bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recombinant heteromeric phenylalanine monooxygenase and the oxygenation of carbon and sulfur substrates
Authors: Boonyapiwat Boontarika , Mitchell Stephen C , Steventon Glyn B 
Published: March 2011

Abstract

Objectives
The aim of this investigation was to provide in-vitro enzyme kinetic data to support the hypothesis that the in-vivo heterozygous dominant phenotype for phenylalanine monooxygenase (hPAH) was responsible for the S-oxidation polymorphism in the metabolism of S-carboxymethyl-l-cysteine reported in humans. Using a dual-vector expression strategy for the co-production of wild-type and mutant human hPAH subunits we report for the first time the kinetic parameters (Km, Vmax, CLE) for the C-oxidation of l-phenylalanine and the S-oxidation of S-carboxymethyl-l-cysteine in homomeric wild-type, heteromeric mutant and homomeric mutant hPAH proteins in vitro.

Methods
A PROTM dual-vector bacterial expression system was used to produce the required hPAH proteins. Enzyme activity was determined by HPLC with fluorescence detection.

Key findings
The heteromeric hPAH proteins (I65T, R68S, R158Q, I174T, R261Q, V338M, R408W and Y414C) all showed significantly decreased Vmax and CLE values when compared to the homomeric wild-type hPAH enzyme. For both substrates, all calculated Km values were significantly higher than homomeric wild-type hPAH enzyme, with the exception of I65T, R68S and Y414C heteromeric hPAH proteins employing l-phenylalanine as substrate.

Conclusions
The net outcome for the heteromeric mutant hPAH proteins was a decrease significantly more dramatic for S-carboxymethyl-l-cysteine S-oxidation (1.0–18.8% of homomeric wild-type hPAH activity) when compared to l-phenylalanine C-oxidation (25.9–52.9% of homomeric wild-type hPAH activity) as a substrate. Heteromeric hPAH enzyme may be related to the variation in S-carboxymethyl-l-cysteine S-oxidation capacity observed in humans.
Antimicrobial activity and chemical composition of the essential oil of Hofmeisteria schaffneri
Authors: Pérez-Vásquez Araceli , Capella Santiago , Linares Edelmira , Bye Robert , Angeles-López Guadalupe , Mata Rachel 
Published: March 2011

Abstract

Objectives
The aims of this study were to establish the antimicrobial potential of Hofmeisteria schaffneri essential oil and its chemical composition.

Methods
The essential oils of Hofmeisteria schaffneri harvested at flowering (batches I and IV) and non-flowering (batches II and III) seasons were prepared by hydrodistillation and analysed by GC and GC-MS. The aqueous and organic (CH2Cl2-MeOH 1 : 1) extracts were prepared by using infusion and maceration techniques, respectively. The in-vitro antimicrobial activity of the preparations and compounds against Candida albicans and some bacteria (Gram-negative and Gram-positive) was assessed using the broth dilution method in 96-microplate wells.

Key findings
Forty-four compounds, representing ∼90% of the total constituents, were identified in the essential oil of Hofmeisteria schaffneri collected in flowering (batches I and IV) and non-flowering (batches II and III) seasons. In all cases, several thymol analogues were the major components of the oils (∼65%); some small differences in the relative proportions of these constituents were observed. The infusion exhibited an antibacterial activity against Staphylococcus aureus and Bacillus subtilis, with a MIC value of 64 µg/ml in each case. The essential oil batches were active against Staphylococcus aureus, with MIC ranging from 48 to 192 µg/ml. They were, however, inactive against Gram-negative bacteria, including Pseudomonas aeruginosa, Escherichia coli and Salmonella typhi (MIC &gt; 1024 µg/ml). On the other hand, the infusion of the plant as well as the oil from batch I displayed anti-Candida albicans activity, with MIC of 128 and 192 µg/ml, respectively. Finally, the organic extract did not displayed significant activity against the tested microorganisms (MIC ≥ 1024 µg/ml). Some of the compounds isolated from the plant were also tested. Compounds 8 and 38, which were present in the essential oils, displayed the best antibacterial effect against Gram-positive bacteria (MIC ranging between 32 and 64 µg/ml). Compounds 6 (present in the infusion) and 10 (present in all preparations) showed higher activity against the yeast (MIC = 128 µg/ml) than the remaining compounds, with MIC values ranging from 256 to 512 µg/ml.

Conclusions
The composition and antimicrobial activity of the oils changed slightly from flowering to non-flowering seasons. The results of the present investigation provide in-vitro scientific support for the use of the plant against skin infections in Mexican folk medicine.
Pharmacokinetics of clomipramine, an antidepressant, in poloxamer 407-induced hyperlipidaemic model rats
Authors: Kobuchi Shinji , Fukushima Keizo , Shibata Masakazu , Ito Yukako , Sugioka Nobuyuki , Takada Kanji 
Published: March 2011

Abstract

Objective
This study was undertaken to investigate the effects of hyperlipidaemia on the pharmacokinetics of clomipramine, an antidepressant, particularly addressing the change of clomipramine distribution to plasma components in poloxamer 407-induced hyperlipidaemia model rats.

Methods
Clomipramine pharmacokinetic studies in hyperlipidaemic rats were performed with clomipramine continuous infusion. Furthermore, clomipramine protein binding and distribution to the brain and plasma components such as lipoproteins were investigated.

Key findings
Mean plasma concentration of clomipramine at steady state during continuous infusion (17.5 µg/min/kg) in hyperlipidaemic rats (0.45 ± 0.01 µg/ml) was significantly higher than that in the control rats (0.30 ± 0.02 µg/ml). However, the amount of clomipramine in the brain in hyperlipidaemic rats (0.31 ± 0.06 µg/g) was dramatically lower than in the control rats (1.89 ± 0.13 µg/g). However, the plasma unbound fraction in hyperlipidaemic rats (0.98 ± 0.05%) was significantly lower than that of the control rats (6.51 ± 0.62%).

Conclusions
Lower distribution to the brain and lower plasma clearance of clomipramine in hyperlipidaemic rats resulted from lower plasma unbound fraction because of higher lipid-rich protein contents in blood. Results of this study provide useful information for dosage adjustment of clomipramine in hyperlipidaemia.
Involvement of an ATP-Dependent Protease, PA0779/AsrA, in Inducing Heat Shock in Response to Tobramycin in Pseudomonas aeruginosa
Authors: Kindrachuk Kristen N. , Fernández Lucía , Bains Manjeet , Hancock Robert E. W. 
Published: March 2011

ABSTRACT

The adaptive resistance of
Pseudomonas aeruginosa
to aminoglycosides is known to occur during chronic lung infections in cystic fibrosis patients in response to nonlethal concentrations of aminoglycosides. Not only is it difficult to achieve high levels of drug throughout the dehydrated mucus in the lung, but also steep oxygen gradients exist across the mucus layer, further reducing the bactericidal activity of aminoglycosides. In this study, microarray analysis was utilized to examine the gene responses of
P. aeruginosa
to lethal, inhibitory, and subinhibitory concentrations of tobramycin under aerobic and anaerobic conditions. While prolonged exposure to subinhibitory concentrations of tobramycin caused increased levels of expression predominantly of the efflux pump genes
mexXY
, the greatest increases in gene expression levels in response to lethal concentrations of tobramycin involved a number of heat shock genes and the PA0779 gene (renamed here
asrA
), encoding an alternate Lon protease. Microarray analysis of an
asrA
::
luxCDABE
transposon mutant revealed that the induction of heat shock genes in response to tobramycin in this mutant was significantly decreased compared to that in the parent strain. The level of expression of
asrA
was induced from an arabinose-inducible promoter to 35-fold greater than wild-type expression levels in the absence of tobramycin, and this overexpression alone caused an increased expression of the heat shock genes, as determined by quantitative PCR (qPCR). This overexpression of
asrA
conferred short-term protection against lethal levels (4 μg/ml) of tobramycin but did not affect the tobramycin MIC. The RpoH heat shock sigma factor was found to be involved in the regulation of
asrA
in response to both heat shock and tobramycin at the posttranscriptional level. The results of this work suggest that the tobramycin concentration has a significant impact on the gene expression of
P. aeruginosa
, with lethal concentrations resulting in immediate adaptations conferring short-term protection, such as the induction of the heat shock response, and with subinhibitory concentrations leading to more sustainable long-term protection mechanisms, such as increased efflux.
Tomatidine Inhibits Replication of Staphylococcus aureus Small-Colony Variants in Cystic Fibrosis Airway Epithelial Cells
Authors: Mitchell Gabriel , Gattuso Mariza , Grondin Gilles , Marsault Éric , Bouarab Kamal , Malouin François 
Published: March 2011

ABSTRACT

Small-colony variants (SCVs) often are associated with chronic
Staphylococcus aureus
infections, such as those encountered by cystic fibrosis (CF) patients. We report here that tomatidine, the aglycon form of the plant secondary metabolite tomatine, has a potent growth inhibitory activity against SCVs (MIC of 0.12 μg/ml), whereas the growth of normal
S. aureus
strains was not significantly altered by tomatidine (MIC, >16 μg/ml). The specific action of tomatidine was bacteriostatic for SCVs and was clearly associated with their dysfunctional electron transport system, as the presence of the electron transport inhibitor 4-hydroxy-2-heptylquinoline-
N
-oxide (HQNO) caused normal
S. aureus
strains to become susceptible to tomatidine. Inversely, the complementation of SCVs' respiratory deficiency conferred resistance to tomatidine. Tomatidine provoked a general reduction of macromolecular biosynthesis but more specifically affected the incorporation of radiolabeled leucine in proteins of HQNO-treated
S. aureus
at a concentration corresponding to the MIC against SCVs. Furthermore, tomatidine inhibited the intracellular replication of a clinical SCV in polarized CF-like epithelial cells. Our results suggest that tomatidine eventually will find some use in combination therapy with other traditional antibiotics to eliminate persistent forms of
S. aureus
.
Molecular Mechanisms of Chlorhexidine Tolerance in Burkholderia cenocepacia Biofilms
Authors: Coenye Tom , Van Acker Heleen , Peeters Elke , Sass Andrea , Buroni Silvia , Riccardi Giovanna , Mahenthiralingam Eshwar 
Published: March 2011

ABSTRACT

The high tolerance of biofilm-grown
Burkholderia cepacia
complex bacteria against antimicrobial agents presents considerable problems for the treatment of infected cystic fibrosis patients and the implementation of infection control guidelines. In the present study, we analyzed the tolerance of planktonic and sessile
Burkholderia cenocepacia
J2315 cultures and examined the transcriptional response of sessile cells to treatment with chlorhexidine. At low (0.0005%) and high (0.05%) concentrations, chlorhexidine had a similar effect on both populations, but at intermediate concentrations (0.015%) the antimicrobial activity was more pronounced in planktonic cultures. The exposure of sessile cells to chlorhexidine resulted in an upregulation of the transcription of 469 (6.56%) and the downregulation of 257 (3.59%) protein-coding genes. A major group of upregulated genes in the treated biofilms encoded membrane-related and regulatory proteins. In addition, several genes coding for drug resistance determinants also were upregulated. The phenotypic analysis of RND (resistance-nodulation-division) efflux pump mutants suggests the presence of lifestyle-specific chlorhexidine tolerance mechanisms; efflux system RND-4 (BCAL2820-BCAL2822) was more responsible for chlorhexidine tolerance in planktonic cells, while other systems (RND-3 [BCAL1672-BCAL1676] and RND-9 [BCAM1945-BCAM1947]) were linked to resistance in sessile cells. After sessile cell exposure, multiple genes encoding chemotaxis and motility-related proteins were upregulated in concert with the downregulation of an adhesin-encoding gene (BCAM2143), suggesting that sessile cells tried to escape the biofilm. We also observed the differential expression of 19 genes carying putative small RNA molecules, indicating a novel role for these regulatory elements in chlorhexidine tolerance.
AmpG Inactivation Restores Susceptibility of Pan-β-Lactam-Resistant Pseudomonas aeruginosa Clinical Strains
Authors: Zamorano Laura , Reeve Thomas M. , Juan Carlos , Moyá Bartolomé , Cabot Gabriel , Vocadlo David J. , Mark Brian L. , Oliver Antonio 
Published: March 2011

ABSTRACT

Constitutive AmpC hyperproduction is the most frequent mechanism of resistance to the weak AmpC inducers antipseudomonal penicillins and cephalosporins. Previously, we demonstrated that inhibition of the β-
N
-acetylglucosaminidase NagZ prevents and reverts this mechanism of resistance, which is caused by
ampD
and/or
dacB
(PBP4) mutations in
Pseudomonas aeruginosa
. In this work, we compared NagZ with a second candidate target, the AmpG permease for GlcNAc-1,6-anhydromuropeptides, for their ability to block AmpC expression pathways. Inactivation of
nagZ
or
ampG
fully restored the susceptibility and basal
ampC
expression of
ampD
or
dacB
laboratory mutants and impaired the emergence of one-step ceftazidime-resistant mutants in population analysis experiments. Nevertheless, only
ampG
inactivation fully blocked
ampC
induction, reducing the MICs of the potent AmpC inducer imipenem from 2 to 0.38 μg/ml. Moreover, through population analysis and characterization of laboratory mutants, we showed that
ampG
inactivation minimized the impact on resistance of the carbapenem porin OprD, reducing the MIC of imipenem for a PAO1 OprD mutant from >32 to 0.5 μg/ml. AmpG and NagZ targets were additionally evaluated in three clinical isolates that are pan-β-lactam resistant due to AmpC hyperproduction, OprD inactivation, and overexpression of several efflux pumps. A marked increase in susceptibility to ceftazidime and piperacillin-tazobactam was observed in both cases, while only
ampG
inactivation fully restored wild-type imipenem susceptibility. Susceptibility to meropenem, cefepime, and aztreonam was also enhanced, although to a lower extent due to the high impact of efflux pumps on the activity of these antibiotics. Thus, our results suggest that development of small-molecule inhibitors of AmpG could provide an excellent strategy to overcome the relevant mechanisms of resistance (OprD inactivation plus AmpC induction) to imipenem, the only currently available β-lactam not significantly affected by
P. aeruginosa
major efflux pumps.
Mortality from non-malignant respiratory diseases among workers in the Norwegian silicon carbide industry: associations with dust exposure
Authors: Bugge Merete Drevvatne , Føreland Solveig , Kjærheim Kristina , Eduard Wijnand , Martinsen Jan Ivar , Kjuus Helge 
Published: March 2011

ObjectivesIncreased mortality from asthma, chronic bronchitis and emphysema has previously been reported among workers in the silicon carbide (SiC) industry. The objective of the present study was to evaluate the influence of specific exposure factors on mortality from obstructive lung diseases (OLD), using a newly revised job-exposure matrix.Materials and methods1687 long-term workers employed in 1913–2003 in the Norwegian SiC industry were characterised with respect to cumulative exposure to quartz, cristobalite, SiC particles and SiC fibres. Standardised mortality ratios (SMRs) for underlying causes of death, 1951–2007, were calculated stratified by category of cumulative exposure, and Poisson regression analyses of OLD were performed using cumulative exposure variables.ResultsAn increased total mortality (SMR 1.1, 95% CI 1.0 to 1.2) and increased mortality from cancer, non-malignant respiratory diseases and external factors, were observed. The SMR of OLD was increased at the highest level of cumulative exposure to all investigated exposure factors. In the internal analyses, a twofold increased risk of OLD was observed with increasing levels of cumulative exposure to SiC particles. In a multivariate model, SiC particles showed the most stable increased risk estimate when controlled for other exposure factors, among workers with less than 15 years of employment. Among workers with more than 15 years of employment, crystalline silica, primarily cristobalite, seemed to be the most important exposure factor.ConclusionExposure to SiC and crystalline silica may contribute to OLD development among SiC industry workers in different time windows, and possibly through different mechanisms.
Scientists, engineers, and computer science; industry and research groups
Authors: Guzdial Mark , Linden Greg 
Published: March 2011

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Mark Guzdial discusses what scientists and engineers should know about computer science, such as Alan Kay's "Triple Whammy." Greg Linden writes about industry's different approaches to research and how to organize researchers in a company.
FKBPL and Peptide Derivatives: Novel Biological Agents That Inhibit Angiogenesis by a CD44-Dependent Mechanism
Authors: Valentine Andrea , O'Rourke Martin , Yakkundi Anita , Worthington Jenny , Hookham Michelle , Bicknell Roy , McCarthy Helen O. , McClelland Keeva , McCallum Lynn , Dyer Hayder , McKeen Hayley , Waugh David J. J. , Roberts Jennifer , McGregor Joanne , Cotton Graham , James Iain , Harrison Timothy , Hirst David G. , Robson Tracy 
Published: March 2011

Abstract
Purpose: Antiangiogenic therapies can be an important adjunct to the management of many malignancies. Here we investigated a novel protein, FKBPL, and peptide derivative for their antiangiogenic activity and mechanism of action.
Experimental Design: Recombinant FKBPL (rFKBPL) and its peptide derivative were assessed in a range of human microvascular endothelial cell (HMEC-1) assays in vitro. Their ability to inhibit proliferation, migration, and Matrigel-dependent tubule formation was determined. They were further evaluated in an ex vivo rat model of neovascularization and in two in vivo mouse models of angiogenesis, that is, the sponge implantation and the intravital microscopy models. Antitumor efficacy was determined in two human tumor xenograft models grown in severe compromised immunodeficient (SCID) mice. Finally, the dependence of peptide on CD44 was determined using a CD44-targeted siRNA approach or in cell lines of differing CD44 status.
Results: rFKBPL inhibited endothelial cell migration, tubule formation, and microvessel formation in vitro and in vivo. The region responsible for FKBPL's antiangiogenic activity was identified, and a 24-amino acid peptide (AD-01) spanning this sequence was synthesized. It was potently antiangiogenic and inhibited growth in two human tumor xenograft models (DU145 and MDA-231) when administered systemically, either on its own or in combination with docetaxel. The antiangiogenic activity of FKBPL and AD-01 was dependent on the cell-surface receptor CD44, and signaling downstream of this receptor promoted an antimigratory phenotype.
Conclusion: FKBPL and its peptide derivative AD-01 have potent antiangiogenic activity. Thus, these agents offer the potential of an attractive new approach to antiangiogenic therapy. Clin Cancer Res; 17(5); 1044–56. ©2011 AACR.
In vivo Evaluation of Mucoadhesive Nanoparticulate Docetaxel for Intravesical Treatment of Non–Muscle-Invasive Bladder Cancer
Authors: Mugabe Clement , Matsui Yoshiyuki , So Alan I. , Gleave Martin E. , Baker Jennifer H. E. , Minchinton Andrew I. , Manisali Irina , Liggins Richard , Brooks Donald E. , Burt Helen M. 
Published: March 2011

Abstract
Purpose: The present work describes the development and in vitro and in vivo evaluation of a mucoadhesive nanoparticulate docetaxel (DTX) formulation for intravesical bladder cancer therapy.
Experimental Design: Mucoadhesive formulations based on hyperbranched polyglycerols (HPG), hydrophobically derivatized with C8/C10 alkyl chains in the core and modified with methoxy-polyethylene glycol (MePEG) and amine groups in the shell (HPG-C8/10-MePEG-NH2) were synthesized and DTX was loaded into these by a solvent evaporation method. Both low-grade (RT4, MGHU3) and high-grade (UMUC3) human urothelial carcinoma cell lines were treated with various concentrations of DTX formulations in vitro. KU7 cells that stably express firefly luciferase (KU7-luc) were inoculated in female nude mice by intravesical instillation and quantified using bioluminescence imaging. Mice with established KU7-luc tumors were given a single intravesical instillation with PBS, Taxotere (DTX from Sanofi-aventis), and DTX-loaded HPG-C8/10-MePEG and/or HPG-C8/10-MePEG-NH2. Drug uptake was conducted using LC/MS-MS (liquid chromatography/tandem mass spectrometry) and tumor microenvironment and uptake of rhodamine labeled HPGs was assessed.
Results: In vitro, all DTX formulations potently inhibited bladder cancer proliferation. However, in vivo, DTX-loaded HPG-C8/10-MePEG-NH2 (mucoadhesive DTX) was the most effective formulation to inhibit tumor growth in an orthotopic model of bladder cancer. Furthermore, mucoadhesive DTX significantly increased drug uptake in mouse bladder tissues. In addition, rhodamine labeled HPG-C8/10-MePEG-NH2 showed enhanced uptake of these nanoparticles in bladder tumor tissues.
Conclusions: Our data show promising in vivo antitumor efficacy and provide preclinical proof of principle for the intravesical application of mucoadhesive nanoparticulate DTX formulation in the treatment of bladder cancer. Clin Cancer Res; 17(9); 2788–98. ©2011 AACR.
Epigenetic Modulation Enhances the Therapeutic Effect of Anti–IL-13Rα2 Antibody in Human Mesothelioma Xenografts
Authors: Takenouchi Makoto , Hirai Sachie , Sakuragi Naoya , Yagita Hideo , Hamada Hirofumi , Kato Kazunori 
Published: March 2011

Abstract
Purpose: The interleukin-13 receptor α2 (IL-13Rα2) is expressed by a variety of human malignant cells. Here, we have examined the constitutive surface expression and the epigenetic regulation of IL-13Rα2 by human mesothelioma. We have also investigated the therapeutic effect of the DNA methylation inhibitor 5-aza-2′-deoxycytidine (5-aza-dC) and anti–IL-13Rα2 monoclonal antibody on mesothelioma xenografts.
Experimental Design: Cell surface expression of IL-13Rα2 by various lung carcinomas was analyzed using flow cytometry. Therapeutic effects of anti–IL-13Rα2 and 5-aza-dC were investigated using antibody-dependent cellular cytotoxicity and proliferation assays and by monitoring the survival of mesothelioma-bearing mice.
Results: We found that human malignant mesotheliomas expressed surface IL-13Rα2 on their surface and that it was upregulated by treatment with 5-aza-dC. This augmented expression of IL-13Rα2 resulted in growth inhibition of the mesothelioma cells when cocultured with anti-IL-13Rα2 and effector cells, such as splenocytes and peritoneal exudate cells. The growth inhibition of mesothelioma cells was mediated by IFN-γ that was only detected in the supernatant when effector cells were exposed to 5-aza-dC–treated tumors in the presence of anti–IL-13Rα2. Compared with the control or either regimen alone, in vivo administration of anti-IL-13Rα2 in combination with 5-aza-dC significantly prolonged the survival of mice with mesothelioma xenografts.
Conclusions: These observations indicate a promising role for IL-13Rα2 as a target for antibody treatment in malignant mesothelioma, and, in combination with epigenetic regulation by a DNA methylation inhibitor, suggest the potential for a novel strategy to enhance therapeutic potency. Clin Cancer Res; 17(9); 2819–29. ©2011 AACR.