bluuebunny/crossref_metadata_2025_split huggingface dataset:
Curing
Mycobacterium ulcerans
Infection in Mice with a Combination of Rifampin-Streptomycin or Rifampin-Amikacin
Authors: Lefrançois Sébastien , Robert Jérôme , Chauffour Aurélie , Ji Baohong , Jarlier Vincent 
Published: November 2006

ABSTRACT

The curing activities of various durations of treatment with a combination of rifampin (RIF) and either streptomycin (STR) or amikacin (AMK) in murine
Mycobacterium ulcerans
infection were compared in two experiments. In the first experiment, treatment was begun 1 week after infection, when the inflammatory footpad lesion had not yet occurred (preventive model), and in the second experiment, treatment was begun 6 weeks after infection, when inflammatory footpad lesions were established (curative model). In the first experiment, 4 weeks of treatment with daily RIF-STR or RIF-AMK was able to postpone the occurrence of footpad lesion by 12 weeks (RIF-STR) or 17 weeks (RIF-AMK), thus demonstrating their promising bactericidal activities, but neither treatment was able to prevent the late occurrence of footpad lesions. In the second experiment, the overall cure rates, as assessed by the lack of rebound of inflammatory lesions or remultiplication of
M. ulcerans
, were only 62% after 2 weeks of treatment with RIF and an aminoglycoside and 85% after 4 weeks; but the cure rate reached 100% after 8 or 12 weeks of treatment. The cure rates were slightly higher with the AMK-containing combination than with the STR-containing combination, but the difference was at the limit of significance (
P
= 0.07). These results show that in the murine model of Buruli ulcer, 8 weeks is the optimal duration of treatment with a combination of RIF and an aminoglycoside.
In Vitro Antibacterial Activity of the Pyrrolopyrazolyl-Substituted Oxazolidinone RWJ-416457
Authors: Foleno Barbara D. , Abbanat Darren , Goldschmidt Raul M. , Flamm Robert K. , Paget Steve D. , Webb Glenda C. , Wira Ellyn , Macielag Mark J. , Bush Karen 
Published: November 2006

ABSTRACT
RWJ-416457, an investigational pyrrolopyrazolyl-substituted oxazolidinone, inhibited the growth of linezolid-susceptible staphylococci, enterococci, and streptococci at concentrations of ≤4 μg/ml, generally exhibiting two- to fourfold-greater potency than that of linezolid. Time-kill studies demonstrated bacteriostatic effects for both RWJ-416457 and linezolid.
Antileishmanial Effect of 3-Aminooxy-1-Aminopropane Is Due to Polyamine Depletion
Authors: Singh Sushma , Mukherjee Angana , Khomutov Alex R. , Persson Lo , Heby Olle , Chatterjee Mitali , Madhubala Rentala 
Published: November 2006

ABSTRACT

The polyamines putrescine, spermidine, and spermine are organic cations that are required for cell growth and differentiation. Ornithine decarboxylase (ODC), the first and rate-limiting enzyme in the polyamine biosynthetic pathway, catalyzes the conversion of ornithine to putrescine. As the polyamine biosynthetic pathway is essential for the growth and survival of
Leishmania donovani
, the causative agent of visceral leishmaniasis, inhibition of the pathway is an important leishmaniacidal strategy. In the present study, we examined for the first time the effects of 3-aminooxy-1-aminopropane (APA), an ODC inhibitor, on the growth of
L. donovani
. APA inhibited the growth of both promastigotes in vitro and amastigotes in the macrophage model, with the 50% inhibitory concentrations being 42 and 5 μM, respectively. However, concentrations of APA up to 200 μM did not affect the viability of macrophages. The effects of APA were completely abolished by the addition of putrescine or spermidine. APA induced a significant decrease in ODC activity and putrescine, spermidine, and trypanothione levels in
L. donovani
promastigotes. Parasites were transfected with an episomal ODC construct, and these ODC overexpressers exhibited significant resistance to APA and were concomitantly resistant to sodium antimony gluconate (Pentostam), indicating a role for ODC overexpression in antimonial drug resistance. Clinical isolates with sodium antimony gluconate resistance were also found to overexpress ODC and to have significant increases in putrescine and spermidine levels. However, no increase in trypanothione levels was observed. The ODC overexpression in these clinical isolates alleviated the antiproliferative effects of APA. Collectively, our results demonstrate that APA is a potent inhibitor of
L. donovani
growth and that its leishmaniacidal effect is due to inhibition of ODC.
Prevalence and Susceptibility Testing of New Species of
Pseudallescheria
and
Scedosporium
in a Collection of Clinical Mold Isolates
Authors: Alastruey-Izquierdo Ana , Cuenca-Estrella Manuel , Monzón Araceli , Rodriguez-Tudela Juan L. 
Published: November 2006

ABSTRACT

The prevalence of new species of
Pseudallescheria
and
Scedosporium
in a collection of 46 clinical isolates was analyzed. Strain identification was done by morphological and molecular methods. Four
Scedosporium aurantiacum
isolates were detected among the panel of clinical strains. The susceptibility profile of
S. aurantiacum
was similar to that of
Scedosporium apiospermum
.
Pyrazinoic Acid and Its
n
-Propyl Ester Inhibit Fatty Acid Synthase Type I in Replicating Tubercle Bacilli
Authors: Zimhony Oren , Vilchèze Catherine , Arai Masayoshi , Welch John T. , Jacobs William R. 
Published: November 2006

ABSTRACT

The activity of different analogs of pyrazinamide on
Mycobacterium tuberculosis
fatty acid synthase type I (FASI) in replicating bacilli was studied. Palmitic acid biosynthesis was diminished by 96% in bacilli treated with
n-
propyl pyrazinoate, 94% in bacilli treated with 5-chloro-pyrazinamide, and 97% in bacilli treated with pyrazinoic acid, the pharmacologically active agent of pyrazinamide. We conclude that the minimal structure of pyrazine ring with an acyl group is sufficient for FASI inhibition and antimycobacterial activity.
Shewanella oneidensis
MR-1 Fluxome under Various Oxygen Conditions
Authors: Tang Yinjie J. , Hwang Judy S. , Wemmer David E. , Keasling Jay D. 
Published: November 2006

ABSTRACT

The central metabolic fluxes of
Shewanella oneidensis
MR-1 were examined under carbon-limited (aerobic) and oxygen-limited (microaerobic) chemostat conditions, using
13
C-labeled lactate as the sole carbon source. The carbon labeling patterns of key amino acids in biomass were probed using both gas chromatography-mass spectrometry (GC-MS) and
13
C nuclear magnetic resonance (NMR). Based on the genome annotation, a metabolic pathway model was constructed to quantify the central metabolic flux distributions. The model showed that the tricarboxylic acid (TCA) cycle is the major carbon metabolism route under both conditions. The Entner-Doudoroff and pentose phosphate pathways were utilized primarily for biomass synthesis (with a flux below 5% of the lactate uptake rate). The anaplerotic reactions (pyruvate to malate and oxaloacetate to phosphoenolpyruvate) and the glyoxylate shunt were active. Under carbon-limited conditions, a substantial amount (9% of the lactate uptake rate) of carbon entered the highly reversible serine metabolic pathway. Under microaerobic conditions, fluxes through the TCA cycle decreased and acetate production increased compared to what was found for carbon-limited conditions, and the flux from glyoxylate to glycine (serine-glyoxylate aminotransferase) became measurable. Although the flux distributions under aerobic, microaerobic, and shake flask culture conditions were different, the relative flux ratios for some central metabolic reactions did not differ significantly (in particular, between the shake flask and aerobic-chemostat groups). Hence, the central metabolism of
S. oneidensis
appears to be robust to environmental changes. Our study also demonstrates the merit of coupling GC-MS with
13
C NMR for metabolic flux analysis to reduce the use of
13
C-labeled substrates and to obtain more-accurate flux values.
Community Structure of Ammonia-Oxidizing Bacteria under Long-Term Application of Mineral Fertilizer and Organic Manure in a Sandy Loam Soil
Authors: Chu Haiyan , Fujii Takeshi , Morimoto Sho , Lin Xiangui , Yagi Kazuyuki , Hu Junli , Zhang Jiabao 
Published: November 2006

ABSTRACT

The effects of mineral fertilizer (NPK) and organic manure on the community structure of soil ammonia-oxidizing bacteria (AOB) was investigated in a long-term (16-year) fertilizer experiment. The experiment included seven treatments: organic manure, half organic manure N plus half fertilizer N, fertilizer NPK, fertilizer NP, fertilizer NK, fertilizer PK, and the control (without fertilization). N fertilization greatly increased soil nitrification potential, and mineral N fertilizer had a greater impact than organic manure, while N deficiency treatment (PK) had no significant effect. AOB community structure was analyzed by PCR-denaturing gradient gel electrophoresis (PCR-DGGE) of the
amoA
gene, which encodes the α subunit of ammonia monooxygenase. DGGE profiles showed that the AOB community was more diverse in N-fertilized treatments than in the PK-fertilized treatment or the control, while one dominant band observed in the control could not be detected in any of the fertilized treatments. Phylogenetic analysis showed that the DGGE bands derived from N-fertilized treatments belonged to
Nitrosospira
cluster 3, indicating that N fertilization resulted in the dominance of
Nitrosospira
cluster 3 in soil. These results demonstrate that long-term application of N fertilizers could result in increased soil nitrification potential and the AOB community shifts in soil. Our results also showed the different effects of mineral fertilizer N versus organic manure N; the effects of P and K on the soil AOB community; and the importance of balanced fertilization with N, P, and K in promoting nitrification functions in arable soils.
Vulnerability of Pathogenic Biofilms to
Micavibrio aeruginosavorus
Authors: Kadouri Daniel , Venzon Nel C. , O'Toole George A. 
Published: November 2006

ABSTRACT

The host specificity of the gram-negative exoparasitic predatory bacterium
Micavibrio aeruginosavorus
was examined.
M. aeruginosavorus
preyed on
Pseudomonas aeruginosa
, as previously reported, as well as
Burkholderia cepacia
,
Klebsiella pneumoniae
, and numerous clinical isolates of these species. In a static assay, a reduction in biofilm biomass was observed as early as 3 hours after exposure to
M. aeruginosavorus
, and an ∼100-fold reduction in biofilm cell viability was detected following a 24-h exposure to the predator. We observed that an initial titer of
Micavibrio
as low as 10 PFU/well or a time of exposure to the predator as short as 30 min was sufficient to reduce a
P. aeruginosa
biofilm. The ability of
Micavibrio
to reduce an existing biofilm was confirmed by scanning electron microscopy. In static and flow cell experiments,
M. aeruginosavorus
was able to modify the overall
P. aeruginosa
biofilm structure and markedly decreased the viability of
P. aeruginosa
. The altered biofilm structure was likely caused by an increase in cell-cell interactions brought about by the presence of the predator or active predation. We also conducted a screen to identify genes important for
P. aeruginosa-Micavibrio
interaction, but no candidates were isolated among the ∼10,000 mutants tested.
SO, a Protein Involved in Hyphal Fusion in
Neurospora crassa
, Localizes to Septal Plugs
Authors: Fleiβner André , Glass N. Louise 
Published: November 2006

ABSTRACT

The colony of a filamentous ascomycete fungus typically grows as a multinucleate syncytium. While this syncytial organization has developmental advantages, it bears the risk of extensive damage caused by local injury of hyphae. Loss of cytoplasm in injured hyphae is restricted by the fast and efficient sealing of the central pores of hyphal crosswalls, or septa, by a peroxisome-derived organelle called the Woronin body. The formation of septal plugs is also associated with development and leads to separation of certain parts of the colony. Septal plugs associated with developmental processes or aging hyphae typically occur by the accumulation of sealing material. Here we report that in
Neurospora crassa
, a protein necessary for hyphal fusion and proper colony development called SO (SOFT) localizes to septal plugs. In response to injury, SO accumulates at the septal plug in a Woronin body-independent manner. However, the presence of the Woronin body affects the speed of accumulation of SO at the septal pore. We determined that SO contributes to, but is not essential for, septal plugging. SO accumulation was also observed at septal plugs formed during hyphal aging and during programmed cell death mediated by genetic differences at heterokaryon incompatibility (
het
) loci.
Characterization of the Outer Membrane Proteome of
Leptospira interrogans
Expressed during Acute Lethal Infection
Authors: Nally Jarlath E. , Whitelegge Julian P. , Bassilian Sara , Blanco David R. , Lovett Michael A. 
Published: November 2006

ABSTRACT

Pathogenic
Leptospira
species adapt to a wide range of environmental conditions during disease transmission and infection. While the proteome of in vitro cultivated
Leptospira
has been characterized in several studies to date, relatively little is known of the proteome as expressed by
Leptospira
during disease processes. Isolates of
Leptospira
obtained from patients suffering the severe pulmonary form of leptospirosis cause acute lethal infection in guinea pigs and chronic asymptomatic infection in rats. Recent studies have demonstrated that protein and lipopolysaccharide constituents of
Leptospira
recovered from acutely infected guinea pig tissue differ from that of
Leptospira
in chronically infected rat tissue and in vitro cultivated
Leptospira
(J. E. Nally, E. Chow, M. C. Fishbein, D. R. Blanco, and M. A. Lovett, Infect. Immun. 73:3251-3260, 2005). In the current study, the proteome of
Leptospira
expressed during disease processes was characterized relative to that of in vitro cultivated
Leptospira
(IVCL) after enrichment for hydrophobic membrane proteins with Triton X-114. Protein samples were separated by two-dimensional gel electrophoresis, and antigens expressed during infection were identified by immunoblotting with monospecific antiserum and convalescent rat serum in addition to mass spectrometry. Results suggest a significant increase in the expression of the outer membrane protein Loa22 during acute infection of guinea pigs relative to other outer membrane proteins, whose expression is generally diminished relative to expression in IVCL. Significant amounts of LipL32 are also expressed by
Leptospira
during acute infection of guinea pigs.
Affinity-Purified Human Immunoglobulin G That Binds a Lacto-N-Neotetraose-Dependent Lipooligosaccharide Structure Is Bactericidal for Serogroup BNeisseria meningitidis
Authors: Estabrook Michele M. , Jarvis Gary A. , McLeod Griffiss J. 
Published: November 2006

ABSTRACTDespite technological advances, no vaccine to prevent serogroup B meningococcal disease is available. The failure to develop a vaccine has shifted the focus to an alternative outer membrane structure, lipooligosaccharide (LOS), because disseminated disease induces bactericidal immunoglobulin G (IgG) that binds LOS. The purpose of this study was to identify the LOS structure(s) that induces human bactericidal IgG by purification and characterization of these antibodies. Human LOS IgG antibodies were affinity purified by passage of intravenous immunoglobulin through purified, type-specific LOS having a known structure coupled to epoxy-activated Sepharose 6B. Pathogenic group B strains representing the major LOS serotypes were used to examine the binding and bactericidal activities of four LOS-specific IgG preparations. All four LOS-specific IgG preparations bound to strains expressing homologous, as well as heterologous, LOS serotypes as determined by flow cytometry and an enzyme-linked immunosorbent assay. With human complement, IgG that was purified with L7 LOS was bactericidal for strains expressing L3,7 and L2,4 LOS, serotypes expressed by the majority of disease-associated group B and C meningococci. In conclusion, we purified human LOS-specific IgG that binds meningococci across LOS glycose-specific serotypes. An antigen that is dependent on the glycose lacto-N-neotetraose induces IgG in humans that is bactericidal for L2, L3, L4, and L7 strains. A vaccine containing this antigen would have the potential to protect against the vast majority of group B meningococcal strains.
Hypothetical Protein Cpn0308 Is Localized in theChlamydia pneumoniaeInclusion Membrane
Authors: Luo Jianhua , Jia Tianjun , Flores Rhonda , Chen Ding , Zhong Guangming 
Published: November 2006

ABSTRACTThe hypothetical protein encoded byChlamydia pneumoniaeopen reading frame cpn0308 was detected in inclusion membranes ofC. pneumoniae-infected cells using antibodies raised with Cpn0308 fusion proteins. The anti-Cpn0308 antibodies did not cross-react with IncA, a knownC. pneumoniaeinclusion membrane protein, although the anti-Cpn0308 antibody staining overlapped with the anti-IncA antibody labeling. The labeling of the inclusion membrane by the anti-Cpn0308 antibody was specifically blocked by the Cpn0308 but not IncA fusion proteins. The Cpn0308 antigen was detectable 24 h after infection and remained in the inclusion membrane throughout the infection course.
Differential Liver Protein Expression during Schistosomiasis
Authors: Harvie Marina , Jordan Thomas William , La Flamme Anne Camille 
Published: November 2006

ABSTRACTThe arrival of eggs in the liver duringSchistosoma mansoniinfection initiates a protective granulomatous response; however, as the infection progresses, this response results in chronic liver fibrosis. To better understand the impact of schistosomiasis on liver function, we used a proteomic approach to identify proteins whose expression was significantly altered in schistosome-infected mice 8 weeks postinfection. Identification of differentially expressed proteins by mass fingerprinting revealed that schistosome infection markedly reduced the abundance of proteins associated with several normal liver functions (i.e., citric acid cycle, fatty acid cycle, and urea cycle), while proteins associated with stress responses, acute phase reactants, and structural components were all significantly more abundant. The expression patterns of several immunity-related proteins (peroxiredoxin 1, arginase 1, and galectin 1) suggested that different protein forms are associated with schistosome infection. These findings indicate that acute schistosomiasis has a significant impact on specific liver functions and, moreover, that the alterations in specific protein isoforms and upregulation of unique proteins may be valuable as new markers of disease.
Ribosome Depurination Is Not Sufficient for Ricin-Mediated Cell Death in
Saccharomyces cerevisiae
Authors: Li Xiao-Ping , Baricevic Marianne , Saidasan Hemalatha , Tumer Nilgun E. 
Published: November 2006

ABSTRACT

The plant toxin ricin is one of the most potent and lethal substances
known. Ricin inhibits protein synthesis by removing a specific adenine
from the highly conserved α-sarcin/ricin loop in the large
rRNA. Very little is known about how ricin interacts with ribosomes and
the molecular mechanism by which it kills cells. To gain insight to the
mechanism of ricin-induced cell death, we set up yeast
(
Saccharomyces cerevisiae
) as a simple and genetically
tractable system to isolate mutants defective in cytotoxicity.
Ribosomes were depurinated in yeast cells expressing the precursor form
of the A chain of ricin (pre-RTA), and these cells displayed apoptotic
markers such as nuclear fragmentation, chromatin condensation, and
accumulation of reactive oxygen species. We conducted a large-scale
mutagenesis of pre-RTA and isolated a panel of nontoxic RTA mutants
based on their inability to kill yeast cells. Several nontoxic RTA
mutants depurinated ribosomes and inhibited translation to the same
extent as wild-type RTA in vivo. The mutant proteins isolated from
yeast depurinated ribosomes in vitro, indicating that they were
catalytically active. However, cells expressing these mutants did not
display hallmarks of apoptosis. These results provide the first
evidence that the ability to depurinate ribosomes and inhibit
translation does not always correlate with ricin-mediated cell death,
indicating that ribosome depurination and translation inhibition do not
account entirely for the cytotoxicity of
ricin.
Surface Proteins and Exotoxins Are Required for the Pathogenesis ofStaphylococcus aureusPneumonia
Authors: Wardenburg Juliane Bubeck , Patel Ravi J. , Schneewind Olaf 
Published: November 2006

ABSTRACTA model ofStaphylococcus aureus-induced pneumonia in adult, immunocompetent C57BL/6J mice is described. This model closely mimics the clinical and pathological features of pneumonia in human patients. Using this system, we defined a role forS. aureusstrain Newman surface proteins and secreted exotoxins in pneumonia-related mortality.
Two Distinct Cytotoxic Activities of Subtilase Cytotoxin Produced by Shiga-Toxigenic
Escherichia coli
Authors: Morinaga Naoko , Yahiro Kinnosuke , Matsuura Gen , Watanabe Masaharu , Nomura Fumio , Moss Joel , Noda Masatoshi 
Published: November 2006

ABSTRACT

Subtilase cytotoxin (SubAB) is a recently identified AB5 subunit toxin produced by Shiga-toxigenic
Escherichia coli.
The A subunit is thought to be a subtilase-like, serine protease, whereas the B subunit binds to the toxin receptor on the cell surface. We cloned the genes from a clinical isolate; the toxin was produced as His-tagged proteins. SubAB induced vacuolation at concentrations greater than 1 μg/ml after 8 h, in addition to the reported cytotoxicity induced at a ng/ml level after 48 h. Vacuolation was induced with the B, but not the A, subunit and was dependent on V-type ATPase. The cytotoxicity of SubAB at low concentrations was associated with the inhibition of protein synthesis; the 50% inhibitory dose was ∼1 ng/ml. The A subunit, containing serine 272, which is thought to be a part of the catalytic triad of a subtilase-like serine protease, plus the B subunit was necessary for this activity, both in vivo and in vitro. SubAB did not cleave azocasein, bovine serum albumin, ovalbumin, or synthetic peptides. These data suggest that SubAB is a unique AB toxin: first, the B subunit alone can induce vacuolation; second, the A subunit containing serine 272 plus the B subunit inhibited protein synthesis, both in vivo and in vitro; and third, the A subunit proteolytic activity may have a strict range of substrate specificity.