bluuebunny/crossref_metadata_2025_split huggingface dataset:
Induction of P-Glycoprotein by Antiretroviral Drugs in Human Brain Microvessel Endothelial Cells
Authors: Chan Gary N. Y. , Patel Rucha , Cummins Carolyn L. , Bendayan Reina 
Published: July 2013

ABSTRACT
The membrane-associated drug transporter P-glycoprotein (P-gp) plays an essential role in drug efflux from the brain. Induction of this protein at the blood-brain barrier (BBB) could further affect the ability of a drug to enter the brain. At present, P-gp induction mediated by antiretroviral drugs at the BBB has not been fully investigated. Since P-gp expression is regulated by ligand-activated nuclear receptors, i.e., human pregnane X receptor (hPXR) and human constitutive androstane receptor (hCAR), these receptors could represent potential pathways involved in P-gp induction by antiretroviral drugs. The aims of this study were (i) to determine whether antiretroviral drugs currently used in HIV pharmacotherapy are ligands for hPXR or hCAR and (ii) to examine P-gp function and expression in human brain microvessel endothelial cells treated with antiretroviral drugs identified as ligands of hPXR and/or hCAR. Luciferase reporter gene assays were performed to examine the activation of hPXR and hCAR by antiretroviral drugs. The hCMEC/D3 cell line, which is known to display several morphological and biochemical properties of the BBB in humans, was used to examine P-gp induction following 72 h of exposure to these agents. Amprenavir, atazanavir, darunavir, efavirenz, ritonavir, and lopinavir were found to activate hPXR, whereas abacavir, efavirenz, and nevirapine were found to activate hCAR. P-gp expression and function were significantly induced in hCMEC/D3 cells treated with these drugs at clinical concentrations in plasma. Together, our data suggest that P-gp induction could occur at the BBB during chronic treatment with antiretroviral drugs identified as ligands of hPXR and/or hCAR.
IMP-43 and IMP-44 Metallo-β-Lactamases with Increased Carbapenemase Activities in Multidrug-Resistant Pseudomonas aeruginosa
Authors: Tada Tatsuya , Miyoshi-Akiyama Tohru , Shimada Kayo , Shimojima Masahiro , Kirikae Teruo 
Published: July 2013

ABSTRACT

Two novel IMP-type metallo-β-lactamase variants, IMP-43 and IMP-44, were identified in multidrug-resistant
Pseudomonas aeruginosa
isolates obtained in medical settings in Japan. Analysis of their predicted amino acid sequences revealed that IMP-43 had an amino acid substitution (Val67Phe) compared with IMP-7 and that IMP-44 had two substitutions (Val67Phe and Phe87Ser) compared with IMP-11. The amino acid residue at position 67 is located at the end of a loop close to the active site, consisting of residues 60 to 66 in IMP-1, and the amino acid residue at position 87 forms a hydrophobic patch close to the active site with other amino acids. An
Escherichia coli
strain expressing
bla
IMP-43
was more resistant to doripenem and meropenem but not to imipenem than one expressing
bla
IMP-7
. An
E. coli
strain expressing
bla
IMP-44
was more resistant to doripenem, imipenem and meropenem than one expressing
bla
IMP-11
. IMP-43 had more efficient catalytic activities against all three carbapenems than IMP-7, indicating that the Val67Phe substitution contributed to increased catalytic activities against carbapenems. IMP-44 had more efficient catalytic activities against all carbapenems tested than IMP-11, as well as increased activities compared with IMP-43, indicating that both the Val67Phe and Phe87Ser substitutions contributed to increased catalytic activities against carbapenems.
Disposition of Mefloquine and Enpiroline Is Highly Influenced by a Chronic Schistosoma mansoni Infection
Authors: Ingram Katrin , Duthaler Urs , Vargas Mireille , Ellis William , Keiser Jennifer 
Published: July 2013

ABSTRACT

Chronic
Schistosoma mansoni
infections lead to severe tissue destruction of the gut wall and liver and can influence drug disposition. This study aimed to investigate the impact of a chronic
S. mansoni
infection on the pharmacokinetic (PK) parameters of two promising antischistosomal lead candidates (mefloquine and enpiroline) in mice. Studies were conducted in two different mouse cohorts (
S. mansoni
-infected and uninfected mice) for both drugs. Plasma samples were collected at various time points after oral treatment (200 mg/kg of body weight) with study drugs. A high-performance liquid chromatography (HPLC) method was validated to analyze enpiroline and mefloquine in plasma. Livers and intestines were collected from infected animals to determine the onset of action, hepatic shift, and worm burden reduction. Following mefloquine administration, hepatic shifting and significant worm burden reductions (79.2%) were observed after 72 h. At 1 week posttreatment with enpiroline, the majority of worms had migrated to the liver and significant worm burden reductions were observed (93.1%). The HPLC method was selective, accurate (87.8 to 111.4%), and precise (<10%) for the analysis of both drugs in plasma samples. The PK profiles revealed increased values for half-life (
t
1/2
) and area under the concentration-time curve (AUC) for both drugs in infected animals compared to the
t
1/2
and AUC values in uninfected animals. Considerable changes were observed for mefloquine, with a 5-fold increase of
t
1/2
(182.7 h versus 33.6 h) and 2-fold increase of AUC (1,116,517.8 ng · h/ml versus 522,409.1 ng · h/ml).
S. mansoni
infections in mice influence the PK profiles of enpiroline and mefloquine, leading to delayed clearance. Our data confirm that drug disposition should be carefully studied in schistosomiasis patients.
Screening for Glycosylphosphatidylinositol-Modified Cell Wall Proteins in Pichia pastoris and Their Recombinant Expression on the Cell Surface
Authors: Zhang Li , Liang Shuli , Zhou Xinying , Jin Zi , Jiang Fengchun , Han Shuangyan , Zheng Suiping , Lin Ying 
Published: July 2013

ABSTRACT

Glycosylphosphatidylinositol (GPI)-anchored glycoproteins have various intrinsic functions in yeasts and different uses
in vitro
. In the present study, the genome of
Pichia pastoris
GS115 was screened for potential GPI-modified cell wall proteins. Fifty putative GPI-anchored proteins were selected on the basis of (i) the presence of a C-terminal GPI attachment signal sequence, (ii) the presence of an N-terminal signal sequence for secretion, and (iii) the absence of transmembrane domains in mature protein. The predicted GPI-anchored proteins were fused to an alpha-factor secretion signal as a substitute for their own N-terminal signal peptides and tagged with the chimeric reporters FLAG tag and mature
Candida antarctica
lipase B (CALB). The expression of fusion proteins on the cell surface of
P. pastoris
GS115 was determined by whole-cell flow cytometry and immunoblotting analysis of the cell wall extracts obtained by β-1,3-glucanase digestion. CALB displayed on the cell surface of
P. pastoris
GS115 with the predicted GPI-anchored proteins was examined on the basis of potential hydrolysis of
p
-nitrophenyl butyrate. Finally, 13 proteins were confirmed to be GPI-modified cell wall proteins in
P. pastoris
GS115, which can be used to display heterologous proteins on the yeast cell surface.
Duodenal-Mucosal Bacteria Associated with Celiac Disease in Children
Authors: Sánchez Ester , Donat Ester , Ribes-Koninckx Carmen , Fernández-Murga Maria Leonor , Sanz Yolanda 
Published: July 2013

ABSTRACTCeliac disease (CD) is an immune-mediated enteropathy triggered by the ingestion of cereal gluten proteins. This disorder is associated with imbalances in the gut microbiota composition that could be involved in the pathogenesis of CD. The aim of this study was to characterize the composition and diversity of the cultivable duodenal mucosa-associated bacteria of CD patients and control children. Duodenal biopsy specimens from patients with active disease on a gluten-containing diet (n= 32), patients with nonactive disease after adherence to a gluten-free diet (n= 17), and controls (n= 8) were homogenized and plated on plate count agar, Wilkins-Chalgren agar, brain heart agar, or yeast, Casitone, and fatty acid agar. The isolates were identified by partial 16S rRNA gene sequencing. Renyi diversity profiles showed the highest diversity values for active CD patients, followed by nonactive CD patients and control individuals. Members of the phylumProteobacteriawere more abundant in patients with active CD than in the other child groups, while those of the phylumFirmicuteswere less abundant. Members of the familiesEnterobacteriaceaeandStaphylococcaceae, particularly the speciesKlebsiella oxytoca,Staphylococcus epidermidis, andStaphylococcus pasteuri, were more abundant in patients with active disease than in controls. In contrast, members of the familyStreptococcaceaewere less abundant in patients with active CD than in controls. Furthermore, isolates of theStreptococcus anginosusandStreptococcus mutansgroups were more abundant in controls than in both CD patient groups, regardless of inflammatory status. The findings indicated that the disease is associated with the overgrowth of possible pathobionts that exclude symbionts or commensals that are characteristic of the healthy small intestinal microbiota.
Occurrence of Waterborne Pathogens and Escherichia coli at Offshore Drinking Water Intakes in Lake Ontario
Authors: Edge T. A. , Khan I. U. H. , Bouchard R. , Guo J. , Hill S. , Locas A. , Moore L. , Neumann N. , Nowak E. , Payment P. , Yang R. , Yerubandi R. , Watson S. 
Published: July 2013

ABSTRACT

The occurrence of waterborne pathogens was investigated at three drinking water intakes located about 2 km offshore in Lake Ontario. Water sampling was conducted over 3 years for
Campylobacter
spp.,
Cryptosporidium
spp.,
Giardia
spp., cultivable enteric viruses, and water quality parameters. All pathogens were detected in the offshore source water for each water treatment plant (WTP1 to WTP3), although at relatively low frequencies and concentrations.
Giardia
was the most common pathogen, occurring in 36% of water samples from the influent of WTP1 (
n
= 46), and with a maximum concentration of 0.70 cysts/liter in this influent.
Cryptosporidium
occurred as frequently as 15% in the WTP2 influent (
n
= 35), with a maximum concentration of 0.40 oocysts/liter in the WTP1 influent. The human
Bacteroidales
HF183 DNA marker was most common in the WTP1 influent (19%), and this was the only WTP where the
Cryptosporidium hominis
genotype was detected. No water quality parameter was predictive of pathogen occurrence across all three WTP influents.
Escherichia coli
was often below detection when pathogens were detected, and spikes in
E. coli
concentrations often did not coincide with pathogen occurrence. After summer rain events, river plumes had
E. coli
concentrations as high as 222 CFU/100 ml in surface waters 2 km offshore, without impacting drinking water intakes below the thermocline on the lake bottom. At times, prechlorination to control mussels at offshore intake cribs compromised the use of
E. coli
for “raw” water quality assessment, particularly for chlorine-resistant
Cryptosporidium. E. coli
measured by standard methods did not reliably predict pathogen occurrence at drinking water intakes in offshore ecosystems.
Diversity, Community Composition, and Dynamics of Nonpigmented and Late-Pigmenting Rapidly Growing Mycobacteria in an Urban Tap Water Production and Distribution System
Authors: Dubrou S. , Konjek J. , Macheras E. , Welté B. , Guidicelli L. , Chignon E. , Joyeux M. , Gaillard J. L. , Heym B. , Tully T. , Sapriel G. 
Published: July 2013

ABSTRACTNonpigmented and late-pigmenting rapidly growing mycobacteria (RGM) have been reported to commonly colonize water production and distribution systems. However, there is little information about the nature and distribution of RGM species within the different parts of such complex networks or about their clustering into specific RGM species communities. We conducted a large-scale survey between 2007 and 2009 in the Parisian urban tap water production and distribution system. We analyzed 1,418 water samples from 36 sites, covering all production units, water storage tanks, and distribution units; RGM isolates were identified by usingrpoBgene sequencing. We detected 18 RGM species and putative new species, with most isolates beingMycobacterium chelonaeandMycobacterium llatzerense. Using hierarchical clustering and principal-component analysis, we found that RGM were organized into various communities correlating with water origin (groundwater or surface water) and location within the distribution network. Water treatment plants were more specifically associated with species of theMycobacterium septicumgroup. On average,M. chelonaedominated network sites fed by surface water, andM. llatzerensedominated those fed by groundwater. Overall, theM. chelonaeprevalence index increased along the distribution network and was associated with a correlative decrease in the prevalence index ofM. llatzerense, suggesting competitive or niche exclusion between these two dominant species. Our data describe the great diversity and complexity of RGM species living in the interconnected environments that constitute the water production and distribution system of a large city and highlight the prevalence index of the potentially pathogenic speciesM. chelonaein the distribution network.
Deletion of
creB
in Aspergillus oryzae Increases Secreted Hydrolytic Enzyme Activity
Authors: Hunter A. J. , Morris T. A. , Jin B. , Saint C. P. , Kelly J. M. 
Published: July 2013

ABSTRACT

Aspergillus oryzae
has been used in the food and beverage industry for centuries, and industrial strains have been produced by multiple rounds of selection. Targeted gene deletion technology is particularly useful for strain improvement in such strains, particularly when they do not have a well-characterized meiotic cycle. Phenotypes of an
Aspergillus nidulans
strain null for the CreB deubiquitinating enzyme include effects on growth and repression, including increased activity levels of various enzymes. We show that
Aspergillus oryzae
contains a functional homologue of the CreB deubiquitinating enzyme and that a null strain shows increased activity levels of industrially important secreted enzymes, including cellulases, xylanases, amylases, and proteases, as well as alleviated inhibition of spore germination on glucose medium. Reverse transcription-quantitative PCR (RT-qPCR) analysis showed that the increased levels of enzyme activity in both
Aspergillus nidulans
and
Aspergillus oryzae
are mirrored at the transcript level, indicating transcriptional regulation. We report that
Aspergillus oryzae
DAR3699, originally isolated from soy fermentation, has a similar phenotype to that of a
creB
deletion mutant of the RIB40 strain, and it contains a mutation in the
creB
gene. Collectively, the results for
Aspergillus oryzae
,
Aspergillus nidulans
,
Trichoderma reesei
, and
Penicillium decumbens
show that deletion of
creB
may be broadly useful in diverse fungi for increasing production of a variety of enzymes.
Structure-Function Relationships in Hydrophobins: Probing the Role of Charged Side Chains
Authors: Lienemann Michael , Gandier Julie-Anne , Joensuu Jussi J. , Iwanaga Atsushi , Takatsuji Yoshiyuki , Haruyama Tetsuya , Master Emma , Tenkanen Maija , Linder Markus B. 
Published: July 2013

ABSTRACT

Hydrophobins are small fungal proteins that are amphiphilic and have a strong tendency to assemble at interfaces. By taking advantage of this property, hydrophobins have been used for a number of applications: as affinity tags in protein purification, for protein immobilization, such as in foam stabilizers, and as dispersion agents for insoluble drug molecules. Here, we used site-directed mutagenesis to gain an understanding of the molecular basis of their properties. We especially focused on the role of charged amino acids in the structure of hydrophobins. For this purpose, fusion proteins consisting of
Trichoderma reesei
hydrophobin I (HFBI) and the green fluorescent protein (GFP) that contained various combinations of substitutions of charged amino acids (D30, K32, D40, D43, R45, K50) in the HFBI structure were produced. The effects of the introduced mutations on binding, oligomerization, and partitioning were characterized in an aqueous two-phase system. It was found that some substitutions caused better surface binding and reduced oligomerization, while some showed the opposite effects. However, all mutations decreased partitioning in surfactant systems, indicating that the different functions are not directly correlated and that partitioning is dependent on finely tuned properties of hydrophobins. This work shows that not all functions in self-assembly are connected in a predictable way and that a simple surfactant model for hydrophobin function is insufficient.
Augmenting the Genetic Toolbox for Sulfolobus islandicus with a Stringent Positive Selectable Marker for Agmatine Prototrophy
Authors: Zhang Changyi , Cooper Tara E. , Krause David J. , Whitaker Rachel J. 
Published: July 2013

ABSTRACT

Sulfolobus
species have become the model organisms for studying the unique biology of the crenarchaeal division of the archaeal domain. In particular,
Sulfolobus islandicus
provides a powerful opportunity to explore natural variation via experimental functional genomics. To support these efforts, we further expanded genetic tools for
S. islandicus
by developing a stringent positive selection for agmatine prototrophs in strains in which the
argD
gene, encoding arginine decarboxylase, has been deleted. Strains with deletions in
argD
were shown to be auxotrophic for agmatine even in nutrient-rich medium, but growth could be restored by either supplementation of exogenous agmatine or reintroduction of a functional copy of the
argD
gene from
S. solfataricus
P2 into the Δ
argD
host. Using this stringent selection, a robust targeted gene knockout system was established via an improved next generation of the MID (
m
arker
i
nsertion and unmarked target gene
d
eletion) method. Application of this novel system was validated by targeted knockout of the
upsEF
genes involved in UV-inducible cell aggregation formation.
Sterile-α- and Armadillo Motif-Containing Protein Inhibits the TRIF-Dependent Downregulation of Signal Regulatory Protein α To Interfere with Intracellular Bacterial Elimination in Burkholderia pseudomallei-Infected Mouse Macrophages
Authors: Baral Pankaj , Utaisincharoen Pongsak 
Published: July 2013

ABSTRACT

Burkholderia pseudomallei
, the causative agent of melioidosis, evades macrophage killing by suppressing the TRIF-dependent pathway, leading to inhibition of inducible nitric oxide synthase (iNOS) expression. We previously demonstrated that virulent wild-type
B. pseudomallei
inhibits the TRIF-dependent pathway by upregulating sterile-α- and armadillo motif-containing protein (SARM) and by inhibiting downregulation of signal regulatory protein α (SIRPα); both molecules are negative regulators of Toll-like receptor signaling. In contrast, the less virulent lipopolysaccharide (LPS) mutant of
B. pseudomallei
is unable to exhibit these features and is susceptible to macrophage killing. However, the functional relationship of these two negative regulators in the evasion of macrophage defense has not been elucidated. We demonstrated here that SIRPα downregulation was observed after inhibition of SARM expression by small interfering RNA in wild-type-infected macrophages, indicating that SIRPα downregulation is regulated by SARM. Furthermore, this downregulation requires activation of the TRIF signaling pathway, as we observed abrogation of SIRPα downregulation as well as restricted bacterial growth in LPS mutant-infected TRIF-depleted macrophages. Although inhibition of SARM expression is correlated to SIRPα downregulation and iNOS upregulation in gamma interferon-activated wild-type-infected macrophages, these phenomena appear to bypass the TRIF-dependent pathway. Similar to live bacteria, the wild-type LPS is able to upregulate SARM and to prevent SIRPα downregulation, implying that the LPS of
B. pseudomallei
may play a crucial role in regulating the expression of these two negative regulators. Altogether, our findings show a previously unrecognized role of
B. pseudomallei
-induced SARM in inhibiting SIRPα downregulation-mediated iNOS upregulation, facilitating the ability of the bacterium to multiply in macrophages.
SdiA Aids Enterohemorrhagic Escherichia coli Carriage by Cattle Fed a Forage or Grain Diet
Authors: Sheng Haiqing , Nguyen Y. N. , Hovde Carolyn J. , Sperandio Vanessa 
Published: July 2013

ABSTRACT

Enterohemorrhagic
Escherichia coli
(EHEC) causes hemorrhagic colitis and life-threatening complications. The main reservoirs for EHEC are healthy ruminants. We reported that SdiA senses acyl homoserine lactones (AHLs) in the bovine rumen to activate expression of the glutamate acid resistance (
gad
) genes priming EHEC's acid resistance before they pass into the acidic abomasum. Conversely, SdiA represses expression of the locus of enterocyte effacement (LEE) genes, whose expression is not required for bacterial survival in the rumen but is necessary for efficient colonization at the rectoanal junction (RAJ) mucosa. Our previous studies show that SdiA-dependent regulation was necessary for efficient EHEC colonization of cattle fed a grain diet. Here, we compared the SdiA role in EHEC colonization of cattle fed a forage hay diet. We detected AHLs in the rumen of cattle fed a hay diet, and these AHLs activated
gad
gene expression in an SdiA-dependent manner. The rumen fluid and fecal samples from hay-fed cattle were near neutrality, while the same digesta samples from grain-fed animals were acidic. Cattle fed either grain or hay and challenged with EHEC orally carried the bacteria similarly. EHEC was cleared from the rumen within days and from the RAJ mucosa after approximately one month. In competition trials, where animals were challenged with both wild-type and SdiA deletion mutant bacteria, diet did not affect the outcome that the wild-type strain was better able to persist and colonize. However, the wild-type strain had a greater advantage over the SdiA deletion mutant at the RAJ mucosa among cattle fed the grain diet.