bluuebunny/crossref_metadata_2025_split huggingface dataset:
Therapeutic Efficacy of “Nubiotics” against Burn Wound Infection by
Pseudomonas aeruginosa
Authors: Dale Roderic M. K. , Schnell Glen , Wong Jonathan P. 
Published: July 2004

ABSTRACT

“Nubiotics” are a novel class of proprietary protonated nucleic acid-based drugs shown to have potent in vitro antibacterial activities against a number of gram-positive and gram-negative bacteria. These nubiotics are evaluated here for their in vivo therapeutic efficacy for the treatment of burn wound infection caused by
Pseudomonas aeruginosa
. To achieve this, a burn wound infection model was established in mice by using a highly pathogenic burn wound clinical isolate of
P. aeruginosa
. Lethal doses of the bacteria were determined for two routes of infection (subcutaneous and topical), representing systemic and local forms of infection, respectively. Using this infection model, treatment with nubiotics by various routes of drug administration was evaluated and optimized. A total of 12 nubiotics and their analogues were tested and of these, Nu-2, -3, -4, and -5 were found to be extremely efficacious in the postexposure treatment of burn wound infection (60 to 100% survival rates versus 0% for untreated control [
P
< 0.05]). These nubiotics were effective when given either systemically by intravenous and/or subcutaneous administration or given locally to the affected site in the skin by topical application. Treatment by these two routes resulted in almost 100% survival rates and complete eradication of the bacteria from infection sites in the livers, spleens, and blood. These nubiotics were found to be as effective as intravenously administered ciprofloxacin, a potent and broad-spectrum fluoroquinolone. These results suggest that nubiotics may be a promising and effective approach for the treatment of burn wound infection caused by
P. aeruginosa
.
Rapid Real-Time PCR Genotyping of Mutations Associated with Sulfadoxine-Pyrimethamine Resistance in
Plasmodium falciparum
Authors: Alker Alisa P. , Mwapasa Victor , Meshnick Steven R. 
Published: July 2004

ABSTRACT

The resistance of
Plasmodium falciparum
to sulfadoxine-pyrimethamine (SP) is an emerging public health threat. Resistance to these drugs is associated with point mutations in the genes encoding dihydropteroate synthase (DHPS) and dihydrofolate reductase (DHFR). We describe here an assay using real-time PCR and sequence-specific probes that detects these mutations. Using DNA from plasmids, cultured strains, and clinical samples, real-time PCR could distinguish four DHPS polymorphisms (codons 437, 540, 581, and 613) and three DHFR polymorphisms (codons 51, 59, and 108). This assay is rapid and sensitive, with a detection limit of 10 copies in most cases. This assay is amenable to large-scale studies of drug resistance.
Isoniazid Pharmacokinetics-Pharmacodynamics in an Aerosol Infection Model of Tuberculosis
Authors: Jayaram Ramesh , Shandil Radha. K. , Gaonkar Sheshagiri , Kaur Parvinder , Suresh B. L. , Mahesh B. N. , Jayashree R. , Nandi Vrinda , Bharath Sowmya , Kantharaj E. , Balasubramanian V. 
Published: July 2004

ABSTRACT

Limited data exist on the pharmacokinetic-pharmacodynamic (PK-PD) parameters of the bactericidal activities of the available antimycobacterial drugs. We report on the PK-PD relationships for isoniazid. Isoniazid exhibited concentration (
C
)-dependent killing of
Mycobacterium tuberculosis
H37Rv in vitro, with a maximum reduction of 4 log
10
CFU/ml. In these studies, 50% of the maximum effect was achieved at a
C
/MIC ratio of 0.5, and the maximum effect did not increase with exposure times of up to 21 days. Conversely, isoniazid produced less than a 0.5-log
10
CFU/ml reduction in two different intracellular infection models (J774A.1 murine macrophages and whole human blood). In a murine model of aerosol infection, isoniazid therapy for 6 days produced a reduction of 1.4 log
10
CFU/lung. Dose fractionation studies demonstrated that the 24-h area under the concentration-time curve/MIC (
r
2
= 0.83) correlated best with the bactericidal efficacy, followed by the maximum concentration of drug in serum/MIC (
r
2
= 0.73).
Disposition of Artesunate and Dihydroartemisinin after Administration of Artesunate Suppositories in Children from Papua New Guinea with Uncomplicated Malaria
Authors: Karunajeewa Harin A. , Ilett Kenneth F. , Dufall Kitiya , Kemiki Adedayo , Bockarie Moses , Alpers Michael P. , Barrett P. Hugh , Vicini Paolo , Davis Timothy M. E. 
Published: July 2004

ABSTRACT
A detailed pharmacokinetic analysis was performed with 47 children from Papua New Guinea with uncomplicated falciparum or vivax malaria treated with artesunate (ARTS) suppositories (Rectocaps) given in two doses of approximately 13 mg/kg of body weight 12 h apart. Following an intensive sampling protocol, samples were assayed for ARTS and its primary active metabolite, dihydroartemisinin (DHA), by liquid chromatography-mass spectrometry. A population pharmacokinetic model was developed to describe the data. Following administration of the first dose, the mean maximal concentrations of ARTS and DHA were 1,085 nmol/liter at 0.9 h and 2,525 nmol/liter at 2.3 h, respectively. The absorption half-life for ARTS was 2.3 h, and the conversion half-life (ARTS to DHA) was 0.27 h, while the elimination half-life of DHA was 0.71 h. The mean common volumes of distribution for ARTS and DHA relative to bioavailability were 42.8 and 2.04 liters/kg, respectively, and the mean clearance values relative to bioavailability were 6 and 2.2 liters/h/kg for ARTS and DHA, respectively. Substantial interpatient variability was observed, and the bioavailability of the second dose relative to that of the first was estimated to be 0.72. The covariates age, sex, and α-thalassemia genotype were not influential in the pharmacokinetic model development; but the inclusion of weight as a covariate significantly improved the performance of the model. An ARTS suppositories dose of 10 of 20 mg/kg is appropriate for use in children with uncomplicated malaria.
Role of Positional Hydrophobicity in the Leishmanicidal Activity of Magainin 2
Authors: Guerrero Esther , Saugar José María , Matsuzaki Katsumi , Rivas Luis 
Published: July 2004

ABSTRACT

The emergence of membrane-active antimicrobial peptides as new alternatives against pathogens with multiantibiotic resistance requires the design of better analogues. Among the different physicochemical parameters involved in the optimization of linear antimicrobial peptides, positional hydrophobicity has recently been incorporated. This takes into consideration the concept of the topological distribution of hydrophobic residues throughout the sequence rather than the classical concept of hydrophobicity as a global parameter of the peptide, calculated as the summation of the individual hydrophobicities of the residues. In order to assess the contribution of this parameter to the leishmanicidal mechanisms of magainin 2 analogues, the activities of two of these analogues, MG-H1 (GIKKFLHIIWKFIKAFVGEIMNS) and MG-H2 (IIKKFLHSIWKFGKAFVGEIMNI), which have similar charges, amino acid compositions, and hydrophobicities but different positional hydrophobicities, against
Leishmania donovani
promastigotes were assayed (T. Tachi, R. F. Epand, R. M. Epand, and K. Matsuzaki, Biochemistry 41:10723-10731, 2002). The activities were compared with that of the parental peptide, F5W-magainin 2 (GIGKWLHSAKKFGKAFVGEIMNS). The three peptides were active at micromolar concentrations, in the order MG-H2 > MG-H1 > F5W-magainin 2. These activities differ from their hemolytic and bactericidal activities. The results demonstrate that positional hydrophobicity, which reflects the presence of short stretches of sequences rich in hydrophobic amino acids, plays an important role in the activities of leishmanicidal peptides.
Pharmacodynamic Evaluation of the Neutralization of Endotoxin by PMX622 in Mice
Authors: Lake Philip , DeLeo Jeffrey , Cerasoli Franklin , Logdberg Lennart , Weetall Marla , Handley Dean 
Published: July 2004

ABSTRACTPolymyxin B (PMB) binds to and neutralizes endotoxin, but its systemic clinical utility is limited by neuro- and nephrotoxicity. PMX622 is a covalent conjugate of PMB and Dextran-70 designed to retain the ability of PMB to neutralize endotoxin and to retain the favorable colloidal, pharmacokinetic, and metabolic properties of Dextran-70. PMX622 has demonstrated efficacy in a number of animal models and effectively neutralized endotoxin in phase I clinical trials. Here, we systematically evaluated the pharmacodynamic properties of PMX622 in a murine model of endotoxin-induced lethality in galactosamine-sensitized mice. PMX622 completely and dose dependently inhibited lethality in this model. A stoichiometric relationship was found between the endotoxin challenge dose and the dose of PMX622 needed for protection. PMX622 neutralized endotoxin from four different genera of gram-negative bacteria but notNeisseria meningitidis. PMX622 was significantly less toxic than PMB in the mouse, suggesting that PMX622 has a better margin of safety than PMB. The timing of PMX622 administration relative to endotoxin was crucial. PMX622 was active for several hours prior to the endotoxin challenge; however, PMX622 did not protect mice if administered ≥15 min after endotoxin challenge. This suggests that PMX622 would best be clinically used prophylactically rather than therapeutically. These studies will be crucial in designing and interpreting human clinical trials assessing PMX622 efficacy.
Comparison of the Susceptibilities of
Burkholderia pseudomallei
to Meropenem and Ceftazidime by Conventional and Intracellular Methods
Authors: Inglis T. J. J. , Rodrigues F. , Rigby P. , Norton R. , Currie B. J. 
Published: July 2004

ABSTRACT

The effect of the two antibiotics ceftazidime and meropenem on a collection of 46
Burkholderia pseudomallei
isolates representing clinical and environmental sources across northern Australia was investigated by using a series of in vitro test methods. The susceptibility testing methods used included Kirby-Bauer disk diffusion, Etest MIC, broth microdilution MIC, and a modification of the microdilution method in which
Acanthamoeba
cells were added to simulate the effect of a professional phagocytic cell on test outcome. In a semiquantitative validation coculture series, the majority of bacteria were intracellular up to a multiplicity of infection of 10 bacteria to one ameba. The optical density and bacterial count (log
10
CFU/ml) correlated across the range tested (
r
2
= 0.77;
P
< 0.0001). Susceptibility test results were compared against clinical outcomes. The MICs of ceftazidime were consistently higher than those of meropenem by all three methods. The MICs of both agents were significantly higher when
Acanthamoeba
trophozoites were added to the broth microdilution method. Conventional and intracellular MIC results were consistent for clinical isolates from the Western Australian outbreak cluster despite the wide variety of clinical outcomes. Further development of the intracellular MIC method is expected to help assess the efficacy of antimicrobial agents on this bacterial species in an intracellular setting.
Nitric Oxide Generated from Isoniazid Activation by KatG: Source of Nitric Oxide and Activity againstMycobacterium tuberculosis
Authors: Timmins Graham S. , Master Sharon , Rusnak Frank , Deretic Vojo 
Published: July 2004

ABSTRACTIsonicotinic acid hydrazide (INH) is a frontline antituberculosis agent. Once taken up byMycobacterium tuberculosis, INH requires activation by the catalase-peroxidase KatG, converting INH from its prodrug form into a range of bactericidal reactive species. Here we used15N-labeled INH together with electron paramagnetic resonance spin trapping techniques to demonstrate that nitric oxide (NO˙) is generated from oxidation at the hydrazide nitrogens during the activation of INH byM. tuberculosisKatG. We also observed that a specific scavenger of NO˙ provided protection against the antimycobacterial activity of INH in bacterial culture. No significant increases in mycobacterial protein nitration were detected, suggesting that NO˙ and not peroxynitrite, a nitrating metabolite of NO·, is involved in antimycobacterial action. In conclusion, INH-derived NO·has biological activity, which directly contributes to the antimycobacterial action of INH.
Impact of Specific
pbp5
Mutations on Expression of β-Lactam Resistance in
Enterococcus faecium
Authors: Rice Louis B. , Bellais Samuel , Carias Lenore L. , Hutton-Thomas Rebecca , Bonomo Robert A. , Caspers Patrick , Page Malcolm G. P. , Gutmann Laurent 
Published: July 2004

ABSTRACT

We tested the impact of individual PBP 5 mutations on expression of ampicillin resistance in
Enterococcus faecium
using a shuttle plasmid designed to facilitate expression of cloned
pbp5
in ampicillin-susceptible
E. faecium
D344SRF. Substitutions that had been implicated in contributing to the resistance of clinical strains conferred only modest levels of resistance when they were present as single point mutations. The levels of resistance were amplified when some mutations were present in combination. In particular, a methionine-to-alanine change at position 485 (in close proximity to the active site) combined with the insertion of a serine at position 466 (located in a loop that forms the outer edge of the active site) was associated with the highest levels of resistance to all β-lactams. Affinity for penicillin generally correlated with β-lactam MICs for the mutants, but these associations were not strictly proportional.
Inhibitors of
Leishmania mexicana
CRK3 Cyclin-Dependent Kinase: Chemical Library Screen and Antileishmanial Activity
Authors: Grant Karen M. , Dunion Morag H. , Yardley Vanessa , Skaltsounis Alexios-Leandros , Marko Doris , Eisenbrand Gerhard , Croft Simon L. , Meijer Laurent , Mottram Jeremy C. 
Published: July 2004

ABSTRACT

The CRK3 cyclin-dependent kinase of
Leishmania
has been shown by genetic manipulation of the parasite to be essential for proliferation. We present data which demonstrate that chemical inhibition of CRK3 impairs the parasite's viability within macrophages, thus further validating CRK3 as a potential drug target. A microtiter plate-based histone H1 kinase assay was developed to screen CRK3 against a chemical library enriched for protein kinase inhibitors. Twenty-seven potent CRK3 inhibitors were discovered and screened against
Leishmania donovani
amastigotes in vitro. Sixteen of the CRK3 inhibitors displayed antileishmanial activity, with a 50% effective dose (ED
50
) of less than 10 μM. These compounds fell into four chemical classes: the 2,6,9-trisubstituted purines, including the C-2-alkynylated purines; the indirubins; the paullones; and derivatives of the nonspecific kinase inhibitor staurosporine. The paullones and staurosporine derivatives were toxic to macrophages. The 2,6,9-trisubstituted purines inhibited CRK3 in vitro, with 50% inhibitory concentrations ranging from high nanomolar to low micromolar concentrations. The most potent inhibitors of CRK3 (compounds 98/516 and 97/344) belonged to the indirubin class; the 50% inhibitory concentrations for these inhibitors were 16 and 47 nM, respectively, and the ED
50
s for these inhibitors were 5.8 and 7.6 μM, respectively. In culture, the indirubins caused growth arrest, a change in DNA content, and aberrant cell types, all consistent with the intracellular inhibition of a cyclin-dependent kinase and disruption of cell cycle control. Thus, use of chemical inhibitors supports genetic studies to confirm CRK3 as a validated drug target in
Leishmania
and provides pharmacophores for further drug development.
Regulation of the Expression of Cell Wall Stress Stimulon Member GenemsrA1in Methicillin-Susceptible or -ResistantStaphylococcus aureus
Authors: Pechous Roger , Ledala Nagender , Wilkinson Brian J. , Jayaswal Radheshyam K. 
Published: July 2004

ABSTRACTGenome-wide transcriptional profiling studies of the response ofStaphylococcus aureusto cell wall-active antibiotics have led to the discovery of a cell wall stress stimulon of genes induced by these agents.msrA1, encoding methionine sulfoxide reductase, is a highly induced member gene of this stimulon. In the present study we show thatmsrA1induction by oxacillin is common to all methicillin-susceptible strains studied but did not occur in two homogeneous and two heterogeneous methicillin-resistant strains. However,msrA1was induced by vancomycin and/ord-cycloserine in methicillin-resistant strains. Lysozyme and lysostaphin treatment did not inducemsrA1expression. Oxacillin-inducedmsrA1expression was enhanced by ca. 30% in a SigB+derivative (SH1000) of the SigB-defective RN450 (NCTC 8325-4) strain.msrA1expression was not affected in mutants in the global regulatory systemsagrandsar. Glycerol monolaurate, an inhibitor of signal transduction, inhibited the oxacillin-induced transcription ofmsrA1and other cell wall stress stimulon member genes,vraSanddnaK. These observations suggest that the cell wall stress stimulon is induced by inhibition of the process of peptidoglycan biosynthesis, and the inhibitory effects of glycerol monolaurate indicate that gene expression is dependent on a signal transduction pathway.
Comparison of Gene Expression Profiles of
Candida albicans
Azole-Resistant Clinical Isolates and Laboratory Strains Exposed to Drugs Inducing Multidrug Transporters
Authors: Karababa Mahir , Coste Alix T. , Rognon Bénédicte , Bille Jacques , Sanglard Dominique 
Published: July 2004

ABSTRACT

Azole resistance in
Candida albicans
can be due to upregulation of multidrug transporters belonging to ABC (ATP-binding cassette) transporters (
CDR1
and
CDR2
) or major facilitators (
CaMDR1
). Upregulation of these genes can also be achieved by exposure to fluphenazine, resulting in specific upregulation of
CDR1
and
CDR2
and by exposure to benomyl, resulting in specific
CaMDR1
upregulation. In this study, these two different states of gene upregulation were used to determine coregulated genes that often share similar functions or similar regulatory regions. The transcript profiles of a laboratory strain exposed to these drugs were therefore determined and compared with those of two matched pairs of azole-susceptible and -resistant strains expressing
CDR1
and
CDR2
(CDR strains) or
CaMDR1
(MDR isolates). The results obtained revealed that, among 42 commonly regulated genes (8.6% of all regulated genes) between fluphenazine-exposed cells and CDR isolates, the most upregulated were
CDR1
and
CDR2
as expected, but also
IFU5
,
RTA3
(which encodes putative membrane proteins),
HSP12
(which encodes heat shock protein), and
IPF4065
(which is potentially involved in stress response). Interestingly, all but
HSP12
and
IPF4065
contain a putative
cis
-acting drug responsive element in their promoters. Among the 57 genes (11.5% of all regulated genes) commonly regulated between benomyl-exposed cells and MDR isolates, the most upregulated were
CaMDR1
as expected but also genes with oxido-reductive functions such as
IFD
genes,
IPF5987
,
GRP2
(all belonging to the aldo-keto reductase family),
IPF7817
[NAD(P)H oxido-reductase], and
IPF17186
. Taken together, these results show that in vitro drug-induced gene expression only partially mimics expression profiles observed in azole-resistant clinical strains. Upregulated genes in both drug-exposed conditions and clinical strains are drug resistance genes but also genes that could be activated under cell damage conditions.
Novel Polymorphisms in
mec
Genes and a New
mec
Complex Type in Methicillin-Resistant
Staphylococcus aureus
Isolates Obtained in Rural Wisconsin
Authors: Shukla Sanjay K. , Ramaswamy Srinivas V. , Conradt Jennifer , Stemper Mary E. , Reich Robert , Reed Kurt D. , Graviss Edward A. 
Published: July 2004

ABSTRACT

We determined allelic polymorphisms in the
mec
complexes of 524 methicillin-resistant
Staphylococcus aureus
isolates by partial or complete sequencing of three
mec
genes,
mecA, mecI
, and
mecR1
. The isolates had been collected over a 10-year period from patients living in rural Wisconsin, where the use of antibiotics was expected to be lower than in the bigger cities. Of the 18 mutation types identified, 16 had not been described previously. The five most common mutations were a mutation 7 nucleotides (nt) upstream from the start site (G→T) in the
mecA
promoter (34.7%), an E246G change encoded by
mecA
(2.2%), a cytosine insertion at codon 257 in
mecA
(13.2%), an N121K change encoded by
mecI
(7.8%), and a major
mecI
-
mecR1
deletion designated as a class B1
mec
complex deletion type (25.4%). There was a high degree of conservation of the amino acid sequence of MecR1. Strains with the same mutations had variable resistance to oxacillin, and the median MIC for isolates that harbored the 7-nt-upstream mutation was lower than that for strains harboring other mutations. Our data suggest that the
mecA
promoter mutation plays a more important role in determining methicillin resistance than mutations in
mecI
and
mecA
do. Eighty-five percent of the tested isolates (
n
= 148) with the
mecA
promoter mutation and the class B1
mec
complex deletion belonged to the same major clonal group, identified as MCG-2, and harbored the type IV staphylococcal cassette chromosome
mec
DNA. There was also a wide range of oxacillin MICs for strains with wild-type
mecA
,
mecI
, and
mecR1
sequences, suggesting that the genetic backgrounds of clinical strains are significant in determining susceptibility to methicillin.
1,2-Dithiole-3-Ones as Potent Inhibitors of the Bacterial 3-Ketoacyl Acyl Carrier Protein Synthase III (FabH)
Authors: He Xin , Reeve Anne McElwee , Desai Umesh R. , Kellogg Glen E. , Reynolds Kevin A. 
Published: July 2004

ABSTRACTThe enzyme FabH catalyzes the initial step of fatty acid biosynthesis via a type II dissociated fatty acid synthase. The pivotal role of this essential enzyme, combined with its unique structural features and ubiquitous occurrence in bacteria, has made it an attractive new target for the development of antibacterial and antiparasitic compounds. We have searched the National Cancer Institute database for compounds bearing structural similarities to thiolactomycin, a natural product which exhibits a weak activity against FabH. This search has yielded several substituted 1,2-dithiole-3-ones that are potent inhibitors of FabH from bothEscherichia coli(ecFabH) andStaphylococcus aureus(saFabH). The most potent inhibitor was 4,5-dichloro-1,2-dithiole-3-one, which had 50% inhibitory concentration (IC50) values of 2 μM (ecFabH) and 0.16 μM (saFabH). The corresponding 3-thione analog exhibited comparable activities. Analogs in which the 4-chloro substituent was replaced with a phenyl group were also potent inhibitors, albeit somewhat less effectively (IC50values of 5.7 and 0.98 μM for ecFabH and saFabH, respectively). All of the 5-chlorinated inhibitors were most effective when they were preincubated with FabH in the absence of substrates. The resulting enzyme-inhibitor complex did not readily regain activity after excess inhibitor was removed, suggesting that a slow dissociation occurs. In stark contrast, a series of inhibitors in which the 5-chloro substituent was replaced with the isosteric and isoelectronic trifluoromethyl group were poorer inhibitors (IC50values typically ranging from 25 to >100 μM for both ecFabH and saFabH), did not require a preincubation period for maximal activity, and generated an enzyme-inhibitor complex which readily dissociated. Possible modes of binding of 5-chloro-1,2-dithiole-3-ones and 5-chloro-1,2-dithiole-3-thiones with FabH which account for the role of the 5-chloro substituent were considered.