bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fatty Acid Synthesis and Pyruvate Metabolism Pathways Remain Active in Dihydroartemisinin-Induced Dormant Ring Stages of Plasmodium falciparum
Authors: Chen Nanhua , LaCrue Alexis N. , Teuscher Franka , Waters Norman C. , Gatton Michelle L. , Kyle Dennis E. , Cheng Qin 
Published: June 2014

ABSTRACT

Artemisinin (ART)-based combination therapy (ACT) is used as the first-line treatment of uncomplicated falciparum malaria worldwide. However, despite high potency and rapid action, there is a high rate of recrudescence associated with ART monotherapy or ACT long before the recent emergence of ART resistance. ART-induced ring-stage dormancy and recovery have been implicated as possible causes of recrudescence; however, little is known about the characteristics of dormant parasites, including whether dormant parasites are metabolically active. We investigated the transcription of 12 genes encoding key enzymes in various metabolic pathways in
P. falciparum
during dihydroartemisinin (DHA)-induced dormancy and recovery. Transcription analysis showed an immediate downregulation for 10 genes following exposure to DHA but continued transcription of 2 genes encoding apicoplast and mitochondrial proteins. Transcription of several additional genes encoding apicoplast and mitochondrial proteins, particularly of genes encoding enzymes in pyruvate metabolism and fatty acid synthesis pathways, was also maintained. Additions of inhibitors for biotin acetyl-coenzyme A (CoA) carboxylase and enoyl-acyl carrier reductase of the fatty acid synthesis pathways delayed the recovery of dormant parasites by 6 and 4 days, respectively, following DHA treatment. Our results demonstrate that most metabolic pathways are downregulated in DHA-induced dormant parasites. In contrast, fatty acid and pyruvate metabolic pathways remain active. These findings highlight new targets to interrupt recovery of parasites from ART-induced dormancy and to reduce the rate of recrudescence following ART treatment.
His224 Alters the R2 Drug Binding Site and Phe218 Influences the Catalytic Efficiency of the Metallo-β-Lactamase VIM-7
Authors: Leiros Hanna-Kirsti S. , Skagseth Susann , Edvardsen Kine Susann Waade , Lorentzen Marit Sjo , Bjerga Gro Elin Kjæreng , Leiros Ingar , Samuelsen Ørjan 
Published: June 2014

ABSTRACT

Metallo-β-lactamases (MBLs) are the causative mechanism for resistance to β-lactams, including carbapenems, in many Gram-negative pathogenic bacteria. One important family of MBLs is the Verona integron-encoded MBLs (VIM). In this study, the importance of residues Asp120, Phe218, and His224 in the most divergent VIM variant, VIM-7, was investigated to better understand the roles of these residues in VIM enzymes through mutations, enzyme kinetics, crystal structures, thermostability, and docking experiments. The tVIM-7-D120A mutant with a tobacco etch virus (TEV) cleavage site was enzymatically inactive, and its structure showed the presence of only the Zn1 ion. The mutant was less thermostable, with a melting temperature (

T
m

) of 48.5°C, compared to 55.3°C for the wild-type tVIM-7. In the F218Y mutant, a hydrogen bonding cluster was established involving residues Asn70, Asp84, and Arg121. The tVIM-7-F218Y mutant had enhanced activity compared to wild-type tVIM-7, and a slightly higher

T
m

(57.1°C) was observed, most likely due to the hydrogen bonding cluster. Furthermore, the introduction of two additional hydrogen bonds adjacent to the active site in the tVIM-7-H224Y mutant gave a higher thermostability (

T
m

, 62.9°C) and increased enzymatic activity compared to those of the wild-type tVIM-7. Docking of ceftazidime in to the active site of tVIM-7, tVIM-7-H224Y, and VIM-7-F218Y revealed that the side-chain conformations of residue 224 and Arg228 in the L3 loop and Tyr67 in the L1 loop all influence possible substrate binding conformations. In conclusion, the residue composition of the L3 loop, as shown with the single H224Y mutation, is important for activity particularly toward the positively charged cephalosporins like cefepime and ceftazidime.
Population Pharmacokinetic Analysis of Voriconazole and Anidulafungin in Adult Patients with Invasive Aspergillosis
Authors: Liu Ping , Mould Diane R. 
Published: June 2014

ABSTRACT

To assess the pharmacokinetics (PK) of voriconazole and anidulafungin in patients with invasive aspergillosis (IA) in comparison with other populations, sparse PK data were obtained for 305 adults from a prospective phase 3 study comparing voriconazole and anidulafungin in combination versus voriconazole monotherapy (voriconazole, 6 mg/kg intravenously [IV] every 12 h [q12h] for 24 h followed by 4 mg/kg IV q12h, switched to 300 mg orally q12h as appropriate; with placebo or anidulafungin IV, a 200-mg loading dose followed by 100 mg q24h). Voriconazole PK was described by a two-compartment model with first-order absorption and mixed linear and time-dependent nonlinear (Michaelis-Menten) elimination; anidulafungin PK was described by a two-compartment model with first-order elimination. For voriconazole, the normal inverse Wishart prior approach was implemented to stabilize the model. Compared to previous models, no new covariates were identified for voriconazole or anidulafungin. PK parameter estimates of voriconazole and anidulafungin are in agreement with those reported previously except for voriconazole clearance (the nonlinear clearance component became minimal). At a 4-mg/kg IV dose, voriconazole exposure tended to increase slightly as age, weight, or body mass index increased, but the difference was not considered clinically relevant. Estimated voriconazole exposures in IA patients at 4 mg/kg IV were higher than those reported for healthy adults (e.g., the average area under the curve over a 12-hour dosing interval [AUC
0–12
] at steady state was 46% higher); while it is not definitive, age and concomitant medications may impact this difference. Estimated anidulafungin exposures in IA patients were comparable to those reported for the general patient population. This study was approved by the appropriate institutional review boards or ethics committees and registered on ClinicalTrials.gov (NCT00531479).
SAMHD1 Specifically Affects the Antiviral Potency of Thymidine Analog HIV Reverse Transcriptase Inhibitors
Authors: Ballana Ester , Badia Roger , Terradas Gerard , Torres-Torronteras Javier , Ruiz Alba , Pauls Eduardo , Riveira-Muñoz Eva , Clotet Bonaventura , Martí Ramon , Esté José A. 
Published: June 2014

ABSTRACT

Sterile alpha motif and histidine-aspartic domain-containing protein 1 (SAMHD1) is a deoxynucleoside triphosphate (dNTP) triphosphohydrolase recently recognized as an antiviral factor that acts by depleting dNTP availability for viral reverse transcriptase (RT). SAMHD1 restriction is counteracted by the human immunodeficiency virus type 2 (HIV-2) accessory protein Vpx, which targets SAMHD1 for proteosomal degradation, resulting in an increased availability of dNTPs and consequently enhanced viral replication. Nucleoside reverse transcriptase inhibitors (NRTI), one of the most common agents used in antiretroviral therapy, compete with intracellular dNTPs as the substrate for viral RT. Consequently, SAMHD1 activity may be influencing NRTI efficacy in inhibiting viral replication. Here, a panel of different RT inhibitors was analyzed for their different antiviral efficacy depending on SAMHD1. Antiviral potency was measured for all the inhibitors in transformed cell lines and primary monocyte-derived macrophages and CD4
+
T cells infected with HIV-1 with or without Vpx. No changes in sensitivity to non-NRTI or the integrase inhibitor raltegravir were observed, but for NRTI, sensitivity significantly changed only in the case of the thymidine analogs (AZT and d4T). The addition of exogenous thymidine mimicked the change in viral sensitivity observed after Vpx-mediated SAMHD1 degradation, pointing toward a differential effect of SAMHD1 activity on thymidine. Accordingly, sensitivity to AZT was also reduced in CD4
+
T cells infected with HIV-2 compared to infection with the HIV-2ΔVpx strain. In conclusion, reduction of SAMHD1 levels significantly decreases HIV sensitivity to thymidine but not other nucleotide RT analog inhibitors in both macrophages and lymphocytes.
Structure-Activity Relationship Study of the Plant-Derived Decapeptide OSIP108 Inhibiting Candida albicans Biofilm Formation
Authors: Delattin Nicolas , De Brucker Katrijn , Craik David J. , Cheneval Olivier , De Coninck Barbara , Cammue Bruno P. A. , Thevissen Karin 
Published: June 2014

ABSTRACT

We performed a structure-activity relationship study of the antibiofilm plant-derived decapeptide OSIP108. Introduction of positively charged amino acids R, H, and K resulted in an up-to-5-fold-increased antibiofilm activity against
Candida albicans
compared to native OSIP108, whereas replacement of R9 resulted in complete abolishment of its antibiofilm activity. By combining the most promising amino acid substitutions, we found that the double-substituted OSIP108 analogue Q6R/G7K had an 8-fold-increased antibiofilm activity.
Substrate Binding Protein SBP2 of a Putative ABC Transporter as a Novel Vaccine Antigen of Moraxella catarrhalis
Authors: Otsuka Taketo , Kirkham Charmaine , Johnson Antoinette , Jones Megan M. , Murphy Timothy F. 
Published: June 2014

ABSTRACT

Moraxella catarrhalis
is a common respiratory tract pathogen that causes otitis media in children and infections in adults with chronic obstructive pulmonary disease. Since the introduction of the pneumococcal conjugate vaccines with/without protein D of nontypeable
Haemophilus influenzae
,
M. catarrhalis
has become a high-priority pathogen in otitis media. For the development of antibacterial vaccines and therapies, substrate binding proteins of ATP-binding cassette transporters are important targets. In this study, we identified and characterized a substrate binding protein, SBP2, of
M. catarrhalis
. Among 30 clinical isolates tested, the
sbp2
gene sequence was highly conserved. In 2 different analyses (whole-cell enzyme-linked immunosorbent assay and flow cytometry), polyclonal antibodies raised to recombinant SBP2 demonstrated that SBP2 expresses epitopes on the bacterial surface of the wild type but not the
sbp2
mutant. Mice immunized with recombinant SBP2 showed significantly enhanced clearance of
M. catarrhalis
from the lung compared to that in the control group at both 25-μg and 50-μg doses (
P
< 0.001). We conclude that SBP2 is a novel, attractive candidate as a vaccine antigen against
M. catarrhalis
.
Involvement of Enterococcus faecalis Small RNAs in Stress Response and Virulence
Authors: Michaux Charlotte , Hartke Axel , Martini Cecilia , Reiss Swantje , Albrecht Dirk , Budin-Verneuil Aurélie , Sanguinetti Maurizio , Engelmann Susanne , Hain Torsten , Verneuil Nicolas , Giard Jean-Christophe 
Published: June 2014

ABSTRACT

Candidate small RNAs (sRNAs) have recently been identified in
Enterococcus faecalis
, a Gram-positive opportunistic pathogen, and six of these candidate sRNAs with unknown functions were selected for a functional study. Deletion mutants and complemented strains were constructed, and their virulence was tested. We were unable to obtain the
ef0869-0870
mutant, likely due to an essential role, and the
ef0820-0821
sRNA seemed not to be involved in virulence. In contrast, the mutant lacking
ef0408-0409
sRNA, homologous to the RNAII component of the toxin-antitoxin system, appeared more virulent and more able to colonize mouse organs. The three other mutants showed reduced virulence. In addition, we checked the responses of these mutant strains to several stresses encountered in the gastrointestinal tract or during the infection process. In parallel, the activities of the sRNA promoters were measured using transcriptional fusion constructions. To attempt to identify the regulons of these candidate sRNAs, proteomics profiles of the mutant strains were compared with that of the wild type. This showed that the selected sRNAs controlled the expression of proteins involved in diverse cellular processes and the stress response. The combined data highlight the roles of certain candidate sRNAs in the adaptation of
E. faecalis
to environmental changes and in the complex transition process from a commensal to a pathogen.
CcpA Is Important for Growth and Virulence of Enterococcus faecium
Authors: Somarajan Sudha R. , Roh Jung H. , Singh Kavindra V. , Weinstock George M. , Murray Barbara E. 
Published: June 2014

ABSTRACT

The collagen adhesin Acm was the first virulence determinant reported to be important for the pathogenesis of
Enterococcus faecium
in a rat infective endocarditis model. We had previously reported that there was a slight growth delay associated with
acm
allelic replacement (
cat
) mutant strain TX6051 used in that study. Recently, we generated a nonpolar markerless
acm
deletion mutant and did not observe a delay in growth. We therefore performed comparative genome sequence analysis of wild-type strain TX82 and TX6051 and found a single mutation, a nonsense mutation in the
ccpA
gene of TX6051. After correcting this mutation, the growth defect of TX6051 was abolished, implicating a role for CcpA in the growth of
E. faecium
. To confirm this, we created a
ccpA
deletion mutant of TX82, which also exhibited a slight delay in growth. Furthermore, the
ccpA
deletion mutant was attenuated (
P
= 0.0024) in a mixed-inoculum (TX82 plus TX82 Δ
ccpA
) rat endocarditis model and also in an
in vitro
competitive growth assay; a
ccpA
-complemented strain showed neither reduced growth nor reduced virulence. We also found attenuation in the endocarditis model with the new
acm
deletion mutant although not as great as that previously observed with TX6051 carrying the
ccpA
mutation. Taken together, our data confirm the role of Acm in the pathogenesis of endocarditis. We also show that CcpA affects the growth of
E. faecium
, that an intact
ccpA
gene is important for full virulence, and that a
ccpA
mutation was partly responsible for the highly attenuated phenotype of TX6051.
GneZ, a UDP-GlcNAc 2-Epimerase, Is Required for S-Layer Assembly and Vegetative Growth of Bacillus anthracis
Authors: Wang Ya-Ting , Missiakas Dominique , Schneewind Olaf 
Published: June 2014

ABSTRACT

Bacillus anthracis
, the causative agent of anthrax, forms an S-layer atop its peptidoglycan envelope and displays S-layer proteins and
Bacillus
S-layer-associated (BSL) proteins with specific functions to support cell separation of vegetative bacilli and growth in infected mammalian hosts. S-layer and BSL proteins bind via the S-layer homology (SLH) domain to the pyruvylated secondary cell wall polysaccharide (SCWP) with the repeat structure [→4)-β-ManNAc-(1→4)-β-GlcNAc-(1→6)-α-GlcNAc-(1→]

n

, where α-GlcNAc and β-GlcNAc are substituted with two and one galactosyl residues, respectively.
B. anthracis
gneY
(BAS5048) and
gneZ
(BAS5117) encode nearly identical UDP-GlcNAc 2-epimerase enzymes that catalyze the reversible conversion of UDP-GlcNAc and UDP-ManNAc. UDP-GlcNAc 2-epimerase enzymes have been shown to be required for the attachment of the phage lysin PlyG with the bacterial envelope and for bacterial growth. Here, we asked whether
gneY
and
gneZ
are required for the synthesis of the pyruvylated SCWP and for S-layer assembly. We show that
gneZ
, but not
gneY
, is required for
B. anthracis
vegetative growth, rod cell shape, S-layer assembly, and synthesis of pyruvylated SCWP. Nevertheless, inducible expression of
gneY
alleviated all the defects associated with the
gneZ
mutant. In contrast to vegetative growth, neither germination of
B. anthracis
spores nor the formation of spores in mother cells required UDP-GlcNAc 2-epimerase activity.
Which outcome measures in SLE clinical trials best reflect medical judgment?
Authors: Thanou Aikaterini , Chakravarty Eliza , James Judith A , Merrill Joan T 
Published: June 2014

ObjectivesTo compare two measures of systemic lupus erythematosus (SLE) response: the British Isles Lupus Assessment Group (BILAG)-based Composite Lupus Assessment (BICLA) and the Systemic Lupus Responder Index (SRI) against a clinician's assessment of improvement.MethodsNinety-one lupus patients were identified with two visits at which Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) and BILAG had been scored and with active disease (SLEDAI≥6) at the first visit. A physician rated the disease activity at the second visit as clinically significant improvement, no change or worsening. SRI and BICLA were scored both with and without the medication criteria often used in trials to restrict response definitions.Results68 patients were considered improved, 17 same and 6 worse at follow-up. SRI versus BICLA, performed without considering medication changes, captured physician-rated improvement with 85% vs 76% sensitivity and 74% vs 78% specificity. With medication limits both instruments had 37% sensitivity and 96% specificity for physician-assessed improvement. Seven patients considered improved by the clinician met the BICLA but not the SRI definition of improvement by failing to achieve a four-point improvement in SLEDAI. 13 clinician-rated responders met SRI but not BICLA by improving in less than all organs.ConclusionsShortfalls of SRI and BICLA may be due to BICLA only requiring partial improvement but in all organs versus SRI requiring full improvement in some manifestation(s) and not all organs. SRI and BICLA with medication restrictions are less likely to denote response when the physician disagrees and could provide stringent proof of efficacy in appropriately powered clinical trials.
Clinical phenotype associations with various types of anti-dsDNA antibodies in patients with recent onset of rheumatic symptoms. Results from a multicentre observational study
Authors: Compagno Michele , Rekvig Ole P , Bengtsson Anders A , Sturfelt Gunnar , Heegaard Niels H H , Jönsen Andreas , Jacobsen Rasmus Sleimann , Eilertsen Gro Ø , Fenton Christopher G , Truedsson Lennart , Nossent Johannes C , Jacobsen Søren 
Published: June 2014

Despite anti-dsDNA antibodies constitute a wide range of specificities, they are considered as the hallmark for systemic lupus erythematosus (SLE).ObjectiveTo identify clinical phenotypes associated with anti-dsDNA antibodies, independently of any clinical diagnoses.MethodsPatients with recent onset of any rheumatic symptoms were screened for antinuclear antibodies (ANA). All ANA-positive and matching ANA-negative patients were examined, and their clinical phenotypes were registered, using a systematic chart formulated after consensus between the participating centres. All patients were tested for different anti-dsDNA antibody specificities with assays habitually used in each participating laboratory. Crithidia Luciliae Immuno Fluorescence Test (CLIFT) was performed three times (with two different commercial kits); solid and solution phase ELISA were performed four times. Associations between clinical phenotypes and results of anti-dsDNA assays were evaluated by linear regression analysis (LRA) and principal component analysis (PCA).ResultsTotally, 292 ANA-positive and 292 matching ANA-negative patients were included in the study. A full dataset for statistical analysis was obtained in 547 patients. Anti-dsDNA antibodies were most frequently detected by ELISA. LRA showed that overall positivity of anti-dsDNA antibodies was associated with proteinuria and pleuritis. Alopecia was significantly associated only with CLIFT-positivity. Besides confirming the same findings, PCA showed that combined positivity of CLIFT and ELISA was also associated with lymphopenia.ConclusionsOur results show that different anti-dsDNA antibody specificities are associated with nephropathy, pleuritis, alopecia and lymphopenia, regardless of the diagnosis. It may challenge the importance of anti-dsDNA antibodies as a diagnostic hallmark for SLE.
Reduced response to Epstein–Barr virus antigens by T-cells in systemic lupus erythematosus patients
Authors: Draborg Anette Holck , Jacobsen Søren , Westergaard Marie , Mortensen Shila , Larsen Janni Lisander , Houen Gunnar , Duus Karen 
Published: June 2014

ObjectiveEpstein–Barr virus (EBV) has for long been associated with systemic lupus erythematosus (SLE). In this study, we investigated the levels of latent and lytic antigen EBV-specific T-cells and antibodies in SLE patients.MethodsT cells were analyzed by flow cytometry and antibodies were analyzed by enzyme-linked immunosorbent assay.ResultsSLE patients showed a significantly reduced number of activated (CD69) T-cells upon ex vivo stimulation with EBV nuclear antigen (EBNA) 1 or EBV early antigen diffuse (EBV-EA/D) in whole blood samples compared with healthy controls. Also, a reduced number of T-cells from SLE patients were found to produce interferon-γ upon stimulation with these antigens. Importantly, responses to a superantigen were normal in SLE patients. Compared with healthy controls, SLE patients had fewer EBV-specific T-cells but higher titres of antibodies against EBV. Furthermore, an inverse correlation was revealed between the number of lytic antigen EBV-specific T-cells and disease activity of the SLE patients, with high-activity SLE patients having fewer T-cells than low-activity SLE patients.ConclusionsThese results indicate a limited or a defective EBV-specific T-cell response in SLE patients, which may suggest poor control of EBV infection in SLE with an immune reaction shift towards a humoral response in an attempt to control viral reactivation. A role for decreased control of EBV as a contributing agent in the development or exacerbation of SLE is proposed.
Causes and outcome of hospitalisations in Tunisian patients with systemic lupus erythematosus
Authors: Jallouli M , Hriz H , Cherif Y , Marzouk S , Snoussi M , Frikha F , Ben Salah R , Masmoudi H , Bahloul Z 
Published: June 2014

ObjectiveTo describe the most common reasons of admission of Tunisian patients with systemic lupus erythematosus (SLE) and the outcomes of these hospitalisations.MethodThe charts of patients with SLE who were hospitalised at our Department of Internal Medicine during a 2-year period from January 2011 to December 2012 were retrospectively reviewed, and the demographic characteristics, clinical and laboratory features, as well as all comorbidities, were collected.ResultsThere were 128 episodes of hospitalisation of 87 patients with SLE. 25 patients (28.7%) were admitted twice or more. The median length of stay for all admissions was 11 days (2–76). The total number of days of hospitalisation was 1896 days, which represent 10.7% of the total number of days of hospitalisation in our department. The most common overall reason for hospitalisation was active SLE (55 events, 43%). In 29 patients, SLE was newly diagnosed during hospitalisation. Other causes of hospitalisation included assessment of the disease, infections (9.4%) and associated autoimmune disease (6.25%). Adverse drug reaction (3.1%) and thromboembolic events (1.25%) were uncommon causes of hospitalisations. There was a significant difference in length of stay between patients admitted with SLE flare and those admitted for non-SLE flare reasons (p<0.01). Four hospitalisations (3%) resulted in death. The principal cause of death was active SLE.ConclusionsHospitalisation of patients with SLE is common in our department. Our study of this North African SLE population confirms the findings of previous studies suggesting that active SLE and infection remain the most common causes of hospitalisation of patients with SLE.