bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhanced Klebsiella pneumoniae Carbapenemase Expression from a Novel Tn
4401
Deletion
Authors: Cheruvanky Anita , Stoesser Nicole , Sheppard Anna E. , Crook Derrick W. , Hoffman Paul S. , Weddle Erin , Carroll Joanne , Sifri Costi D. , Chai Weidong , Barry Katie , Ramakrishnan Girija , Mathers Amy J.
Published: April 2017

The
Klebsiella pneumoniae
carbapenemase gene (
bla
KPC
) is typically located within mobile transposon Tn
4401
. Enhanced KPC expression has been associated with deletions in the putative promoter region upstream of
bla
KPC
. Illumina sequences from
bla
KPC
-positive clinical isolates from a single institution were mapped to a Tn
4401
b reference sequence, which carries no deletions. The novel isoform Tn
4401
h (188-bp deletion [between
istB
and
bla
KPC
]) was present in 14% (39/281) of clinical isolates. MICs showed that
Escherichia coli
strains containing plasmids with Tn
4401
a and Tn
4401
h were more resistant to meropenem (≥16 and ≥16, respectively), ertapenem (≥8 and 4, respectively), and cefepime (≥64 and 4, respectively) than
E. coli
strains with Tn
4401
b (0.5, ≤0.5, and ≤1, respectively). Quantitative real-time PCR (qRT-PCR) demonstrated that Tn
4401
a had a 16-fold increase and Tn
4401
h a 4-fold increase in
bla
KPC
mRNA levels compared to the reference Tn
4401
b. A
lacZ
reporter plasmid was used to test the activity of the promoter regions from the different variants, and the results showed that the Tn
4401
a and Tn
4401
h promoter sequences generated higher β-galactosidase activity than the corresponding Tn
4401
b sequence. Further dissection of the promoter region demonstrated that putative promoter P1 was not functional. The activity of the isolated P2 promoter was greatly enhanced by inclusion of the P1-P2 intervening sequence. These studies indicated that gene expression could be an important consideration in understanding resistance phenotypes predicted by genetic signatures in the context of sequencing-based rapid diagnostics.
Antimicrobial Effects of β-Lactams on Imipenem-Resistant Ceftazidime-Susceptible Pseudomonas aeruginosa
Authors: Wi Yu Mi , Choi Ji-Young , Lee Ji-Young , Kang Cheol-In , Chung Doo Ryeon , Peck Kyong Ran , Song Jae-Hoon , Ko Kwan Soo
Published: April 2017

We studied the resistance mechanism and antimicrobial effects of β-lactams on imipenem-resistant
Pseudomonas aeruginosa
isolates that were susceptible to ceftazidime as detected by time-kill curve methods. Among 215
P. aeruginosa
isolates from hospitalized patients in eight hospitals in the Republic of Korea, 18 isolates (23.4% of 77 imipenem-resistant isolates) were imipenem resistant and ceftazidime susceptible. Multilocus sequence typing revealed diverse genotypes, which indicated independent emergence. These 18 isolates were negative for carbapenemase genes. All 18 imipenem-resistant ceftazidime-susceptible isolates showed decreased mRNA expression of
oprD
, and overexpression of
mexB
was observed in 13 isolates. In contrast, overexpression of
ampC
,
mexD
,
mexF
, or
mexY
was rarely found. Time-kill curve methods were applied to three selected imipenem-resistant ceftazidime-susceptible isolates at a standard inoculum (5 × 10
5
CFU/ml) or at a high inoculum (5 × 10
7
CFU/ml) to evaluate the antimicrobial effects of β-lactams. Inoculum effects were detected for all three β-lactam antibiotics, ceftazidime, cefepime, and piperacillin-tazobactam, against all three isolates. The antibiotics had significant killing effects in the standard inoculum, but no effects in the high inoculum were observed. Our results suggest that β-lactam antibiotics should be used with caution in patients with imipenem-resistant ceftazidime-susceptible
P. aeruginosa
infection, especially in high-inoculum infections such as endocarditis and osteomyelitis.
Molecular Characterization of Escherichia coli Isolates Carrying
mcr-1
,
fosA3
, and Extended-Spectrum-β-Lactamase Genes from Food Samples in China
Authors: Liu Xiaobo , Li Ruichao , Zheng Zhiwei , Chen Kaichao , Xie Miaomiao , Chan Edward Wai-Chi , Geng Shu , Chen Sheng
Published: April 2017

This study surveyed the prevalence of
mcr-1
in extended-spectrum-β-lactamase (ESBL)-producing
Escherichia coli
strains of food origin in China and identified strains that carried
mcr-1
,
fosA3
, and ESBL genes, which were carried in various plasmids. The
mcr-1
and ESBL genes could be cotransferred by one or more types of plasmids. The presence of these multidrug-resistant
E. coli
strains in food products might pose a huge threat to public health.
Lung Tissue Concentrations of Pyrazinamide among Patients with Drug-Resistant Pulmonary Tuberculosis
Authors: Kempker Russell R. , Heinrichs M. Tobias , Nikolaishvili Ketino , Sabulua Irina , Bablishvili Nino , Gogishvili Shota , Avaliani Zaza , Tukvadze Nestani , Little Brent , Bernheim Adam , Read Timothy D. , Guarner Jeannette , Derendorf Hartmut , Peloquin Charles A. , Blumberg Henry M. , Vashakidze Sergo
Published: April 2017

Improved knowledge regarding the tissue penetration of antituberculosis drugs may help optimize drug management. Patients with drug-resistant pulmonary tuberculosis undergoing adjunctive surgery were enrolled. Serial serum samples were collected, and microdialysis was performed using
ex vivo
lung tissue to measure pyrazinamide concentrations. Among 10 patients, the median pyrazinamide dose was 24.7 mg/kg of body weight. Imaging revealed predominant lung lesions as cavitary (
n
= 6 patients), mass-like (
n
= 3 patients), or consolidative (
n
= 1 patient). On histopathology examination, all tissue samples had necrosis; eight had a pH of ≤5.5. Tissue samples from two patients were positive for
Mycobacterium tuberculosis
by culture (pH 5.5 and 7.2). All 10 patients had maximal serum pyrazinamide concentrations within the recommended range of 20 to 60 μg/ml. The median lung tissue free pyrazinamide concentration was 20.96 μg/ml. The median tissue-to-serum pyrazinamide concentration ratio was 0.77 (range, 0.54 to 0.93). There was a significant inverse correlation between tissue pyrazinamide concentrations and the amounts of necrosis (
R
= −0.66,
P
= 0.04) and acid-fast bacilli (
R
= −0.75,
P
= 0.01) identified by histopathology. We found good penetration of pyrazinamide into lung tissue among patients with pulmonary tuberculosis with a variety of radiological lesion types. Our tissue pH results revealed that most lesions had a pH conducive to pyrazinamide activity. The tissue penetration of pyrazinamide highlights its importance in both drug-susceptible and drug-resistant antituberculosis treatment regimens.
Evolutionary Origin of the Staphylococcal Cassette Chromosome
mec
(SCC
mec
)
Authors: Rolo Joana , Worning Peder , Nielsen Jesper Boye , Bowden Rory , Bouchami Ons , Damborg Peter , Guardabassi Luca , Perreten Vincent , Tomasz Alexander , Westh Henrik , de Lencastre Hermínia , Miragaia Maria
Published: April 2017

Several lines of evidence indicate that the most primitive staphylococcal species, those of the
Staphylococcus sciuri
group, were involved in the first stages of evolution of the staphylococcal cassette chromosome
mec
(SCC
mec
), the genetic element carrying the β-lactam resistance gene
mecA
. However, many steps are still missing from this evolutionary history. In particular, it is not known how
mecA
was incorporated into the mobile element SCC prior to dissemination among
Staphylococcus aureus
and other pathogenic staphylococcal species. To gain insights into the possible contribution of several species of the
Staphylococcus sciuri
group to the assembly of SCC
mec
, we sequenced the genomes of 106 isolates, comprising
S. sciuri
(
n
= 76),
Staphylococcus vitulinus
(
n
= 18), and
Staphylococcus fleurettii
(
n
= 12) from animal and human sources, and characterized the native location of
mecA
and the SCC insertion site by using a variety of comparative genomic approaches. Moreover, we performed a single nucleotide polymorphism (SNP) analysis of the genomes in order to understand SCC
mec
evolution in relation to phylogeny. We found that each of three species of the
S. sciuri
group contributed to the evolution of SCC
mec
:
S. vitulinus
and
S. fleurettii
contributed to the assembly of the
mec
complex, and
S. sciuri
most likely provided the mobile element in which
mecA
was later incorporated. We hypothesize that an ancestral SCC
mec
III cassette (an element carried by one of the most epidemic methicillin-resistant
S. aureus
clones) originated in
S. sciuri
possibly by a recombination event in a human host or a human-created environment and later was transferred to
S. aureus
.
Delamanid Kills Dormant Mycobacteria
In Vitro
and in a Guinea Pig Model of Tuberculosis
Authors: Chen Xiuhao , Hashizume Hiroyuki , Tomishige Tatsuo , Nakamura Izuru , Matsuba Miki , Fujiwara Mamoru , Kitamoto Ryuki , Hanaki Erina , Ohba Yoshio , Matsumoto Makoto
Published: April 2017

Tuberculosis (TB) treatment is long and requires multiple drugs, likely due to various phenotypes of TB bacilli with variable drug susceptibilities. Drugs with broad activity are urgently needed. This study aimed to evaluate delamanid's activity against growing or dormant bacilli
in vitro
as well as
in vivo
. Cultures of
Mycobacterium bovis
BCG Tokyo under aerobic and anaerobic conditions were used to study the activity of delamanid against growing and dormant bacilli, respectively. Delamanid exhibited significant bactericidal activity against replicating and dormant bacilli at or above concentrations of 0.016 and 0.4 mg/liter, respectively. To evaluate delamanid's antituberculosis activity
in vivo
, we used a guinea pig model of chronic TB infection in which the lung lesions were similar to those in human TB disease. In the guinea pig TB model, a daily dose of 100 mg delamanid/kg of body weight for 4 or 8 weeks demonstrated strong bactericidal activity against
Mycobacterium tuberculosis
. Importantly, histological examination revealed that delamanid killed TB bacilli within hypoxic lesions of the lung. The combination regimens containing delamanid with rifampin and pyrazinamide or delamanid with levofloxacin, ethionamide, pyrazinamide, and amikacin were more effective than the standard regimen (rifampin, isoniazid, and pyrazinamide). Our data show that delamanid is effective in killing both growing and dormant bacilli
in vitro
and in the guinea pig TB model. Adding delamanid to current TB regimens may improve treatment outcomes, as demonstrated in recent clinical trials with pulmonary multidrug-resistant (MDR) TB patients. Delamanid may be an important drug for consideration in the construction of new regimens to shorten TB treatment duration.
Results from a 13-Year Prospective Cohort Study Show Increased Mortality Associated with Bloodstream Infections Caused by Pseudomonas aeruginosa Compared to Other Bacteria
Authors: Thaden Joshua T. , Park Lawrence P. , Maskarinec Stacey A. , Ruffin Felicia , Fowler Vance G. , van Duin David
Published: April 2017

The impact of bacterial species on outcome in bloodstream infections (BSI) is incompletely understood. We evaluated the impact of bacterial species on BSI mortality, with adjustment for patient, bacterial, and treatment factors. From 2002 to 2015, all adult inpatients with monomicrobial BSI caused by
Staphylococcus aureus
or Gram-negative bacteria at Duke University Medical Center were prospectively enrolled. Kaplan-Meier curves and multivariable Cox regression with propensity score models were used to examine species-specific bacterial BSI mortality. Of the 2,659 enrolled patients, 999 (38%) were infected with
S. aureus
, and 1,660 (62%) were infected with Gram-negative bacteria. Among patients with Gram-negative BSI,
Enterobacteriaceae
(81% [1,343/1,660]) were most commonly isolated, followed by non-lactose-fermenting Gram-negative bacteria (16% [262/1,660]). Of the 999
S. aureus
BSI isolates, 507 (51%) were methicillin resistant. Of the 1,660 Gram-negative BSI isolates, 500 (30%) were multidrug resistant. The unadjusted time-to-mortality among patients with Gram-negative BSI was shorter than that of patients with
S. aureus
BSI (
P
= 0.003), due to increased mortality in patients with non-lactose-fermenting Gram-negative BSI generally (
P
< 0.0001) and
Pseudomonas aeruginosa
BSI (
n
= 158) in particular (
P
< 0.0001). After adjustment for patient demographics, medical comorbidities, bacterial antibiotic resistance, timing of appropriate antibiotic therapy, and source control in patients with line-associated BSI,
P. aeruginosa
BSI remained significantly associated with increased mortality (hazard ratio = 1.435; 95% confidence interval = 1.043 to 1.933;
P
= 0.02).
P. aeruginosa
BSI was associated with increased mortality relative to
S. aureus
or other Gram-negative BSI. This effect persisted after adjustment for patient, bacterial, and treatment factors.
Clumping Factor B Promotes Adherence of Staphylococcus aureus to Corneocytes in Atopic Dermatitis
Authors: Fleury Orla M. , McAleer Maeve A. , Feuillie Cécile , Formosa-Dague Cécile , Sansevere Emily , Bennett Désirée E. , Towell Aisling M. , McLean W. H. Irwin , Kezic Sanja , Robinson D. Ashley , Fallon Padraic G. , Foster Timothy J. , Dufrêne Yves F. , Irvine Alan D. , Geoghegan Joan A.
Published: April 2017

Staphylococcus aureus
skin infection is a frequent and recurrent problem in children with the common inflammatory skin disease atopic dermatitis (AD).
S. aureus
colonizes the skin of the majority of children with AD and exacerbates the disease. The first step during colonization and infection is bacterial adhesion to the cornified envelope of corneocytes in the outer layer, the stratum corneum. Corneocytes from AD skin are structurally different from corneocytes from normal healthy skin. The objective of this study was to identify bacterial proteins that promote the adherence of
S. aureus
to AD corneocytes.
S. aureus
strains from clonal complexes 1 and 8 were more frequently isolated from infected AD skin than from the nasal cavity of healthy children. AD strains had increased ClfB ligand binding activity compared to normal nasal carriage strains. Adherence of single
S. aureus
bacteria to corneocytes from AD patients
ex vivo
was studied using atomic force microscopy. Bacteria expressing ClfB recognized ligands distributed over the entire corneocyte surface. The ability of an isogenic ClfB-deficient mutant to adhere to AD corneocytes compared to that of its parent clonal complex 1 clinical strain was greatly reduced. ClfB from clonal complex 1 strains had a slightly higher binding affinity for its ligand than ClfB from strains from other clonal complexes. Our results provide new insights into the first step in the establishment of
S. aureus
colonization in AD patients. ClfB is a key adhesion molecule for the interaction of
S. aureus
with AD corneocytes and represents a target for intervention.
Practices and attitudes of doctors and patients to downward referral in Shanghai, China
Authors: Yu Wenya , Li Meina , Nong Xin , Ding Tao , Ye Feng , Liu Jiazhen , Dai Zhixing , Zhang Lulu
Published: April 2017

Objectives

In China, the rate of downward referral is relatively low, as most people are unwilling to be referred from hospitals to community health systems (CHSs). The aim of this study was to explore the effect of doctors' and patients' practices and attitudes on their willingness for downward referral and the relationship between downward referral and sociodemographic characteristics.

Methods

Doctors and patients of 13 tertiary hospitals in Shanghai were stratified through random sampling. The questionnaire surveyed their sociodemographic characteristics, attitudes towards CHSs and hospitals, understanding of downward referral, recognition of the community first treatment system, and downward referral practices and willingness. Descriptive statistics, χ2test and stepwise logistic regression analysis were employed for statistical analysis.

Results

Only 20.8% (161/773) of doctors were willing to accept downward referrals, although this proportion was higher among patients (37.6%, 326/866). Doctors' willingness was influenced by education, understanding of downward referral, and perception of health resources in hospitals. Patients' willingness was influenced by marital status, economic factors and recognition of the community first treatment system. Well-educated doctors who do not consider downward referral would increase their workloads and those with a more comprehensive understanding of hospitals and downward referral process were more likely to make a downward referral decision. Single-injury patients fully recognising the community first treatment system were more willing to accept downward referral. Patients' willingness was significantly increased if downward referral was cost-saving. A better medical insurance system was another key factor for patients to accept downward referral decisions, especially for the floating population.

Conclusions

To increase the rate of downward referral, the Chinese government should optimise the current referral system and conduct universal publicity for downward referral. Doctors and patients should promote understandings of downward referral. Hospitals should realise the necessity of downward referral, effectively reduce workloads and provide continuing education for doctors. Increasing monetary reimbursement is urgent, as is improving the medical insurance system.
Association between rhinovirus wheezing illness and the development of childhood asthma: a meta-analysis
Authors: Liu Lu , Pan Yilin , Zhu Yanting , Song Yang , Su Xiaofan , Yang Lan , Li Manxiang
Published: April 2017

Objective

The relation between early-life rhinovirus (RV) wheezing illness and later onset of wheezing/asthma remains a subject of debate. Therefore, we conducted this meta-analysis to evaluate the association between RV wheezing illness in the first 3 years of life and the subsequent development of wheezing/asthma.

Design

Systematic review and meta-analysis.

Methods

The PubMed, EMBASE, Web of Science, Chinese National Knowledge Infrastructure (CNKI) and Wanfang databases were systematically searched for studies published between 1988 and February 2017, and additional studies were found by searching reference lists of relevant articles. 2 reviewers independently extracted data and assessed the quality of each study. Results were pooled using fixed-effect models or random-effects models as appropriate.

Results

The meta-analysis included 15 original articles which met the criteria, while 10 articles reported the results of 4 longitudinal cohort studies with different follow-up periods. RV wheezing illness in the first 3 years of life was associated with an increased risk of wheezing/asthma in later life (relative risk (RR)=2.00, 95% CI 1.62 to 2.49, p<0.001). In subgroup analysis by age at follow-up, the association still remained significant in <10 years (RR=2.02, 95% CI 1.70 to 2.39, p<0.001) and ≥10 years (RR=1.92, 95% CI 1.36 to 2.72, p<0.001).

Conclusions

The meta-analysis suggests an association between RV-induced wheezing in the first 3 years of life and the subsequent development of wheezing/asthma. Large-scale and well-designed studies that adequately address concerns for potential confounding factors are required to validate the risk identified in the current meta-analysis.
Factors associated with participation in cervical cancer screening among young Koreans: a nationwide cross-sectional study
Authors: Chang Ha Kyun , Myong Jun-Pyo , Byun Seung Won , Lee Sung-Jong , Lee Yong Seok , Lee Hae-Nam , Lee Keun Ho , Park Dong Choon , Kim Chan Joo , Hur Soo Young , Park Jong Sup , Park Tae Chul
Published: April 2017

Objectives

Despite the possibility of early detection of cervical cancer, participation in screening programmes among young Koreans is low. We sought to identify associations between risk factors and participation in screening for cervical cancer among young Koreans.

Design

Nationwide cross-sectional study.

Setting

Republic of Korea.

Participants

3734.

Main outcome measures

The Korea National Health and Nutrition Examination Survey (KNHANES V: 2010–2012) was used to evaluate factors associated with attendance for cervical cancer screening among women aged 15–39. After excluding those who were previously diagnosed with cervical cancer and those with incomplete responses to questionnaires, a total of 3734 subjects were eligible. Multi-dimensional covariates as potential predictors of cervical cancer screening were adjusted in multiple logistic regression analysis.

Results

The participation rate for cervical cancer screening was 46% among women aged 40 or younger. The logistic analyses showed that age, education, total household income, smoking and job status among women aged 15–39 were associated with participation in cervical cancer screening (p<0.05). After age stratification, the associated factors differed by age groups. Moreover, a dose–response between participation in cervical cancer screening and high total household income in the 30–39 age group was seen.

Conclusions

Predictive factors differed among young women (aged 15–29 vs 30–39). Thus, age-specific tailored interventions and policies are needed to increase the participation rate in screening for cervical cancer.
Patient perceptions of glucocorticoid side effects: a cross-sectional survey of users in an online health community
Authors: Costello Ruth , Patel Rikesh , Humphreys Jennifer , McBeth John , Dixon William G
Published: April 2017

Objectives

To identify the side effects most important to glucocorticoid (GC) users through a survey of a UK online health community (Healthunlocked.com).

Design

Online cross-sectional survey.

Setting

Participants were recruited through Healthunlocked.com, an online social network for health.

Participants

Adults who were currently taking GCs, or had taken GCs in the past month.

Method

Responders scored the importance of listed side effects from 1 to 10, with 10 being of high importance to them. For each side effect, histograms were plotted, and the median rating and IQR were determined. Side effects were ranked by median ranking (largest to smallest) and then IQR (smallest to largest). The scores were categorised as low (scores 1–3), medium (scores 4–7) and high (scores 8–10) importance.

Results

604 responders completed the survey. Histograms of side effect scores showed a skew towards high importance for weight gain, a U-shaped distribution for cardiovascular disease (CVD), diabetes, eye disease and infections, and a skew towards low importance for acne. When ranked, the side effect of most importance to responders was weight gain (median score=9, IQR 6–10) followed by insomnia and moon face with equal median score (8) and IQR (5–10). Three serious side effects, CVD, diabetes and infections, were ranked of lower importance overall but had wide ranging scores (median score=8, IQR 1–10).

Conclusions

The three most highly rated side effects were not clinically serious but remained important to patients, perhaps reflecting their impact on quality of life and high prevalence. This should be taken into consideration when discussing treatment options and planning future GC safety studies.
The Effect of Vitrectomy Infusion Solutions on Postoperative Electroretinography and Retina Histology
Authors: AbdEl Dayem Hisham , Hartzer Michael , Williams George , Ferrone Philip
Published: April 2017

Purpose

A prospective, randomised, masked study comparing three different intraocular infusion solutions used during vitrectomy on postoperative electroretinography (ERG) and retinal histology of rabbit eyes.

Methods, materials and animals

Twelve rabbit eyes were used with each group of three intraocular infusion solutions: Lactated Ringers (LR), balanced salt solution (BSS) and balanced salt solution-plus (BSS-Plus).

Results

At 24 hours postoperatively, the ERG values were 36%, 68% and 75% of the normal values for LR, BSS and BSS-Plus, respectively. At 72 hours postoperatively, the ERG values were 50%, 84% and 100% of the normal values for LR, BSS and BSS-Plus, respectively. At 72 hours postoperatively, 3/12, 10/12 and 12/12 of the vitrectomised eyes had regained normal-value ERGs for LR, BSS, and BSS-Plus eyes, respectively. At 1 week postoperatively, 4/12 and 12/12 of LR and BSS eyes, respectively, had normal ERGs. The number of LR eyes regaining normal ERG values was 4/12, 6/12 and 9/12, measured at 1, 4 and 15 weeks postoperatively, respectively.

Retina histology

At 15 weeks follow-up, histopathology was performed on several rabbit eyes. Histological examination of LR-irrigated eyes showed 2/7 normal retinas, whereas 5/7 showed changes that ranged from vacuoles in the inner retina to numerous vacuoles in both the outer and inner retina with disruption of the inner nuclear layer. The histology of BSS-infused and BSS-Plus-infused rabbit eyes was normal.

Conclusion

LR solution, when used during vitrectomy, has a more prolonged negative effect on ERG than BSS and BSS-Plus. Histological changes seen in LR eyes may explain the ERG results.
Plasma sphingolipids in HIV-associated chronic obstructive pulmonary disease
Authors: Hodgson Shane , Griffin Timothy J , Reilly Cavan , Harvey Stephen , Witthuhn Bruce A , Sandri Brian J , Kunisaki Ken M , Wendt Chris H
Published: April 2017

Introduction

Chronic obstructive pulmonary disease (COPD) is a significant cause of morbidity in persons living with HIV (PLWH) and HIV appears to uniquely cause COPD, independent of smoking. The mechanisms by which HIV leads to COPD are not clear. The objective of this study was to identify metabolomic biomarkers and potential mechanistic pathways of HIV-associated COPD (HIV-COPD).

Methods

We performed case–control metabolite profiling via mass spectrometry in plasma from 38 individuals with HIV-COPD (cases), comparing to matched controls with/without HIV and with/without COPD. Untargeted metabolites of interest were identified with liquid chromatography with mass spectrometry (LC-MS/mass spectrometry (MS)), and targeted metabolomics for tryptophan (Trp) and kynurenine (Kyn) were measured by selective reaction monitoring (SRM) with LC-MS/MS. We used mixed-effects models to compare metabolite concentrations in cases compared with controls while controlling for relevant biological variables.

Results

We identified 1689 analytes associated with HIV-COPD at a false discovery rate (FDR) of 10%. In PLWH, we identified 263 analytes (10% FDR) between those with and without COPD. LC MS/MS identified Trp and 17 lipids, including sphingolipids and diacylglycerol. After adjusting for relevant covariates, the Kyn/Trp ratio measured by SRM was significantly higher in PLWH (p=0.022), but was not associated with COPD status (p=0.95).

Conclusions

There is a unique metabolite profile in HIV-COPD that includes sphingolipids. Trp metabolism is increased in HIV, but does not appear to independently contribute to HIV-COPD.

Trial registration numbers

NCT01810289,NCT01797367,NCT00608764.
Highly sensitive determination of copper (II) ions using fluorescence and chemiluminescence emissions of modified CdS quantum dots after it’s preconcentration by dispersive liquid–liquid microextraction
Authors: Saeedi Zohreh , Lotfi Ali , Hassanzadeh Javad , Bagheri Nafiseh
Published: April 2017

Two highly sensitive and selective methods based on fluorescence (FL) and chemiluminescence (CL) emissions of 8-mercaptoquinoline-capped CdS quantum dots (MCQ-CdS QDs) were described for the determination of copper (II) after it’s preconcentration. High fluorescent CdS QDs, synthesized in an aqueous medium, generated a relatively intense CL emission in the presence of potassium permanganate as an oxidant. Furthermore, low quantities of copper (II) ions showed a remarkable quenching effect on both of the CL and FL emissions of MCQ-CdS QDs. Based on this effect, two selective and simple methods were established for Cu2+, and the detection limits of 0.28 and 0.026 ng mL−1 were obtained for the FL and CL methods, respectively. Also, due to the high propensity of MCQ to Cu2+, good selectivity was obtained and no sensible interfering effects from other metal ions were observed. To more sensitize the developed method, an efficient preconcentration process was designed based on the high-yield ultrasound-assisted temperature-controlled ionic liquid dispersive liquid–liquid microextraction (UA-TIL-DLLME) method. Under the optimum conditions, the extracted Cu2+ showed a suppressing effect on the FL and CL emissions of CdS QDs proportional to its initial concentration over the ranges of 0.008–1.4 and 0.001–1.4 ng mL−1, respectively. The limits of detection of 3.7 and 0.37 pg mL−1, respectively, were also achieved. The established methods showed great features and were satisfactorily applied to the monitoring of ultratrace Cu2+ in some different environmental samples.
Synthesis of a poly(amidoamine) dendrimer having a 1,10-bis(decyloxy)decane core and its use in fabrication of carbon nanotube/calcium carbonate hybrids through biomimetic mineralization
Authors: Nishimura Shunichi , Tajima Tomoyuki , Hasegawa Tatsuki , Tanaka Tomoaki , Takaguchi Yutaka , Oaki Yuya , Imai Hiroaki
Published: April 2017

A new dendritic dispersant of carbon nanotubes (CNTs) was synthesized and applied for the noncovalent functionalization of single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs). The 1,10-bis(decyloxy)decane core of the poly(amidoamine) dendrimer strongly adhered to the sidewalls of CNTs to form CNT/dendrimer supramolecular nanocomposites having many carboxyl groups (–COOH) on the surface. Then, crystallization of calcium carbonate (CaCO3) by the CO2 diffusion technique in aqueous environments using the CNT/dendrimer supramolecular nanocomposites as scaffolds afforded monodisperse spherical CNT/CaCO3 nanohybrids consisting of CNTs and calcite nanocrystals. The morphologies of the SWCNT/CaCO3 hybrids and MWCNT/CaCO3 hybrids were almost the same.
On limiting velocity with Weber-like potentials
Authors: Montes J.M.
Published: April 2017

This work analyses the problem of a charge moving perpendicularly to the plates of a charged capacitor. The results obtained from the current theoretical framework (Maxwell–Lorentz electromagnetism and special relativity theory) are compared with the results obtained from Weber’s electrodynamic potential, with the Phipps’s potential and a new potential proposed here. The aim of this comparison is to analyse the causes of the inability of these Weber-like potentials to predict the existence of a limiting velocity for this problem, as special relativity theory does indeed predict and many experimental results confirm. To overcome this incapacity, the need to employ an effective potential to solve the capacitor problem is shown. In the adoption of this strategy, it is shown that the potential proposed here reproduces the same relativistic result. Finally, the origin and possible interpretation of the aforementioned effective potential are analysed.
Experiences with integrative Indigenous and Western knowledge in water research and management: a systematic realist review of literature from Canada, Australia, New Zealand, and the United States
Authors: Stefanelli Robert D. , Castleden Heather , Harper Sherilee L. , Martin Debbie , Cunsolo Ashlee , Hart Catherine
Published: April 2017

The implementation of Indigenous and Western knowledge systems in integrative water research and management is gaining prominence in the realm of academia, particularly in four countries with a shared, albeit different, history of British colonialism: Canada, Australia, New Zealand, and the United States. While integrative water research in particular is gaining popularity, currently there is a gap in our understanding regarding where, when, why, how, and for whom this type of research has been successful. A systematic review method was used to identify peer-reviewed literature from each of the four countries and to understand where and when integrative water research projects were taking place. Then, we used a realist review method to synthesize and analyze the included peer-reviewed literature to determine why, how, and for whom this type of research has been successful, or not. Our systematic literature search provided 669 peer-reviewed articles from across the four countries, of which 97 met our inclusion criteria and were analyzed. Our findings indicate that the total number of integrative water research projects has been increasing since 2009, though these projects are largely concentrated within the realm of social science and conducted by non-Indigenous authors. Recognition of the value of Indigenous knowledge systems, coupled with an understanding that the use of Western knowledge systems alone has not remedied the disparity in access to safe water sources in Indigenous communities, has led researchers to recommend collaborative partnerships and governance structures as a potential pathway to effective integrative water research. Our research was conducted to enhance contemporary understanding of the strengths of implementing Indigenous and Western knowledge systems and to encourage readers to continue working towards a common goal of reconciliation and equality in all partnerships.
Physiological responses to a short-term, environmentally realistic, acute heat stress in Atlantic salmon,Salmo salar
Authors: Gallant Melanie J. , LeBlanc Sacha , MacCormack Tyson J. , Currie Suzanne
Published: April 2017

Atlantic salmon populations are declining, and warming river temperatures in the summer months are thought to be a significant contributing factor. We describe the time course of cellular and metabolic responses to an ecologically relevant short-term thermal cycle in juvenile Atlantic salmon. We then examined whether this heat event would affect tolerance to a subsequent heat shock in terms of critical thermal maximum (CTmax). Fish induced heat shock protein 70 in red blood cells, heart, liver, and red and white muscle; whole blood glucose and lactate transiently increased during the heat cycle. In contrast, we observed no significant effect of a prior heat shock on CTmax. The CTmaxwas positively correlated with Fulton’s condition factor suggesting that fish with greater energy reserves are more thermally tolerant. Atlantic salmon activate cellular protection pathways in response to a single thermal cycle and appear to cope with this short-term, ∼1 d heat shock, but this challenge may compromise the ability to cope with subsequent heat events.
Deterministic Construction of Compressed Sensing Matrices from Codes
Authors: Wang Xiang , Fu Fang-Wei
Published: April 2017

Compressed sensing is a sparse sampling theory. Compared with the Nyquist-Shannon sampling theory, in compressed sensing one could reconstruct a sparse signal from a few linear and non-adaptive measurements. How to construct a good sensing matrix which captures the full information of a sparse signal is an important problem in compressed sensing. In this paper, we present a new deterministic construction using a linear or nonlinear code, which is a generalization of DeVore’s construction and Li et al.’s construction. By choosing some appropriate linear codes or nonlinear codes, we will construct some good binary sensing matrices which are superior to DeVore’s ones and Li et al.’s ones.
Regular Sequences and the Joint Spectral Radius
Authors: Coons Michael
Published: April 2017

We classify the growth of a k-regular sequence based on information from its k-kernel. In order to provide such a classification, we introduce the notion of a growth exponent for k-regular sequences and show that this exponent is equal to the base-k logarithm of the joint spectral radius of any set of a special class of matrices determined by the k-kernel.
Identifying Generalized Reed-Muller Codewords by Quantum Queries
Authors: Arnold Stefan
Published: April 2017

We provide an exact quantum query algorithm that identifies uncorrupted codewords from a degree-d generalized Reed-Muller code of length qn over the finite field of size q. When d is constant, the algorithm needs 𝒪(nd-1) quantum queries, which is optimal. Classically, Ω(nd) queries are necessary to accomplish this task, even with constant probability of error admitted. Our work extends a result by Montanaro about learning multilinear polynomials.
Photon-assisted transport through a 1D-dot-graphene similar to STM model device
Authors: Zhao Zhiyun , Min Yi , Zhou Pengxia , Huang Yanyan , Zhong Chonggui
Published: April 2017

By using the nonequilibrium Green function method, the photon-assisted electron transport through a graphene-based device similar to STM model is studied theoretically and numerically. The device is composed of a single central site (quantum dot) modulated by an oscillating electric field, a one-dimensional quantum wire and a two-dimensional graphene sheet. Some interesting results on transmission probability and current–voltage ([Formula: see text]–[Formula: see text]) characteristics of the device are given in this paper. In the presence of an oscillating electric field, we find that besides the central two transmission peaks caused by graphene part, there appear photon-assisted peaks which are distributed on both sides of the Fermi level. The positions of the photon-assisted peaks are linear to the frequency of the oscillating electric field, and the widths of the photon-assisted peaks are relevant to the amplitude of the oscillating electric field. It is found that the current–voltage graphs exhibit step growth due to the existence of photon-assisted tunneling. We hope these results may have guidance meaning for the fabrication of optoelectronic devices.
Robust and controllable electronic local transports in armchair silicene nanoribbons under a perpendicular electric field
Authors: Chen Xiongwen , Shi Zhengang , Chen Baoju , Song Kehui
Published: April 2017

We study the electronic local distribution and transports in pristine armchair-edge silicene nanoribbons (ASiNRs) based on the tight-binding approximation. By calculating the local densities of states at different sites and the bond current between two adjacent sites, we show that comparing to the pristine armchair-edge graphene nanoribbons, a similar “[Formula: see text]” rule and multiple low-electron transport channels exist in the pristine [Formula: see text]-ASiNRs. However, differently, they are controllable to appear and disappear by applying an electric field perpendicular to the ribbon plane. Therefore, one can manipulate the semiconducting channels and realize the current switch “on/off,” unchanging their structures. Moreover, the results are robust against the edge-passivation and a few structural defects, which ensures their stability for the practical application in the silicene-based device.
First-principle studies of the optoelectronic properties of ASnF3 (A = Na, K, Rb and Cs)
Authors: Khan Imad , Shehzad Nasir , Ahmad Iftikhar , Ali Zahid , Jalali-Asadabadi S.
Published: April 2017

In this paper, we communicate a new type of Auger-free luminescence (AFL) compounds, alkali tin fluorides ASnF3 (A = Na, K, Rb and Cs). The luminescence in these compounds originates due to the electron transition from the top valence band (VB) of tin-[Formula: see text] orbital to the outermost core levels of halogen, i.e., halogen-[Formula: see text] orbital ([Formula: see text]-[Formula: see text] transitions). The AFL of these compounds is expected to be of L-type. Furthermore, the electronic band structures and optical properties such as dielectric functions, refractive index and energy loss function are also investigated using ab initio calculations.
Design of a Compact Dual-Mode Dual-Band Bandpass Filter Using Stacked-Loop Resonators Structure
Authors: Babajanzadeh Mohammad , Dousti Massoud
Published: April 2017

Design, fabrication and measurement of a high-selectivity dual-mode dual-band bandpass filter are presented in this paper. The resonance frequencies of the filter are 1.8[Formula: see text]GHz and 2.4[Formula: see text]GHz which are generated by a meander-loop resonator and a square-loop resonator. The two dual-mode single-band-loop resonators are stacked on each other and create a dual-band bandpass filter. Some advantages of our design are compact size, high selectivity, low loss and also no dependence of two bands, resonance frequencies on each other. The measurement results exhibit that the minimum insertion losses are 0.19[Formula: see text]dB for 1.8[Formula: see text]GHz and 0.32[Formula: see text]dB for 2.4[Formula: see text]GHz. Moreover return losses are better than 43.2[Formula: see text]dB and 40.6[Formula: see text]dB for 1.8[Formula: see text]GHz and 2.4[Formula: see text]GHz, respectively. The proposed filter has a size of [Formula: see text][Formula: see text]mm2. This microstrip filter is fabricated on RT/Duroid6010 substrate with dielectric constant 10.8 and thickness 1.27[Formula: see text]mm and its equivalent circuit is also offered. The measured results exhibit good agreement with the simulated ones.
A Low-Voltage Low-Power Resistor-Based Current Mirror and Its Applications
Authors: Safari Leila , Minaei Shahram
Published: April 2017

In this paper, a CMOS resistor-based current mirror (RBCM) aimed to be used in low-voltage applications is presented. The main features of the proposed current mirror are very low input voltage requirement (a few mV), low output voltage requirement, high output impedance and simple circuitry. The core structure of the proposed RBCM consists of three transistors (excluding bias circuitry) and two low value grounded resistors. The proposed circuit alleviates the need for cascode structures which are conventionally used to boost the output impedance and linearity. SPICE simulations using 0.18[Formula: see text][Formula: see text]m CMOS technology parameters under supply voltage of 0.9[Formula: see text]V are reported which show input and output voltage requirements of 40[Formula: see text]mV and 0.1[Formula: see text]V respectively, low THD of 1.2%, [Formula: see text] of 496[Formula: see text][Formula: see text], [Formula: see text] of 1[Formula: see text]M[Formula: see text], [Formula: see text]3[Formula: see text]dB bandwidth of 181[Formula: see text]MHz and power dissipation of 154[Formula: see text][Formula: see text]W. A high CMRR differential amplifier and a high performance current difference circuit as applications of the proposed RBCM are given. The proposed RBCM is very useful in tackling restrictions of modern technologies such as reduced supply voltage and transistors low intrinsic output impedance.
Dynamical properties of scaling solutions in teleparallel dark energy cosmologies with nonminimal coupling
Authors: Marciu Mihai
Published: April 2017

The dynamical aspects of scaling solutions for the dark energy component in the theoretical framework of teleparallel gravity are considered, where dark energy is represented by a scalar field nonminimally coupled with the torsion and with a boundary term, where the boundary coupling term represents the divergence of the torsion vector. The behavior and stability of the scaling solutions are studied for scalar fields endowed with inverse power law potentials and with exponential potentials. It is shown that for scalar fields endowed with inverse power-law potentials, the stability conditions are not affected by the coupling coefficients. For the scalar fields endowed with exponential potentials, two cases are studied: at first, we have considered an infinitesimal deviation from the scaling solution in the corresponding Klein–Gordon equation, and the impact of distinct coupling coefficients on the stability of the solution are analyzed. Secondly, the potential-free case is considered where the dominance of the coupling terms over the potential term is analyzed, discussing the validity of the corresponding particular solution.
Thermodynamic metric of deformed Schwarzschild black holes
Authors: Wen Wen-Yu
Published: April 2017

Thermodynamic metric usually works only for those black holes with more than one conserved charge, thereby excluding the Schwarzschild black hole. In this paper, however, different versions of thermodynamic metric are computed and compared for the Schwarzschild-like black hole by introducing new degrees of freedom. These new degrees of freedom have two purposes. First, the deformed metric may be treated offshell to the ordinary Schwarzschild black hole, and onshell physics corresponds to the submanifold by gauge fixing of this additional degree of freedom. In particular, the thermal Ricci scalar for the Schwarzschild black hole, though different for various deformations, can be obtained by switching off the deformation. Second, while deformed metric is treated onshell, a divergent Ricci scalar may signal an exotic phase in which new physical degrees of freedom manifest. This paper considers the new degree of freedom as the running Newton constant, a cutoff scale for regular black holes, a noncommutative deformation or the deformed parameter in the nonextensive Tsallis–Rènyi entropy.
SIZE EFFECT ON SPECIFIC ENERGY DISTRIBUTION IN PARTICLE COMMINUTION
Authors: XU YONGFU , WANG YIDONG
Published: April 2017

A theoretical study is made to derive an energy distribution equation for the size reduction process from the fractal model for the particle comminution. Fractal model is employed as a valid measure of the self-similar size distribution of comminution daughter products. The tensile strength of particles varies with particle size in the manner of a power function law. The energy consumption for comminuting single particle is found to be proportional to the 5(D−3)/3rd order of the particle size, [Formula: see text] being the fractal dimension of particle comminution daughter. The Weibull statistics is applied to describe the relationship between the breakage probability and specific energy of particle comminution. A simple equation is derived for the breakage probability of particles in view of the dependence of fracture energy on particle size. The calculated exponents and Weibull coefficients are generally in conformity with published data for fracture of particles.
FRACTAL CHARACTERIZATION OF DYNAMIC FRACTURE NETWORK EXTENSION IN POROUS MEDIA
Authors: CAI JIANCHAO , WEI WEI , HU XIANGYUN , LIU RICHENG , WANG JINJIE
Published: April 2017

Fracture network and fractured porous media as well as their transport properties have received great attentions in many fields from engineering application and basic theoretical researches. Fracture will dynamically extend in length and aperture to form complex fracture network under some external conditions such as percussion drilling, wave propagation, desiccation and hydrofracturing. The complexity of fracture network can be well quantitatively characterized by fractal dimension. In this work, the dynamic characterization of fracture network extension in porous media under drying process is measured by the improved box-counting technique, and fractal dimensions of fracture network are respectively related to drying time, average aperture, moisture content and fracture porosity. The fractal dimension increases exponentially with drying time and average aperture, and decreases with moisture content in the form of power law. Specially, the fractal dimension is approximatively increased with porosity in the form of linearity in a narrow porosity range. The transport capacity of fracture network, described by seepage coefficient, is also related to the fractal dimension with drying time in the form of exponential function. The presented fractal analysis of fracture network could also shed light on the hydrofracturing application in subsurface unconventional oil and gas reservoirs.
Cross-National CSR Web Reporting: A Comparative Analysis of Multinational Corporations in the U.S. and South Korea
Authors: Kane Victor , Dikeç Altay , Park Jin Yong
Published: April 2017

This study investigated the extent of corporate social responsibility (CSR) Web reporting and the variations in CSR indicators among publicly traded, multinational corporations in the US and South Korea. The study supports previous research in CSR Web reporting across countries and regions of the world that CSR development is more advanced in the Western world where CSR as a concept was originated. Indeed, the U.S. companies in this study showed greater depth and scope of CSR information disclosure compared to the less developed country of South Korea.