bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification of EnvC and Its Cognate Amidases as Novel Determinants of Intrinsic Resistance to Cationic Antimicrobial Peptides
Authors: Oguri Tamiko , Yeo Won-Sik , Bae Taeok , Lee Hyunwoo 
Published: January 2016

ABSTRACT

Cationic antimicrobial peptides (CAMPs) are an essential part of the innate immune system. Some Gram-negative enteric pathogens, such as
Salmonella enterica
, show intrinsic resistance to CAMPs. However, the molecular basis of intrinsic resistance is poorly understood, largely due to a lack of information about the genes involved. In this study, using a microarray-based genomic technique, we screened the Keio collection of 3,985
Escherichia coli
mutants for altered susceptibility to human neutrophil peptide 1 (HNP-1) and identified
envC
and
zapB
as novel genetic determinants of intrinsic CAMP resistance. In CAMP killing assays, an
E. coli
Δ
envC
Ec
or Δ
zapB
Ec
mutant displayed a distinct profile of increased susceptibility to both LL-37 and HNP-1. Both mutants, however, displayed wild-type resistance to polymyxin B and human β-defensin 3 (HBD3), suggesting that the intrinsic resistance mediated by EnvC or ZapB is specific to certain CAMPs. A corresponding
Salmonella
Δ
envC
Se
mutant showed similarly increased CAMP susceptibility. The
envC
mutants of both
E. coli
and
S. enterica
displayed increased surface negativity and hydrophobicity, which partly explained the increased CAMP susceptibility. However, the Δ
envC
Ec
mutant, but not the Δ
envC
Se
mutant, was defective in outer membrane permeability, excluding this defect as a common factor contributing to the increased CAMP susceptibility. Animal experiments showed that the
Salmonella
Δ
envC
Se
mutant had attenuated virulence. Taken together, our results indicate that the role of
envC
in intrinsic CAMP resistance is likely conserved among Gram-negative enteric bacteria, demonstrate the importance of intrinsic CAMP resistance for full virulence of
S. enterica
, and provide insight into distinct mechanisms of action of CAMPs.
Azithromycin Dose To Maximize Efficacy and Suppress Acquired Drug Resistance in Pulmonary Mycobacterium avium Disease
Authors: Deshpande Devyani , Pasipanodya Jotam G. , Gumbo Tawanda 
Published: January 2016

ABSTRACT

Mycobacterium avium
complex is now the leading mycobacterial cause of chronic pneumonia in the United States. Macrolides and ethambutol form the backbone of the regimen used in the treatment of pulmonary disease. However, therapy outcomes remain poor, with microbial cure rates of 4% in cavitary disease. The treatment dose of azithromycin has mostly been borrowed from that used to treat other bacterial pneumonias; there are no formal dose-response studies in pulmonary
M. avium
disease and the optimal dose is unclear. We utilized population pharmacokinetics and pharmacokinetics/pharmacodynamics-derived azithromycin exposures associated with optimal microbial kill or resistance suppression to perform 10,000 patient Monte Carlo simulations of dose effect studies for daily azithromycin doses of 0.5 to 10 g. The currently recommended dose of 500 mg per day achieved the target exposures in 0% of patients. Exposures associated with optimal kill and resistance suppression were achieved in 87 and 54% of patients, respectively, only by the very high dose of 8 g per day. The azithromycin susceptibility breakpoint above which patients failed therapy on the very high doses of 8 g per day was an MIC of 16 mg/liter, suggesting a critical concentration of 32 mg/liter, which is 8-fold lower than the currently used susceptibility breakpoint of 256 mg/liter. If the standard dose of 500 mg a day were used, then the critical concentration would fall to 2 mg/liter, 128-fold lower than 256 mg/liter. The misclassification of resistant isolates as susceptible could explain the high failure rates of current doses.
Garcinol Inhibits GCN5-Mediated Lysine Acetyltransferase Activity and Prevents Replication of the Parasite Toxoplasma gondii
Authors: Jeffers Victoria , Gao Hongyu , Checkley Lisa A. , Liu Yunlong , Ferdig Michael T. , Sullivan William J. 
Published: January 2016

ABSTRACT

Lysine acetylation is a critical posttranslational modification that influences protein activity, stability, and binding properties. The acetylation of histone proteins in particular is a well-characterized feature of gene expression regulation. In the protozoan parasite
Toxoplasma gondii
, a number of lysine acetyltransferases (KATs) contribute to gene expression and are essential for parasite viability. The natural product garcinol was recently reported to inhibit enzymatic activities of GCN5 and p300 family KATs in other species. Here we show that garcinol inhibits TgGCN5b, the only nuclear GCN5 family KAT known to be required for
Toxoplasma
tachyzoite replication. Treatment of tachyzoites with garcinol led to a reduction of global lysine acetylation, particularly on histone H3 and TgGCN5b itself. We also performed transcriptome sequencing (RNA-seq), which revealed increasing aberrant gene expression coincident with increasing concentrations of garcinol. The majority of the genes that were most significantly affected by garcinol were also associated with TgGCN5b in a previously reported chromatin immunoprecipitation assay with microarray technology (ChIP-chip) analysis. The dysregulated gene expression induced by garcinol significantly inhibits
Toxoplasma
tachyzoite replication, and the concentrations used exhibit no overt toxicity on human host cells. Garcinol also inhibits
Plasmodium falciparum
asexual replication with a 50% inhibitory concentration (IC
50
) similar to that for
Toxoplasma
. Together, these data support that pharmacological inhibition of TgGCN5b leads to a catastrophic failure in gene expression control that prevents parasite replication.
Uncovering an Important Role for YopJ in the Inhibition of Caspase-1 in Activated Macrophages and Promoting Yersinia pseudotuberculosis Virulence
Authors: Schoberle Taylor J. , Chung Lawton K. , McPhee Joseph B. , Bogin Ben , Bliska James B. 
Published: January 2016

ABSTRACT

Pathogenic
Yersinia
species utilize a type III secretion system to translocate Yop effectors into infected host cells. Yop effectors inhibit innate immune responses in infected macrophages to promote
Yersinia
pathogenesis. In turn,
Yersinia-
infected macrophages respond to translocation of Yops by activating caspase-1, but different mechanisms of caspase-1 activation occur, depending on the bacterial genotype and the state of phagocyte activation. In macrophages activated with lipopolysaccharide (LPS) prior to
Yersinia pseudotuberculosis
infection, caspase-1 is activated by a rapid inflammasome-dependent mechanism that is inhibited by translocated YopM. The possibility that other effectors cooperate with YopM to inhibit caspase-1 activation in LPS-activated macrophages has not been investigated. Toward this aim, epistasis analysis was carried out in which the phenotype of a
Y. pseudotuberculosis
yopM
mutant was compared to that of a
yopJ yopM
,
yopE yopM
,
yopH yopM
,
yopT yopM
, or
ypkA yopM
mutant. Activation of caspase-1 was measured by cleavage of the enzyme, release of interleukin-1β (IL-1β), and pyroptosis in LPS-activated macrophages infected with wild-type or mutant
Y. pseudotuberculosis
strains. Results show enhanced activation of caspase-1 after infection with the
yopJ yopM
mutant relative to infection by any other single or double mutant. Similar results were obtained with the
yopJ
,
yopM
, and
yopJ yopM
mutants of
Yersinia pestis
. Following intravenous infection of mice, the
Y. pseudotuberculosis
yopJ
mutant was as virulent as the wild type, while the
yopJ yopM
mutant was significantly more attenuated than the
yopM
mutant. In summary, through epistasis analysis this work uncovered an important role for YopJ in inhibiting caspase-1 in activated macrophages and in promoting
Yersinia
virulence.
Interleukin-13 Receptor α1-Dependent Responses in the Intestine Are Critical to Parasite Clearance
Authors: Sun Rex , Urban Joseph F. , Notari Luigi , Vanuytsel Tim , Madden Kathleen B. , Bohl Jennifer A. , Ramalingam Thirumalai R. , Wynn Thomas A. , Zhao Aiping , Shea-Donohue Terez 
Published: January 2016

ABSTRACTNematode infection upregulates interleukin-4 (IL-4) and IL-13 and induces STAT6-dependent changes in gut function that promote worm clearance. IL-4 and IL-13 activate the type 2 IL-4 receptor (IL-4R), which contains the IL-13Rα1 and IL-4Rα chains. We used mice deficient in IL-13Rα1 (IL-13Rα1−/−) to examine the contribution of IL-13 acting at the type 2 IL-4R to immune and functional responses to primary (Hb1) and secondary (Hb2) infections with the gastrointestinal nematode parasiteHeligmosomoides bakeri. There were differences between strains in the IL-4 and IL-13 expression responses to Hb1 but not Hb2 infection. Following Hb2 infection, deficient mice had impaired worm expulsion and higher worm fecundity despite normal production of Th2-derived cytokines. The upregulation of IL-25 and IL-13Rα2 in Hb1- and Hb2-infected wild-type (WT) mice was absent in IL-13Rα1−/−mice. Goblet cell numbers and resistin-like molecule beta (RELM-β) expression were attenuated significantly in IL-13Rα1−/−mice following Hb2 infections. IL-13Rα1 contributes to the development of alternatively activated macrophages, but the type 1 IL-4R is also important. Hb1 infection had no effects on smooth muscle function or epithelial permeability in either strain, while the enhanced mucosal permeability and changes in smooth muscle function and morphology observed in response to Hb2 infection in WT mice were absent in IL-13Rα1−/−mice. Notably, the contribution of claudin-2, which has been linked to IL-13, does not mediate the increased mucosal permeability following Hb2 infection. These results show that activation of IL-13Rα1 is critical for key aspects of the immune and functional responses to Hb2 infection that facilitate expulsion.
Trk2 Potassium Transport System in Streptococcus mutans and Its Role in Potassium Homeostasis, Biofilm Formation, and Stress Tolerance
Authors: Binepal Gursonika , Gill Kamal , Crowley Paula , Cordova Martha , Brady L. Jeannine , Senadheera Dilani B. , Cvitkovitch Dennis G. 
Published: January 2016

ABSTRACT

Potassium (K
+
) is the most abundant cation in the fluids of dental biofilm. The biochemical and biophysical functions of K
+
and a variety of K
+
transport systems have been studied for most pathogenic bacteria but not for oral pathogens. In this study, we establish the modes of K
+
acquisition in
Streptococcus mutans
and the importance of K
+
homeostasis for its virulence attributes. The
S. mutans
genome harbors four putative K
+
transport systems that included two Trk-like transporters (designated Trk1 and Trk2), one glutamate/K
+
cotransporter (GlnQHMP), and a channel-like K
+
transport system (Kch). Mutants lacking Trk2 had significantly impaired growth, acidogenicity, aciduricity, and biofilm formation. [K
+
] less than 5 mM eliminated biofilm formation in
S. mutans
. The functionality of the Trk2 system was confirmed by complementing an
Escherichia coli
TK2420 mutant strain, which resulted in significant K
+
accumulation, improved growth, and survival under stress. Taken together, these results suggest that Trk2 is the main facet of the K
+
-dependent cellular response of
S. mutans
to environment stresses.

IMPORTANCE
Biofilm formation and stress tolerance are important virulence properties of caries-causing
Streptococcus mutans
. To limit these properties of this bacterium, it is imperative to understand its survival mechanisms. Potassium is the most abundant cation in dental plaque, the natural environment of
S. mutans
. K
+
is known to function in stress tolerance, and bacteria have specialized mechanisms for its uptake. However, there are no reports to identify or characterize specific K
+
transporters in
S. mutans
. We identified the most important system for K
+
homeostasis and its role in the biofilm formation, stress tolerance, and growth. We also show the requirement of environmental K
+
for the activity of biofilm-forming enzymes, which explains why such high levels of K
+
would favor biofilm formation.
SagB Glucosaminidase Is a Determinant of Staphylococcus aureus Glycan Chain Length, Antibiotic Susceptibility, and Protein Secretion
Authors: Chan Yvonne G. Y. , Frankel Matthew B. , Missiakas Dominique , Schneewind Olaf 
Published: January 2016

ABSTRACT

The envelope of
Staphylococcus aureus
is comprised of peptidoglycan and its attached secondary polymers, teichoic acid, capsular polysaccharide, and protein. Peptidoglycan synthesis involves polymerization of lipid II precursors into glycan strands that are cross-linked at wall peptides. It is not clear whether peptidoglycan structure is principally determined during polymerization or whether processive enzymes affect cell wall structure and function, for example, by generating conduits for protein secretion. We show here that
S. aureus
lacking SagB, a membrane-associated
N
-acetylglucosaminidase, displays growth and cell-morphological defects caused by the exaggerated length of peptidoglycan strands. SagB cleaves polymerized glycan strands to their physiological length and modulates antibiotic resistance in methicillin-resistant
S. aureus
(MRSA). Deletion of
sagB
perturbs protein trafficking into and across the envelope, conferring defects in cell wall anchoring and secretion, as well as aberrant excretion of cytoplasmic proteins.

IMPORTANCE
Staphylococcus aureus
is thought to secrete proteins across the plasma membrane via the Sec pathway; however, protein transport across the cell wall envelope has heretofore not been studied. We report that
S. aureus sagB
mutants generate elongated peptidoglycan strands and display defects in protein secretion as well as aberrant excretion of cytoplasmic proteins. These results suggest that the thick peptidoglycan layer of staphylococci presents a barrier for protein secretion and that SagB appears to extend the Sec pathway across the cell wall envelope.
Electroacupuncture Protects against Articular Cartilage Erosion by Inhibiting Mitogen-Activated Protein Kinases in a Rat Model of Osteoarthritis
Authors: Liao Ying , Li Xinhong , Li Neng , Zhou Jun 
Published: January 2016

Objective The therapeutic effects of electroacupuncture (EA) on osteoarthritis (OA) are well documented; however, the precise mechanisms of action have not yet been fully elucidated. The present study aimed to investigate the effect of EA on cartilage in an experimental animal model of OA induced by anterior cruciate ligament transection (ACLT) and to examine for concomitant changes in the expression of mitogen-activated protein kinases (MAPKs) in the articular cartilage. Methods Thirty-three-month-old male Sprague Dawley rats were randomly divided into the following three groups (n=10 each): sham operated group (Control group), ACLT without treatment (ACLT group), and ACLT with EA treatment (ACLT+EA group). One week after ACLT, rats in the ACLT+EA group received 12 weeks of EA treatment. Histological analysis and quantitative real-time PCR were used to investigate the effects of EA on cartilage morphology (quantified using modified Mankin scores) and expression of MAPKs (p38, c-Jun N-terminal kinase (c-Jun), and extracellular signal-regulated kinase (ERK)1), respectively. Results ACLT produced coarse cartilage surfaces, fibrous degeneration, and fissuring, all of which were suppressed by EA treatment. Although Mankin scores in the ACLT+EA group were significantly higher compared to the Control group (p<0.01), they were significantly lower than the (untreated) ACLT group (p<0.01). The increase in mRNA expression of p38, c-Jun, ERK1, and matrix metalloproteinase (MMP)-13 observed in cartilage after ACLT was significantly inhibited by EA. Conclusions EA appears to prevent the degeneration of articular cartilage, at least partly through regulation of MMP-13 and inhibition of MAPKs in the cartilage of rats with ACLT-induced OA.
Bevacizumab Prevents Brain Metastases Formation in Lung Adenocarcinoma
Authors: Ilhan-Mutlu Aysegül , Osswald Matthias , Liao Yunxiang , Gömmel Miriam , Reck Martin , Miles David , Mariani Paola , Gianni Luca , Lutiger Beatrix , Nendel Viktor , Srock Stefanie , Perez-Moreno Pablo , Thorsen Frits , von Baumgarten Louisa , Preusser Matthias , Wick Wolfgang , Winkler Frank 
Published: January 2016

Abstract
Patients with nonsquamous non–small cell lung cancer (nsNSCLC; largely lung adenocarcinoma) are at high risk of developing brain metastases. Preclinical data suggested that anti–VEGF-A therapy may prevent the formation of nsNSCLC brain metastases. Whether non-brain metastases are also prevented, and whether bevacizumab shows a brain metastases–preventive activity in cancer patients is unknown. Data of one nsNSCLC (stage IIIB/IV, AVAiL) and two breast cancer bevacizumab trials (HER2 negative, AVADO; HER2 positive, AVEREL) were retrospectively analyzed regarding the frequency of the brain versus other organs being the site of first relapse. For animal studies, the outgrowth of PC14-PE6 lung adenocarcinoma cells to brain macrometastases in mice was measured by intravital imaging: under control IgG (25 mg/kg) treatment, or varying doses of bevacizumab (25 mg/kg, 2.5 mg/kg, 0.25 mg/kg). Brain metastases as site of first relapse were significantly less frequent in the bevacizumab arm of the AVAiL trial (HR = 0.36, P &lt; 0.001). In AVADO and AVEREL, no significant difference was seen. In mice, bevacizumab treatment led to secondary regressions of non-brain macrometastases, but did not reduce their total incidence, and did not improve survival. In a brain-seeking nsNSCLC metastasis model, treatment with bevacizumab inhibited brain metastases formation, which resulted in improved overall survival. In summary, bevacizumab has the potential to prevent brain metastases in nsNSCLC, but no preventive activity could be detected outside the brain. These data indicate that anti–VEGF-A agents might be particularly relevant for those stage III nsNSCLC patients who are at high risk to develop future brain metastases. Mol Cancer Ther; 15(4); 702–10. ©2016 AACR.
Tumor Cell–Driven Extracellular Matrix Remodeling Drives Haptotaxis during Metastatic Progression
Authors: Oudin Madeleine J. , Jonas Oliver , Kosciuk Tatsiana , Broye Liliane C. , Guido Bruna C. , Wyckoff Jeff , Riquelme Daisy , Lamar John M. , Asokan Sreeja B. , Whittaker Charlie , Ma Duanduan , Langer Robert , Cima Michael J. , Wisinski Kari B. , Hynes Richard O. , Lauffenburger Douglas A. , Keely Patricia J. , Bear James E. , Gertler Frank B. 
Published: January 2016

Abstract
Fibronectin (FN) is a major component of the tumor microenvironment, but its role in promoting metastasis is incompletely understood. Here, we show that FN gradients elicit directional movement of breast cancer cells, in vitro and in vivo. Haptotaxis on FN gradients requires direct interaction between α5β1 integrin and MENA, an actin regulator, and involves increases in focal complex signaling and tumor cell–mediated extracellular matrix (ECM) remodeling. Compared with MENA, higher levels of the prometastatic MENAINV isoform associate with α5, which enables 3-D haptotaxis of tumor cells toward the high FN concentrations typically present in perivascular space and in the periphery of breast tumor tissue. MENAINV and FN levels were correlated in two breast cancer cohorts, and high levels of MENAINV were significantly associated with increased tumor recurrence as well as decreased patient survival. Our results identify a novel tumor cell–intrinsic mechanism that promotes metastasis through ECM remodeling and ECM-guided directional migration.
Significance: Here, we provide new insight into how tumor cell:ECM interactions generate signals and structures that promote directed tumor cell migration, a critical component of metastasis. Our results identify a tumor cell–intrinsic mechanism driven by the actin regulatory protein MENA that promotes ECM remodeling and haptotaxis along FN gradients. Cancer Discov; 6(5); 516–31. ©2016 AACR.
See related commentary by Santiago-Medina and Yang, p. 474.
This article is highlighted in the In This Issue feature, p. 461
EFEITO DO FOGO SOBRE VEGETAÇÃO E SOLO A PARTIR DE ESTUDO EXPERIMENTAL EM AMBIENTE DE CERRADO
Authors: COSTA YASMMIN TADEU , RODRIGUES SILVIO CARLOS 
Published: January 2016

<p>Muito se discute sobre o efeito do fogo ao ecossistema, podendo ser positivo ou desprezível para seu desenvolvimento ou ainda degradante do meio. Contudo, o seu efeito e intensidade de alteração no ambiente terá influência de acordo com as características do ecossistema que atinge. Sendo assim, o presente trabalho tem como objetivo compreender e quantificar o efeito do fogo sobre um ambiente de Cerrado mineiro em estado de recuperação, utilizando como parâmetro de análise o tempo de reestabelecimento da vegetação, as alterações físico-químicas e a ocorrência de processos erosivos, os quais foram obtidos através dos seguintes procedimentos metodológicos: análise foto-comparativa através do software ENVI, análises de solo laboratoriais e coletas semanais de escoamento superficial e perda de solo, respectivamente. O período de coleta de dados do estudo se deu de fevereiro de 2014 a abril de 2015 e se baseou em 5 parcelas de 1m² localizadas na Fazenda Experimental do Glória (Uberlândia – MG) com características fitofisionômicas diferentes, onde se aplicaram duas queimadas experimentais em diferentes épocas do ano. Conclui-se neste trabalho que as duas queimadas de baixa intensidade aplicadas sobre ambiente de Cerrado não contribuíram para degradação intensa das áreas analisadas.</p>
First record of Scotophilus kuhlii Leach, 1821 (Chiroptera: Vespertilionidae) from Nepal
Authors: Dahal Dibya , Thapa Sanjan , Basnet Khadga 
Published: January 2016

<p>Occurrence of <em>Scotophilus kuhlii</em> was speculated throughout the southern plain (Tarai) of Nepal. However, there was no record of voucher specimen of the species from Nepal. We collected a specimen from the Tikulia tole, Pakali Village Development Committee, Sunsari District of southeastern Nepal and deposited at Central Department of Zoology (CDZ) Museum, Tribhuvan University, Kathmandu. The specimen was identified as <em>S. kuhlii </em>based on measurement of external body, cranial, dental parts and detail description of the species. This is the first specific locality record of the species from Nepal that confirms its presence in the country.</p><div> </div>
Three species of Phallus (Basidiomycota: Agaricomycetes: Phallaceae) from Jammu & Kashmir, India
Authors: Kour Harpreet , Yangdol Rigzin , Kumar Sanjeev , Sharma Yash Pal 
Published: January 2016

<p>In this paper, three species of <em>Phallus </em>viz., <em>P. macrosporus, P. rubicundus</em> and <em>P. hadriani </em>are described, illustrated and discussed along with habitat photographs and line drawings of microscopic features. Out of these, <em>P. macrosporus</em> is new to India. <em>P. rubicundus</em> is new to Jammu &amp; Kashmir whereas <em>P. hadriani </em>constitutes a new report of its occurrence from the Jammu Province. A key to the investigated species is also provided.</p><div> </div>