampC
,
mexB
,
mexY
,
mexD
, and
mexF
were determined by real-time reverse transcription (RT)-PCR. Up to 39% of the isolates overexpressed at least one of the mechanisms.
ampC
overexpression (24.2%) was the most prevalent mechanism, followed by
mexY
(13.2%),
mexB
(12.6%),
mexF
(4.2%), and
mexD
(2.2%). The overexpression of
mexB
plus
mexY
, documented for 5.3% of the isolates, was the only combination showing a significantly (
P
= 0.02) higher prevalence than expected from the frequencies of the individual mechanisms (1.6%). Additionally, all imipenem-resistant isolates studied (25 representative isolates) showed inactivating mutations in
oprD
. Most of the isolates nonsusceptible to piperacillin-tazobactam (96%) and ceftazidime (84%) overexpressed
ampC
, while
mexB
(25%) and
mexY
(29%) overexpressions gained relevance among cefepime-nonsusceptible isolates. Nevertheless, the prevalence of
mexY
overexpression was highest among tobramycin-nonsusceptible isolates (37%), and that of
mexB
was highest among meropenem-nonsusceptible isolates (33%). Regarding ciprofloxacin-resistant isolates, besides the expected increased prevalence of efflux pump overexpression, a highly significant link to
ampC
overexpression was documented for the first time: up to 52% of ciprofloxacin-nonsusceptible isolates overexpressed
ampC
, sharply contrasting with the 24% documented for the complete collection (
P
< 0.001). In summary, mutation-driven resistance was frequent in
P. aeruginosa
isolates from bloodstream infections, whereas metallo-β-lactamases, detected in 2 isolates (1%) producing VIM-2, although with increasing prevalences, were still uncommon.
In VitroandIn VivoAntiplasmodial Activities of Risedronate and Its Interference with Protein Prenylation in Plasmodium falciparum
Authors: Jordão Fabiana Morandi , Saito Alexandre Yukio , Miguel Danilo Ciccone , de Jesus Peres Valnice , Kimura Emília Akemi , Katzin Alejandro Miguel 
Published: March 2011

ABSTRACTThe increasing resistance of malarial parasites to almost all available drugs calls for the identification of new compounds and the detection of novel targets. Here, we establish the antimalarial activities of risedronate, one of the most potent bisphosphonates clinically used to treat bone resorption diseases, against blood stages ofPlasmodium falciparum(50% inhibitory concentration [IC50] of 20.3 ± 1.0 μM). We also suggest a mechanism of action for risedronate against the intraerythrocytic stage ofP. falciparumand show that protein prenylation seems to be modulated directly by this drug. Risedronate inhibits the transfer of the farnesyl pyrophosphate group to parasite proteins, an effect not observed for the transfer of geranylgeranyl pyrophosphate. Ourin vivoexperiments further demonstrate that risedronate leads to an 88.9% inhibition of the rodent parasitePlasmodium bergheiin mice on the seventh day of treatment; however, risedronate treatment did not result in a general increase of survival rates.
Analysis of the Borrelia burgdorferi Cyclic-di-GMP-Binding Protein PlzA Reveals a Role in Motility and Virulence
Authors: Pitzer Joshua E. , Sultan Syed Z. , Hayakawa Yoshihiro , Hobbs Gerry , Miller Michael R. , Motaleb Md A. 
Published: March 2011

ABSTRACT

The cyclic-dimeric-GMP (c-di-GMP)-binding protein PilZ has been implicated in bacterial motility and pathogenesis. Although BB0733 (PlzA), the only PilZ domain-containing protein in
Borrelia burgdorferi
, was reported to bind c-di-GMP, neither its role in motility or virulence nor it's affinity for c-di-GMP has been reported. We determined that PlzA specifically binds c-di-GMP with high affinity (dissociation constant [

K
d

], 1.25 μM), consistent with

K
d

values reported for c-di-GMP-binding proteins from other bacteria. Inactivation of the monocistronically transcribed
plzA
resulted in an opaque/solid colony morphology, whereas the wild-type colonies were translucent. While the swimming pattern of mutant cells appeared normal, on swarm plates, mutant cells exhibited a significantly reduced swarm diameter, demonstrating a role of
plzA
in motility. Furthermore, the
plzA
mutant cells were significantly less infectious in experimental mice (as determined by 50% infectious dose [ID
50
]) relative to wild-type spirochetes. The mutant also had survival rates in fed ticks lower than those of the wild type. Consequently,
plzA
mutant cells failed to complete the mouse-tick-mouse infection cycle, indicating
plzA
is essential for the enzootic life cycle of
B. burgdorferi
. All of these defects were corrected when the mutant was complemented in
cis
. We propose that failure of
plzA
mutant cells to infect mice was due to altered motility; however, the possibility that an unidentified factor(s) contributed to interruption of the
B. burgdorferi
enzootic life cycle cannot yet be excluded.
Regulation of Trypanosoma cruzi-Induced Myocarditis by Programmed Death Cell Receptor 1
Authors: Gutierrez Fredy R. S. , Mariano Flávia S. , Oliveira Carlo J. F. , Pavanelli Wander R. , Guedes Paulo M. M. , Silva Grace K. , Campanelli Ana P. , Milanezi Cristiane M. , Azuma Miyuki , Honjo Tasuku , Teixeira Mauro M. , Aliberti Julio C. S. , Silva João S. 
Published: March 2011

ABSTRACTTrypanosoma cruziinfection causes intense myocarditis, leading to cardiomyopathy and severe cardiac dysfunction. Protective adaptive immunity depends on balanced signaling through a T cell receptor and coreceptors expressed on the T cell surface. Such coreceptors can trigger stimulatory or inhibitory signals after binding to their ligands in antigen-presenting cells (APC).T. cruzimodulates the expression of coreceptors in lymphocytes after infection. Deregulated inflammation may be due to unbalanced expression of these molecules. Programmed death cell receptor 1 (PD-1) is a negative T cell coreceptor that has been associated with T cell anergy or exhaustion and persistent intracellular infections. We aimed to study the role of PD-1 duringT. cruzi-induced acute myocarditis in mice. Cytometry assays showed that PD-1 and its ligands are strongly upregulated in lymphocytes and APC in response toT. cruziinfectionin vivoandin vitro. Lymphocytes infiltrating the myocardium exhibited high levels of expression of these molecules. An increased cardiac inflammatory response was found in mice treated with blocking antibodies against PD-1, PD-L1, and to a lesser extent, PD-L2, compared to that found in mice treated with rat IgG. Similar results in PD-1−/−mice were obtained. Moreover, the PD-1 blockade/deficiency led to reduced parasitemia and tissue parasitism but increased mortality. These results suggest the participation of a PD-1 signaling pathway in the control of acute myocarditis induced byT. cruziand provide additional insight into the regulatory mechanisms in the pathogenesis of Chagas' disease.
Heterologous Plasmid DNA Prime-Recombinant Human Adenovirus 5 Boost Vaccination Generates a Stable Pool of Protective Long-Lived CD8
+
T Effector Memory Cells Specific for a Human Parasite, Trypanosoma cruzi
Authors: Rigato Paula Ordonhez , de Alencar Bruna C. , de Vasconcelos José Ronnie C. , Dominguez Mariana R. , Araújo Adriano F. , Machado Alexandre V. , Gazzinelli Ricardo T. , Bruna-Romero Oscar , Rodrigues Mauricio M. 
Published: March 2011

ABSTRACT

Recently, we described a heterologous prime-boost strategy using plasmid DNA followed by replication-defective human recombinant adenovirus type 5 as a powerful strategy to elicit long-lived CD8
+
T-cell-mediated protective immunity against experimental systemic infection of mice with a human intracellular protozoan parasite,
Trypanosoma cruzi
. In the present study, we further characterized the protective long-lived CD8
+
T cells. We compared several functional and phenotypic aspects of specific CD8
+
T cells present 14 or 98 days after the last immunizing dose and found the following: (i) the numbers of specific cells were similar, as determined by multimer staining or by determining the number of gamma interferon (IFN-γ)-secreting cells by enzyme-linked immunospot (ELISPOT) assay; (ii) these cells were equally cytotoxic
in vivo
; (iii) following
in vitro
stimulation, a slight decline in the frequency of multifunctional cells (CD107a
+
IFN-γ
+
or CD107a
+
IFN-γ
+
tumor necrosis factor alpha positive [TNF-α
+
]) was paralleled by a significant increase of CD107a singly positive cells after 98 days; (iv) the expression of several surface markers was identical, except for the reexpression of CD127 after 98 days; (v) the use of genetically deficient mice revealed a role for interleukin-12 (IL-12)/IL-23, but not IFN-γ, in the maintenance of these memory cells; and (vi) subsequent immunizations with an unrelated virus or a plasmid vaccine or the depletion of CD4
+
T cells did not significantly erode the number or function of these CD8
+
T cells during the 15-week period. From these results, we concluded that heterologous plasmid DNA prime-adenovirus boost vaccination generated a stable pool of functional protective long-lived CD8
+
T cells with an effector memory phenotype.
ArcA-Regulated Glycosyltransferase Lic2B Promotes Complement Evasion and Pathogenesis of Nontypeable Haemophilus influenzae
Authors: Wong Sandy M. S. , St. Michael Frank , Cox Andrew , Ram Sanjay , Akerley Brian J. 
Published: March 2011

ABSTRACTSignaling mechanisms used byHaemophilus influenzaeto adapt to conditions it encounters during stages of infection and pathogenesis are not well understood. The ArcAB two-component signal transduction system controls gene expression in response to respiratory conditions of growth and contributes to resistance to bactericidal effects of serum and to bloodstream infection byH. influenzae. We show that ArcA of nontypeableH. influenzae(NTHI) activates expression of a glycosyltransferase gene,lic2B.Structural comparison of the lipooligosaccharide (LOS) of alic2Bmutant to that of the wild-type strain NT127 revealed thatlic2Bis required for addition of a galactose residue to the LOS outer core. Thelic2Bgene was crucial for optimal survival of NTHI in a mouse model of bacteremia and for evasion of serum complement. The results demonstrate that ArcA, which controls cellular metabolism in response to environmental reduction and oxidation (redox) conditions, also coordinately controls genes that are critical for immune evasion, providing evidence that NTHI integrates redox signals to regulate specific countermeasures against host defense.
Recognition and Blocking of Innate Immunity Cells by Candida albicans Chitin
Authors: Mora-Montes Héctor M. , Netea Mihai G. , Ferwerda Gerben , Lenardon Megan D. , Brown Gordon D. , Mistry Anita R. , Kullberg Bart Jan , O'Callaghan Chris A. , Sheth Chirag C. , Odds Frank C. , Brown Alistair J. P. , Munro Carol A. , Gow Neil A. R. 
Published: March 2011

ABSTRACTChitin is a skeletal cell wall polysaccharide of the inner cell wall of fungal pathogens. As yet, little about its role during fungus-host immune cell interactions is known. We show here that ultrapurified chitin fromCandida albicanscell walls did not stimulate cytokine production directly but blocked the recognition ofC. albicansby human peripheral blood mononuclear cells (PBMCs) and murine macrophages, leading to significant reductions in cytokine production. Chitin did not affect the induction of cytokines stimulated by bacterial cells or lipopolysaccharide (LPS), indicating that blocking was not due to steric masking of specific receptors. Toll-like receptor 2 (TLR2), TLR4, and Mincle (the macrophage-inducible C-type lectin) were not required for interactions with chitin. Dectin-1 was required for immune blocking but did not bind chitin directly. Cytokine stimulation was significantly reduced upon stimulation of PBMCs with heat-killed chitin-deficientC. albicanscells but not with live cells. Therefore, chitin is normally not exposed to cells of the innate immune system but is capable of influencing immune recognition by blocking dectin-1-mediated engagement with fungal cell walls.
Direct Current Electrical Stimulation of Acupuncture Needles for Peripheral Nerve Regeneration: An Exploratory Case Series
Authors: Inoue Motohiro , Katsumi Yasukazu , Itoi Megumi , Hojo Tatsuya , Nakajima Miwa , Ohashi Suzuyo , Oi Yuki , Kitakoji Hiroshi 
Published: March 2011

Objective To examine the therapeutic effect of a novel therapeutic method based on electroacupuncture with intermittent direct current (DCEA) and associated adverse events in patients with peripheral nerve damage and a poor clinical prognosis. Methods In seven older patients with peripheral nerve damage (neurapraxia 2, axonotmesis 4, neuromesis 1), an acupuncture needle connected to an anode electrode was inserted proximal to the site of the injury along the route of the nerve, while the cathode electrode was inserted into the innervated muscle, and DCEA was performed (100 Hz for 20 min, weekly). Muscular paralysis was evaluated weekly with manual muscle testing, the active range of motion of joints related to the muscular paralysis and, when necessary, needle electromyography. Adverse events were also recorded during the course of the treatment. Results Complete functional recovery was observed in the two cases with neurapraxia and two with axonotmesis, while one axonotmesis case achieved improvement and the other showed reinnervation potential without functional recovery. No improvement was observed in the neurotmesis case. Pigmentation of the skin where the anode needle was inserted occurred in three cases. Although there was no definite causal link, one case showed excessive formation and resorption of bone in the area close to the cathode needle site. Discussion Accelerated nerve regeneration caused by DCEA may contribute to recovery. The skin pigmentation and callus formation suggest that the shape of the anode electrode, current intensity and other factors should be examined to establish a safer treatment method.