bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ex Vivo
Activity of Endoperoxide Antimalarials, Including Artemisone and Arterolane, against Multidrug-Resistant Plasmodium falciparum Isolates from Cambodia
Authors: Lanteri Charlotte A. , Chaorattanakawee Suwanna , Lon Chanthap , Saunders David L. , Rutvisuttinunt Wiriya , Yingyuen Kritsanai , Bathurst Ian , Ding Xavier C. , Tyner Stuart D. 
Published: July 2014

ABSTRACT

Novel synthetic endoperoxides are being evaluated as new components of artemisinin combination therapies (ACTs) to treat artemisinin-resistant
Plasmodium falciparum
malaria. We conducted blinded
ex vivo
activity testing of fully synthetic (OZ78 and OZ277) and semisynthetic (artemisone, artemiside, artesunate, and dihydroartemisinin) endoperoxides in the histidine-rich protein 2 enzyme-linked immunosorbent assay against 200
P. falciparum
isolates from areas of artemisinin-resistant malaria in western and northern Cambodia in 2009 and 2010. The order of potency and geometric mean (GM) 50% inhibitory concentrations (IC
50
s) were as follows: artemisone (2.40 nM) > artesunate (8.49 nM) > dihydroartemisinin (11.26 nM) > artemiside (15.28 nM) > OZ277 (31.25 nM) > OZ78 (755.27 nM).
Ex vivo
activities of test endoperoxides positively correlated with dihydroartemisinin and artesunate. The isolates were over 2-fold less susceptible to dihydroartemisinin than the artemisinin-sensitive
P. falciparum
W2 clone and showed sensitivity comparable to those with test endoperoxides and artesunate, with isolate/W2 IC
50
susceptibility ratios of <2.0. All isolates had
P. falciparum
chloroquine resistance transporter mutations, with negative correlations in sensitivity to endoperoxides and chloroquine. The activities of endoperoxides (artesunate, dihydroartemisinin, OZ277, and artemisone) significantly correlated with that of the ACT partner drug, mefloquine. Isolates had mutations associated with clinical resistance to mefloquine, with 35% prevalence of
P. falciparum
multidrug resistance gene 1 (
pfmdr1
) amplification and 84.5% occurrence of the
pfmdr1
Y184F mutation. GM IC
50
s for mefloquine, lumefantrine, and endoperoxides (artesunate, dihydroartemisinin, OZ277, OZ78, and artemisone) correlated with
pfmdr1
copy number. Given that current ACTs are failing potentially from reduced sensitivity to artemisinins and partner drugs, newly identified mutations associated with artemisinin resistance reported in the literature and
pfmdr1
mutations should be examined for their combined contributions to emerging ACT resistance.
Bacterial Drug Tolerance under Clinical Conditions Is Governed by Anaerobic Adaptation but not Anaerobic Respiration
Authors: Hemsley Claudia M. , Luo Jamie X. , Andreae Clio A. , Butler Clive S. , Soyer Orkun S. , Titball Richard W. 
Published: July 2014

ABSTRACT

Noninherited antibiotic resistance is a phenomenon whereby a subpopulation of genetically identical bacteria displays phenotypic tolerance to antibiotics. We show here that compared to
Escherichia coli
, the clinically relevant genus
Burkholderia
displays much higher levels of cells that tolerate ceftazidime. By measuring the dynamics of the formation of drug-tolerant cells under conditions that mimic
in vivo
infections, we show that in
Burkholderia
bacteria, oxygen levels affect the formation of these cells. The drug-tolerant cells are characterized by an anaerobic metabolic signature and can be eliminated by oxygenating the system or adding nitrate. The transcriptome profile suggests that these cells are not dormant persister cells and are likely to be drug tolerant as a consequence of the upregulation of anaerobic nitrate respiration, efflux pumps, β-lactamases, and stress response proteins. These findings have important implications for the treatment of chronic bacterial infections and the methodologies and conditions that are used to study drug-tolerant and persister cells
in vitro
.
Time-Kill Assay and Etest Evaluation for Synergy with Polymyxin B and Fluconazole against Candida glabrata
Authors: Pankey George , Ashcraft Deborah , Kahn Heather , Ismail Abdulrahim 
Published: July 2014

ABSTRACT

Fluconazole-resistant
Candida glabrata
is an emerging pathogen that causes fungemia. Polymyxin B, a last-resort antibiotic used to treat multidrug-resistant Gram-negative bacterial infections, has been found to possess
in vitro
fungicidal activity and showed synergy with fluconazole against a single strain of
C. glabrata
. Since both agents may be used simultaneously in intensive care unit (ICU) patients, this study was performed to test for possible synergy of this combination against 35
C. glabrata
blood isolates, using 2 methods: a time-kill assay and an experimental MIC-MIC Etest method. Thirty-five genetically unique
C. glabrata
bloodstream isolates were collected from 2009 to 2011, identified using an API 20C system, and genotyped by repetitive sequence-based PCR (rep-PCR). MICs were determined by Etest and broth microdilution methods. Synergy testing was performed using a modified bacterial Etest synergy method and time-kill assay, with final results read at 24 h. The Etest method showed synergy against 19/35 (54%) isolates; the time-kill assay showed synergy against 21/35 (60%) isolates. Isolates not showing drug synergy had an indifferent status. Concordance between methods was 60%.
In vitro
synergy of polymyxin B and fluconazole against the majority of
C. glabrata
isolates was demonstrated by both methods. The bacterial Etest synergy method adapted well when used with
C. glabrata
. Etest was easier to perform than time-kill assay and may be found to be an acceptable alternative to time-kill assay with antifungals.
Phase 1b Study of New Posaconazole Tablet for Prevention of Invasive Fungal Infections in High-Risk Patients with Neutropenia
Authors: Duarte Rafael F. , López-Jiménez Javier , Cornely Oliver A. , Laverdiere Michel , Helfgott David , Haider Shariq , Chandrasekar Pranatharthi , Langston Amelia , Perfect John , Ma Lei , van Iersel Marlou L. P. S. , Connelly Nancy , Kartsonis Nicholas , Waskin Hetty 
Published: July 2014

ABSTRACT

Posaconazole tablets, a new oral formulation of posaconazole, can be effective when given as antifungal prophylaxis to neutropenic patients at high risk for invasive fungal infection (e.g., those with acute myelogenous leukemia or myelodysplastic syndrome). Such effectiveness might be specifically important to patients with poor oral intake because of nausea, vomiting, or chemotherapy-associated mucositis. This was a prospective, global study in high-risk patients to characterize the pharmacokinetics and safety profile of posaconazole tablets and to identify the dose of posaconazole tablets that would provide exposure within a predefined range of exposures (steady-state average concentration [area under the concentration-time curve/24 h] of ≥500 ng/ml and ≤2,500 ng/ml in >90% of patients). The study evaluated two sequential dosing cohorts: 200 mg posaconazole once daily (
n
= 20) and 300 mg posaconazole once daily (
n
= 34) (both cohorts had a twice-daily loading dose on day 1) taken without regard to food intake during the neutropenic period for ≤28 days. The exposure target was reached (day 8) in 15 of 19 (79%) pharmacokinetic-evaluable patients taking 200 mg posaconazole once daily and in 31 of 32 (97%) patients taking 300 mg posaconazole once daily; 300 mg posaconazole once daily achieved the desired exposure target. Posaconazole tablets were generally well tolerated in high-risk neutropenic patients. (This study has been registered at
ClinicalTrials.gov
under registration no. NCT01777763.)
In Vitro
Analysis of Finasteride Activity against Candida albicans Urinary Biofilm Formation and Filamentation
Authors: Chavez-Dozal Alba A. , Lown Livia , Jahng Maximillian , Walraven Carla J. , Lee Samuel A. 
Published: July 2014

ABSTRACT

Candida albicans
is the 3rd most common cause of catheter-associated urinary tract infections, with a strong propensity to form drug-resistant catheter-related biofilms. Due to the limited efficacy of available antifungals against biofilms, drug repurposing has been investigated in order to identify novel agents with activities against fungal biofilms. Finasteride is a 5-α-reductase inhibitor commonly used for the treatment of benign prostatic hyperplasia, with activity against human type II and III isoenzymes. We analyzed the
Candida
Genome Database and identified a
C. albicans
homolog of type III 5-α-reductase, Dfg10p, which shares 27% sequence identity and 41% similarity to the human type III 5-α-reductase. Thus, we investigated finasteride for activity against
C. albicans
urinary biofilms, alone and in combination with amphotericin B or fluconazole. Finasteride alone was highly effective in the prevention of
C. albicans
biofilm formation at doses of ≥16 mg/liter and the treatment of preformed biofilms at doses of ≥128 mg/liter. In biofilm checkerboard analyses, finasteride exhibited synergistic activity in the prevention of biofilm formation in a combination of 4 mg/liter finasteride with 2 mg/liter fluconazole. Finasteride inhibited filamentation, thus suggesting a potential mechanism of action. These results indicate that finasteride alone is highly active in the prevention of
C. albicans
urinary biofilms
in vitro
and has synergistic activity in combination with fluconazole. Further investigation of the clinical utility of finasteride in the prevention of urinary candidiasis is warranted.
Simple and Rapid Method To Determine Antimycobacterial Potency of Compounds by Using Autoluminescent Mycobacterium tuberculosis
Authors: Sharma Sreevalli , Gelman Ekaterina , Narayan Chandan , Bhattacharjee Deepa , Achar Vijayashree , Humnabadkar Vaishali , Balasubramanian V. , Ramachandran Vasanthi , Dhar Neeraj , Dinesh Neela 
Published: July 2014

ABSTRACT

A major obstacle in the process of discovery of drugs against
Mycobacterium tuberculosis
is its extremely slow growth rate and long generation time (∼20 to 24 h). Consequently, determination of MICs and minimum bactericidal concentrations (MBCs) of potential drug candidates using current methods requires 7 days (resazurin-based MIC assay [REMA]) and 1 month (CFU enumeration), respectively. We employed a synthetic luciferase operon optimized for expression in high-GC-content bacteria and adapted it for use in mycobacteria. Using luminescence-based readouts, we were able to determine the MICs and bactericidal activities of approved tuberculosis (TB) drugs, which correlated well with currently used methods. Although luminescence-based readouts have been used previously to determine the MICs and bactericidal activities of approved TB drugs, in this study we adapted this assay to carry out a pilot screen using a library of 1,114 compounds belonging to diverse chemical scaffolds. We found that MICs derived from a 3-day luminescence assay matched well with REMA-based MIC values. To determine the bactericidal potencies of compounds, a 1:10 dilution of the cultures from the MIC plate was carried out on day 7, and the bactericidal concentrations determined based on time to positivity in 2 weeks were found to be comparable with MBC values determined by the conventional CFU approach. Thus, the luminescent mycobacterium-based approach not only is very simple and inexpensive but also allowed us to generate the information in half the time required by conventional methods.
Effect of Coadministered Fat on the Tolerability, Safety, and Pharmacokinetic Properties of Dihydroartemisinin-Piperaquine in Papua New Guinean Children with Uncomplicated Malaria
Authors: Moore B. R. , Benjamin J. M. , Salman S. , Griffin S. , Ginny E. , Page-Sharp M. , Robinson L. J. , Siba P. , Batty K. T. , Mueller I. , Davis T. M. E. 
Published: July 2014

ABSTRACT

Coadministration of dihydroartemisinin-piperaquine (DHA-PQ) with fat may improve bioavailability and antimalarial efficacy, but it might also increase toxicity. There have been no studies of these potential effects in the pediatric age group. The tolerability, safety, efficacy, and pharmacokinetics of DHA-PQ administered with or without 8.5 g fat were investigated in 30 Papua New Guinean children aged 5 to 10 years diagnosed with uncomplicated falciparum malaria. Three daily 2.5:11.5-mg-base/kg doses were given with water (
n
= 14, group A) or milk (
n
= 16, group B), with regular clinical/laboratory assessment and blood sampling over 42 days. Plasma PQ was assayed by high-performance liquid chromatography with UV detection, and DHA was assayed using liquid chromatography-mass spectrometry. Compartmental pharmacokinetic models for PQ and DHA were developed using a population-based approach. DHA-PQ was generally well tolerated, and initial fever and parasite clearance were prompt. There were no differences in the areas under the concentration-time curve (AUC
0–∞
) for PQ (median, 41,906 versus 36,752 μg · h/liter in groups A and B, respectively;
P
= 0.24) or DHA (4,047 versus 4,190 μg · h/liter;
P
= 0.67). There were also no significant between-group differences in prolongation of the corrected electrocardiographic QT interval (QT
c
) initially during follow-up, but the QT
c
tended to be higher in group B children at 24 h (mean ± standard deviation [SD], 15 ± 10 versus 6 ± 15 ms
0.5
in group A,
P
= 0.067) and 168 h (10 ± 18 versus 1 ± 23 ms
0.5
,
P
= 0.24) when plasma PQ concentrations were relatively low. A small amount of fat does not change the bioavailability of DHA-PQ in children, but a delayed persistent effect on ventricular repolarization cannot be excluded.
Mutations in
mmpL
and in the Cell Wall Stress Stimulon Contribute to Resistance to Oxadiazole Antibiotics in Methicillin-Resistant Staphylococcus aureus
Authors: Xiao Qiaobin , Vakulenko Sergei , Chang Mayland , Mobashery Shahriar 
Published: July 2014

ABSTRACT

Staphylococcus aureus
is a leading cause of hospital- and community-acquired infections, which exhibit broad resistance to various antibiotics. We recently disclosed the discovery of the oxadiazole class of antibiotics, which has
in vitro
and
in vivo
activities against methicillin-resistant
S. aureus
(MRSA). We report herein that MmpL, a putative member of the resistance, nodulation, and cell division (RND) family of proteins, contributes to oxadiazole resistance in the
S. aureus
strain COL. Through serial passages, we generated two
S. aureus
COL variants that showed diminished susceptibilities to an oxadiazole antibiotic. The MICs for the oxadiazole against one strain (designated
S. aureus
COL
I
) increased reproducibly 2-fold (to 4 μg/ml), while against the other strain (
S. aureus
COL
R
), they increased >4-fold (to >8 μg/ml, the limit of solubility). The COL
R
strain was derived from the COL
I
strain. Whole-genome sequencing revealed 31 mutations in
S. aureus
COL
R
, of which 29 were shared with COL
I
. Consistent with our previous finding that oxadiazole antibiotics inhibit cell wall biosynthesis, we found 13 mutations that occurred either in structural genes or in promoters of the genes of the cell wall stress stimulon. Two unique mutations in
S. aureus
COL
R
were substitutions in two genes that encode the putative thioredoxin (SACOL1794) and MmpL (SACOL2566). A role for
mmpL
in resistance to oxadiazoles was discerned from gene deletion and complementation experiments. To our knowledge, this is the first report that a cell wall-acting antibiotic selects for mutations in the cell wall stress stimulon and the first to implicate MmpL in resistance to antibiotics in
S. aureus
.
Porphyromonas gingivalis-Induced Reactive Oxygen Species Activate JAK2 and Regulate Production of Inflammatory Cytokines through c-Jun
Authors: Wang Huizhi , Zhou Huaxin , Duan Xiaoxian , Jotwani Ravi , Vuddaraju Himabindu , Liang Shuang , Scott David A. , Lamont Richard J. 
Published: July 2014

ABSTRACT

Pathogen-induced reactive oxygen species (ROS) play a crucial role in host innate immune responses through regulating the quality and quantity of inflammatory mediators. However, the underlying molecular mechanisms of this effect have yet to be clarified. In this study, we examined the mechanism of action of ROS stimulated by
Porphyromonas gingivalis
in gingival epithelial cells.
P. gingivalis
induced the rapid production of ROS, which lead to the phosphorylation of JAK2 and increased levels of secreted proinflammatory cytokines interleukin-6 (IL-6) and IL-1β. Neutralization of ROS by
N
-acetyl-
l
-cysteine (NAC) abrogated the phosphorylation of JAK2 and suppressed the production of IL-6 and IL-1β. ROS-mediated phosphorylation of JAK2 induced the phosphoactivation of c-Jun amino-terminal protein kinase (JNK) and the downstream transcriptional regulator c-Jun. Inhibition of JAK2, either pharmacologically or by small interfering RNA (siRNA), reduced both the phosphorylation of these molecules and the production of proinflammatory cytokines in response to
P. gingivalis
. Furthermore, pharmacological inhibition or siRNA-mediated gene silencing of JNK or c-Jun mimicked the effect of JAK2 inhibition to suppress
P. gingivalis
-induced IL-6 and IL-1β levels. The results show that ROS-mediated activation of JAK2 is required for
P. gingivalis
-induced inflammatory cytokine production and that the JNK/c-Jun signaling axis is involved in the ROS-dependent regulation of IL-1β and IL-6 production.
Porphyromonas gingivalis Exacerbates Ligature-Induced, RANKL-Dependent Alveolar Bone Resorption via Differential Regulation of Toll-Like Receptor 2 (TLR2) and TLR4
Authors: Lin Jiang , Bi Liangjia , Yu Xiaoqian , Kawai Toshihisa , Taubman Martin A. , Shen Baozhong , Han Xiaozhe 
Published: July 2014

ABSTRACT

Toll-like receptors (TLRs) play a key role in the innate immune responses to periodontal pathogens in periodontal disease. The present study was performed to determine the roles of TLR2 and TLR4 signaling in alveolar bone resorption, using a
Porphyromonas gingivalis
-associated ligature-induced periodontitis model in mice. Wild-type (WT), Tlr2
−/−
, and Tlr4
−/−
mice (8 to 10 weeks old) in the C57/BL6 background were used. Silk ligatures were applied to the maxillary second molars in the presence or absence of live
P. gingivalis
infection. Ligatures were removed from the second molars on day 14, and mice were kept for another 2 weeks before sacrifice for final analysis (day 28). On day 14, there were no differences in alveolar bone resorption and gingival RANKL expression between mice treated with ligation plus
P. gingivalis
infection and mice treated with ligation alone. Gingival interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α) expression was increased, whereas IL-10 expression was decreased in WT and Tlr2
−/−
mice but not in Tlr4
−/−
mice. On day 28, WT and Tlr4
−/−
mice treated with ligation plus
P. gingivalis
infection showed significantly increased bone loss and gingival RANKL expression compared to those treated with ligation alone, whereas such an increase was diminished in Tlr2
−/−
mice. Gingival TNF-α upregulation and IL-10 downregulation were observed only in WT and Tlr4
−/−
mice, not in Tlr2
−/−
mice. In all mice, bone resorption induced by ligation plus
P. gingivalis
infection was antagonized by local anti-RANKL antibody administration. This study suggests that
P. gingivalis
exacerbates ligature-induced, RANKL-dependent periodontal bone resorption via differential regulation of TLR2 and TLR4 signaling.
Distinct Susceptibilities of Corneal Pseudomonas aeruginosa Clinical Isolates to Neutrophil Extracellular Trap-Mediated Immunity
Authors: Shan Qiang , Dwyer Markryan , Rahman Samir , Gadjeva Mihaela 
Published: July 2014

ABSTRACT

Ocular bacterial keratitis, often associated with
Pseudomonas aeruginosa
bacterial infection, commonly occurs in contact lens wearers and may lead to vision impairment. In this study, we analyzed the contribution of neutrophil extracellular traps (NETs) to the mediation of protection during ocular keratitis. Both invasive and cytotoxic
P. aeruginosa
clinical isolates induced NET release by neutrophils. NETs carried the characteristic histone proteins, elastase, lysozyme, myeloperoxidase, and metabolic enzymes. While the invasive
P. aeruginosa
strains PAO1 (serogroup O5) and 6294 (serogroup O6) were trapped by NETs, the cytotoxic
P. aeruginosa
strains 6077, 6206 (serogroup O11), and PA14 (serogroup 010) were less sensitive to NET capture. The mechanism of escape by the cytotoxic strains from adhesion to NETs involved the shedding of outer membrane vesicles (OMVs) that outcompeted the cytotoxic
P. aeruginosa
strains for NET binding. When ocular infection was caused by an invasive strain
in vivo
, NETs were released at the ocular surface to capture bacteria, limiting their spread. Treatment with MNase I had a dose-dependent effect, with low doses of MNase speeding up bacterial clearance and high doses of MNase having toxic consequences. Cumulatively, our data suggest that NET-mediated immunity is a two-step process. Initially, pathogens attach to NET fragments; subsequently, upon nuclease activity, active serine proteases, which proteolytically degrade NET-associated proteins and promote DNase activity, are released. Therefore, a balance between NET production and NET degradation is needed to achieve maximal NET immunity.
Consecutive transcatheter valve-in-valve implantations: the first in the aortic position, the second in the mitral position, in a patient with failing aortic and mitral bioprostheses
Authors: Duncan Alison , Davies Simon , Rosendahl Ulrich , Moat Neil 
Published: July 2014

A 69-year-old man with a failing aortic valve homograft and failing mitral valve xenograft was admitted with an inability to complete full sentences and pulmonary oedema with right ventricular overload. Severe aortic and mitral regurgitation, severe biventricular impairment and pulmonary hypertension were confirmed on transthoracic and transoesophageal echocardiography. An urgent transfemoral valve-in-valve transcatheter valve implantation (TAVI) was performed within the aortic valve homograft with full resolution of aortic regurgitation. Three months later, a semielective trans-apical valve-in-valve procedure was performed in the mitral position, under cardiopulmonary bypass, with full resolution of mitral regurgitation. His exercise tolerance increased from 5 yards to half a mile. This case report summarises a staged double valve-in-valve procedure in a patient who had three previous sternotomies and who had severe heart failure due to failing aortic and mitral bioprostheses. We report two different delivery approaches, using two different transcatheter devices, and describe valve-in-valve techniques, including cardiopulmonary bypass, in the catheter laboratory.
Learning a manifold of fonts
Authors: Campbell Neill D. F. , Kautz Jan 
Published: July 2014

The design and manipulation of typefaces and fonts is an area requiring substantial expertise; it can take many years of study to become a proficient typographer. At the same time, the use of typefaces is ubiquitous; there are many users who, while not experts, would like to be more involved in tweaking or changing existing fonts without suffering the learning curve of professional typography packages.
Given the wealth of fonts that are available today, we would like to exploit the expertise used to produce these fonts, and to enable everyday users to create, explore, and edit fonts. To this end, we build a generative manifold of standard fonts. Every location on the manifold corresponds to a unique and novel typeface, and is obtained by learning a non-linear mapping that intelligently interpolates and extrapolates existing fonts. Using the manifold, we can smoothly interpolate and move between existing fonts. We can also use the manifold as a constraint that makes a variety of new applications possible. For instance, when editing a single character, we can update all the other glyphs in a font simultaneously to keep them compatible with our changes.