bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro model to study the effects of matrix stiffening on Ca2+ handling and myofilament function in isolated adult rat cardiomyocytes
Authors: van Deel Elza D. , Najafi Aref , Fontoura Dulce , Valent Erik , Goebel Max , Kardux Kim , Falcão‐Pires Inês , van der Velden Jolanda 
Published: May 2017

Key points
This paper describes a novel model that allows exploration of matrix‐induced cardiomyocyte adaptations independent of the passive effect of matrix rigidity on cardiomyocyte function.
Detachment of adult cardiomyocytes from the matrix enables the study of matrix effects on cell shortening, Ca2+ handling and myofilament function.
Cell shortening and Ca2+ handling are altered in cardiomyocytes cultured for 24 h on a stiff matrix.
Matrix stiffness‐impaired cardiomyocyte contractility is reversed upon normalization of extracellular stiffness.
Matrix stiffness‐induced reduction in unloaded shortening is more pronounced in cardiomyocytes isolated from obese ZSF1 rats with heart failure with preserved ejection fraction compared to lean ZSF1 rats.
AbstractExtracellular matrix (ECM) stiffening is a key element of cardiac disease. Increased rigidity of the ECM passively inhibits cardiac contraction, but if and how matrix stiffening also actively alters cardiomyocyte contractility is incompletely understood. In vitro models designed to study cardiomyocyte–matrix interaction lack the possibility to separate passive inhibition by a stiff matrix from active matrix‐induced alterations of cardiomyocyte properties. Here we introduce a novel experimental model that allows exploration of cardiomyocyte functional alterations in response to matrix stiffening. Adult rat cardiomyocytes were cultured for 24 h on matrices of tuneable stiffness representing the healthy and the diseased heart and detached from their matrix before functional measurements. We demonstrate that matrix stiffening, independent of passive inhibition, reduces cell shortening and Ca2+ handling but does not alter myofilament‐generated force. Additionally, detachment of adult cultured cardiomyocytes allowed the transfer of cells from one matrix to another. This revealed that stiffness‐induced cardiomyocyte changes are reversed when matrix stiffness is normalized. These matrix stiffness‐induced changes in cardiomyocyte function could not be explained by adaptation in the microtubules. Additionally, cardiomyocytes isolated from stiff hearts of the obese ZSF1 rat model of heart failure with preserved ejection fraction show more pronounced reduction in unloaded shortening in response to matrix stiffening. Taken together, we introduce a method that allows evaluation of the influence of ECM properties on cardiomyocyte function separate from the passive inhibitory component of a stiff matrix. As such, it adds an important and physiologically relevant tool to investigate the functional consequences of cardiomyocyte–matrix interactions.
The Tetrazole VT-1161 Is a Potent Inhibitor of Trichophyton rubrum through Its Inhibition of T. rubrum CYP51
Authors: Warrilow Andrew G. S. , Parker Josie E. , Price Claire L. , Garvey Edward P. , Hoekstra William J. , Schotzinger Robert J. , Wiederhold Nathan P. , Nes W. David , Kelly Diane E. , Kelly Steven L. 
Published: May 2017

ABSTRACT

Prior to characterization of antifungal inhibitors that target CYP51,
Trichophyton rubrum
CYP51 was expressed in
Escherichia coli
, purified, and characterized.
T. rubrum
CYP51 bound lanosterol, obtusifoliol, and eburicol with similar affinities (dissociation constant [

K
d

] values, 22.7, 20.3, and 20.9 μM, respectively) but displayed substrate specificity, insofar as only eburicol was demethylated in CYP51 reconstitution assays (turnover number, 1.55 min
−1
;

K
m

value, 2 μM). The investigational agent VT-1161 bound tightly to
T. rubrum
CYP51 (

K
d

= 242 nM) with an affinity similar to that of clotrimazole, fluconazole, ketoconazole, and voriconazole (

K
d

values, 179, 173, 312, and 304 nM, respectively) and with an affinity lower than that of itraconazole (

K
d

= 53 nM). Determinations of 50% inhibitory concentrations (IC
50
s) using 0.5 μM CYP51 showed that VT-1161 was a tight-binding inhibitor of
T. rubrum
CYP51 activity, yielding an IC
50
of 0.14 μM, whereas itraconazole, fluconazole, and ketoconazole had IC
50
s of 0.26, 0.4, and 0.6 μM, respectively. When the activity of VT-1161 was tested against 34 clinical isolates, VT-1161 was a potent inhibitor of
T. rubrum
growth, with MIC
50
, MIC
90
, and geometric mean MIC values of ≤0.03, 0.06, and 0.033 μg ml
−1
, respectively. With its selectivity versus human CYP51 and drug-metabolizing cytochrome P450s having already been established, VT-1161 should prove to be safe and effective in combating
T. rubrum
infections in patients.
Comparative Analysis of Extended-Spectrum-β-Lactamase CTX-M-65-Producing Salmonella enterica Serovar Infantis Isolates from Humans, Food Animals, and Retail Chickens in the United States
Authors: Tate Heather , Folster Jason P. , Hsu Chih-Hao , Chen Jessica , Hoffmann Maria , Li Cong , Morales Cesar , Tyson Gregory H. , Mukherjee Sampa , Brown Allison C. , Green Alice , Wilson Wanda , Dessai Uday , Abbott Jason , Joseph Lavin , Haro Jovita , Ayers Sherry , McDermott Patrick F. , Zhao Shaohua 
Published: May 2017

ABSTRACT

We sequenced the genomes of 10
Salmonella enterica
serovar Infantis isolates containing
bla
CTX-M-65
obtained from chicken, cattle, and human sources collected between 2012 and 2015 in the United States through routine National Antimicrobial Resistance Monitoring System (NARMS) surveillance and product sampling programs. We also completely assembled the plasmids from four of the isolates. All isolates had a D87Y mutation in the
gyrA
gene and harbored between 7 and 10 resistance genes [
aph(4)-Ia
,
aac(3)-IVa
,
aph(3
′
)-Ic
,
bla
CTX-M-65
,
fosA3
,
floR
,
dfrA14
,
sul1
,
tetA
,
aadA1
] located in two distinct sites of a megaplasmid (∼316 to 323 kb) similar to that described in a
bla
CTX-M-65
-positive
S
. Infantis isolate from a patient in Italy. High-quality single nucleotide polymorphism (hqSNP) analysis revealed that all U.S. isolates were closely related, separated by only 1 to 38 pairwise high-quality SNPs, indicating a high likelihood that strains from humans, chickens, and cattle recently evolved from a common ancestor. The U.S. isolates were genetically similar to the
bla
CTX-M-65
-positive
S
. Infantis isolate from Italy, with a separation of 34 to 47 SNPs. This is the first report of the
bla
CTX-M-65
gene and the pESI (plasmid for emerging
S
. Infantis)-like megaplasmid from
S
. Infantis in the United States, and it illustrates the importance of applying a global One Health human and animal perspective to combat antimicrobial resistance.
Genetic and Functional Characterization of
bla
CTX-M-199
, a Novel Tazobactam and Sulbactam Resistance-Encoding Gene Located in a Conjugative
mcr-1
-Bearing IncI2 Plasmid
Authors: Cai Jiachang , Cheng Qipeng , Shen Yingbo , Gu Danxia , Fang Ying , Chan Edward Wai-Chi , Chen Sheng 
Published: May 2017

ABSTRACT

We report the genetic and functional characterization of a novel CTX-M-199 β-lactamase, which was encoded by a
bla
CTX-M-64
variant gene found in a conjugative
mcr-1
-bearing IncI2 plasmid and exhibited resistance to β-lactamase inhibitors, tazobactam, and sulbactam.
Identification of Candida parapsilosis Sensu Lato in Pediatric Patients and Antifungal Susceptibility Testing
Authors: Cattana Maria Emilia , Dudiuk Catiana , Fernández Mariana , Rojas Florencia , Alegre Liliana , Córdoba Susana , Garcia-Effron Guillermo , Giusiano Gustavo 
Published: May 2017

ABSTRACT

A total of 59
Candida parapsilosis sensu stricto
and 1
Candida orthopsilosis
recovered from catheters and blood cultures of pediatric patients from the northeastern region of Argentina were studied. Susceptibility to azoles, amphotericin B, and echinocandins was tested by the broth microdilution method. According to CLSI clinical breakpoints, >91% of the strains were azole susceptible, whereas 15% showed high amphotericin B MICs.
Exploring the Amino Acid Residue Requirements of the RNA Polymerase (RNAP) α Subunit C-Terminal Domain for Productive Interaction between Spx and RNAP of Bacillus subtilis
Authors: Birch Cierra A. , Davis Madison J. , Mbengi Lea , Zuber Peter 
Published: May 2017

ABSTRACT

Bacillus subtilis
Spx is a global transcriptional regulator that is conserved among Gram-positive bacteria, in which Spx is required for preventing oxidatively induced proteotoxicity. Upon stress induction, Spx engages RNA polymerase (RNAP) through interaction with the C-terminal domain of the
rpoA
-encoded RNAP α subunit (αCTD). Previous mutational analysis of
rpoA
revealed that substitutions of Y263 in αCTD severely impaired Spx-activated transcription. Attempts to substitute alanine for αCTD R261, R268, R289, E255, E298, and K294 were unsuccessful, suggesting that these residues are essential. To determine whether these RpoA residues were required for productive Spx-RNAP interaction, we ectopically expressed the putatively lethal
rpoA
mutant alleles in the

rpoA
Y263C

mutant, where “
Y263C
” indicates the amino acid change that results from mutation of the allele. By complementation analysis, we show that Spx-bound αCTD amino acid residues are not essential for Spx-activated transcription
in vivo
but that R261A, E298A, and E255A mutants confer a partial defect in NaCl-stress induction of Spx-controlled genes. In addition, strains expressing

rpoA
E255A

are defective in disulfide stress resistance and produce RNAP having a reduced affinity for Spx. The E255 residue corresponds to
Escherichia coli
αD259, which has been implicated in αCTD-σ
70
interaction (σ
70
R603, corresponding to R362 of
B. subtilis
σ
A
). However, the combined

rpoA
E255A

and

sigA
R362A

mutations have an additive negative effect on Spx-dependent expression, suggesting the residues' differing roles in Spx-activated transcription. Our findings suggest that, while αCTD is essential for Spx-activated transcription, Spx is the primary DNA-binding determinant of the Spx-αCTD complex.

IMPORTANCE
Though extensively studied in
Escherichia coli
, the role of αCTD in activator-stimulated transcription is largely uncharacterized in
Bacillus subtilis
. Here, we conduct phenotypic analyses of putatively lethal αCTD alanine codon substitution mutants to determine whether these residues function in specific DNA binding at the Spx-αCTD-DNA interface. Our findings suggest that multisubunit RNAP contact to Spx is optimal for activation while Spx fulfills the most stringent requirement of upstream promoter binding. Furthermore, several αCTD residues targeted for mutagenesis in this study are conserved among many bacterial species and thus insights on their function in other regulatory systems may be suggested herein.
Class III Histidine Kinases: a Recently Accessorized Kinase Domain in Putative Modulators of Type IV Pilus-Based Motility
Authors: Adebali Ogun , Petukh Marharyta G. , Reznik Alexander O. , Tishkov Artem V. , Upadhyay Amit A. , Zhulin Igor B. 
Published: May 2017

ABSTRACT

Histidine kinases are key components of regulatory systems that enable bacteria to respond to environmental changes. Two major classes of histidine kinases are recognized on the basis of their modular design: classical (HKI) and chemotaxis specific (HKII). Recently, a new type of histidine kinase that appeared to have features of both HKIs and HKIIs was identified and termed HKIII; however, the details of HKIII's relationship to other two classes of histidine kinases, their function, and evolutionary history remain unknown. Here, we carried out genomic, phylogenetic, and protein sequence analyses that allowed us to reveal the unusual evolutionary history of this protein family, formalize its distinctive features, and propose its putative function. HKIIIs are characterized by the presence of sensory domains and the lack of a dimerization domain, which is typically present in all histidine kinases. In addition to a single-domain response regulator, HKIII signal transduction systems utilize CheX phosphatase and, in many instances, an unorthodox soluble chemoreceptor that are usual components of chemotaxis signal transduction systems. However, many HKIII genes are found in genomes completely lacking chemotaxis genes, thus decoupling their function from chemotaxis. By contrast, all HKIII-containing genomes also contain
pilT
, a marker gene for bacterial type IV pilus-based motility, whose regulation is proposed as a putative function for HKIII. These signal transduction systems have a narrow phyletic distribution but are present in many emerging and opportunistic pathogens, thus offering an attractive potential target for future antimicrobial drug design.

IMPORTANCE
Bacteria adapt to their environment and their hosts by detecting signals and regulating their cellular functions accordingly. Here, we describe a largely unexplored family of signal transduction histidine kinases, called HKIII, that have a unique modular design. While they are currently identified in a relatively short list of bacterial species, this list contains many emerging pathogens. We show that HKIIIs likely control bacterial motility across solid surfaces, which is a key virulence factor in many bacteria, including those causing severe infections. Full understanding of this putative function may help in designing effective drugs against pathogens that will not affect the majority of the beneficial human microbiome.
Noncanonical Translation Initiation Comes of Age
Authors: Babitzke Paul , O'Connor Michael 
Published: May 2017

ABSTRACT

The canonical translation initiation mechanism involves base pairing between the mRNA and 16S rRNA. However, a variety of identified mechanisms deviate from this conventional route. Beck and Janssen (J Bacteriol 199:e00091-17, 2017,
https://doi.org/10.1128/JB.00091-17
) have recently described another noncanonical mode of translation initiation. Here, we describe how this process differs from previously reported mechanisms, with the hope that it will foster increased awareness of the diversity of regulatory mechanisms that await discovery.
Using Tn-seq To Identify Pigmentation-Related Genes of Porphyromonas gingivalis: Characterization of the Role of a Putative Glycosyltransferase
Authors: Klein Brian A. , Cornacchione Louis P. , Collins Marisha , Malamy Michael H. , Duncan Margaret J. , Hu Linden T. 
Published: May 2017

ABSTRACTCellular pigmentation is an important virulence factor of the oral pathogenPorphyromonas gingivalis. Pigmentation has been associated with many bacterial functions, including but not limited to colonization, maintaining a local anaerobic environment by binding oxygen molecules, and defense against reactive oxygen species (ROS) produced by immune cells. Pigmentation-associated loci identified to date have involved lipopolysaccharide, fimbriae, and heme acquisition and processing. We utilized a transposon mutant library ofP. gingivalisstrain ATCC 33277 and screened for pigmentation-defective colonies using massively parallel sequencing of the transposon junctions (Tn-seq) to identify genes involved in pigmentation. Transposon insertions at 235 separate sites, located in 67 genes and 15 intergenic regions, resulted in altered pigmentation: 7 of the genes had previously been shown to be involved in pigmentation, while 75 genes and intergenic regions had not. To further confirm identification, we generated a smaller transposon mutant library inP. gingivalisstrain W83 and identified pigment mutations in several of the same loci as those identified in the screen in ATCC 33277 but also eight that were not identified in the ATCC 33277 screen. PGN_0361/PG_0264, a putative glycosyltransferase gene located between two tRNA synthetase genes and adjacent to a miniature inverted-repeat transposable element, was identified in the Tn-seq screen and then verified through targeted deletion and complementation. Deletion mutations in PGN_0361/PG_0264 glycosyltransferase abolish pigmentation, modulate gingipain protease activity, and alter lipopolysaccharide. The mechanisms of involvement in pigmentation for other loci identified in this study remain to be determined, but our screen provides the most complete survey of genes involved in pigmentation to date.IMPORTANCEP. gingivalishas been implicated in the onset and progression of periodontal disease. One important virulence factor is the bacterium's ability to produce pigment. Using a transposon library, we were able to identify both known and novel genes involved in pigmentation ofP. gingivalis. We identified a glycosyltransferase, previously not associated with pigmentation, that is required for pigmentation and determined its mechanism of involvement. A better understanding of the genes involved in pigmentation may lead to new insights into the complex mechanisms involved in this important virulence characteristic and could facilitate development of novel therapeutics.
Education, immigration and income as risk factors for hemoglobin A1c >70 mmol/mol when diagnosed with type 2 diabetes or latent autoimmune diabetes in adult: a population-based cohort study
Authors: Martinell Mats , Pingel Ronnie , Hallqvist Johan , Dorkhan Mozhgan , Groop Leif , Rosengren Anders , Storm Petter , Stålhammar Jan 
Published: May 2017

ObjectivesThe aim of this research is to study education, income and immigration as risk factors for high hemoglobin A1c (HbA1c >70 mmol/mol (8.6%)) when diagnosed with type 2 diabetes (T2D) or latent autoimmune diabetes in the adult (LADA).Research design and methodsPatients were included from the All New Diabetics in Scania study (2008-2013). Level of education, disposable income and immigration year were retrieved from the longitudinal integrated database for labour market research (LISA) register compiled by Statistics Sweden. Logistic regression models were used to estimate ORs for HbA1c >70 mmol/mol (8.6%) at diagnosis.ResultsA total of 3794 patients with incident T2D (n=3 525) or LADA (n=269) were included. Patients with T2D with a low (≤9 years) or medium (10-12 years) levels of education were more likely to have high HbA1c at diagnosis compared with patients with T2D with a high (>12 years) level of education (OR 1.34, 95% CI 1.08 to1.66, OR 1.26, 95% CI 1.03 to 1.54). Low-income patients with T2D (<60% of median) were more likely to have high HbA1c at diagnosis compared with high-income patients withT2D (>150% of median) (OR 1.35, 95% CI 1.02 to 1.79).ConclusionsPatients with lower levels of education or low income and are more likely to have HbA1c is >70 mmol/mol (8.6%) when diagnosed with T2D. An understanding of how socioeconomic position influences the clinical presentation at diagnosis may facilitate screening programs designed to target populations at risk for delayed diagnosis.
Discovering successful strategies for diabetic self-management: a qualitative comparative study
Authors: Weller Susan C , Baer Roberta , Nash Anita , Perez Noe 
Published: May 2017

ObjectiveThis project explored lifestyles of patients in good and poor control to identify naturally occurring practices and strategies that result in successful diabetes management.Research design and methodsSemistructured interviews with adult patients with type 2 diabetes explored diet, food preparation, physical activity, medication use and glucose monitoring. Patients (n=56) were classified into good (A1C <7.0%), fair (7.0%<A1C<8.0%) or poor (A1C >8.0%) control groups and matched across groups on diabetes duration (±5 years) and medication modality (none, oral, insulin±oral) to control for non-lifestyle factors. A qualitative comparative analysis identified practices that distinguished glycemic groups.ResultsGood control patients were more likely to test their glucose two or more times a day and reduce their sodium intake, as well as increase fruits and vegetables and limit portion sizes, some attaining good control without exercise. Fair control patients discussed several dietary strategies including limiting sweets, drinking non-caloric beverages, reducing carbs, ‘cheating’ (eating only a few sweets/limiting carbs in one meal to have more in another meal) and tested their glucose once a day. Poor control patients were more likely to skip antidiabetic medications and not test their glucose.ConclusionsAlthough clinical trials indicate most self-management practices have limited effectiveness over time, increased glucose monitoring is a valuable component in daily management. Research is needed on effectiveness of dietary strategies that emphasize sodium monitoring and allow some degree of cheating. Reoffering diabetes education classes and providing pill boxes as memory aids may help improve poor control.
Individuals with obesity and type 2 diabetes have additional immune dysfunction compared with obese individuals who are metabolically healthy
Authors: Richard Caroline , Wadowski Michael , Goruk Susan , Cameron Lisa , Sharma Arya M , Field Catherine J 
Published: May 2017

ObjectiveThe objective of the current study was to compare the responses to different ex vivo immunogenic challenges between immune cells derived from metabolically healthy subjects with obesity and subjects with obesity and type 2 diabetes.Research design and methodsWe recruited 10 metabolically healthy subjects with obesity (Edmonton Obesity Staging System (EOSS) stage 0) and 9 subjects with obesity and type 2 diabetes (EOSS stage 2) aged between 21 years and 70 years and matched for body mass index. Peripheral blood mononuclear cells (PBMCs) were isolated and immune cell phenotypes and ex vivo cytokine production after phytohaemagglutinin (PHA, a T cell mitogen) stimulation were determined. Neutrophil oxidative burst activity was assessed in whole blood.ResultsPBMCs from subjects with stage 2 obesity produced significantly less interleukin (IL)-2, IL-6 and tumour necrosis factor α after PHA stimulation than PBMCs from subjects with stage 0 obesity (all, p<0.05). Subjects with stage 2 obesity also had higher proportions of cytotoxic T cells, activated helper T cells (CD4+CD278+) and inflammatory monocytes (CD14+CRTh2+, all p<0.05). Poststimulation, neutrophils from subjects with stage 2 obesity produced significantly more free radicals, were larger and more granular and had a lower stimulation index (all p<0.05).ConclusionsOur results suggest that compared with obese individuals metabolically healthy individuals with obesity and type 2 diabetes have an impaired neutrophil function and T cell response on challenge despite having a T cell population expressing more activation markers which may be partly responsible for the increased prevalence of infection reported in this population.