bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pharmacodynamics of Amphotericin B in a Neutropenic-Mouse Disseminated-Candidiasis Model
Authors: Andes D. , Stamsted T. , Conklin R. 
Published: July 2002

ABSTRACT

In vivo pharmacodynamic parameters have been described for a variety of antibacterials. These parameters have been studied in correlation with in vivo outcomes in order to determine which dosing parameter is predictive of outcome and the magnitude of that parameter associated with efficacy. Very little is known about pharmacodynamics for antifungal agents. We utilized a neutropenic mouse model of disseminated candidiasis to correlate pharmacodynamic parameters (percent time above MIC [
T
> MIC], area under the concentration time curve [AUC]/MIC ratio, and peak serum level/MIC ratio) for amphotericin B in vivo with efficacy, as measured by organism number in homogenized kidney cultures after 72 h of therapy. Amphotericin B was administered by the intraperitoneal route. Drug kinetics for amphotericin B in infected mice were nonlinear. Serum half-lives ranged from 13 to 27 h. Infection was achieved by intravenous inoculation with 10
6
CFU of yeast cells per ml via the lateral tail vein of neutropenic mice. Groups of mice were treated with fourfold escalating total doses of amphotericin B ranging from 0.08 to 20 mg/kg of body weight divided into 1, 3, or 6 doses over 72 h. Increasing doses produced concentration-dependent killing, ranging from 0 to 2 log
10
CFU/kidney compared to the organism number at the start of therapy. Amphotericin B also produced prolonged dose-dependent suppression of growth after serum levels had fallen below the MIC. Nonlinear regression analysis was used to determine which pharmacodynamic parameter best correlated with efficacy. Peak serum level in relation to the MIC (peak serum level/MIC ratio) was the parameter best predictive of outcome, while the AUC/MIC ratio and
T
> MIC were only slightly less predictive (peak serum level/MIC ratio, coefficient of determination [
R
2
] = 90 to 93%; AUC/MIC ratio,
R
2
= 49 to 69%;
T
> MIC,
R
2
= 67 to 85%). The total amount of drug necessary to achieve various microbiological outcomes over the treatment period was 4.8- to 7.6-fold smaller when the dosing schedule called for large single doses than when the same amount of total drug was administered in 2 to 6 doses. Given the narrow therapeutic window of amphotericin B and frequent treatment failures, these results suggest the need for a reevaluation of current dosing regimens.
Mutations of the
Helicobacter pylori
Genes
rdxA
and
pbp1
Cause Resistance against Metronidazole and Amoxicillin
Authors: Paul Ralf , Postius Stefan , Melchers Klaus , Schäfer Klaus P. 
Published: July 2002

ABSTRACT

To investigate amoxicillin and metronidazole resistance of
Helicobacter pylori
, we compared putative resistance genes between resistant strains obtained in vitro and their sensitive parent strain. All metronidazole-resistant strains had
rdxA
mutations, and an amoxicillin-resistant strain had
pbp1
and
pbp2
mutations. By transforming PCR products of these mutated genes into antibiotic-sensitive strains, we showed that
rdxA
null mutations were sufficient for metronidazole resistance
,
while
pbp1
mutations contributed to amoxicillin resistance of
H. pylori
.
Combination Treatment with Intralesional Cidofovir and Viral-DNA Vaccination Cures Large Cottontail Rabbit Papillomavirus-Induced Papillomas and Reduces Recurrences
Authors: Christensen Neil D. , Han Ricai , Cladel Nancy M. , Pickel Martin D. 
Published: July 2002

ABSTRACT
We used the cottontail rabbit papillomavirus (CRPV) New Zealand White rabbit model to test a combination treatment of large established papillomas with intralesional cidofovir and DNA vaccination to cure sites and reduce recurrences. Intralesional 1% (wt/vol) (0.036 M) cidofovir treatment of rabbit papillomas led to elimination, or “cure,” of the papillomas over a 6- to 8-week treatment period (N. D. Christenson, M. D. Pickel, L. R. Budgeon, and J. W. Kreider, Antivir. Res. 48:131–142, 2000). However, recurrences at periods from 1 to 8 weeks after treatment cessation were observed at approximately 50% of cured sites. DNA vaccinations with CRPV E1, E2, E6, and E7 were initiated either after or at the time of intralesional treatments, and the recurrence rates were observed. When DNA vaccinations were started after intralesional cures, recurrence rates were similar to those of vector-vaccinated rabbits. A small proportion of recurrent sites subsequently regressed (4 out of 10, or 40%) in the vaccinated group versus no regression of recurrences in the vector-immunized group (0 out of 19, or 0%), indicating partial effectiveness. In contrast, when DNA vaccinations were conducted during intralesional treatments, a significant reduction of recurrences (from 10 out of 19, or 53%, of sites in vector-immunized rabbits to 3 out of 20, or 15%, of sites in viral-DNA-immunized rabbits) was observed. DNA vaccination without intralesional treatments had a minimal effect on preexisting papillomas. These data indicated that treatment with a combination of antiviral compounds and specific immune stimulation may lead to long-term cures of lesions without the ensuing problem of papilloma recurrence.
Influence of Human Serum on Antifungal Pharmacodynamics with
Candida albicans
Authors: Zhanel George G. , Saunders David G. , Hoban Daryl J. , Karlowsky James A. 
Published: July 2002

ABSTRACT

Antifungal susceptibilities (NCCLS, approved standard M27-A, 1997) were determined for the reference strain ATCC 90028 and 21 clinical isolates of
Candida albicans
with varying levels of fluconazole susceptibility using RPMI 1640 (RPMI) and 80% fresh human serum–20% RPMI (serum). Sixty-four percent (14 of 22) of the isolates tested demonstrated significant decreases (≥4-fold) in fluconazole MICs in the presence of serum, and the remaining eight isolates exhibited no change. Itraconazole and ketoconazole, two highly protein-bound antifungal agents, had MICs in serum that were increased or unchanged for 46% (10 of 22) and 41% (9 of 22) of the isolates, respectively. All 10 isolates tested against an investigational antifungal agent, LY303366, demonstrated significant increases in the MIC required in serum, while differences in amphotericin B MICs in the two media were not observed. Four of 10 isolates tested demonstrated fourfold higher flucytosine MICs in serum than in RPMI. Postantifungal effects (PAFEs) and 24-h kill curves were determined by standard methods for selected isolates. At the MIC, fluconazole, itraconazole, ketoconazole, flucytosine, and LY303366 kill curves and PAFEs in RPMI were similar to those in serum. Isolates of fluconazole-resistant
C. albicans
required lower MICs in serum than in RPMI, without relative increases in fungal killing or PAFEs. Isolates tested against amphotericin B demonstrated significantly reduced killing and shorter PAFEs in serum than in RPMI without observable changes in MIC. In conclusion, antifungal pharmacodynamics in RPMI did not consistently predict antifungal activity in serum for azoles and amphotericin B. Generally speaking, antifungal agents with high protein binding exhibited some form of reduced activity (MIC, killing, or PAFE) in the presence of serum compared to those with low protein binding.
Antifungal Activities of Posaconazole, Ravuconazole, and Voriconazole Compared to Those of Itraconazole and Amphotericin B against 239 Clinical Isolates of
Aspergillus
spp. and Other Filamentous Fungi: Report from SENTRY Antimicrobial Surveillance Program, 2000
Authors: Pfaller M. A. , Messer S. A. , Hollis R. J. , Jones R. N. 
Published: July 2002

ABSTRACT

Posaconazole, ravuconazole, and voriconazole are new triazole derivatives that possess potent, broad-spectrum antifungal activity. We evaluated the in vitro activity of these investigational triazoles compared with that of itraconazole and amphotericin B against 239 clinical isolates of filamentous fungi from the SENTRY Program, including
Aspergillus
spp. (198 isolates),
Fusarium
spp. (7 isolates),
Penicillium
spp. (19 isolates),
Rhizopus
spp. (4 isolates),
Mucor
spp. (2 isolates), and miscellaneous species (9 isolates). The isolates were obtained from 16 different medical centers in the United States and Canada between January and December 2000. In vitro susceptibility testing was performed using the microdilution broth method outlined in the National Committee for Clinical Laboratory Standards M38-P document. Overall, posaconazole was the most active compound, inhibiting 94% of isolates at a MIC of ≤1 μg/ml, followed by voriconazole (91%), amphotericin B (89%), ravuconazole (88%), and itraconazole (70%). All three new triazoles demonstrated excellent activity (MIC, ≤1 μg/ml) against
Aspergillus
spp. (114
Aspergillus fumigatus
, 22
Aspergillus niger
, 13
Aspergillus flavus
, 9
Aspergillus versicolor
, 8
Aspergillus terreus
, and 32
Aspergillus
spp.): posaconazole (98%), voriconazole (98%), ravuconazole (92%), amphotericin B (89%), and itraconazole (72%). None of the triazoles were active against
Fusarium
spp. (MIC at which 50% of the isolates tested were inhibited [MIC
50
], >8 μg/ml) or
Mucor
spp. (MIC
50
, >8 μg/ml). Posaconazole and ravuconazole were more active than voriconazole against
Rhizopus
spp. (MIC
50
, 1 to 2 μg/ml versus >8 μg/ml, respectively). Based on these results, all three new triazoles exhibited promising activity against
Aspergillus
spp. and other less commonly encountered isolates of filamentous fungi. The clinical value of these in vitro data remains to be seen, and in vitro-in vivo correlation is needed for both new and established antifungal agents. Surveillance efforts should be expanded in order to monitor the spectrum of filamentous fungal pathogens and their in vitro susceptibility as these new antifungal agents are introduced into clinical use.
Efficacies of Fluconazole, Caspofungin, and Amphotericin B inCandida glabrata-Infected p47phox−/−Knockout Mice
Authors: Ju Justina Y. , Polhamus Cynthia , Marr Kieren A. , Holland Steven M. , Bennett John E. 
Published: July 2002

ABSTRACTCandida glabratais the second leading cause of adult candidemia, resulting in high mortality. Amphotericin B is considered the treatment of choice, while the efficacy of fluconazole is controversial and caspofungin efficacy is unknown. To ascertain drug efficacy in vivo, the utility of a murine model ofC. glabratainfection was investigated.C. glabratawas found to cause progressive, lethal infection when injected intravenously into C57BL/6 mice with reduced oxidative microbicidal capacity due to knockout of the p47phoxgene. Spleen and kidney organ CFU counts were determined in groups of mice 2 days after the mice completed 6 days of daily intraperitoneal drug treatment, which began on the day of infection. Daily injections of fluconazole at 80 mg/kg did not reduce spleen or kidney CFU counts after infection withC. glabratastrains having in vitro fluconazole MICs of 2, 32, or 256 μg/ml compared to saline-treated controls. However, this fluconazole regimen reduced spleen CFU counts in mice infected withCandida albicans, an infection that is known to be responsive to fluconazole. Caspofungin at 5 mg/kg and amphotericin B at 5 mg/kg were both effective in reducing fungal burden in spleens and kidneys ofC. glabrata-infected mice. Ten mice treated for 6 days with caspofungin at 1 mg/kg survived for 15 days, though all 10 saline-injected mice died or were so ill that they had to be sacrificed by 96 h postinfection. This murine model provided evidence of the efficacy of amphotericin B and caspofungin but not of fluconazole againstC. glabratainfection.
New Mg
2+
-Dependent Oxytetracycline Resistance Determinant Tet 34 in
Vibrio
Isolates from Marine Fish Intestinal Contents
Authors: Nonaka Lisa , Suzuki Satoru 
Published: July 2002

ABSTRACT

A new oxytetracycline (OTC) resistance (Otc
r
) determinant, Tet 34, was cloned from chromosomal DNA of
Vibrio
sp. no. 6 isolated from intestinal contents of cultured yellowtail (
Seriola quinqueradiata
). The transformant, containing cloned Tet 34, could grow in broth containing 25 μg of drug per ml with 10 mM MgCl
2
. Tet 34 encoded an open reading frame (ORF) 154 amino acids long. The amino acid sequence of the ORF was homologous to sequences of several bacterial xanthine-guanine phosphoribosyltransferases (XPRTs), which act in purine nucleotide salvage synthesis. Mg
2+
binding site residues and the active site were highly conserved in XPRT and the ORF of Tet 34. The results suggest that Tet 34 encodes a new Mg
2+
-dependent Otc
r
mechanism.
Interaction between Grapefruit Juice and Praziquantel in Humans
Authors: Castro Nelly , Jung Helgi , Medina Roberto , González-Esquivel Dinora , Lopez Mario , Sotelo Julio 
Published: July 2002

ABSTRACT

After a single oral dose of praziquantel with 250 ml of grapefruit juice, the area under the concentration-time curve and the maximum concentration in plasma of praziquantel (
C
max
) were significantly increased (
C
max
for water treatment, 637.71 ± 128.5 ng/ml; and
C
max
for grapefruit juice treatment, 1,037.65 ± 305.7 ng/ml,
P
< 0.05). No statistically significant differences were found in the time to maximum concentration of drug in plasma or elimination half-life.
A Bead-Based Method for Multiplexed Identification and Quantitation of DNA Sequences Using Flow Cytometry
Authors: Spiro Alexander , Lowe Mary , Brown Drew 
Published: July 2002

ABSTRACT
A new multiplexed, bead-based method which utilizes nucleic acid hybridizations on the surface of microscopic polystyrene spheres to identify specific sequences in heterogeneous mixtures of DNA sequences is described. The method consists of three elements: beads (5.6-μm diameter) with oligomer capture probes attached to the surface, three fluorophores for multiplexed detection, and flow cytometry instrumentation. Two fluorophores are impregnated within each bead in varying amounts to create different bead types, each associated with a unique probe. The third fluorophore is a reporter. Following capture of fluorescent cDNA sequences from environmental samples, the beads are analyzed by flow cytometric techniques which yield a signal intensity for each capture probe proportional to the amount of target sequences in the analyte. In this study, a direct hybrid capture assay was developed and evaluated with regard to sequence discrimination and quantitation of abundances. The target sequences (628 to 728 bp in length) were obtained from the 16S/23S intergenic spacer region of microorganisms collected from polluted groundwater at the nuclear waste site in Hanford, Wash. A fluorescence standard consisting of beads with a known number of fluorescent DNA molecules on the surface was developed, and the resolution, sensitivity, and lower detection limit for measuring abundances were determined. The results were compared with those of a DNA microarray using the same sequences. The bead method exhibited far superior sequence discrimination and possesses features which facilitate accurate quantitation.
PCR Primers That Amplify Fungal rRNA Genes from Environmental Samples
Authors: Borneman James , Hartin R. Jack 
Published: July 2002

ABSTRACT

Two PCR primer pairs were designed to amplify rRNA genes (rDNA) from all four major phyla of fungi:
Ascomycota
,
Basidiomycota
,
Chytridomycota
, and
Zygomycota
. PCRs performed with these primers showed that both pairs amplify DNA from organisms representing the major taxonomic groups of fungi but not from nonfungal sources. To test the ability of the primers to amplify fungal rDNA from environment samples, clone libraries from two avocado grove soils were constructed and analyzed. These soils possess different abilities to inhibit avocado root rot caused by
Phythophthora cinnamomi
. Analysis of the two rDNA clone libraries revealed differences in the two fungal communities. It also revealed a markedly different depiction of the soil fungal community than that generated by a culture-based analysis, confirming the value of rDNA-based approaches for identifying organisms that may not readily grow on agar media. Additional evidence of the usefulness of the primers was obtained by identifying fungi associated with avocado leaves. In both the soil and leaf analyses, no nonfungal rDNA sequences were identified, illustrating the selectivity of these PCR primers. This work demonstrates the ability of two newly developed PCR primer sets to amplify fungal rDNA from soil and plant tissue, thereby providing unique tools to examine this vast and mostly undescribed community of organisms.
Engineering Increased Stability in the Antimicrobial Peptide Pediocin PA-1
Authors: Johnsen Line , Fimland Gunnar , Eijsink Vincent , Nissen-Meyer Jon 
Published: July 2002

ABSTRACT
Pediocin PA-1 is a food grade antimicrobial peptide that has been used as a food preservative. Upon storage at 4°C or room temperature, pediocin PA-1 looses activity, and there is a concomitant 16-Da increase in the molecular mass. It is shown that the loss of activity follows first-order kinetics and that the instability can be prevented by replacing the single methionine residue (Met31) in pediocin PA-1. Replacing Met by Ala, Ile, or Leu protected the peptide from oxidation and had only minor effects on bacteriocin activity (for most indicator strains 100% activity was maintained). Replacement of Met by Asp was highly deleterious for bacteriocin activity.
Colonization of the Stratified Squamous Epithelium of the Nonsecreting Area of Horse Stomach by Lactobacilli
Authors: Yuki Norikatsu , Shimazaki Tomoko , Kushiro Akira , Watanabe Koichi , Uchida Kazumi , Yuyama Teruhiko , Morotomi Masami 
Published: July 2002

ABSTRACTSelective adhesion to only certain epithelia is particularly common among the bacterial members of the indigenous microflora of mammals. We have found that the stratified squamous epithelium of the nonsecreting area of horse stomach is colonized by gram-positive rods. The microscopic features of a dense layer of these bacteria on the epithelium were found to be similar to those reported in mice, rats, and swine. Adhering microorganisms were isolated and identified asLactobacillus salivarius,L. crispatus,L. reuteri, andL. agilisby DNA-DNA hybridization and 16S rRNA gene sequencing techniques. These lactobacilli associated with the horse, except forL. reuteri, were found to adhere to horse epithelial cells in vitro but not to those of rats. A symbiotic relationship of these lactobacilli with the horse is suggested.
Peptide Nucleic Acid-Mediated PCR Clamping as a Useful Supplement in the Determination of Microbial Diversity
Authors: von Wintzingerode Friedrich , Landt Olfert , Ehrlich Angelika , Göbel Ulf B. 
Published: July 2002

ABSTRACT
Peptide nucleic acid (PNA)-mediated PCR clamping (H. Ørum, P. E. Nielsen, M. Egholm, R. H. Berg, O. Buchardt, and C. Stanley, Nucleic Acids Res. 21:5332–5336, 1993) was introduced as a novel procedure to selectively amplify ribosomal DNAs (rDNAs) which are not frequently found in clone libraries generated by standard PCR from complex microbial consortia. Three different PNA molecules were used; two of these molecules (PNA-ALF and PNA-EUB353) overlapped with one of the amplification primers, whereas PNA-1114F hybridized to the middle of the amplified region. Thus, PCR clamping was achieved either by competitive binding between the PNA molecules and the forward or reverse primers (competitive clamping) or by hindering polymerase readthrough (elongation arrest). Gene libraries generated from mixed rDNA templates by using PCR clamping are enriched for clones that do not contain sequences homologous to the appropriate PNA oligomer. This effect of PCR clamping was exploited in the following two ways: (i) analysis of gene libraries generated by PCR clamping with PNA-ALF together with standard libraries reduced the number of clones which had to be analyzed to detect all of the different sequences present in an artificial rDNA mixture; and (ii) PCR clamping with PNA-EUB353 and PNA-1114F was used to selectively recover rDNA sequences which represented recently described phylogenetic groups (NKB19, TM6, cluster related to green nonsulfur bacteria) from an anaerobic, dechlorinating consortium described previously. We concluded that PCR clamping might be a useful supplement to standard PCR amplification in rDNA-based studies of microbial diversity and could be used to selectively recover members of undescribed phylogenetic clusters from complex microbial communities.
Increased Levels of Markers of Microbial Exposure in Homes with Indoor Storage of Organic Household Waste
Authors: Wouters Inge M. , Douwes Jeroen , Doekes Gert , Thorne Peter S. , Brunekreef Bert , Heederik Dick J. J. 
Published: July 2002

ABSTRACTAs part of environmental management policies in Europe, separate collection of organic household waste and nonorganic household waste has become increasingly common. As waste is often stored indoors, this policy might increase microbial exposure in the home environment. In this study we evaluated the association between indoor storage of organic waste and levels of microbial agents in house dust. The levels of bacterial endotoxins, mold β(1→3)-glucans, and fungal extracullar polysaccharides (EPS) ofAspergillusandPenicilliumspecies were determined in house dust extracts as markers of microbial exposure. House dust samples were collected in 99 homes in The Netherlands selected on the basis of whether separated organic waste was present in the house. In homes in which separated organic waste was stored indoors for 1 week or more the levels of endotoxin, EPS, and glucan were 3.2-, 7.6-, and 4.6-fold higher, respectively (allP< 0.05), on both living room and kitchen floors than the levels in homes in which only nonorganic residual waste was stored indoors. Increased levels of endotoxin and EPS were observed, 2.6- and 2.1-fold (P< 0.1), respectively, when separated organic waste was stored indoors for 1 week or less, whereas storage of nonseparated waste indoors had no effect on microbial agent levels (P> 0.2). The presence of textile floor covering was another major determinant of microbial levels (P< 0.05). Our results indicate that increased microbial contaminant levels in homes are associated with indoor storage of separated organic waste. These increased levels might increase the risk of bioaerosol-related respiratory symptoms in susceptible people.