bluuebunny/crossref_metadata_2025_split huggingface dataset:
Target Gene Sequencing To Characterize the Penicillin G Susceptibility of
Neisseria meningitidis
Authors: Taha Muhamed-Kheir , Vázquez Julio A. , Hong Eva , Bennett Desiree E. , Bertrand Sophie , Bukovski Suzana , Cafferkey Mary T. , Carion Françoise , Christensen Jens Jørgen , Diggle Mathew , Edwards Giles , Enríquez Rocío , Fazio Cecilia , Frosch Matthias , Heuberger Sigrid , Hoffmann Steen , Jolley Keith A. , Kadlubowski Marcin , Kechrid Amel , Kesanopoulos Konstantinos , Kriz Paula , Lambertsen Lotte , Levenet Ileanna , Musilek Martin , Paragi Metka , Saguer Aouatef , Skoczynska Anna , Stefanelli Paola , Thulin Sara , Tzanakaki Georgina , Unemo Magnus , Vogel Ulrich , Zarantonelli Maria Leticia 
Published: May 2007

ABSTRACT

Clinical isolates of
Neisseria meningitidis
with reduced susceptibility to penicillin G (intermediate isolates, Pen
I
) harbor alterations in the
penA
gene encoding the penicillin binding protein 2 (PBP2). A 402-bp DNA fragment in the 3′ half of
penA
was sequenced from a collection of 1,670 meningococcal clinical isolates from 22 countries that spanned 60 years. Phenotyping, genotyping, and the determination of MICs of penicillin G were also performed. A total of 139 different
penA
alleles were detected with 38 alleles that were highly related, clustered together in maximum-likelihood analysis and corresponded to the penicillin G-susceptible isolates. The remaining 101
penA
alleles were highly diverse, corresponded to different genotypes or phenotypes, and accounted for 38% of isolates, but no clonal expansion was detected. Analysis of the altered alleles that were represented by at least five isolates showed high correlation with the Pen
I
phenotype. The deduced amino acid sequence of the corresponding PBP2 comprised five amino acid residues that were always altered. This correlation was not complete for rare alleles, suggesting that other mechanisms may also be involved in conferring reduced susceptibility to penicillin. Evidence of mosaic structures through events of interspecies recombination was also detected in altered alleles. A new website was created based on the data from this work (
http://neisseria.org/nm/typing/penA
). These data argue for the use of
penA
sequencing to identify isolates with reduced susceptibility to penicillin G and as a tool to improve typing of meningococcal isolates, as well as to analyze DNA exchange among
Neisseria
species.
Inhaled Large Porous Particles of Capreomycin for Treatment of Tuberculosis in a Guinea Pig Model
Authors: Garcia-Contreras L. , Fiegel J. , Telko M. J. , Elbert K. , Hawi A. , Thomas M. , VerBerkmoes J. , Germishuizen W. A. , Fourie P. B. , Hickey A. J. , Edwards D. 
Published: May 2007

ABSTRACT
Capreomycin is used for the treatment of multidrug-resistant tuberculosis (MDR-TB), but it is limited therapeutically by its severe side effects. The objectives of the present studies were (i) to design low-density porous capreomycin sulfate particles for efficient pulmonary delivery to improve local and systemic drug bioavailability and capacity to reduce the bacillary load in the lungs in a manner similar to that achieved with intramuscular injections; (ii) to determine pharmacokinetic parameters after pulmonary administration of these capreomycin particles; and (iii) to evaluate the efficacy of these particles in treating animals in a small-aerosol-inoculum guinea pig model of TB. Capreomycin particles were manufactured by spray drying and characterized in terms of size and drug content. Pharmacokinetic parameters were determined by noncompartmental methods with healthy guinea pigs after administration of capreomycin particles by insufflation. The efficacy of the particles was evaluated by histopathological analysis and in terms of wet organ weight and bacterial burden in TB-infected animals. Lungs of animals receiving a 14.5-mg/kg dose of capreomycin particles showed significantly lower wet weights and smaller bacterial burdens than those of animals receiving any other treatment. These results were supported by histopathological analysis. The feasibility of inhaling capreomycin in a novel powder form, with the ultimate objective of the treatment of MDR-TB, is demonstrated by pharmacokinetic and pharmacodynamic studies with guinea pigs. If applied to humans with MDR-TB, such a therapeutic approach might simplify drug delivery by eliminating injections and might reduce adverse effects through lowering the dose.
Population Pharmacokinetics of Tafenoquine during Malaria Prophylaxis in Healthy Subjects
Authors: Charles Bruce G. , Miller Ann K. , Nasveld Peter E. , Reid Mark G. , Harris Ivor E. , Edstein Michael D. 
Published: May 2007

ABSTRACT

The population pharmacokinetics of tafenoquine were studied in Australian soldiers taking tafenoquine for malarial prophylaxis. The subjects (476 males and 14 females) received a loading dose of 200 mg tafenoquine base daily for 3 days, followed by a weekly dose of 200 mg tafenoquine for 6 months. Blood samples were collected from each subject after the last loading dose and then at weeks 4, 8, and 16. Plasma tafenoquine concentrations were determined by liquid chromatography-tandem mass spectrometry. Population modeling was performed with NONMEM, using a one-compartment model. Typical values of the first-order absorption rate constant (

K
a

), clearance (CL/
F
), and volume of distribution (
V
/
F
) were 0.243 h
−1
, 0.056 liters/h/kg, and 23.7 liters/kg, respectively. The intersubject variability (coefficient of variation) in CL/
F
and
V
/
F
was 18% and 22%, respectively. The interoccasion variability in CL/
F
was 18%, and the mean elimination half-life was 12.7 days. A positive linear association between weight and both CL/
F
and
V
/
F
was found, but this had insufficient impact to warrant dosage adjustments. Model robustness was assessed by a nonparametric bootstrap (200 samples). A degenerate visual predictive check indicated that the raw data mirrored the postdose concentration-time profiles simulated (
n
= 1,000) from the final model. Individual pharmacokinetic estimates for tafenoquine did not predict the prophylactic outcome with the drug for four subjects who relapsed with
Plasmodium vivax
malaria, as they had similar pharmacokinetics to those who were free of malaria infection. No obvious pattern existed between the plasma tafenoquine concentration and the pharmacokinetic parameter values for subjects with and without drug-associated moderate or severe adverse events. This validated population pharmacokinetic model satisfactorily describes the disposition and variability of tafenoquine used for long-term malaria prophylaxis in a large cohort of soldiers on military deployment.
In Vitro Interactions between Apricitabine and Other Deoxycytidine Analogues
Authors: Bethell R. , De Muys J. , Lippens J. , Richard A. , Hamelin B. , Ren C. , Collins P. 
Published: May 2007

ABSTRACT

Apricitabine is a novel deoxycytidine analogue reverse transcriptase inhibitor that is under development for the treatment of human immunodeficiency virus type 1 (HIV-1) infection. Apricitabine is phosphorylated to its active triphosphate by deoxycytidine kinase, which is also responsible for the intracellular phosphorylation of lamivudine (3TC) and emtricitabine (FTC); hence, in vitro studies were performed to investigate possible interactions between apricitabine and these agents. Human peripheral blood mononuclear cells (PBMC) were incubated for 24 h with various concentrations of
3
H-labeled or unlabeled apricitabine, 3TC, or FTC. Intracellular concentrations of parent compounds and their phosphorylated derivatives were measured by high-performance liquid chromatography. In other experiments, viral reverse transcriptase activity was measured in PBMC infected with HIV-1 bearing M184V in the presence of various concentrations of apricitabine and 3TC. [
3
H]apricitabine and [
3
H]3TC were metabolized intracellularly to form mono-, di-, and triphosphates. 3TC and FTC (1 to 10 μM) produced concentration-dependent decreases in apricitabine phosphorylation; in contrast, apricitabine at concentrations of up to 30 μM had no effect on the phosphorylation of 3TC or FTC. The combination of apricitabine and 3TC reduced the antiviral activity of apricitabine against HIV-1: apricitabine concentrations producing 50% inhibition of viral reverse transcriptase were increased two- to fivefold in the presence of 3TC. These findings suggest that nucleoside reverse transcriptase inhibitors with similar modes of action may show biochemical interactions that affect their antiviral efficacy. It is therefore essential that potential interactions between combinations of new and existing agents be thoroughly investigated before such combinations are introduced into clinical practice.
Systematic Derivation of Marker Sets for Staphylococcal Cassette Chromosome
mec
Typing
Authors: Stephens Alex J. , Huygens Flavia , Giffard Philip M. 
Published: May 2007

ABSTRACT

The aim of this study was to identify optimized sets of genotyping targets for the staphylococcal cassette chromosome
mec
(SCC
mec
). We analyzed the gene contents of 46 SCC
mec
variants in order to identify minimal subsets of targets that provide useful resolution. This was achieved by firstly identifying and characterizing each available SCC
mec
element based on the presence or absence of 34 binary targets. This information was used as input for the software “Minimum SNPs,” which identifies the minimum number of targets required to differentiate a set of genotypes up to a predefined Simpson's index of diversity (
D
) value. It was determined that 22 of the 34 targets were required to genotype the 46 SCC
mec
variants to a
D
of 1. The first 6, 9, 12, and 15 targets were found to define 21, 29, 35, and 39 SCC
mec
variants, respectively. The genotypes defined by these marker subsets were largely consistent with the relationships between SCC
mec
variants and the accepted nomenclature. Consistency was made virtually complete by forcing the computer program to include
ccr1
and
ccr5
in the target set. An alternative target set biased towards discriminating abundant SCC
mec
variants was derived by analyzing an input file in which common SCC
mec
variants were repeated, thus ensuring that markers that discriminate abundant variants had a large effect on
D
. Finally, it was determined that
mecA
single nucleotide polymorphisms (SNPs) can increase the overall genotyping resolution, as different
mecA
alleles were found in otherwise identical SCC
mec
variants.
Experimental Phage Therapy against
Staphylococcus aureus
in Mice
Authors: Capparelli Rosanna , Parlato Marianna , Borriello Giorgia , Salvatore Paola , Iannelli Domenico 
Published: May 2007

ABSTRACT

The present study describes a bacteriophage (M
Sa
) active against
Staphylococcus aureus
, including methicillin-resistant staphylococcal strains. When inoculated into mice simultaneously with
S. aureus
A170 (10
8
CFU/mouse), phage (10
9
PFU) rescued 97% of the mice; when applied to nonlethal (5 × 10
6
CFU/mouse) 10-day infections, the phage also fully cleared the bacteria. The phage M
Sa
, delivered inside macrophages by
S. aureus
, kills the intracellular staphylococci in vivo and in vitro. The phage can also prevent abscess formation and reduce the bacterial load and weight of abscesses. These results suggest a potential use of the phage for the control of both local and systemic human
S. aureus
infections.
Effects of Rifampin and Multidrug Resistance Gene Polymorphism on Concentrations of Moxifloxacin
Authors: Weiner Marc , Burman William , Luo Chi-Cheng , Peloquin Charles A. , Engle Melissa , Goldberg Stefan , Agarwal Vipin , Vernon Andrew 
Published: May 2007

ABSTRACT

Treatment regimens combining moxifloxacin and rifampin for drug-susceptible tuberculosis are being studied intensively. However, rifampin induces enzymes that transport and metabolize moxifloxacin. We evaluated the effect of rifampin and the human multidrug resistance gene (MDR1) C3435T polymorphisms (P-glycoprotein) on moxifloxacin pharmacokinetic parameters. This was a single-center, sequential design study with 16 volunteers in which sampling was performed after four daily oral doses of moxifloxacin (400 mg) and again after 10 days of combined rifampin (600 mg) and moxifloxacin. After daily coadministration of rifampin, the area under the concentration-time curve from 0 to 24 h (AUC
0-24
) for moxifloxacin decreased 27%. Average bioequivalence between moxifloxacin coadministered with rifampin and moxifloxacin alone was not demonstrated: the ratio of geometric means (RGM) of the moxifloxacin AUC
0-24
was 73.3 (90% confidence intervals [CI], 64.3, 83.5) (total
P
value, 0.87 for two one-sided
t
tests). Peak moxifloxacin concentrations, however, were equivalent: the RGM of the maximum concentration of the drug in serum was 93.6 (90% CI, 80.2, 109.3) (total
P
value, 0.049). Concentrations of the sulfate conjugate metabolite of moxifloxacin were increased twofold following rifampin coadministration (AUC
0-24
, 1.29 versus 2.79 μg·h/ml). Concomitant rifampin administration resulted in a 27% decrease in the mean moxifloxacin AUC
0-24
and a marked increase in the AUC
0-24
of the microbiologically inactive M1 metabolite. Additional studies are required to understand the clinical significance of the moxifloxacin-rifampin interaction.
Endogenous Interleukin-18 Improves the Early Antimicrobial Host Response in Severe Melioidosis
Authors: Wiersinga W. Joost , Wieland Catharina W. , van der Windt Gerritje J. W. , de Boer Anita , Florquin Sandrine , Dondorp Arjen , Day Nicholas P. , Peacock Sharon J. , van der Poll Tom 
Published: May 2007

ABSTRACTMelioidosis is caused by the soil saprophyteBurkholderia pseudomalleiand is endemic in Southeast Asia. The pathogenesis of melioidosis is still largely unknown, although gamma interferon (IFN-γ) seems to play an obligatory role in host defense. Previously, we have shown that IFN-γ production in melioidosis is controlled in part by interleukin-18 (IL-18). The aim of the present study was to determine the role of IL-18 in the immune response toB. pseudomallei. For this the following investigations were performed. (i) Plasma IL-18 and blood monocyte IL-18 mRNA levels were elevated in 34 patients with culture-proven melioidosis compared to the levels in 32 local healthy controls; in addition, IL-18 binding protein levels were markedly elevated in patients, strongly correlating with mortality. (ii) IL-18 gene-deficient (IL-18 knockout [KO]) mice showed accelerated mortality after intranasal infection with a lethal dose ofB. pseudomallei, which was accompanied by enhanced bacterial growth in their lungs, livers, spleens, kidneys, and blood at 24 and 48 h postinfection, compared to wild-type mice. In addition, IL-18 KO mice displayed evidence of enhanced hepatocellular injury and renal insufficiency. Together, these data indicate that the enhanced production of IL-18 in melioidosis is an essential part of a protective immune response to this severe infection.
Heterogeneity of a
Campylobacter jejuni
Protein That Is Secreted through the Flagellar Filament
Authors: Poly Frédéric , Ewing Cheryl , Goon Scarlett , Hickey Thomas E. , Rockabrand David , Majam Gary , Lee Lanfong , Phan Julie , Savarino Nicholas J. , Guerry Patricia 
Published: May 2007

ABSTRACT

Cj0859c, or FspA, is a small, acidic protein of
Campylobacter jejuni
that is expressed by a σ
28
promoter. Analysis of the
fspA
gene in 41 isolates of
C. jejuni
revealed two overall variants of the predicted protein, FspA1 and FspA2. Secretion of FspA occurs in broth-grown bacteria and requires a minimum flagellar structure. The addition of recombinant FspA2, but not FspA1, to INT407 cells in vitro resulted in a rapid induction of apoptosis. These data define a novel
C. jejuni
virulence factor, and the observed heterogeneity among
fspA
alleles suggests alternate virulence potential among different strains.
Surface-Exposed Proteins ofEhrlichia chaffeensis
Authors: Ge Yan , Rikihisa Yasuko 
Published: May 2007

ABSTRACTThe surface proteins ofEhrlichia chaffeensisprovide an important interface for pathogen-host interactions. To investigate the surface proteins ofE. chaffeensis, membrane-impermeable, cleavable Sulfo-NHS-SS-Biotin was used to label intact bacteria. The biotinylated bacterial surface proteins were isolated by streptavidin-agarose affinity purification. The affinity-captured proteins were separated by electrophoresis, and five relatively abundant protein bands containing immunoreactive proteins were subjected to capillary-liquid chromatography-nanospray tandem mass spectrometry analysis. Nineteen out of 22 OMP-1/P28 family proteins, including P28 (which previously was shown to be surface exposed), were detected inE. chaffeensiscultured in human monocytic leukemia THP-1 cells. For the first time, with the exception of P28 and P28-1, 17 OMP-1/P28 family proteins were demonstrated to be expressed at the protein level. The surface exposure of OMP-1A and OMP-1N was verified by immunofluorescence microscopy. OMP-1B was undetectable either by surface biotinylation or by Western blotting of the whole bacterial lysate, suggesting that it is not expressed byE. chaffeensiscultured in THP-1 cells. AdditionalE. chaffeensissurface proteins detected were OMP85, hypothetical protein ECH_0525 (here named Esp73), immunodominant surface protein gp47, and 11 other proteins. The identification ofE. chaffeensissurface-exposed proteins provides novel insights into theE. chaffeensissurface and lays the foundation for rational studies on pathogen-host interactions and vaccine development.
Clostridium difficileToxins A and B Directly Stimulate Human Mast Cells
Authors: Meyer Gesa K. A. , Neetz Anne , Brandes Gudrun , Tsikas Dimitrios , Butterfield Joseph H. , Just Ingo , Gerhard Ralf 
Published: May 2007

ABSTRACTClostridium difficiletoxins A and B (TcdA and TcdB) are the causative agents of antibiotic-associated pseudomembranous colitis. Mucosal mast cells play a crucial role in the inflammatory processes underlying this disease. We studied the direct effects of TcdA and TcdB on the human mast cell line HMC-1 with respect to degranulation, cytokine release, and the activation of proinflammatory signal pathways. TcdA and TcdB inactivate Rho GTPases, the master regulators of the actin cytoskeleton. The inactivation of Rho GTPases induced a reorganization of the actin cytoskeleton accompanied by morphological changes of cells. The TcdB-induced reorganization of the actin cytoskeleton in HMC-1 cells reduced the number of electron-dense mast cell-specific granules. Accordingly, TcdB induced the release of hexosaminidase, a marker for degranulation, in HMC-1 cells. The actin rearrangement was found to be responsible for degranulation since latrunculin B induced a comparable hexosaminidase release. In addition, TcdB as well as latrunculin B induced the activation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase 1/2 and also resulted in a p38 MAPK-dependent increased formation of prostaglandins D2and E2. The autocrine stimulation of HMC-1 cells by prostaglandins partially contributed to the degranulation. Interestingly, TcdB-treated HMC-1 cells, but not latrunculin B-treated HMC-1 cells, showed a strong p38 MAPK-dependent increase in interleukin-8 release. Differences in the mast cell responses to TcdB and latrunculin B are probably due to the presence of functionally inactive Rho GTPases in toxin-treated cells. Thus, the HMC-1 cell line is a promising model for studying the direct effects ofC. difficiletoxins on mast cells independently of the tissue context.
Plasmodium yoelii
Sporozoites with Simultaneous Deletion of P52 and P36 Are Completely Attenuated and Confer Sterile Immunity against Infection
Authors: Labaied Mehdi , Harupa Anke , Dumpit Ronald F. , Coppens Isabelle , Mikolajczak Sebastian A. , Kappe Stefan H. I. 
Published: May 2007

ABSTRACT

Malaria infection starts when sporozoites are transmitted to the mammalian host during a mosquito bite. Sporozoites enter the blood circulation, reach the liver, and infect hepatocytes. The formation of a parasitophorous vacuole (PV) establishes their intracellular niche. Recently, two members of the 6-Cys domain protein family, P52 and P36, were each shown to play an important albeit nonessential role in
Plasmodium berghei
sporozoite infectivity for the rodent host. Here, we generated
p52/p36
-deficient
Plasmodium yoelii
parasites by the simultaneous deletion of both genes using a single genetic manipulation.
p52/p36
-deficient parasites exhibited normal progression through the life cycle during blood-stage infection, transmission to mosquitoes, mosquito-stage development, and sporozoite infection of the salivary glands.
p52/p36
-deficient sporozoites also showed normal motility and cell traversal activity. However, immunofluorescence analysis and electron microscopic observations revealed that
p52/p36
-deficient parasites did not form a PV within hepatocytes in vitro and in vivo. The
p52/p36
-deficient parasites localized as free entities in the host cell cytoplasm or the host cell nucleoplasm and did not develop as liver stages. Consequently, they did not cause blood-stage infections even at high sporozoite inoculation doses. Mice immunized with
p52/p36
-deficient sporozoites were completely protected against infectious sporozoite challenge. Our results demonstrate for the first time the generation of two-locus gene deletion-attenuated parasites that infect the liver but do not progress to blood-stage infection. The study will critically guide the design of
Plasmodium falciparum
live attenuated malaria vaccines.
Pathogen Specificity and Autoimmunity Are Distinct Features of Antigen-Driven Immune Responses in Neuroborreliosis
Authors: Kuenzle Sandra , von Büdingen Hans-Christian , Meier Mirjam , Harrer Melanie D. , Urich Eduard , Becher Burkhard , Goebels Norbert 
Published: May 2007

ABSTRACT

Neuroborreliosis (NB) is a chronic infectious disease of the central nervous system (CNS) caused by a tick-borne spirochete,
Borrelia burgdorferi
. In addition to direct effects of the causative infectious agent, additional immunity-mediated mechanisms are thought to play a role in the CNS pathology of NB. In order to further understand the involvement of humoral immune mechanisms in NB, we dissected the intrathecal antibody responses down to the single-plasma-cell level. Starting with single-cell reverse transcription-PCR of fluorescence-activated cell sorter-sorted cerebrospinal fluid plasma cells from an NB patient, we identified expanded clones and resurrected the antigen specificity of their secreted antibodies through recombinant expression of the correctly paired immunoglobulin heavy- and light-chain genes as monoclonal antibodies (MAbs). As expected, we found specificity for the causative infectious agent,
B. burgdorferi
, among the clonally expanded plasma cell (cePC)-derived MAbs. However, from an independent cePC of the same patient, we could derive MAbs specific for human CNS myelin, without detectable cross-reactivity with
B. burgdorferi
antigens. While reactivity against
B. burgdorferi
is a known feature of humoral immune responses in NB, we show (i) that immune responses specific for self antigens may be a distinct feature of CNS infections independent of pathogen reactivity and (ii) that humoral autoimmunity in NB (since found in cePC) is the result of a truly antigen-driven immune response. Our findings indicate that in NB mechanisms may be at play that induce distinct immune responses specific for pathogen and self antigens independent from “molecular mimicry.”