bluuebunny/crossref_metadata_2025_split huggingface dataset:
Activity of Gatifloxacin Alone or in Combination with Pyrimethamine or Gamma Interferon against
Toxoplasma gondii
Authors: Khan Anis A. , Slifer Teri R. , Araujo Fausto G. , Remington Jack S. 
Published: July 2002

ABSTRACT

The activity of gatifloxacin against
Toxoplasma gondii
, either alone or in combination with pyrimethamine or gamma interferon (IFN-γ), was examined in vitro and in vivo. In vitro, gatifloxacin significantly inhibited intracellular replication of tachyzoites of the RH strain with a 50% inhibitory concentration of 0.21 μg/ml at 48 h after addition of the drug to the cultures. Toxicity for host cells was not observed at this concentration. A synergistic effect (combination indices < 0.5) was demonstrated in vitro following 48 h of treatment with the combination of gatifloxacin and pyrimethamine (1:1 ratio). Doses of gatifloxacin of 100 and 200 mg/kg of body weight/day administered orally to mice for 10 days resulted in significant (
P
values of 0.056 and <0.0001, respectively) prolongation in time to death following infection with a lethal inoculum of tachyzoites. A dose of 400 mg/kg resulted in 20% survival (
P
= 0.0001). Mortality was 100% in untreated control mice and in mice treated with 25 or 50 mg/kg/day. Treatment of infected mice with a combination of gatifloxacin at 200 mg/kg/day and pyrimethamine at 12.5 mg/kg/day resulted in 85% survival, whereas 100 and 80% of mice treated with gatifloxacin alone or pyrimethamine alone, respectively, died (
P
< 0.0001). Moreover, a gatifloxacin dose of 200 mg/kg/day administered orally for 10 days plus 2 μg of recombinant murine IFN-γ/day administered intraperitoneally for 10 days resulted in significant survival compared with IFN-γ alone (
P
< 0.0001) or gatifloxacin alone (
P
< 0.007).
In Vitro and In Vivo Effects of 14α-Demethylase (
ERG11
) Depletion in
Candida glabrata
Authors: Nakayama Hironobu , Nakayama Noboru , Arisawa Mikio , Aoki Yuko 
Published: July 2002

ABSTRACT

Sterol 14α-demethylase (
ERG11
) is the target enzyme of azole antifungals that are widely used for the treatment of fungal infections.
Candida glabrata
is known to be less susceptible to fluconazole than most
Candida albicans
strains, and the incidence of
C. glabrata
infection has been increasing mostly in conjunction with the use of azole antifungals. Recently, it has been reported that
C. glabrata
can rescue the defect of ergosterol biosynthesis by incorporating cholesterol from serum. To explore the effect of inactivating Erg11p in
C. glabrata
, we generated mutant strains in which the
ERG11
gene was placed under the control of tetracycline-regulatable promoters. In these mutants, expression of the
ERG11
gene can be repressed by doxycycline (DOX). All mutants showed a growth defect in the presence of DOX. The numbers of CFU of the mutants were lowered by only 1/10 with DOX treatment. In these mutants, accumulation of 4,14-dimethylzymosterol, which differs from an accumulated abnormal sterol detected in
C. albicans
and
Saccharomyces cerevisiae
treated with fluconazole, was observed by DOX treatment. Although such phenotypes were also observed in serum-containing media by DOX treatment, they were alleviated. Furthermore, the mutant could grow in DOX-treated mice without a severe reduction in the number of cells. Thus, depleting the expression of the
ERG11
gene lowered the number of CFU by only 1/10 due to the accumulation of 4,14-demethylzymosterol in vitro, and it did not result in the defective growth of fungal cells in mice. These results suggested that Erg11p is not an ideal target molecule of antifungals for
C. glabrata
.
Reversal of Chloroquine Resistance in
Plasmodium falciparum
Using Combinations of Chemosensitizers
Authors: van Schalkwyk Donelly A. , Walden Jason C. , Smith Peter J. 
Published: July 2002

ABSTRACT

Research into chloroquine resistance reversal in
Plasmodium falciparum
has revealed a widespread range of functionally and structurally diverse chemosensitizers. However, nearly all of these chemosensitizers reverse resistance optimally only at concentrations that are toxic to humans. Verapamil, desipramine, and trifluoperazine were shown to potentiate chloroquine accumulation in a chloroquine-resistant (CQ
r
) strain of
P. falciparum
, while progesterone, ivermectin, and cyclosporin A were not shown to potentiate chloroquine accumulation. The simultaneous use of two or even three of these chemosensitizers at concentrations within their therapeutic ranges in humans displayed an additive effect in potentiating chloroquine accumulation in the CQ
r
strain. The levels of resistance reversal achieved with these multiple combinations were comparable to those achieved with high concentrations of the single agents used to enhance the activity of chloroquine. No chemosensitizer, whether used singly or in combination, potentiated any change in chloroquine accumulation or a shift in the 50% inhibitory concentration for the chloroquine-sensitive strain. The use of combinations of chemosensitizers at concentrations not toxic to humans could effectively reverse chloroquine resistance without the marked toxicity from the use of a single agent at high concentrations. This cocktail of chemosensitizers may serve as a viable treatment to restore the efficacy of chloroquine in patients with malaria.
Pharmacokinetics of the Protease Inhibitor Indinavir in Human Immunodeficiency Virus Type 1-Infected Children
Authors: Burger David M. , van Rossum Annemarie M. C. , Hugen Patricia W. H. , Suur Marja H. , Hartwig Nico G. , Geelen Sibyl P. M. , Scherpbier Henriette J. , Hoetelmans Richard M. W. , Vulto Arnold G. , de Groot Ronald 
Published: July 2002

ABSTRACTThe objective of this study was to evaluate the pharmacokinetics of indinavir in human immunodeficiency virus-infected children as part of a prospective, open, uncontrolled, multicenter study in The Netherlands. Human immunodeficiency virus type 1-infected children were monitored over 6 months of treatment with zidovudine (120 mg/m2every 8 h [q8h]), lamivudine (4 mg/kg of body weight q12h), and indinavir (33mg/kg of metabolic weight [MW] q8h). Four weeks after the start of treatment, the steady-state pharmacokinetics of indinavir were determined by high-pressure liquid chromatography. If patients had an indinavir area under the concentration-time curve (AUC) of below 10 or above 30 mg/liter · h, a dose increase or a dose reduction was made and pharmacokinetic measurements were repeated 4 weeks later. Nineteen patients started with the dose of 33 mg/kg of MW q8h. The median AUC (range) was 10.5 (2.8 to 51.0) mg/liter · h. The median AUC (range) in 17 children treated with 50 mg/kg of MW q8h was 20.6 (4.1 to 38.7) mg/liter · h. Finally, five patients had a dose increase to 67 mg/kg of MW q8h, resulting in a median AUC (range) of 36.6 (27.2 to 80.0) mg/liter · h. After 6 months of treatment, there were 11 children with an AUC of below 20 mg/liter · h, of whom 5 (45%) had a detectable viral load, while this was the case in none of the 11 children with an AUC of higher than 20 mg/liter · h. We conclude that the optimal dose of indinavir in children to obtain drug exposure similar to that observed in adult patients is 50 mg/kg of MW q8h, which approximates 600 mg/m2q8h. It would even be better to adjust the indinavir dose based on an AUC of greater than 20 mg/liter · h.
Pharmacokinetic Evaluation of Oral Levofloxacin in Human Immunodeficiency Virus-Infected Subjects Receiving Concomitant Antiretroviral Therapy
Authors: Villani P. , Viale P. , Signorini L. , Cadeo B. , Marchetti F. , Villani A. , Fiocchi C. , Regazzi M. B. , Carosi G. 
Published: July 2002

ABSTRACTThe purpose of this study was to evaluate the pharmacokinetics (PK) profile of oral levofloxacin in human immunodeficiency virus-positive patients in steady-state treatment with nelfinavir (NFV) or with efavirenz (EFV) and to determine the effects of levofloxacin on the PK parameters of these two antiretroviral agents. For levofloxacin, plasma samples were obtained at steady state during a 24-h dosing interval. Plasma NFV and EFV concentrations were evaluated before and after 4 days of levofloxacin treatment. Levofloxacin PK do not seem affected by NFV and EFV. There was no significant difference between NFV and EFV plasma levels obtained with and without levofloxacin.
Pfmdr1
Alleles and Response to Ultralow-Dose Mefloquine Treatment in Gabonese Patients
Authors: Mawili-Mboumba Denise P. , Kun Jürgen F. J. , Lell Bertrand , Kremsner Peter G. , Ntoumi Francine 
Published: July 2002

ABSTRACT

The identification of parasite molecular markers involved in resistance to antimalarial compounds is of great interest for monitoring the development and spread of resistance in the field. Polymorphisms in
Plasmodium falciparum
multidrug resistance gene 1 (
pfmdr1
) have been associated with chloroquine resistance and mefloquine susceptibility. In the present study, carried out in Lambaréné, Gabon, we investigated the relationship between the presence of mutations at codons 86, 184, 1034, 1042, and 1246 in the
pfmdr1
gene and the success of ultralow-dose mefloquine treatment (1.1 mg/kg of body weight). Sixty-nine patients were included in the study, and depending on the level of in vivo resistance to mefloquine, they were classified as sensitive responders (S), patients with low-grade resistance (RI), and nonresponders (NR). We found that the prevalences of the Tyr-86 mutation among isolates from patients in groups S, RI, and NR were 100, 96, and 90%, respectively, and that the prevalence of the Phe-184 mutation among the isolates was 80% in each group. A prevalence of about 10% point mutations at codons 1042 and 1246 was detected only in isolates from patients in groups RI and NR. There was no statistically significant association between the presence of the Tyr-86 mutation and the in vivo response (
P
= 0.79). Among the parasite isolates from patients with drug-resistant infections, 83% had the wild-type
pfmdr1
genotype (S
1034
-N
1042
-D
1246
). No link between the presence of this genotype and parasite resistance was detected (
P
= 0.42). Among the isolates analyzed, 85 had double mutations (Y
86
-F
184
or Y
86
-Y
1246
) and 11 had triple mutations (Y
86
-D
1042
-Y
1246
, Y
86
-F
184
-Y
1246
, or Y
86
-F
184
-D
1042
). These findings are not consistent with those of previous in vitro studies and suggest that further evaluation of
pfmdr1
gene polymorphism and in vivo mefloquine sensitivity are needed.
Susceptibilities of Herpes Simplex Viruses to Penciclovir and Acyclovir in Eight Cell Lines
Authors: Leary Jeffry J. , Wittrock Robert , Sarisky Robert T. , Weinberg Adriana , Levin Myron J. 
Published: July 2002

ABSTRACT

The commonly used antiviral drugs acyclovir (ACV) and penciclovir (PCV) possess similarly potent antiviral activities in vivo against herpes simplex virus (HSV). Assay methods for sensitivity to ACV are not necessarily transferable to PCV, even though the two drugs have similar in vivo potencies and mechanisms of action. We determined by plaque reduction assay the relative activities of ACV and PCV against five laboratory-adapted strains of HSV types 1 and 2 (including sensitive and resistant strains) in seven human cell lines and one nonhuman primate cell line. Seven characteristics were used to evaluate the cell lines. All cell lines were similar in their plating efficiencies and abilities to discriminate between sensitive and resistant HSV isolates. Vero and MRC-5 cells yielded the most discordant 50% inhibitory concentrations (IC
50
s) for the two HSV types, while Vero and WI-38 VA-13 cells yielded large differences in the IC
50
s of ACV and PCV. The limited life spans and poor plaque morphologies of the fibroblast lines were undesirable characteristics. Among the transformed cell lines producing well-defined plaques, A549 cells provided the best concordance between IC
50
s for the two HSV types and two antiherpes drugs. Comparison experiments with a yield reduction format indicated that the use of assays of this type might allow some of the cell-specific properties observed in plaque reduction assays to be avoided.
Acyclovir, Ganciclovir, and Zidovudine Transfer into Rat Milk
Authors: Alcorn Jane , McNamara Patrick J. 
Published: July 2002

ABSTRACT
Treatment with antiviral agents that accumulate in breast milk may offer a novel approach to reduce the rates of vertical transmission of important viruses and the risk of clinical illness in suckling neonates. The present study evaluated the extent and mechanism of transfer of three antiviral nucleoside analogues into milk in a lactating rat model system. Acyclovir (0.26 mg/h), ganciclovir (0.13 mg/h), and zidovudine (0.5 mg/h) were each infused to steady-state concentrations in six rats 15 to 16 days postpartum. The observed ratios of the concentrations in milk to the concentrations in serum (observed milk-to-serum ratio), calculated from the ratio of the steady-state concentration in serum to the steady-state concentration in milk, determined the extent of drug transfer into milk. To identify the mechanism of transfer into milk, the observed milk-to-serum ratio was compared to a predicted milk-to-serum ratio estimated from an in vitro passive diffusion model of transfer of each drug into milk. High-pressure liquid chromatography methods determined milk and serum drug concentrations. Mean ± standard deviation observed milk-to-serum ratios for acyclovir, ganciclovir, and zidovudine were 5.1 ± 1.4, 1.6 ± 0.33, and 1.0 ± 0.29, respectively, compared with their corresponding predicted ratios of 1.1, 0.85, and 0.71. These results suggest that acyclovir accumulates in milk due to active transport mechanisms, while passive diffusion processes govern the transfer of both ganciclovir and zidovudine into milk. The presence of all three antiviral drugs in milk and the potential for active drug transfer into milk warrants further investigation of the accumulation of other antiviral drugs in milk and their therapeutic benefits in reducing the vertical transmission of viruses and clinical sequelae in the breast-feeding infant.
Bacterial Functional Redundancy along a Soil Reclamation Gradient
Authors: Yin Bei , Crowley David , Sparovek Gerd , De Melo Wanderley Jose , Borneman James 
Published: July 2002

ABSTRACT

A strategy to measure bacterial functional redundancy was developed and tested with soils collected along a soil reclamation gradient by determining the richness and diversity of bacterial groups capable of in situ growth on selected carbon substrates. Soil cores were collected from four sites along a transect from the Jamari tin mine site in the Jamari National Forest, Rondonia, RO, Brazil: denuded mine spoil, soil from below the canopy of invading pioneer trees, revegetated soil under new growth on the forest edge, and the forest floor of an adjacent preserved forest. Bacterial population responses were analyzed by amending these soil samples with individual carbon substrates in the presence of bromodeoxyuridine (BrdU). BrdU-labeled DNA was then subjected to a 16S-23S rRNA intergenic analysis to depict the actively growing bacteria from each site. The number and diversity of bacterial groups responding to four carbon substrates (
l
-serine,
l
-threonine, sodium citrate, and α-lactose hydrate) increased along the reclamation-vegetation gradient such that the preserved forest soil samples contained the highest functional redundancy for each substrate. These data suggest that bacterial functional redundancy increases in relation to the regrowth of plant communities and may therefore represent an important aspect of the restoration of soil biological functionality to reclaimed mine spoils. They also suggest that bacterial functional redundancy may be a useful indicator of soil quality and ecosystem functioning.
A PCR Assay To Discriminate Human and Ruminant Feces on the Basis of Host Differences in
Bacteroides-Prevotella
Genes Encoding 16S rRNA
Authors: Bernhard Anne E. , Field Katharine G. 
Published: July 2002

ABSTRACT

Our purpose was to develop a rapid, inexpensive method of diagnosing the source of fecal pollution in water. In previous research, we identified
Bacteroides-Prevotella
ribosomal DNA (rDNA) PCR markers based on analysis. These markers length heterogeneity PCR and terminal restriction fragment length polymorphism distinguish cow from human feces. Here, we recovered 16S rDNA clones from natural waters that were close phylogenetic relatives of the markers. From the sequence data, we designed specific PCR primers that discriminate human and ruminant sources of fecal contamination.
Antibacterial Activity Evaluation of Microcin J25 against Diarrheagenic
Escherichia coli
Authors: Sable Sophie , Pons Anne-Marie , Gendron-Gaillard Sandrine , Cottenceau Gilles 
Published: July 2002

ABSTRACT

The inhibitory activities of known microcins were evaluated against some diarrheagenic
Escherichia coli
strains. Some antibacterial properties of microcin J25, the most active one, were studied. A rapid two-step purification was performed. The MIC and the minimum bactericidal concentration of J25 against
E. coli
O157:H7 were 1 and 100 μg ml
−1
, respectively. A 10
4
-CFU ml
−1
contamination by this strain was destroyed in milk and meat extract by 6.25 μg of J25 ml
−1
and in half-diluted egg yolk by 50 μg of J25 ml
−1
.
Evidence for Contribution of Neutral Trehalase in Barotolerance of
Saccharomyces cerevisiae
Authors: Iwahashi Hitoshi , Nwaka Solomon , Obuchi Kaoru 
Published: July 2002

ABSTRACT

In yeast, trehalose accumulation and its hydrolysis, which is catalyzed by neutral trehalase, are believed to be important for thermotolerance. We have shown that trehalose is one of the important factors for barotolerance (resistance to hydrostatic pressure); however, nothing is known about the role of neutral trehalase in barotolerance. To estimate the contribution of neutral trehalase in resisting high hydrostatic pressure, we measured the barotolerance of neutral trehalase I and/or neutral trehalase II deletion strains. Under 180 MPa of pressure for 2 h, the neutral trehalase I deletion strain showed higher barotolerance in logarithmic-phase cells and lower barotolerance in stationary-phase cells than the wild-type strain. Introduction of the neutral trehalase I gene (
NTH1
) into the deletion mutant restored barotolerance defects in stationary-phase cells. Furthermore, we assessed the contribution of neutral trehalase during pressure and recovery conditions by varying the expression of
NTH1
or neutral trehalase activity with a galactose-inducible
GAL1
promoter with either glucose or galactose. The low barotolerance observed with glucose repression of neutral trehalase from the
GAL1
promoter was restored during recovery with galactose induction. Our results suggest that neutral trehalase contributes to barotolerance, especially during recovery.
Relationship between Nitrite Reduction and Active Phosphate Uptake in the Phosphate-Accumulating Denitrifier
Pseudomonas
sp. Strain JR 12
Authors: Barak Yoram , van Rijn Jaap 
Published: July 2002

ABSTRACT

Phosphate uptake by the phosphate-accumulating denitrifier
Pseudomonas
sp. JR12 was examined with different combinations of electron and carbon donors and electron acceptors. Phosphate uptake in acetate-supplemented cells took place with either oxygen or nitrate but did not take place when nitrite served as the final electron acceptor. Furthermore, nitrite reduction rates by this denitrifier were shown to be significantly reduced in the presence of phosphate. Phosphate uptake assays in the presence of the H
+
-ATPase inhibitor
N,N
′-dicyclohexylcarbodiimide (DCCD), in the presence of the uncoupler carbonyl cyanide 3-chlorophenylhydrazone (CCCP), or with osmotic shock-treated cells indicated that phosphate transport over the cytoplasmic membrane of this bacterium was mediated by primary and secondary transport systems. By examining the redox transitions of whole cells at 553 nm we found that phosphate addition caused a significant oxidation of a
c
-type cytochrome. Based on these findings, we propose that this
c
-type cytochrome serves as an intermediate in the electron transfer to both nitrite reductase and the site responsible for active phosphate transport. In previous studies with this bacterium we found that the oxidation state of this
c
-type cytochrome was significantly higher in acetate-supplemented, nitrite-respiring cells (incapable of phosphate uptake) than in phosphate-accumulating cells incubated with different combinations of electron donors and acceptors. Based on the latter finding and results obtained in the present study it is suggested that phosphate uptake in this bacterium is subjected to a redox control of the active phosphate transport site. By means of this mechanism an explanation is provided for the observed absence of phosphate uptake in the presence of nitrite and inhibition of nitrite reduction by phosphate in this organism. The implications of these findings regarding denitrifying, phosphate removal wastewater plants is discussed.
Sequencing Bands of Ribosomal Intergenic Spacer Analysis Fingerprints for Characterization and Microscale Distribution of Soil Bacterium Populations Responding to Mercury Spiking
Authors: Ranjard Lionel , Brothier Elisabeth , Nazaret Sylvie 
Published: July 2002

ABSTRACT

Two major emerging bands (a 350-bp band and a 650-bp band) within the RISA (ribosomal intergenic spacer analysis) profile of a soil bacterial community spiked with Hg(II) were selected for further identification of the populations involved in the response of the community to the added metal. The bands were cut out from polyacrylamide gels, cloned, characterized by restriction analysis, and sequenced for phylogenetic affiliation of dominant clones. The sequences were the intergenic spacer between the
rrs
and
rrl
genes and the first 130 nucleotides of the
rrl
gene. Comparison of sequences derived from the 350-bp band to The GenBank database permitted us to identify the bacteria as being mostly close relatives to low G+C firmicutes (
Clostridium
-like genera), while the 650-bp band permitted us to identify the bacteria as being mostly close relatives to β-proteobacteria (
Ralstonia
-like genera). Oligonucleotide probes specific for the identified dominant bacteria were designed and hybridized with the RISA profiles derived from the control and spiked communities. These studies confirmed the contribution of these populations to the community response to the metal. Hybridization of the RISA profiles from subcommunities (bacterial pools associated with different soil microenvironments) also permitted to characterize the distribution and the dynamics of these populations at a microscale level following mercury spiking.
Rapid Method for Coextraction of DNA and RNA from Natural Environments for Analysis of Ribosomal DNA- and rRNA-Based Microbial Community Composition
Authors: Griffiths Robert I. , Whiteley Andrew S. , O'Donnell Anthony G. , Bailey Mark J. 
Published: July 2002

ABSTRACT
A rapid protocol for the extraction of total nucleic acids from environmental samples is described. The method facilitates concomitant assessment of microbial 16S rRNA diversity by PCR and reverse transcription-PCR amplification from a single extraction. Denaturing gradient gel electrophoresis microbial community analysis differentiated the active component (rRNA derived) from the total bacterial diversity (ribosomal DNA derived) down the horizons of an established grassland soil.