bluuebunny/crossref_metadata_2025_split huggingface dataset:
Potential Basis for Amphotericin B Resistance in
Aspergillus terreus
Authors: Blum Gerhard , Perkhofer Susanne , Haas Hubertus , Schrettl Markus , Würzner Reinhard , Dierich Manfred P. , Lass-Flörl Cornelia 
Published: February 2008

ABSTRACT

This study investigated the basis for intrinsic amphotericin B (AMB) resistance in
Aspergillus terreus
. The ergosterol content, cell wall composition, and lipid peroxidation level had no influence on AMB resistance. The level of catalase production in
A. terreus
was significantly higher than that in
A. fumigatus
(
P
< 0.05). This higher-level production may contribute to AMB resistance in
A. terreus
since oxidative damage has been implicated in AMB action.
DNA Gyrase from the Albicidin Producer
Xanthomonas albilineans
Has Multiple-Antibiotic-Resistance and Unusual Enzymatic Properties
Authors: Hashimi Saeed M. , Huang Guozhong , Maxwell Anthony , Birch Robert G. 
Published: February 2008

ABSTRACT

The sugarcane pathogen
Xanthomonas albilineans
produces a family of antibiotics and phytotoxins termed albicidins, which inhibit plant and bacterial DNA gyrase supercoiling activity, with a 50% inhibitory concentration (50 nM) comparable to those of coumarins and quinolones. Here we show that
X. albilineans
has an unusual, antibiotic-resistant DNA gyrase. The
X. albilineans gyrA
and
gyrB
genes are not clustered with previously described albicidin biosynthesis and self-protection genes. The GyrA and GyrB products differ from
Escherichia coli
homologues through several insertions and through changes in several amino acid residues implicated in quinolone and coumarin resistance. Reconstituted
X. albilineans
DNA gyrase showed 20- to 25-fold-higher resistance than
E. coli
DNA gyrase to albicidin and ciprofloxacin and 8-fold-higher resistance to novobiocin in the supercoiling assay. The
X. albilineans
DNA gyrase is unusual in showing a high degree of distributive supercoiling and little DNA relaxation activity.
X. albilineans
GyrA (XaA) forms a functional gyrase heterotetramer with
E. coli
GyrB (EcB) and can account for albicidin and quinolone resistance and low levels of relaxation activity. XaB probably contributes to both coumarin resistance and the distributive supercoiling pattern. Although XaB shows fewer apparent changes relative to EcB, the EcA·XaB hybrid relaxed DNA in the presence or absence of ATP and was unable to supercoil. A fuller understanding of structural differences between albicidin-sensitive and -resistant gyrases may provide new clues into features of the enzyme amenable to interference by novel antibiotics.
Stimulation of Inducible Nitric Oxide Synthase Expression by Beta Interferon Increases Necrotic Death of Macrophages uponListeria monocytogenesInfection
Authors: Zwaferink Heather , Stockinger Silvia , Reipert Siegfried , Decker Thomas 
Published: February 2008

ABSTRACTMurine macrophage death upon infection withListeria monocytogeneswas previously shown to be increased by beta interferon, produced by the infected cells. We saw that interferon-upregulated caspase activation or other interferon-inducible, death-associated proteins, including TRAIL, protein kinase R, and p53, were not necessary for cell death. Macrophage death was reduced when inducible nitric oxide synthase (iNOS) was inhibited during infection, and iNOS-deficient macrophages were less susceptible to death upon infection than wild-type cells. The production of nitric oxide correlated with increased death, while no role was seen for iNOS in control ofListerianumbers during infection of resting macrophages. This indicates that the induction of iNOS by beta interferon in cells infected withL. monocytogenescontributes to cell death. Based on morphology, the maintenance of mitochondrial membrane potential, and a lack of dependence on caspase 1, we characterize the type of cell death occurring and show that infected macrophages die by interferon-upregulated necrosis.
Subcutaneous Vaccination with Attenuated
Salmonella enterica
Serovar Choleraesuis C500 Expressing Recombinant Filamentous Hemagglutinin and Pertactin Antigens Protects Mice against Fatal Infections with both
S. enterica
Serovar Choleraesuis and
Bordetella bronchiseptica
Authors: Zhao Zhanqin , Xue Yun , Wu Bin , Tang Xibiao , Hu Ruiming , Xu Yindi , Guo Aizhen , Chen Huanchun 
Published: February 2008

ABSTRACT

Salmonella enterica
serovar Choleraesuis strain C500 is a live, attenuated vaccine that has been used in China for over 40 years to prevent piglet paratyphoid. We compared the protective efficacies of subcutaneous (s.c.) and oral vaccination of BALB/c mice with C500 expressing the recombinant filamentous hemagglutinin type I domain and pertactin region 2 domain antigen (rF1P2) of
Bordetella bronchiseptica
. Protective efficacy against both
S. enterica
serovar Choleraesuis infection in an oral fatal challenge model and
B. bronchiseptica
infection in a model of fatal acute pneumonia was evaluated. Both the s.c. and oral vaccines conferred complete protection against fatal infection with the virulent parent
S. enterica
serovar Choleraesuis strain (C78-1). All 20 mice vaccinated s.c. survived intranasal challenge with four times the 50% lethal dose of virulent
B. bronchiseptica
(HH0809) compared with 4 of 20 vector-treated controls and 1 of 18 phosphate-buffered saline-treated controls that survived, but no significant protection against HH0809 was observed in orally vaccinated animals. Both the s.c. and oral vaccines elicited rF1P2-specific serum immunoglobulin G (IgG) and IgA antibodies. However, lung homogenates from s.c. vaccinated animals had detectably high levels of rF1P2-specific IgG and IgA; a much lower level of rF1P2-specific IgG was detected in samples from orally vaccinated mice, and the latter showed no evidence of local IgA. Furthermore, a more abundant and longer persistence of vaccine organisms was observed in the lungs of mice immunized s.c. than in those of mice immunized orally. Our results suggest that s.c. rather than oral vaccination is more efficacious in protecting mice from fatal challenge with
B. bronchiseptica
.
Combined Inactivation of the
Candida albicans GPR1
and
TPS2
Genes Results in Avirulence in a Mouse Model for Systemic Infection
Authors: Maidan Mykola M. , De Rop Larissa , Relloso Miguel , Diez-Orejas Rosalia , Thevelein Johan M. , Van Dijck Patrick 
Published: February 2008

ABSTRACT

Inhibition of the biosynthesis of trehalose, a well-known stress protectant in pathogens, is an interesting approach for antifungal or antibacterial therapy. Deletion of
TPS2
, encoding trehalose-6-phosphate (T6P) phosphatase, results in strongly reduced virulence of
Candida albicans
due to accumulation of T6P instead of trehalose in response to stress. To further aggravate the deregulation in the pathogen, we have additionally deleted the
GPR1
gene, encoding the nutrient receptor that activates the cyclic AMP-protein kinase A signaling pathway, which negatively regulates trehalose accumulation in yeasts. A
gpr1
mutant is strongly affected in morphogenesis on solid media as well as in vivo in a mouse model but has only a slightly decreased virulence. The
gpr1 tps2
double mutant, on the other hand, is completely avirulent in a mouse model for systemic infection. This strain accumulates very high T6P levels under stress conditions and has a growth defect at higher temperatures. We also show that a
tps2
mutant is more sensitive to being killed by macrophages than the wild type or the
gpr1
mutant. A double mutant has susceptibility similar to that of the single
tps2
mutant. For morphogenesis on solid media, on the other hand, the
gpr1 tps2
mutant shows a phenotype similar to that of the single
gpr1
mutant. Taken together these results show that there is synergism between Gpr1 and Tps2 and that their combined inactivation results in complete avirulence. Combination therapy targeting both proteins may prove highly effective against pathogenic fungi with increased resistance to the currently used antifungal drugs.
Candida albicans
Uses Multiple Mechanisms To Acquire the Essential Metabolite Inositol during Infection
Authors: Chen Ying-Lien , Kauffman Sarah , Reynolds Todd B. 
Published: February 2008

ABSTRACT

Candida albicans
is an important cause of life-threatening systemic bloodstream infections in immunocompromised patients. In order to cause infections,
C. albicans
must be able to synthesize the essential metabolite inositol or acquire it from the host. Based on the similarity of
C. albicans
to
Saccharomyces cerevisiae
, it was predicted that
C. albicans
may generate inositol de novo, import it from the environment, or both. The
C. albicans
inositol synthesis gene
INO1
(
orf19.7585
) and inositol transporter gene
ITR1
(
orf19.3526
) were each disrupted. The
ino1
Δ/
ino1
Δ mutant was an inositol auxotroph, and the
itr1
Δ/
itr1
Δ mutant was unable to import inositol from the medium. Each of these mutants was fully virulent in a mouse model of systemic infection. It was not possible to generate an
ino1
Δ/
ino1
Δ
itr1
Δ/
itr1
Δ double mutant, suggesting that in the absence of these two genes,
C. albicans
could not acquire inositol and was nonviable. A conditional double mutant was created by replacing the remaining wild-type allele of
ITR1
in an
ino1
Δ/
ino1
Δ
itr1
Δ/
ITR1
strain with a conditionally expressed allele of
ITR1
driven by the repressible
MET3
promoter. The resulting
ino1
Δ/
ino1
Δ
itr1
Δ/

P
MET3

::
ITR1
strain was found to be nonviable in medium containing methionine and cysteine (which represses the

P
MET3

promoter), and it was avirulent in the mouse model of systemic candidiasis. These results suggest a model in which
C. albicans
has two equally effective mechanisms for obtaining inositol while in the host. It can either generate inositol de novo through Ino1p, or it can import it from the host through Itr1p.
Wheat Germ Cell-Free System-Based Production of Malaria Proteins for Discovery of Novel Vaccine Candidates
Authors: Tsuboi Takafumi , Takeo Satoru , Iriko Hideyuki , Jin Ling , Tsuchimochi Masateru , Matsuda Shusaku , Han Eun-Taek , Otsuki Hitoshi , Kaneko Osamu , Sattabongkot Jetsumon , Udomsangpetch Rachanee , Sawasaki Tatsuya , Torii Motomi , Endo Yaeta 
Published: February 2008

ABSTRACT

One of the major bottlenecks in malaria research has been the difficulty in recombinant protein expression. Here, we report the application of the wheat germ cell-free system for the successful production of malaria proteins. For proof of principle, the Pfs25, PfCSP, and PfAMA1 proteins were chosen. These genes contain very high A/T sequences and are also difficult to express as recombinant proteins. In our wheat germ cell-free system, native and codon-optimized versions of the Pfs25 genes produced equal amounts of proteins. PfCSP and PfAMA1 genes without any codon optimization were also expressed. The products were soluble, with yields between 50 and 200 μg/ml of the translation mixture, indicating that the cell-free system can be used to produce malaria proteins without any prior optimization of their biased codon usage. Biochemical and immunocytochemical analyses of antibodies raised in mice against each protein revealed that every antibody retained its high specificity to the parasite protein in question. The development of parasites in mosquitoes fed patient blood carrying
Plasmodium falciparum
gametocytes and supplemented with our mouse anti-Pfs25 sera was strongly inhibited, indicating that both Pfs25-3D7/WG and Pfs25-TBV/WG retained their immunogenicity. Lastly, we carried out a parallel expression assay of proteins of blood-stage
P. falciparum
. The PCR products of 124
P. falciparum
genes chosen from the available database were used directly in a small-scale format of transcription and translation reactions. Autoradiogram testing revealed the production of 93 proteins. The application of this new cell-free system-based protocol for the discovery of malaria vaccine candidates will be discussed.
Effects of Levosimendan on Left Ventricular Relaxation and Early Filling at Maintained Preload and Afterload Conditions After Aortic Valve Replacement for Aortic Stenosis
Authors: Jörgensen Kirsten , Bech-Hanssen Odd , Houltz Erik , Ricksten Sven-Erik 
Published: February 2008

Background—We determined the effects of levosimendan, a calcium sensitizer, on left ventricular (LV) diastolic function in patients with LV hypertrophy.Methods and Results—In this prospective, randomized, blinded study, 23 patients received either levosimendan (0.1 and 0.2 μg · kg−1· min−1; n=12) or placebo (n=11) after aortic valve replacement for aortic stenosis. The effects on LV performance, dimensions, filling patterns, and isovolumic relaxation time, as well as systemic hemodynamics, were assessed by pulmonary artery thermodilution catheterization and transesophageal 2-dimensional Doppler echocardiography. To circumvent the confounding effects of the levosimendan-induced hemodynamic changes on Doppler echocardiographic indexes of LV early relaxation, heart rate and mean arterial and central venous pressures were kept constant during levosimendan/placebo infusion by atrial pacing, vasopressor, and colloid infusions. In the levosimendan group, dose-dependent increases in cardiac output (28%;P<0.001) and stroke volume (26%;P<0.001) and a decrease in systemic vascular resistance (−22%;P<0.001) were observed. There was a trend for an increase in LV ejection fraction (12%;P=0.058) with levosimendan. There were no significant differences in systolic, diastolic arterial, or LV filling pressures or LV end-diastolic area between the 2 groups. Isovolumic relaxation time decreased (−23%;P<0.001), as did the deceleration slope of early diastolic filling (−45%;P<0.01), whereas peak early diastolic filling velocity (16%,P<0.01) and peak late diastolic filling velocity (15%;P<0.001) increased after levosimendan compared with placebo.Conclusion—Levosimendan, in addition to its inotropic effects, exerts a direct positive lusitropic effect in patients with LV hypertrophy as it shortens isovolumic relaxation time and improves LV filling.
A Two-Dimensional Solution of the Advection–Diffusion Equation with Dry Deposition to the Ground
Authors: Tirabassi Tiziano , Buske Daniela , Moreira Davidson M. , Vilhena Marco T. 
Published: February 2008

Abstract
A mathematical scheme is developed to simulate the vertical turbulent dispersion of air pollution that is absorbed or deposited to the ground. The scheme is an exact analytical solution of the atmospheric diffusion equation, without any restriction to the vertical profile of wind speed and eddy diffusivities, and taking into account the dry deposition by a boundary condition of a nonzero flux to the ground. The performances of the solution, with a proper parameterization of the vertical profiles of the wind and eddy diffusivities, were evaluated against the dataset from the Hanford (Washington) diffusion experiment, in which two tracers (one depositing and one nondepositing) were released simultaneously. In addition, the solution derived in this work is compared with four different models, with deposition at the ground, found in the literature.
Estimation of Rainfall Based on the Results of Polarimetric Echo Classification
Authors: Giangrande Scott E. , Ryzhkov Alexander V. 
Published: February 2008

Abstract
The quality of polarimetric radar rainfall estimation is investigated for a broad range of distances from the polarimetric prototype of the Weather Surveillance Radar-1988 Doppler (WSR-88D). The results of polarimetric echo classification have been integrated into the study to investigate the performance of radar rainfall estimation contingent on hydrometeor type. A new method for rainfall estimation that capitalizes on the results of polarimetric echo classification (EC method) is suggested. According to the EC method, polarimetric rainfall relations are utilized if the radar resolution volume is filled with rain (or rain and hail), and multiple R(Z) relations are used for different types of frozen hydrometeors. The intercept parameters in the R(Z) relations for each class are determined empirically from comparisons with gauges. It is shown that the EC method exhibits better performance than the conventional WSR-88D algorithm with a reduction by a factor of 1.5–2 in the rms error of 1-h rainfall estimates up to distances of 150 km from the radar.
Frequency Distribution of Daily ITCZ Patterns over the Western–Central Pacific
Authors: Chen Baode , Lin Xin , Bacmeister Julio T. 
Published: February 2008

Abstract
This study attempts to explore a comprehensive and compact approach for delineating the multiscale and multivariate characteristics of the ITCZ over the western–central Pacific based on daily satellite observations of precipitation, SSTs, and surface winds. Essentially six distinct ITCZ spatial patterns—namely, the north, south, equator, double, full, and weak—are identified according to the daily percentage coverage of deep convection within different latitudinal bands on and off the equator over the western–central Pacific. The evolving structure of the ITCZ over the western–central Pacific is investigated with a focus on the transient statistical characteristics. The relationship between these daily ITCZ patterns and SSTs, and near-surface winds, is also examined.
The north (37%), south (24%), and weak (24%) ITCZs represent the three major ITCZ daily patterns over the western–central Pacific, and combined they account for almost 85% of the total number of days within a 10-yr period. The other three ITCZ patterns, namely, the equator (3%), double (6%), and full (5%) ITCZs, occur infrequently. The climatology of the ITCZ, such as monthly, seasonal, and annual means, can be approximately determined by how often and intense these ITCZ daily spatial patterns occur within a specified period. Taking the long-term mean statistics for each ITCZ daily type into account, the double ITCZ deep convection typically observed over the western–central Pacific in monthly, seasonal, and annual mean plots appears to be mainly associated with the frequent occurrence of the north and south ITCZ patterns, instead of the double ITCZ pattern in which an ITCZ appears on each side of the equator simultaneously on a daily basis.
Consistent with the strong seasonality in their frequency of occurrence, the three major ITCZ patterns indicate a dominant correspondence with the seasonal meridional migration of warm SSTs. In contrast, the three less frequent ITCZ patterns show a close relationship with the positive or negative SST anomaly over the equatorial central and eastern Pacific, namely, the extension and retraction of the equatorial cool tongue and its strength. Surface wind divergence/convergence does not show any distinct patterns for these ITCZ spatial patterns, suggesting that little relationship between low-level convergence and precipitation can be discerned from daily data.
As an application of the method proposed, the frequency distribution of daily ITCZ patterns, as derived from a recent version of the National Aeronautics and Space Administration (NASA) Goddard Earth Observing System (GEOS) general circulation model (GCM), is evaluated against observations. Preliminary comparisons indicate that the GEOS-5 GCM is capable of simulating the correct ITCZ spatial patterns, but their occurrence frequencies can be further improved, in particular, the weak ITCZ and the patterns with fewer occurrences, which may be associated with significantly different control mechanisms and/or feedbacks.
Decadal Variability of the Indo-Pacific Warm Pool and Its Association with Atmospheric and Oceanic Variability in the NCEP–NCAR and SODA Reanalyses
Authors: Wang Hui , Mehta Vikram M. 
Published: February 2008

Abstract
Decadal variability of the Indo-Pacific warm pool (IPWP) sea surface temperature (SST) and its association with atmospheric and oceanic circulations are investigated with observed 50-yr (1952–2001) SST, and the NCEP–NCAR atmospheric and Simple Ocean Data Assimilation (SODA) oceanic reanalysis data. The decadal variability of the IPWP SSTs was analyzed by applying an empirical orthogonal function technique to low-pass-filtered SSTs. Two leading empirical modes (EMs) well represent the IPWP SST decadal variations. EM1 is an ENSO-like pattern with out-of-phase SST anomalies in the western Pacific and the Indian Ocean, whereas EM2 displays an in-phase relationship between SST anomalies in the two regions. Consequently, spatial evolution of EM1 is dominated by opposing changes in zonal and meridional dimensions and thus a strong deformation of the warm pool on decadal time scales. EM2 is dominated by changes in size and intensity of the warm pool.
Analyses of ocean thermodynamic fields associated with the two SST EMs indicate that decadal changes in the IPWP can extend down to 300-m depth. Oceanic processes may thus be involved in the IPWP decadal variability, including advections of mean temperature by both mean and anomalous ocean currents and effects of shallow tropical circulations (STCs) on the IPWP SST, which is consistent with some previous studies on tropical decadal variability. The results may also indicate the existence of both positive and negative feedbacks between the IPWP SST and the STCs.
Both December–January–February (DJF) and June–July–August (JJA) atmospheric circulations exhibit thermally direct responses to the two decadal IPWP SST EMs by altering the Hadley and Walker circulations. In addition, significant upper-level rotational flow anomalies in the extratropics are found to be associated with the decadal IPWP SST variability. Consistent with the upper-level flow anomalies and 850-hPa convergence–divergence patterns associated with the two SST EMs are rainfall anomalies over the United States. In DJF, the rainfall anomalies are mainly in Florida, the Gulf Coast, southern Texas, Arizona, and along the West Coast. In JJA, the rainfall anomalies are mainly in the Midwest and the Southeast. Since these rainfall anomalies are a significant fraction of seasonal-average rainfall and since these anomalies persist for many years, they potentially make a significant impact on U.S. water resources and agriculture. Further analysis of observations and modeling studies are required to understand the physics of the IPWP SST decadal variability and its impacts on global climate, and to assess its predictability.
Orientation Angle Distributions of Drops after an 80-m Fall Using a 2D Video Disdrometer
Authors: Huang Gwo-Jong , Bringi V. N. , Thurai M. 
Published: February 2008

Abstract
This note reports on the use of a 2D video disdrometer to estimate the orientation of drops (&gt;2 mm) that were generated artificially and allowed to fall 80 m from a bridge with no obstruction and under calm conditions. This experimental setup enabled a large number of drops to be generated, up to 10 mm in horizontal dimension.
The distribution of the canting angles for all drops &gt;2 mm was found to be nearly symmetric about 0° with standard deviation between 7° and 8°. From the canting angle distributions derived from the two orthogonal camera view planes, the distributions of the polar (θ) and azimuth (ϕ) angles were deduced; these two angles describe the 2D orientation of the symmetry axis. The azimuthal angle distribution was found to be nearly uniform in the range (0, 2π), whereas the distribution of pΩ(θ) = p(θ) sinθ was similar in shape to a special form of the Fisher distribution that is valid for describing the statistics on a spherical surface. The standard deviation of pΩ(θ) showed that larger drops are more stably oriented than smaller ones. This is in agreement with previous radar-based results of standard deviation of the canting angle decreasing with increasing Zdr.