bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Optimized Mouse Thigh Infection Model for Enterococci and Its Impact on Antimicrobial Pharmacodynamics
Authors: Rodriguez Carlos A. , Agudelo Maria , Gonzalez Javier M. , Vesga Omar , Zuluaga Andres F. 
Published: October 2014

ABSTRACT

Negligible
in vivo
growth of enterococci and high-level dispersion of data have led to inaccurate estimations of antibiotic pharmacodynamics (PD). Here we improved an
in vivo
model apt for PD studies by optimizing the
in vitro
culture conditions for enterococci. The PD of vancomycin (VAN), ampicillin-sulbactam (SAM), and piperacillin-tazobactam (TZP) against enterococci were determined
in vivo
, comparing the following different conditions of inoculum preparation: aerobiosis, aerobiosis plus mucin, and anaerobiosis plus mucin. Drug exposure was expressed as the ratio of the area under the concentration-time curve for the free, unbound fraction of the drug to the MIC (
f
AUC/MIC) (VAN) or the time in a 24-h period that the drug concentration for the free, unbound fraction exceeded the MIC under steady-state pharmacokinetic conditions (
fT
>MIC
) (SAM and TZP) and linked to the change in log
10
CFU/thigh. Only anaerobiosis plus mucin enhanced the
in vivo
growth, yielding significant PD parameters with all antibiotics. In conclusion, robust
in vivo
growth of enterococci was crucial for better determining the PD of tested antibacterial agents, and this was achieved by optimizing the procedure for preparing the inoculum.
Antimalarial Action of Artesunate Involves DNA Damage Mediated by Reactive Oxygen Species
Authors: Gopalakrishnan Anusha M. , Kumar Nirbhay 
Published: October 2014

ABSTRACT

Artemisinin-based combination therapy (ACT) is the recommended first-line treatment for
Plasmodium falciparum
malaria. It has been suggested that the cytotoxic effect of artemisinin is mediated by free radicals followed by the alkylation of
P. falciparum
proteins. The endoperoxide bridge, the active moiety of artemisinin derivatives, is cleaved in the presence of ferrous iron, generating reactive oxygen species (ROS) and other free radicals. However, the emergence of resistance to artemisinin in
P. falciparum
underscores the need for new insights into the molecular mechanisms of antimalarial activity of artemisinin. Here we show that artesunate (ART) induces DNA double-strand breaks in
P. falciparum
in a physiologically relevant dose- and time-dependent manner. DNA damage induced by ART was accompanied by an increase in the intracellular ROS level in the parasites. Mannitol, a ROS scavenger, reversed the cytotoxic effect of ART and reduced DNA damage, and modulation of glutathione (GSH) levels was found to impact ROS and DNA damage induced by ART. Accumulation of ROS, increased DNA damage, and the resulting antiparasite effect suggest a causal relationship between ROS, DNA damage, and parasite death. Finally, we also show that ART-induced ROS production involves a potential role for NADPH oxidase, an enzyme involved in the production of superoxide anions. Our results with
P. falciparum
provide novel insights into previously unknown molecular mechanisms underlying the antimalarial activity of artemisinin derivatives and may help in the design of next-generation antimalarial drugs against the most virulent
Plasmodium
species.
High-Content Screening Technology Combined with a Human Granuloma Model as a New Approach To Evaluate the Activities of Drugs against Mycobacterium tuberculosis
Authors: Silva-Miranda Mayra , Ekaza Euloge , Breiman Adrien , Asehnoune Karim , Barros-Aguirre David , Pethe Kevin , Ewann Fanny , Brodin Priscille , Ballell-Pages Lluís , Altare Frédéric 
Published: October 2014

ABSTRACT

Tuberculosis remains a major health problem due to the emergence of drug-resistant strains of
Mycobacterium tuberculosis
. Some models have provided valuable information about drug resistance and efficacy; however, the translation of these results into effective human treatments has mostly proven unsuccessful. In this study, we adapted high-content screening (HCS) technology to investigate the activities of antitubercular compounds in the context of an
in vitro
granuloma model. We observed significant shifts in the MIC
50
s between the activities of the compounds under extracellular and granuloma conditions.
Stratification of the Impact of Inappropriate Empirical Antimicrobial Therapy for Gram-Negative Bloodstream Infections by Predicted Prognosis
Authors: Cain Sarah E. , Kohn Joseph , Bookstaver P. Brandon , Albrecht Helmut , Al-Hasan Majdi N. 
Published: October 2014

ABSTRACT

The bloodstream infection mortality risk score (BSIMRS) predicts the outcome of patients with Gram-negative bloodstream infections (BSI) with high discrimination. This retrospective cohort study examined the impact of inappropriate antimicrobial therapy on mortality in adult patients with Gram-negative BSI admitted to Palmetto Health Hospitals in Columbia, SC, USA, from 1 January 2011 to 31 December 2012 after stratification by predicted prognosis at initial presentation using BSIMRS. A multivariate Cox regression model was used to identify independent risk factors for 28-day mortality overall and within each predefined BSIMRS category (<5, 5 to 9, and ≥10). Relative risk reduction (RRR), absolute risk reduction (ARR), and number needed to treat (NNT) were calculated from a predictive logistic regression model of mortality. Overall, 390 unique patients with first episodes of Gram-negative BSI were identified. The median age was 66 years, and 229 (59%) were women. There was significant association between inappropriate antimicrobial therapy and mortality in patients with BSIMRS of 5 to 9 (adjusted hazard ratio [aHR], 3.55; 95% confidence intervals [CI], 1.22 to 8.31;
P
= 0.02) and BSIMRS of ≥10 (aHR, 4.99; 95% CI, 1.09 to 22.87;
P
= 0.04) but not in those with BSIMRS of <5 (aHR, 3.34; 95% CI, 0.17 to 22.77;
P
= 0.34). RRR, ARR, and NNT were 0.25, 0.02, and 63 for BSIMRS of <5; 0.56, 0.32, and 3 for BSIMRS of 5 to 9; and 0.39, 0.39, and 3 for BSIMRS of ≥10, respectively. There is a significant benefit from appropriate antimicrobial therapy in patients with Gram-negative BSI with guarded (BSIMRS of 5 to 9) and poor (BSIMRS of ≥10) predicted prognosis. Survival difference remains unclear among those with good predicted prognosis (BSIMRS of <5) at initial presentation.
In Vitro
and Intracellular Activities of Peptide Deformylase Inhibitor GSK1322322 against Legionella pneumophila Isolates
Authors: Dubois Jacques , Dubois Maïtée , Martel Jean-François , Aubart Kelly , Butler Deborah 
Published: October 2014

ABSTRACT

GSK1322322, a novel peptide deformylase inhibitor currently in development as an oral and intravenous agent for the treatment of hospitalized community-acquired bacterial pneumonia, showed poor
in vitro
activity against a panel of 50
Legionella pneumophila
strains, with MICs ranging from 1 to 16 μg/ml and an MIC
90
of 16 μg/ml, but very potent intracellular activity, with the minimum extracellular concentrations capable of inhibiting intracellular proliferation (MIECs) ranging from 0.12 to 2 μg/ml and 98% of the strains being inhibited by concentrations of ≤1 μg/ml.
Target-Based Resistance in Pseudomonas aeruginosa and Escherichia coli to NBTI 5463, a Novel Bacterial Type II Topoisomerase Inhibitor
Authors: Nayar Asha S. , Dougherty Thomas J. , Reck Folkert , Thresher Jason , Gao Ning , Shapiro Adam B. , Ehmann David E. 
Published: October 2014

ABSTRACT

In a previous report (T. J. Dougherty, A. Nayar, J. V. Newman, S. Hopkins, G. G. Stone, M. Johnstone, A. B. Shapiro, M. Cronin, F. Reck, and D. E. Ehmann, Antimicrob Agents Chemother 58:2657–2664, 2014), a novel bacterial type II topoisomerase inhibitor, NBTI 5463, with activity against Gram-negative pathogens was described. First-step resistance mutations in
Pseudomonas aeruginosa
arose exclusively in the
nfxB
gene, a regulator of the MexCD-OprJ efflux pump system. The present report describes further resistance studies with NBTI 5463 in both
Pseudomonas aeruginosa
and
Escherichia coli
. Second-step mutations in
P. aeruginosa
arose at aspartate 82 of the gyrase A subunit and led to 4- to 8-fold increases in the MIC over those seen in the parental strain with a first-step
nfxB
efflux mutation. A third-step mutant showed additional GyrA changes, with no changes in topoisomerase IV. Despite repeated efforts, resistance mutations could not be selected in
E. coli
. Genetic introduction of the Asp82 mutations observed in
P. aeruginosa
did not significantly increase the NBTI MIC in
E. coli
. However, with the aspartate 82 mutation present, it was possible to select second-step mutations in topoisomerase IV that did lead to MIC increases of 16- and 128-fold. As with the gyrase aspartate 82 mutation, the mutations in topoisomerase IV did not by themselves raise the NBTI MIC in
E. coli
. Only the presence of mutations in both targets of
E. coli
led to an increase in NBTI MIC values. This represents a demonstration of the value of balanced dual-target activity in mitigating resistance development.
In Vitro
Efficacy of High-Dose Tobramycin against Burkholderia cepacia Complex and Stenotrophomonas maltophilia Isolates from Cystic Fibrosis Patients
Authors: Ratjen Anina , Yau Yvonne , Wettlaufer Jillian , Matukas Larissa , Zlosnik James E. A. , Speert David P. , LiPuma John J. , Tullis Elizabeth , Waters Valerie 
Published: October 2014

ABSTRACT

Burkholderia cepacia
complex and
Stenotrophomonas maltophilia
infections are associated with poor clinical outcomes in persons with cystic fibrosis (CF). The MIC
50
based on planktonic growth and the biofilm concentration at which 50% of the isolates tested are inhibited (BIC
50
) of tobramycin were measured for 180
B. cepacia
complex and 101
S. maltophilia
CF isolates and were 100 μg/ml for both species. New inhalation devices that deliver high tobramycin levels to the lung may be able to exceed these MICs.
Genomic Analysis of Reduced Susceptibility to Tigecycline in Enterococcus faecium
Authors: Cattoir Vincent , Isnard Christophe , Cosquer Thibaud , Odhiambo Arlène , Bucquet Fiona , Guérin François , Giard Jean-Christophe 
Published: October 2014

ABSTRACT

Tigecycline (TIG) is approved for use for the treatment of complicated intra-abdominal infections, skin and skin structure infections, as well as pneumonia. Acquired resistance or reduced susceptibility to TIG has been observed in Gram-negative rods, has seldom been reported in Gram-positive organisms, and has not yet been reported in
Enterococcus faecium
. Using the serial passage method,
in vitro
mutant AusTig and
in vitro
mutants HMtig1 and HMtig2 with decreased TIG susceptibility (MICs, 0.25 μg/ml) were obtained from strains
E. faecium
Aus0004 and HM1070 (MICs, 0.03 μg/ml), respectively. In addition, two vancomycin-resistant
E. faecium
clinical isolates (EF16 and EF22) with reduced susceptibility to TIG (MICs, 0.5 and 0.25 μg/ml, respectively) were studied. Compared to the wild-type strains, the
in vitro
mutants also showed an increase in the MICs of other tetracyclines. An efflux mechanism did not seem to be involved in the reduced TIG susceptibility, since the presence of efflux pump inhibitors (reserpine or pantoprazole) did not affect the MICs of TIG. Whole-genome sequencing of AusTig was carried out, and genomic comparison with the Aus0004 genome was performed. Four modifications leading to an amino acid substitution were found. These mutations affected the
rpsJ
gene (
efau004_00094
, coding for the S10 protein of the 30S ribosomal subunit),
efau004_01228
(encoding a cation transporter),
efau004_01636
(coding for a hypothetical protein), and
efau004_02455
(encoding the
l
-lactate oxidase). The four other strains exhibiting reduced TIG susceptibility were screened for the candidate mutations. This analysis revealed that three of them showed an amino acid substitution in the same region of the RpsJ protein. In this study, we characterized for the first time genetic determinants linked to reduced TIG susceptibility in enterococci.
Lymphocytes Modulate Innate Immune Responses and Neuronal Damage in Experimental Meningitis
Authors: Hoffmann Olaf , Rung Olga , Held Josephin , Boettcher Chotima , Prokop Stefan , Stenzel Werner , Priller Josef 
Published: October 2014

ABSTRACT

In bacterial meningitis, excessive immune responses carry significant potential for damage to brain tissue even after successful antibiotic therapy. Bacterial meningitis is regarded primarily as the domain of innate immunity, and the role of lymphocytes remains unclear. We studied the contribution of lymphocytes to acute inflammation and neurodegeneration in experimental Toll-like receptor 2-driven meningitis, comparing wild-type mice with RAG-1-deficient mice that have no mature T and B lymphocytes. At 24 h after intrathecal challenge with the synthetic bacterial lipopeptide Pam
3
CysSK
4
, RAG-1-deficient mice displayed more pronounced clinical impairment and an increased concentration of neutrophils, reduced expression of interleukin-10 (IL-10) mRNA, and increased expression of CXCL1 mRNA in the cerebrospinal fluid. Conversely, neuronal loss in the dentate gyrus was reduced in RAG-1-deficient mice, and expression of IL-10, transforming growth factor β and CCL2 mRNA by microglia was increased compared to wild-type mice. Adoptive transfer of wild-type lymphocytes reversed the enhanced meningeal inflammation and functional impairment observed in RAG-1-deficient mice. Our findings suggest compartment-specific effects of lymphocytes during acute bacterial meningitis, including attenuation of meningeal inflammation and shifting of microglial activation toward a more neurotoxic phenotype.
The Rate of Osmotic Downshock Determines the Survival Probability of Bacterial Mechanosensitive Channel Mutants
Authors: Bialecka-Fornal Maja , Lee Heun Jin , Phillips Rob 
Published: October 2014

ABSTRACT

Mechanosensitive (MS) channels allow cells to sense and respond to environmental changes. In bacteria, these channels are believed to protect against an osmotic shock. The physiological function of these channels has been characterized primarily by a standardized assay, where aliquots of batch-cultured cells are rapidly pipetted into a hypotonic medium. Under this method, it has been inferred many types of MS channels (MscS homologs in
Escherichia coli
) demonstrate limited effectiveness against shock, typically rescuing less than 10% of the cells when expressed at native levels. We introduce a single-cell-based assay which allows us to control how fast the osmolarity changes, over time scales ranging from a fraction of a second to several minutes. We find that the protection provided by MS channels depends strongly on the rate of osmotic change, revealing that, under a slow enough osmotic drop, MscS homologs can lead to survival rates comparable to those found in wild-type strains. Further, after the osmotic downshift, we observe multiple death phenotypes, which are inconsistent with the prevailing paradigm of how cells lyse. Both of these findings require a reevaluation of our basic understanding of the physiology of MS channels.
Eocene magmatism in the Tethyan Himalaya, southern Tibet
Authors: Zeng Lingsen , Gao Li-E , Tang Suohang , Hou Kejun , Guo Chunli , Hu Guyue 
Published: October 2014

Abstract

Recent studies in the Yardoi gneiss dome of the Tethyan Himalaya, southern Tibet demonstrated that the Himalayan orogenic belt experienced a major episode of crustal melting in the Mid-Eocene (
c.
44–40 Ma), represented by the genesis of a suite of high Sr/Y two-mica granites (TMGs) accompanied by leucogranites. Geochemical and U–Pb age data indicate that (1) both the leucogranite and the porphyritic leucogranite formed at
c.
44–41 Ma are characterized by similar Sr–Nd–Hf isotope systematics to those in the less evolved TMGs; (2) these three suites of rocks might represent a Mid-Eocene igneous complex derived from partial melting of amphibolite under crustal thickened conditions; and (3) in contrast with the TMGs, leucogranites experienced hydrothermal-magma interactions as well as plagioclase fractional crystallization as revealed from pronounced negative Eu anomalies, much lower Sr concentrations, and elevated common Pb and U concentrations in the latest magmatic zircon overgrowth. Our data suggest that magmatic differentiation of more primitive magmas could have played a critical role in the generation of leucogranites. Documentation of partial melting of deep crustal rocks during the earliest phase of the tectonic evolution of the Himalayan orogen implies that the large-scale collisional orogenic belt could experience intensive partial melting under contraction and thickening conditions, which could profoundly affect the geophysical and geochemical properties as well as rheological properties and facilitate the initiation of movement or flow of deep crustal rocks.
Homeoprotein Six2 Promotes Breast Cancer Metastasis via Transcriptional and Epigenetic Control of E-Cadherin Expression
Authors: Wang Chu-An , Drasin David , Pham Catherine , Jedlicka Paul , Zaberezhnyy Vadym , Guney Michelle , Li Howard , Nemenoff Raphael , Costello James C. , Tan Aik-Choon , Ford Heide L. 
Published: October 2014

AbstractMisexpression of developmental transcription factors occurs often in human cancers, where embryonic programs may be reinstated in a context that promotes or sustains malignant development. In this study, we report the involvement of the kidney development transcription factor Six2 in the metastatic progression of human breast cancer. We found that Six2 promoted breast cancer metastasis by a novel mechanism involving both transcriptional and epigenetic regulation of E-cadherin. Downregulation of E-cadherin by Six2 was necessary for its ability to increase soft agar growth and in vivo metastasis in an immunocompetent mouse model of breast cancer. Mechanistic investigations showed that Six2 represses E-cadherin expression by upregulating Zeb2, in part, through a microRNA-mediated mechanism and by stimulating promoter methylation of the E-cadherin gene (Cdh1). Clinically, SIX2 expression correlated inversely with CDH1 expression in human breast cancer specimens, corroborating the disease relevance of their interaction. Our findings establish Six2 as a regulator of metastasis in human breast cancers and demonstrate an epigenetic function for SIX family transcription factors in metastatic progression through the regulation of E-cadherin. Cancer Res; 74(24); 7357–70. ©2014 AACR.
Impact of Chronic Graft-versus-Host Disease on Late Relapse and Survival on 7,489 Patients after Myeloablative Allogeneic Hematopoietic Cell Transplantation for Leukemia
Authors: Boyiadzis Michael , Arora Mukta , Klein John P. , Hassebroek Anna , Hemmer Michael , Urbano-Ispizua Alvaro , Antin Joseph H. , Bolwell Brian J. , Cahn Jean-Yves Y. , Cairo Mitchell S. , Cutler Corey S. , Flowers Mary E. , Gale Robert P. , Herzig Roger , Isola Luis M. , Jacobsohn David A. , Jagasia Madan H. , Klumpp Thomas R. , Lee Stephanie J. , Petersdorf Effie W. , Santarone Stella , Spellman Stephen R. , Schouten Harry C. , Verdonck Leo F. , Wingard John R. , Weisdorf Daniel J. , Horowitz Mary M. , Pavletic Steven Z. 
Published: October 2014

Abstract
Purpose: Malignancy relapse remains a major obstacle for successful allogeneic hematopoietic cell transplantation (HCT). Chronic graft-versus-host disease (cGVHD) is associated with fewer relapses. However, when studying effects of cGVHD on relapse, it is difficult to separate from acute GVHD effects as most cases of cGVHD occur within the first year after transplant at the time when acute GVHD is still active.
Experimental Design: This study based on CIBMTR registry data investigated cGVHD and its association with the incidence of late relapse and survival in 7,489 patients with acute myelogenous leukemia (AML), acute lymphoblastic leukemia (ALL), chronic myelogenous leukemia (CML), and myelodysplastic syndromes (MDS), who were leukemia free at 12 months after myeloablative allogeneic HCT.
Results: Forty-seven percent of the study population was diagnosed with cGVHD at 12 months after transplant. The protective effect of cGVHD on late relapse was present only in patients with CML [RR, 0.47; 95% confidence interval (CI), 0.37–0.59; P &lt; 0.0001). cGVHD was significantly associated with higher risk of treatment-related mortality (TRM; RR, 2.43; 95% CI, 2.09–2.82; P &lt; 0.0001) and inferior overall survival (RR, 1.56; 95% CI, 1.41–1.73; P &lt; 0.0001) for all diseases. In patients with CML, all organ sites and presentation types of cGVHD were equally associated with lower risk of late relapse.
Conclusions: These results indicate that clinically relevant antileukemia effects of cGVHD on late relapses are present only in CML but not in AML, ALL, or MDS. Chronic GVHD in patients who are 1-year survivors after myeloablative allogeneic HCT is primarily associated with higher TRM and inferior survival. Clin Cancer Res; 21(9); 2020–8. ©2014 AACR.
See related commentary by Gill, p. 1981
Low Expression of the E3 Ubiquitin Ligase CBL Confers Chemoresistance in Human Pancreatic Cancer and Is Targeted by Epidermal Growth Factor Receptor Inhibition
Authors: Kadera Brian E. , Toste Paul A. , Wu Nanping , Li Luyi , Nguyen Andrew H. , Dawson David W. , Donahue Timothy R. 
Published: October 2014

Abstract
Purpose: Expression of CBL, an ubiquitin ligase, is decreased in 60% of human pancreatic ductal adenocarcinomas (PDAC) and is associated with shorter overall survival. We sought to determine how low CBL directly contributes to clinically more aggressive PDAC.
Experimental Design: Human PDACs were stained for CBL, pEGFR, and EGFR. CBL-low was modeled in PDAC cells (Panc-1, L3.6pl, and AsPC-1) via transient transfection (siRNA) or stable knockdown (shRNA). Cell viability and apoptosis were measured by MTT assays and FACS. Immunoblot and a phospho-receptor tyrosine kinase (pRTK) array were used to probe signal transduction. NOD-scid-IL2Rγnull mice were subcutaneously implanted with PDAC or PDACCBL-low cells on opposite flanks and treated with gemcitabine ± erlotinib for ≥4 weeks.
Results: There was an inverse correlation between CBL and pEGFR protein expression in 12 of 15 tumors. CBL knockdown increased PDAC resistance to gemcitabine and 5-fluorouracil (5-FU) by upregulating pEGFR (Y1068), pERK, and pAKT. A pRTK array of PDACCBL-low cells revealed additional activated tyrosine kinases but all to a much lower magnitude than EGFR. Increased chemoresistance from low CBL was abrogated by the EGFR inhibitor erlotinib both in vitro and in vivo. Erlotinib+gemcitabine–treated PDACCBL-low cells exhibited greater apoptosis by cleaved PARP, caspase-3, and Annexin V/PI.
Conclusions: Low CBL causes chemoresistance in PDAC via stress-induced EGFR activation that can be effectively abrogated by EGFR inhibition. These results suggest that dysregulation of ubiquitination is a key mechanism of EGFR hyperactivation in PDAC and that low CBL may define PDAC tumors likely to respond to erlotinib treatment. Clin Cancer Res; 21(1); 157–65. ©2014 AACR.