bluuebunny/crossref_metadata_2025 huggingface dataset:
OUTWARD‐ORIENTED POLICY REFORMS AND INDUSTRIALISATION IN SRI LANKA
Authors: ATHUKORALA PREMA‐CHANDRA
Published: April 2010

This paper examines the industrialisation experience in Sri Lanka following the outward‐oriented policy reforms initiated in 1977. The reforms helped transform a primary product exporting economy into one in which manufactures dominate exports. The improved performance of the economy is seen in significant terms of trade gains, improvement in output growth, and employment generation, with a notable shift in labour absorption in favour of workers belonging to low‐income families. Were it not for the civil strife and inconsistent macroeconomic policies that existed during much of the post‐liberalisation period, the economy would have performed even better than it did. The experience over the past two decades makes a strong case for a firm commitment to an export‐led growth strategy while guarding against possible policy backsliding emanating from the newfound enthusiasm for state activism.
IMPROVING THE PROCESS OF CHANGE IN AUSTRALIAN FINANCIAL SECTOR REGULATION
Authors: HANRAHAN PAMELA
Published: April 2010

Various initiatives have recently been proposed for improving the process of regulatory change as it affects the Australian financial sector. This paper argues that, while these initiatives are valuable, we also need to do more to engage with the rhetoric of regulation as part of the formulation, as well as the implementation, of regulatory policy.
REGULATION IMPACT ASSESSMENT
Authors: SERPELL ANDREW
Published: April 2010

Regulation impact assessment is a process by which policy makers can systematically assess the impact on affected stakeholder groups of various feasible alternatives for addressing an identified regulatory problem. This should enable better regulatory decisions to be made. The regulation impact assessment requirements for Commonwealth Government entities are set out in the Best Practice Regulation Handbook (OBPR, 2007).

The general approach set out in the Handbook is sound. Clearly policy makers should first work out whether or not there is a problem before they attempt to fix it. Having clearly identified a problem, they should then carefully consider whether regulation is a justified response. Although the fundamental thinking behind the Handbook is sound, numerous issues and challenges will arise for government departments and agencies—as well as affected stakeholder groups—in complying with the new requirements.
COMPARATIVE ADVANTAGE AND AUSTRALIA‐CHINA BILATERAL TRADE
Authors: SHENG YU , SONG LIGANG
Published: April 2010

Bilateral trade between Australia and China has expanded in recent years. This paper examines the determinants of bilateral trade at the two‐digit commodity level using a modified gravity model with explicitly specified revealed comparative advantage incorporated. This methodology allows us to explore how the relative comparative advantage of Australia and China to the world, mirroring their individual pattern of factor endowments, affects the pattern of trade between the two countries and to identify whether there exists a kind of complimentarity international specialisation between the two countries against the backdrop of each country's booming trade with the rest of the world. Key commodities such as agricultural products, iron ore, petroleum, textiles and clothing, and machinery goods are considered to estimate net welfare in terms of added value deriving from bilateral trade. The findings have policy implications for forging future trade and economic cooperation between Australia and China.
THE IMPLICATIONS OF CHINA'S RAPID GROWTH ON DEMAND FOR ENERGY AND MINING PRODUCTS IMPORTED FROM AUSTRALIA
Authors: ZHANG YONGSHENG , ZHENG CHAOYU
Published: April 2010

This article investigates the implications of China's rapid economic growth on the demand for energy and minerals, especially on the demand for these products imported from Australia. Since China's rapid growth is likely to continue for about another two decades, its demand for energy and minerals will expand as well. Nonetheless, as the share of manufacturing decreases, the expansion in demand for energy and minerals in China will slow over that period. While China's aggregate demand for energy and minerals will not expand as rapidly as its economy, its import needs, including imports from Australia, will increase more rapidly than its economy.
THE IMPACT OF TERRORISM ON UNITED STATES INDUSTRIES
Authors: CAM MARIE‐ANNE
Published: April 2010

This research tests United States industry equity indices returns in order to determine if terrorism has some industry‐specific effect. I use the event‐study approach applied to 135 industrial equity return series in assessing industry level reaction to 11 September, the Bali bombing and the Madrid bombing. The event study method used in this paper is adjusted for GARCH effects. The results show that industries react unevenly to terrorism. Following 11 September, airline, hotel and leisure industries exhibit negative abnormal returns while water, defence and telecom experienced positive returns. There was little impact on the US industry equity returns with the Bali and the Madrid attacks, suggesting that US industries were only moderately sensitive to these attacks.
MANAGING THE MURRAY‐DARLING BASIN: SOME IMPLICATIONS FOR CLIMATE CHANGE POLICY
Authors: QUIGGIN JOHN
Published: April 2010

Among the many environmental problems facing Australia, the problems of managing the Murray‐Darling Basin and of responding to climate change are notable for their complexity, intractability and for the wide range of people and regions affected. Consideration of policy successes and failures in the management of the Murray‐Darling Basin may help in the design of a more effective, and cost‐effective, response to the problem of climate change.
SOME EMERGING ISSUES IN URBAN WATER SUPPLY AND PRICING
Authors: FREEBAIRN JOHN
Published: April 2010

In the future, the marginal cost curve for urban water will be an increasing function. This fact favours a single volumetric water price to meet both equity and revenue adequacy criteria, and in some cities an explicit resource rent tax should be imposed. Although desalination and recycled water are likely to be more expensive than rain‐fed water, their comparative stability and security of supply gives them a stabilisation value, and in a portfolio model framework there is a good case for their inclusion as a component of the urban water supply.
AUSTRALIA'S LONG‐RUN ECONOMIC STRATEGY, PERFORMANCE, AND POLICY: A NEW DYNAMIC PERSPECTIVE
Authors: SNOOKS GRAEME DONALD
Published: April 2010

This essay attempts to quantify and explain the economic performance of Australia from the first European settlement to the present, and beyond. A general dynamic theory—the ‘dynamic‐strategy’ theory—has been employed to provide a new interpretation of ‘dynamics Downunder’. It is shown, among other things, that the bold attempt from the 1910s to the 1960s to turn aside from the traditional development policy of exogenously driven natural‐resource exploitation in order to embark on an endogenously determined dynamic process, has broken down during the course of the present generation. This was mainly due to a failure of ‘strategic leadership’ on the part of recent Australian governments that have, quite rightly, dismantled the framework of protection but have failed to replace it with the infrastructure of strategically relevant technological ideas. Once again Australia's economic prosperity depends heavily on the fluctuating fortunes of the global economy. While in the nineteenth century this took the form of reliance on the prosperity of Britain, today it centres on the continuing growth of Japan and China. This critical problem has been exacerbated by the misconceived policy of inflation targeting, which is damaging the central endogenous dynamic mechanism. What then of the future? It all depends on whether strategic leadership can ever be rediscovered, and a new dynamic economic strategy be adopted.
THE JOB NETWORK AND UNDEREMPLOYMENT
Authors: STROMBACK THORSTEN
Published: April 2010

The paper notes how long‐term unemployment has been replaced with long‐term underemployment and examines the role of the Job Network in this new environment. The paper discusses how the structure of unemployment has changed, how the Job Network has evolved and comments on its performance. It is noted that the Job Network has become more and more driven by tightly specified processes and services supported by an ever tighter compliance regime. This business model has much in common with franchising and this analogy is used to interpret the observed outcomes and the concerns expressed by providers and other interested parties. The paper concludes that there are some inherent problems with the franchising model and suggests that less prescriptive arrangements may be preferable.
GAUGING ECONOMIC PERFORMANCE UNDER CHANGING TERMS OF TRADE: REAL GROSS DOMESTIC INCOME OR REAL GROSS DOMESTIC PRODUCT?
Authors: COLEMAN WILLIAM
Published: April 2010

The paper presents a simple theoretical case for the superiority of the notion of Real Gross Domestic Income to Gross Domestic Product. It is shown that, in a multi‐period version of the familiar neoclassical model of a small, open economy, a temporary improvement in its terms of trade will increase welfare and RGDI, and produce a trade surplus in current prices; but will decrease real GDP, on account of it creating a trade deficit at constant prices.
FINANCIAL REFORMS IN AN EMERGING ECONOMY: THE CASE OF MALAYSIA
Authors: SIVALINGAM G.
Published: April 2010

This paper traces the financial reforms that were introduced to stabilise and strengthen the financial system in Malaysia after the 1997 East Asian Financial crisis. It begins with a discussion of the causes of the crisis and the subsequent institution of capital controls and a fixed exchange rate regime and the efforts to introduce reforms behind the shelter of controls. Reform measures to reduce the ratio of non‐performing loans, to improve the balance sheet of banks and corporations, and to protect depositors are then evaluated, together with attempts to merge banks and strengthen the prudential regulation, corporate governance, and the risk management of financial institutions. The discussion is in the context of two forward‐looking master plans to reform and strengthen Malaysia's financial sector and the capital market. The paper ends with a discussion of the positive effects of the reform on economic recovery after the crisis. However, it is noted that the financial system persists as a relationship‐based system rather than a market‐based system in view of the Government's insistence on directed lending and the continued implementation of the New Economic Policy.
Basal and insulin‐stimulated pyruvate dehydrogenase complex activation, glycogen synthesis and metabolic gene expression in human skeletal muscle the day after a single bout of exercise
Authors: Stephens F. B. , Norton L. , Jewell K. , Chokkalingam K. , Parr T. , Tsintzas K.
Published: April 2010

The role of pyruvate dehydrogenase complex (PDC) in insulin‐stimulated glycogen replenishment the day after exercise, and its molecular control, has not been examined. This study investigated the effect of acute exercise on basal and insulin‐stimulated PDC activity (the rate‐limiting step in glucose oxidation), glycogen synthesis and the expression of metabolic genes and transcription factors associated with changes in PDC activation and glucose metabolism. Eight healthy men (age 24 ± 2 years, body mass 79 ± 4 kg) underwent a euglycaemic, hyperinsulinaemic clamp 22 h after 90 min of one‐legged cycling at 60% maximal oxygen consumption. Skeletal muscle glycogen content was similar in the exercised (EX) and non‐exercised leg (CON) preclamp (471 ± 30 versus 463 ± 50 mmol (kg dry matter)−1, respectively) but increased during the clamp in EX to 527 ± 20 mmol (kg dry matter)−1, such that it was 17% greater than in CON (449 ± 35 mmol (kg dry matter)−1, P < 0.05). This increase in insulin‐mediated glycogen storage was independent of insulin‐stimulated Akt serine473 phosphorylation and activation of PDC. Prior exercise did not modulate the mRNA expression and protein content of pyruvate dehydrogenase kinase 4 (PDK4) in skeletal muscle, but was associated with increased hexokinase II mRNA expression and protein content and upregulation of peroxisome proliferator‐activated receptor (PPAR)‐γ coactivator 1α (PGC1α) and PPARδ gene expression. Collectively, these findings suggest that prior exercise does not alter basal and insulin‐stimulated PDC activation and the protein content of PDK4 the following day, but is associated with increased capacity (through upregulation of hexokinase II content) of muscle to phosphorylate and divert glucose towards glycogen storage.
Interactions between heart rate variability and pulmonary gas exchange efficiency in humans
Authors: Sin Peter Y. W. , Webber Matthew R. , Galletly Duncan C. , Ainslie Philip N. , Brown Stephen J. , Willie Chris K. , Sasse Alexander , Larsen Peter D. , Tzeng Yu‐Chieh
Published: April 2010

The respiratory component of heart rate variability (respiratory sinus arrhythmia, RSA) has been associated with improved pulmonary gas exchange efficiency in humans via the apparent clustering and scattering of heart beats in time with the inspiratory and expiratory phases of alveolar ventilation, respectively. However, since human RSA causes only marginal redistribution of heart beats to inspiration, we tested the hypothesis that any association between RSA amplitude and pulmonary gas exchange efficiency may be indirect. In 11 patients with fixed‐rate cardiac pacemakers and 10 healthy control subjects, we recorded R–R intervals, respiratory flow, end‐tidal gas tension and the ventilatory equivalents for carbon dioxide 
 and oxygen 
 during ‘fast’ (0.25 Hz) and ‘slow’ paced breathing (0.10 Hz). Mean heart rate, mean arterial blood pressure, mean arterial pressure fluctuations, tidal volume, end‐tidal CO2,
 and 
 were similar between pacemaker and control groups in both the fast and slow breathing conditions. Although pacemaker patients had no RSA and slow breathing was associated with a 2.5‐fold RSA amplitude increase in control subjects (39 ± 21 versus 97 ± 45 ms, P < 0.001), comparable 
 (main effect for breathing frequency, F(1,19) = 76.54, P < 0.001) and 
 reductions (main effect for breathing frequency, F(1,19) = 23.90, P < 0.001) were observed for both cohorts during slow breathing. In addition, the degree of 
 (r=−0.36, P= 0.32) and 
 reductions (r=−0.29, P= 0.43) from fast to slow breathing were not correlated to the degree of associated RSA amplitude enhancements in control subjects. These findings suggest that the association between RSA amplitude and pulmonary gas exchange efficiency during variable‐frequency paced breathing observed in prior human work is not contingent on RSA being present. Therefore, whether RSA serves an intrinsic physiological function in optimizing pulmonary gas exchange efficiency in humans requires further experimental validation.
Photothermal Response of Tissue Phantoms Containing Multi-Walled Carbon Nanotubes
Authors: Sarkar Saugata , Fisher Jessica , Rylander Christopher , Rylander Marissa Nichole
Published: April 2010

Inclusion of multi-walled carbon nanotubes (MWNTs) into tissue prior to laser therapy has the potential to enhance the selectivity and effectiveness of cancer therapy by providing greater and more controlled thermal deposition. The purpose of this study was to investigate the optical and thermal response of tissue representative phantoms containing MWNTs to optical radiation. Tissue representative phantoms 20 mm in diameter and 1 mm in thickness were created from sodium alginate. Following the inclusion of MWNTs (900 nm in length, 40–60 nm in diameter) in phantoms, the distribution of MWNTs was observed using transmission electron microscopy. A predominantly, evenly dispersed and randomly oriented distribution of MWNTs was observed with a rare presence of MWNT clustering or clumping. In order to characterize the response of MWNT inclusion on optical properties of phantoms, the transmittance and reflectance spectra of phantoms with and without MWNT inclusion were measured with a spectrophotometer over a wavelength range of 200–1400 nm. Inclusion of MWNTs in phantoms dramatically enhanced light absorption across the entire wavelength range as evidenced by a diminished transmittance and reflectance compared with phantoms without MWNTs. In order to evaluate the spatiotemporal temperature distribution associated with laser irradiation of phantoms with and without MWNTs, the temperature was measured at discrete radial distances from the center of the incident laser beam using thermocouples. The rate of temperature increase and peak temperature for phantoms containing MWNTs was much greater compared with phantoms without MWNTs at all measurement locations. In conclusion, MWNT inclusion in tissue phantoms increases the optical absorption and temperature elevation, which may enable more effective photothermal therapies of human disease utilizing lasers.
Adaptation of a Rabbit Myocardium Material Model for Use in a Canine Left Ventricle Simulation Study
Authors: Doyle Matthew G. , Tavoularis Stavros , Bourgault Yves
Published: April 2010

The myocardium of the left ventricle (LV) of the heart comprises layers of muscle fibers whose orientation varies through the heart wall. Because of these fibers, accurate modeling of the myocardium stress-strain behavior requires models that are nonlinear, anisotropic, and time-varying. This article describes the development and testing of a material model of the canine LV myocardium, which will be used in ongoing simulations of the mechanics of the LV with fluid-structure interaction. The model assumes that myocardium deformation has two extreme states: one during which the muscle fibers are fully relaxed, and another during which the muscle fibers are fully contracted. During the second state, the “total” stresses are assumed to be the sum of “passive” stresses, which represent the fully relaxed muscle fibers, and “active” stresses, which are additional stresses due to the contraction of the muscle fibers. The canine LV myocardium is modeled as a transversely isotropic material for which material properties vary in the fiber and cross-fiber directions. The material behavior is considered to be hyperelastic and is modeled by a strain-energy density function in a manner that is an adaptation of an approach based on measurements of the stress-strain behavior of rabbit LV myocardia. A numerical method has been developed to calculate suitable parameter values for the passive material model using previous passive canine LV myocardium stress measurements and taking into account existing physical and numerical constraints. In the absence of published measurements of total canine LV myocardium stresses, a method has been developed to estimate these stresses from available passive and total rabbit LV myocardium stresses and then to calculate active material parameter values. Material parameter values were calculated for passive and active canine LV myocardium. Passive stresses calculated using the model compare well to previous stress measurements while active stresses calculated using the model compare well with those approximated from rabbit measurements. The adapted material model of the canine LV myocardium is deemed to be suitable for use in simulations of the operation of both idealized and realistic canine hearts. The estimated model parameter values can be easily revised to more appropriate ones if measurements of active canine LV myocardium stresses become available. The extension of this material model to a fully orthotropic one is also possible but determination of its parameters would require stress-stretch measurements in the fiber and both cross-fiber directions.
Genomewide Screening for Novel Genetic Variations Associated with Ciprofloxacin Resistance in
Bacillus anthracis
Authors: Serizawa Masakuni , Sekizuka Tsuyoshi , Okutani Akiko , Banno Satomi , Sata Tetsutaro , Inoue Satoshi , Kuroda Makoto
Published: April 2010

Fluoroquinolone (FQ) resistance of
Bacillus anthracis
is a serious concern in the fields of biodefense and bioterrorism since FQs are very effective antibiotics and are recommended as first-line treatment against this lethal bacterium. In this study, we obtained 2 strains of
B. anthracis
showing resistance or intermediate resistance to ciprofloxacin (CIP) by a stepwise selection procedure with increasing CIP concentrations. Fifteen genetic variations were identified between the parental and CIP-resistant strains by next-generation sequencing. Nonsynonymous mutations in the quinolone resistance-determining region (QRDR) of type II DNA topoisomerase were identified in the resistant strain but not in the intermediate-resistant strain. The GBAA0834 (TetR-type transcriptional regulator) locus was also revealed to be a novel “mutation hot spot” that leads to the increased expression of multidrug efflux systems for CIP resistance. As an initial step of CIP resistance in
B. anthracis
, such disruptive mutations of GBAA0834 appear to be more easily acquired than those in an essential gene, such as that encoding type II DNA topoisomerase. Such an intermediate-resistant phenotype could increase a cell population under CIP-selective pressure and might promote the emergence of highly resistant isolates. Our findings reveal, in addition to QRDR, crucial genetic targets for the investigation of intermediate resistance of
B. anthracis
to FQs.
Pharmacokinetics of Darunavir at 900 Milligrams and Ritonavir at 100 Milligrams Once Daily when Coadministered with Efavirenz at 600 Milligrams Once Daily in Healthy Volunteers
Authors: Soon Gaik H. , Shen Ping , Yong Eu-Leong , Pham Paul , Flexner Charles , Lee Lawrence
Published: April 2010

Ritonavir-boosted darunavir with efavirenz may be considered a nucleoside-sparing regimen for treatment-naïve HIV-infected patients. However, the pharmacokinetics of this combination administered once daily have not been studied. We conducted a three-period interaction study with healthy volunteers. The subjects were given darunavir at 900 mg with ritonavir at 100 mg once daily for 10 days. Efavirenz at 600 mg once daily was added for 14 days. Darunavir-ritonavir was then stopped and efavirenz alone was given for 14 days. At the end of each period, blood was taken predosing and for up to 24 h postdosing to measure the drug concentrations. We recruited seven males and five females ages 24 to 49 years and weighing 50 to 83 kg. The darunavir trough concentrations were reduced after efavirenz administration (geometric mean ratio [GMR], 0.43; 90% confidence interval [CI], 0.32 to 0.57];P< 0.001). The mean darunavir trough concentrations were 1,180 ng/ml (standard deviation, 1,138 ng/ml) after efavirenz administration, but all darunavir trough concentrations were above the 50% effective concentration (EC50) of 55 ng/ml for the wild-type virus. For darunavir, the area under the concentration-time curve from 0 to 24 h (AUC0-24) (GMR, 0.86; 90% CI, 0.75 to 0.97;P= 0.05) and the half-life (GMR, 0.56; 90% CI, 0.49 to 0.65;P< 0.001) were also significantly reduced. The darunavir peak concentrations were not significantly changed (GMR, 0.92; 90% CI, 0.82 to 1.03;P= 0.23). The ritonavir trough concentrations (GMR, 0.46; 90% CI, 0.33 to 0.63;P= 0.001), AUC0-24(GMR, 0.74; 90% CI, 0.64 to 0.86;P= 0.004), and half-life (GMR, 0.80; 90% CI, 0.75 to 0.86;P< 0.001) were also significantly reduced. The efavirenz half-life was significantly longer when it was coadministered with darunavir-ritonavir than when it was given alone (GMR, 1.66; 90% CI, 1.24 to 2.23;P= 0.01), but there were no differences in the efavirenz trough or peak concentration or AUC0-24when it was coadministered with darunavir-ritonavir. Efavirenz reduced the trough concentrations of darunavir significantly, but the concentrations remained above the EC50for the wild-type virus. This regimen should be evaluated with treatment-naïve patients with no preexisting resistance.
Population Pharmacokinetics of Doripenem Based on Data from Phase 1 Studies with Healthy Volunteers and Phase 2 and 3 Studies with Critically Ill Patients
Authors: Nandy Partha , Samtani Mahesh N. , Lin Rachel
Published: April 2010

A population pharmacokinetic model of doripenem was constructed using data pooled from phase 1, 2, and 3 studies utilizing nonlinear mixed effects modeling. A 2-compartment model with zero-order input and first-order elimination best described the log-transformed concentration-versus-time profile of doripenem. The model was parameterized in terms of total clearance (CL), central volume of distribution (

V
c

), peripheral volume of distribution (

V
p

), and distribution clearance between the central and peripheral compartments (
Q
). The final model was described by the following equations (for
j
th subject): CL

j

(liters/h) = 13.6·(CL
CR

j

/98 ml/min)
0.659
·(1 + CL
race

j

[0 for Caucasian]);

V
c

j

(liters) = 11.6·(weight

j

/73 kg)
0.596
;

Q
j

(liters/h) = 4.74·(weight

j

/73)
1.06
; and

V
p

j

(liters) = 6.04·(CL
CR

j

/98 ml/min)
0.417
·(weight

j

/73 kg)
0.840
·(age

j

/40 years)
0.307
. According to the final model, population mean parameter estimates and interindividual variability (percent coefficient of variation [% CV]) for CL (liters/h),

V
c

(liters),

V
p

(liters), and
Q
(liters/h) were 13.6 (19%), 11.6 (19%), 6.0 (25%), and 4.7 (42%), respectively. Residual variability, estimated using three separate additive residual error models, was 0.17 standard deviation (SD), 0.55 SD, and 0.92 SD for phase 1, 2, and 3 data, respectively. Creatinine clearance was the most significant predictor of doripenem clearance. Mean Bayesian clearance was approximately 33%, 55%, and 76% lower for individuals with mild, moderate, or severe renal impairment, respectively, than for those with normal renal function. The population pharmacokinetic model based on healthy volunteer data and patient data informs us of doripenem disposition in a more general population as well as of the important measurable intrinsic and extrinsic factors that significantly influence interindividual pharmacokinetic differences.
Cellular Pharmacokinetics of the Novel Biaryloxazolidinone Radezolid in Phagocytic Cells: Studies with Macrophages and Polymorphonuclear Neutrophils
Authors: Lemaire Sandrine , Tulkens Paul M. , Van Bambeke Françoise
Published: April 2010

Radezolid (RX-1741) is the first biaryloxazolidinone in clinical development. It shows improved activity, including against linezolid-resistant strains. Radezolid differs from linezolid by the presence of a biaryl spacer and of a heteroaryl side chain, which increases the ionization and hydrophilicity of the molecule at physiological pH and confers to it a dibasic character. The aim of this study was to determine the accumulation and subcellular distribution of radezolid in phagocytic cells and to decipher the underlying mechanisms. In THP-1 human macrophages, J774 mouse macrophages, and human polymorphonuclear neutrophils, radezolid accumulated rapidly and reversibly (half-lives of approximately 6 min and 9 min for uptake and efflux, respectively) to reach, at equilibrium, a cellular concentration 11-fold higher than the extracellular one. This process was concentration and energy independent but pH dependent (accumulation was reduced to 20 to 30% of control values for cells in medium at a pH of <6 or in the presence of monensin, which collapses pH gradients between the extracellular and intracellular compartments). The accumulation at equilibrium was not affected by efflux pump inhibitors (verapamil and gemfibrozil) and was markedly reduced at 4°C but was further increased in medium with low serum content. Subcellular fractionation studies demonstrated a dual subcellular distribution for radezolid, with ∼60% of the drug colocalizing to the cytosol and ∼40% to the lysosomes, with no specific association with mitochondria. These observations are compatible with a mechanism of transmembrane diffusion of the free fraction and partial segregation of radezolid in lysosomes by proton trapping, as previously described for macrolides.
Cellular Pharmacodynamics of the Novel Biaryloxazolidinone Radezolid: Studies with Infected Phagocytic and Nonphagocytic cells, UsingStaphylococcus aureus,Staphylococcus epidermidis,Listeria monocytogenes, andLegionella pneumophila
Authors: Lemaire Sandrine , Kosowska-Shick Klaudia , Appelbaum Peter C. , Verween Gunther , Tulkens Paul M. , Van Bambeke Françoise
Published: April 2010

Radezolid is a novel biaryloxazolidinone in clinical development which shows improved activity, including against linezolid-resistant strains. In a companion paper (29), we showed that radezolid accumulates about 11-fold in phagocytic cells, with ∼60% of the drug localized in the cytosol and ∼40% in the lysosomes of the cells. The present study examines its activity against (i) bacteria infecting human THP-1 macrophages and located in different subcellular compartments (Listeria monocytogenes, cytosol;Legionella pneumophila, vacuoles;Staphylococcus aureusandStaphylococcus epidermidis, mainly phagolysosomal), (ii) strains ofS. aureuswith clinically relevant mechanisms of resistance, and (iii) isogenic linezolid-susceptible and -resistantS. aureusstrains infecting a series of phagocytic and nonphagocytic cells. Radezolid accumulated to similar levels (∼10-fold) in all cell types (human keratinocytes, endothelial cells, bronchial epithelial cells, osteoblasts, macrophages, and rat embryo fibroblasts). At equivalent weight concentrations, radezolid proved consistently 10-fold more potent than linezolid in all these models, irrespective of the bacterial species and resistance phenotype or of the cell type infected. This results from its higher intrinsic activity and higher cellular accumulation. Time kill curves showed that radezolid's activity was more rapid than that of linezolid both in broth and in infected macrophages. These data suggest the potential interest of radezolid for recurrent or persistent infections where intracellular foci play a determinant role.
Moxifloxacin Pharmacokinetics/Pharmacodynamics and Optimal Dose and Susceptibility Breakpoint Identification for Treatment of DisseminatedMycobacterium aviumInfection
Authors: Deshpande Devyani , Srivastava Shashikant , Meek Claudia , Leff Richard , Hall Gerri S. , Gumbo Tawanda
Published: April 2010

Organisms of theMycobacterium avium-intracellularecomplex (MAC) have been demonstrated to be susceptible to moxifloxacin. However, clinical data on how to utilize moxifloxacin to treat disseminated MAC are scanty. In addition, there have been no moxifloxacin pharmacokinetic-pharmacodynamic (PK/PD) studies performed for MAC infection. We utilized anin vitroPK/PD model of intracellular MAC to study moxifloxacin PK/PD for disseminated disease. Moxifloxacin doses, based on a serum half-life of 12 h, were administered, and the 0- to 24-h area under the concentration-time curve (AUC0-24) to MIC ratios associated with 1.0 log10CFU/ml per week kill and 90% of maximal kill (EC90) were identified. The AUC0-24/MIC ratio associated with 1.0 log10CFU/ml kill was 17.12, and that with EC90was 391.56 (r2= 0.97). Next, the moxifloxacin MIC distribution in 102 clinical isolates of MAC was identified. The median MIC was 1 to 2 mg/liter. Monte Carlo simulations of 10,000 patients with disseminated MAC were performed to determine the probability that daily moxifloxacin doses of 400 and 800 mg/day would achieve or exceed 1.0 log10CFU/ml per week kill or EC90. Doses of 400 and 800 mg/day achieved the AUC0-24/MIC ratio of 17.12 in 64% and 92% of patients, respectively. The critical concentration of moxifloxacin against MAC was identified as 0.25 mg/liter in Middlebrook media. The proposed susceptibility breakpoint means that a larger proportion of clinical isolates is resistant to moxifloxacin prior to therapy. For patients infected with susceptible isolates, however, 800 mg a day should be examined for safety and efficacy for disseminatedM. aviumdisease.
phrR
-Like Gene
praR
of
Azorhizobium caulinodans
ORS571 Is Essential for Symbiosis with
Sesbania rostrata
and Is Involved in Expression of
reb
Genes
Authors: Akiba Noriko , Aono Toshihiro , Toyazaki Hiroki , Sato Satoru , Oyaizu Hiroshi
Published: April 2010

This study focuses on the function of the gene
praR
that encodes a putative transcription factor in
Azorhizobium caulinodans
ORS571, a microsymbiont of
Sesbania rostrata
. The
praR
gene is a homolog of the
phrR
gene of
Sinorhizobium medicae
WSM419, and the
praR
and
phrR
homologs are distributed throughout the class
Alphaproteobacteria
. The growth and nitrogen fixation activity of an
A. caulinodans praR
deletion mutant in the free-living state were not significantly different from those of the wild-type strain. However, the stem nodules formed by the
praR
mutant showed lower nitrogen fixation activity than the wild-type stem nodules. Microscopy revealed that infected host cells with an oval or elongated shape were observed at early stages in the nodules formed by the
praR
mutant, but these infected cells gradually fell into two types. One maintained an oval or elongated shape, but the vacuoles in these cells gradually enlarged and the bacteria gradually disappeared. The other cells were shrunken with bacteria remaining inside. Microarrays revealed that genes homologous to the
reb
genes of
Caedibacter taeniospiralis
were highly expressed in the
praR
mutant. Furthermore, the stem nodules formed by an
A. caulinodans
mutant with a deletion of
praR
and
reb
-homologous genes showed high nitrogen fixation activity, comparable to that of the wild-type stem nodules, and were filled with oval or elongated host cells. These results suggest that PraR controls the expression of the
reb
-homologous genes and that high expression of
reb
-homologous genes causes aberrance in
A. caulinodans
-
S. rostrata
symbiosis.
Nonstarch Polysaccharides Modulate Bacterial Microbiota, Pathways for Butyrate Production, and Abundance of Pathogenic
Escherichia coli
in the Pig Gastrointestinal Tract
Authors: Metzler-Zebeli Barbara U. , Hooda Seema , Pieper Robert , Zijlstra Ruurd T. , van Kessel Andrew G. , Mosenthin Rainer , Gänzle Michael G.
Published: April 2010

The impact of nonstarch polysaccharides (NSP) differing in their functional properties on intestinal bacterial community composition, prevalence of butyrate production pathway genes, and occurrence of
Escherichia coli
virulence factors was studied for eight ileum-cannulated growing pigs by use of terminal restriction fragment length polymorphism (TRFLP) and quantitative PCR. A cornstarch- and casein-based diet was supplemented with low-viscosity, low-fermentability cellulose (CEL), with high-viscosity, low-fermentability carboxymethylcellulose (CMC), with low-viscosity, high-fermentability oat β-glucan (LG), and with high-viscosity, high-fermentability oat β-glucan (HG). Only minor effects of NSP fractions on the ileal bacterial community were observed, but NSP clearly changed the digestion in the small intestine. Compared to what was observed for CMC, more fermentable substrate was transferred into the large intestine with CEL, LG, and HG, resulting in higher levels of postileal dry-matter disappearance. Linear discriminant analysis of NSP and TRFLP profiles and 16S rRNA gene copy numbers for major bacterial groups revealed that CMC resulted in a distinctive bacterial community in comparison to the other NSP, which was characterized by higher gene copy numbers for total bacteria,
Bacteroides-Prevotella-Porphyromonas
,
Clostridium
cluster XIVa, and
Enterobacteriaceae
and increased prevalences of
E. coli
virulence factors in feces. The numbers of butyryl-coenzyme A (CoA) CoA transferase gene copies were higher than those of butyrate kinase gene copies in feces, and these quantities were affected by NSP. The present results suggest that the NSP fractions clearly and distinctly affected the taxonomic composition and metabolic features of the fecal microbiota. However, the effects were more linked to the individual NSP and to their effect on nutrient flow into the large intestine than to their shared functional properties.
Growth of Bacteria on 3-Nitropropionic Acid as a Sole Source of Carbon, Nitrogen, and Energy
Authors: Nishino Shirley F. , Shin Kwanghee A. , Payne Rayford B. , Spain Jim C.
Published: April 2010

3-Nitropropionic acid (3NPA) is a widespread nitroaliphatic toxin found in a variety of legumes and fungi. Several enzymes have been reported that can transform the compound, but none led to the mineralization of 3NPA. We report here the isolation of bacteria that grow on 3NPA and its anion, propionate-3-nitronate (P3N), as the sole source of carbon, nitrogen, and energy. Experiments with resting cells, cell extracts, and purified enzymes indicate that the pathway involves conversion of 3NPA to P3N, which upon denitration yields malonic semialdehyde, nitrate, nitrite, and traces of H
2
O
2
. Malonic semialdehyde is decarboxylated to acetyl coenzyme A. The gene that encodes the enzyme responsible for the denitration of P3N was cloned and expressed, and the enzyme was purified. Stoichiometry of the reaction indicates that the enzyme is a monooxygenase. The gene sequence is related to a large group of genes annotated as 2-nitropropane dioxygenases, but the P3N monooxygenase and closely related enzymes form a cluster within COG2070 that differs from previously characterized 2-nitropropane dioxygenases by their substrate specificities and reaction products. The results suggest that the P3N monooxygenases enable bacteria to exploit 3NPA in natural habitats as a growth substrate.
Paenibacillus
sp. Strain E18 Bifunctional Xylanase-Glucanase with a Single Catalytic Domain
Authors: Shi Pengjun , Tian Jian , Yuan Tiezheng , Liu Xin , Huang Huoqing , Bai Yingguo , Yang Peilong , Chen Xiaoyan , Wu Ningfeng , Yao Bin
Published: April 2010

Xylanases are utilized in a variety of industries for the breakdown of plant materials. Most native and engineered bifunctional/multifunctional xylanases have separate catalytic domains within the same polypeptide chain. Here we report a new bifunctional xylanase (XynBE18) produced by
Paenibacillus
sp. E18 with xylanase and β-1,3-1,4-glucanase activities derived from the same active center by substrate competition assays and site-directed mutagenesis of xylanase catalytic Glu residues (E129A and E236A). The gene consists of 981 bp, encodes 327 amino acids, and comprises only one catalytic domain that is highly homologous to the glycoside hydrolase family 10 xylanase catalytic domain. Recombinant XynBE18 purified from
Escherichia coli
BL21(DE3) showed specificity toward oat spelt xylan and birchwood xylan and β-1,3-1,4-glucan (barley β-glucan and lichenin). Homology modeling and molecular dynamic simulation were used to explore structure differences between XynBE18 and the monofunctional xylanase XynE2, which has enzymatic properties similar to those of XynBE18 but does not hydrolyze β-1,3-1,4-glucan. The cleft containing the active site of XynBE18 is larger than that of XynE2, suggesting that XynBE18 is able to bind larger substrates such as barley β-glucan and lichenin. Further molecular docking studies revealed that XynBE18 can accommodate xylan and β-1,3-1,4-glucan, but XynE2 is only accessible to xylan. These results indicate a previously unidentified structure-function relationship for substrate specificities among family 10 xylanases.
Rapid Functional Screening of
Streptomyces coelicolor
Regulators by Use of a pH Indicator and Application to the MarR-Like Regulator AbsC
Authors: Yang Yung-Hun , Song Eunjung , Lee Bo-Rahm , Kim Eun-jung , Park Sung-Hee , Kim Yun-Gon , Lee Chang-Soo , Kim Byung-Gee
Published: April 2010

To elucidate the function of an unknown regulator in
Streptomyces
, differences in phenotype and antibiotic production between a deletion mutant and a wild-type strain (WT) were compared. These differences are easily hidden by complex media. To determine the specific nutrient conditions that reveal such differences, we used a multiwell method containing different nutrients along with bromothymol blue. We found several nutrients that provide key information on characterization conditions. By comparing the growth of wild-type and mutant strains on screened nutrients, we were able to measure growth, organic acid production, and antibiotic production for the elucidation of regulator function. As a result of this method, a member of the MarR-like regulator family, SCO5405 (AbsC), was newly characterized to control pyruvate dehydrogenase in
Streptomyces coelicolor
. Deletion of SCO5405 increased the pH of the culture broth due to decreased production of organic acids such as pyruvate and α-ketoglutarate and increased extracellular actinorhodin (ACT) production in minimal medium containing glucose and alanine (MMGA). This method could therefore be a high-throughput method for the characterization of unknown regulators.
Diversity of Bacteria and Glycosyl Hydrolase Family 48 Genes in Cellulolytic Consortia Enriched from Thermophilic Biocompost
Authors: Izquierdo Javier A. , Sizova Maria V. , Lynd Lee R.
Published: April 2010

The enrichment from nature of novel microbial communities with high cellulolytic activity is useful in the identification of novel organisms and novel functions that enhance the fundamental understanding of microbial cellulose degradation. In this work we identify predominant organisms in three cellulolytic enrichment cultures with thermophilic compost as an inoculum. Community structure based on 16S rRNA gene clone libraries featured extensive representation of clostridia from cluster III, with minor representation of clostridial clusters I and XIV and a novel
Lutispora
species cluster. Our studies reveal different levels of 16S rRNA gene diversity, ranging from 3 to 18 operational taxonomic units (OTUs), as well as variability in community membership across the three enrichment cultures. By comparison, glycosyl hydrolase family 48 (GHF48) diversity analyses revealed a narrower breadth of novel clostridial genes associated with cultured and uncultured cellulose degraders. The novel GHF48 genes identified in this study were related to the novel clostridia
Clostridium straminisolvens
and
Clostridium clariflavum
, with one cluster sharing as little as 73% sequence similarity with the closest known relative. In all, 14 new GHF48 gene sequences were added to the known diversity of 35 genes from cultured species.
Variation of Physiochemical Properties and Cell Association Activity of Membrane Vesicles with Growth Phase in
Pseudomonas aeruginosa
Authors: Tashiro Yosuke , Ichikawa Sosaku , Shimizu Motoyuki , Toyofuku Masanori , Takaya Naoki , Nakajima-Kambe Toshiaki , Uchiyama Hiroo , Nomura Nobuhiko
Published: April 2010

Pseudomonas aeruginosa
and other Gram-negative bacteria release membrane vesicles (MVs) from their surfaces, and MVs have an ability to interact with bacterial cells. Although it has been known that many bacteria have mechanisms that control their phenotypes with the transition from exponential phase to stationary phase, changes of properties in released MVs have been poorly understood. Here, we demonstrate that MVs released by
P. aeruginosa
during the exponential and stationary phases possess different physiochemical properties. MVs purified from the stationary phase had higher buoyant densities than did those purified from the exponential phase. Surface charge, characterized by zeta potential, of MVs tended to be more negative as the growth shifted to the stationary phase, although the charges of PAO1 cells were not altered.
Pseudomonas
quinolone signal (PQS), one of the regulators related to MV production in
P. aeruginosa
, was lower in MVs purified from the exponential phase than in those from the stationary phase. MVs from the stationary phase more strongly associated with
P. aeruginosa
cells than did those from the exponential phase. Our findings suggest that properties of MVs are altered to readily interact with bacterial cells along with the growth transition in
P. aeruginosa
.
Huanglongbing, a Systemic Disease, Restructures the Bacterial Community Associated with Citrus Roots
Authors: Trivedi Pankaj , Duan Yongping , Wang Nian
Published: April 2010

To examine the effect of pathogens on the diversity and structure of plant-associated bacterial communities, we carried out a molecular analysis using citrus and huanglongbing as a host-disease model. 16S rRNA gene clone library analysis of citrus roots revealed shifts in microbial diversity in response to pathogen infection. The clone library of the uninfected root samples has a majority of phylotypes showing similarity to well-known plant growth-promoting bacteria, including
Caulobacter
,
Burkholderia
,
Lysobacter
,
Pantoea
,
Pseudomonas
,
Stenotrophomonas
,
Bacillus
, and
Paenibacillus
. Infection by “
Candidatus
Liberibacter asiaticus” restructured the native microbial community associated with citrus roots and led to the loss of detection of most phylotypes while promoting the growth of bacteria such as
Methylobacterium
and
Sphingobacterium
. In pairwise comparisons, the clone library from uninfected roots contained significantly higher 16S rRNA gene diversity, as reflected in the higher Chao 1 richness estimation (
P
≤ 0.01) of 237.13 versus 42.14 for the uninfected and infected clone libraries, respectively. Similarly, the Shannon index of the uninfected clone library (4.46) was significantly higher than that of the infected clone library (2.61). Comparison of the uninfected clone library with the infected clone library using LIBSHUFF statistics showed a significant difference (
P
≤ 0.05). Quantitative PCR analysis revealed that the bacterial community changes not only qualitatively but also quantitatively. The relative proportions of different groups of bacteria changed significantly after infection with the pathogen. These data indicate that infection of citrus by “
Ca
. Liberibacter asiaticus” has a profound effect on the structure and composition of the bacterial community associated with citrus roots.
Moderately Thermophilic Magnetotactic Bacteria from Hot Springs in Nevada
Authors: Lefèvre Christopher T. , Abreu Fernanda , Schmidt Marian L. , Lins Ulysses , Frankel Richard B. , Hedlund Brian P. , Bazylinski Dennis A.
Published: April 2010

Populations of a moderately thermophilic magnetotactic bacterium were discovered in Great Boiling Springs, Nevada, ranging from 32 to 63°C. Cells were small, Gram-negative, vibrioid to helicoid in morphology, and biomineralized a chain of bullet-shaped magnetite magnetosomes. Phylogenetically, based on 16S rRNA gene sequencing, the organism belongs to the phylum
Nitrospirae
.
Identification of Diverse Antimicrobial Resistance Determinants Carried on Bacterial, Plasmid, or Viral Metagenomes from an Activated Sludge Microbial Assemblage
Authors: Parsley Larissa C. , Consuegra Erin J. , Kakirde Kavita S. , Land Andrew M. , Harper Willie F. , Liles Mark R.
Published: April 2010

Using both sequence- and function-based metagenomic approaches, multiple antibiotic resistance determinants were identified within metagenomic libraries constructed from DNA extracted from bacterial chromosomes, plasmids, or viruses within an activated sludge microbial assemblage. Metagenomic clones and a plasmid that in
Escherichia coli
expressed resistance to chloramphenicol, ampicillin, or kanamycin were isolated, with many cloned DNA sequences lacking any significant homology to known antibiotic resistance determinants.