bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ganciclovir and Cidofovir Treatment of Cytomegalovirus-Induced Myocarditis in Mice
Authors: Lenzo Jason C. , Shellam Geoffrey R. , Lawson Cassandra M. 
Published: July 2002

ABSTRACTThe cardiovascular disease myocarditis is characterized by inflammation and necrosis of cardiac muscle. This disease has been associated with various viral etiologies, including cytomegalovirus (CMV). Murine CMV (MCMV) infection of adult BALB/c mice produces a disease with acute and chronic phases similar to that found in humans. In our murine model, we have investigated the therapeutic efficacy of antiviral drug administration on myocarditis. Two drugs commonly used for CMV treatment, ganciclovir and cidofovir, were subjected to trials, with both drugs showing potent antiviral activity against MCMV both in vitro and in vivo. The acute phase of myocarditis was significantly reduced when antiviral therapy commenced 24 h postinfection. Such treatment also reduced the severity of the chronic phase of myocarditis. In contrast, antiviral treatment commencing after the acute phase had no effect on chronic myocarditis. Reinfection of mice with MCMV caused exacerbation of myocardial inflammation. Such an increase in severity of myocarditis could be prevented with either ganciclovir or cidofovir treatment, but the preexisting inflammation and necrosis of the myocardium persisted. These data highlight possible therapeutic uses of antiviral drugs in viral myocarditis as well as further elucidating the pathogenic nature of the disease.
Absence of Mutations in
marRAB
or
soxRS
in
acrB
-Overexpressing Fluoroquinolone-Resistant Clinical and Veterinary Isolates of
Escherichia coli
Authors: Webber Mark A. , Piddock Laura J. V. 
Published: July 2002

ABSTRACT

The amount of
acrB, marA
, and
soxS
mRNA was determined in 36 fluoroquinolone-resistant
E. coli
from humans and animals, 27 of which displayed a multiple-resistance phenotype.
acrB
mRNA was elevated in 11 of 36 strains. A mutation at codon 45 (Arg→Cys) in
acrR
was found in 6 of these 11 strains. Ten of the 36 isolates appeared to overexpress
soxS
, and five appeared to overexpress
marA
. A number of mutations were found in the
marR
and
soxR
repressor genes, correlating with greater amounts of
marA
and
soxS
mRNA, respectively.
Novel Bifunctional Inhibitor of Xylanase and Aspartic Protease: Implications for Inhibition of Fungal Growth
Authors: Dash Chandravanu , Ahmad Absar , Nath Devyani , Rao Mala 
Published: July 2002

ABSTRACTA novel bifunctional inhibitor (ATBI) from an extremophilicBacillussp. exhibiting an activity against phytopathogenic fungi, includingAlternaria, Aspergillus, Curvularia, Colletotricum, Fusarium, andPhomopsisspecies, and the saprophytic fungusTrichodermasp. has been investigated. The 50% inhibitory concentrations of ATBI ranged from 0.30 to 5.9 μg/ml, whereas the MIC varied from 0.60 to 3.5 μg/ml for the fungal growth inhibition. The negative charge and the absence of periodic secondary structure in ATBI suggested an alternative mechanism for fungal growth inhibition. Rescue of fungal growth inhibition by the hydrolytic products of xylanase and aspartic protease indicated the involvement of these enzymes in cellular growth. The chemical modification of Asp or Glu or Lys residues of ATBI by 2,4,6-trinitrobenzenesulfonic acid and Woodward's reagent K, respectively, abolished its antifungal activity. In addition, ATBI also inhibited xylanase and aspartic protease competitively, withKivalues 1.75 and 3.25 μM, respectively. Our discovery led us to envisage a paradigm shift in the concept of fungal growth inhibition for the role of antixylanolytic activity. Here we report for the first time a novel class of antifungal peptide, exhibiting bifunctional inhibitory activity.
Role of Penicillin-Binding Protein 5 in Expression of Ampicillin Resistance and Peptidoglycan Structure in
Enterococcus faecium
Authors: Sifaoui Farid , Arthur Michel , Rice Louis , Gutmann Laurent 
Published: July 2002

ABSTRACT

The contribution of penicillin-binding protein 5 (PBP 5) to intrinsic and acquired β-lactam resistance was investigated by constructing isogenic strains of
Enterococcus faecium
producing different PBP 5. The
pbp5
genes from three
E. faecium
clinical isolates (BM4107, D344, and
H80721
) were cloned into the shuttle vector pAT392 and introduced into
E. faecium
D344S, a spontaneous derivative of
E. faecium
D344 highly susceptible to ampicillin due to deletion of
pbp5
(MIC, 0.03 μg/ml). Immunodetection of PBP5 indicated that cloning of the
pbp5
genes into pAT392 resulted in moderate overproduction of PBP 5 in comparison to wild-type strains. This difference may be attributed to a difference in gene copy number. Expression of the
pbp5
genes from BM4107 (MIC, 2 μg/ml), D344 (MIC, 24 μg/ml), and
H80721
(MIC, 512 μg/ml) in D344S conferred relatively low levels of resistance to ampicillin (MICs, 6, 12, and 20 μg/ml, respectively). A methionine-to-alanine substitution was introduced at position 485 of the BM4107 PBP 5 by site-directed mutagenesis. In contrast to previous hypotheses based on comparison of nonisogenic strains, this substitution resulted in only a 2.5-fold increase in the ampicillin MIC. The reversed-phase high-performance liquid chromatography muropeptide profiles of D344 and D344S were similar, indicating that deletion of
pbp5
was not associated with a detectable defect in cell wall synthesis. These results indicate that
pbp5
is a nonessential gene responsible for intrinsic resistance to moderate levels of ampicillin and by itself cannot confer high-level resistance.
In Vitro Activities of New and Conventional Antifungal Agents against ClinicalScedosporiumIsolates
Authors: Meletiadis Joseph , Meis Jacques F. G. M. , Mouton Johan W. , Rodriquez-Tudela Juan Luis , Donnelly J. Peter , Verweij Paul E. , the EUROFUNG Network  
Published: July 2002

ABSTRACTThe susceptibilities of 13 clinical isolates ofScedosporium apiospermumand 55 clinical isolates ofS. prolificansto new and conventional drugs belonging to three different classes of antifungal agents, the azoles (miconazole, itraconazole, voriconazole, UR-9825, posaconazole), the polyenes (amphotericin B, nystatin and liposomal nystatin), and allylamines (terbinafine), were studied by use of proposed standard M38-P of NCCLS. Low growth-inhibitory antifungal activities were found in vitro for most of the drugs tested againstS. prolificansisolates, with the MICs at which 90% of isolates are inhibited (MIC90s) being >8 μg/ml; the MIC90s of voriconazole and UR-9825, however, were 4 μg/ml.S. apiospermumisolates were more susceptible in vitro, with the highest activity exhibited by voriconazole (MIC90s, 0.5 μg/ml), followed by miconazole (MIC90s, 1 μg/ml), UR-9825 and posaconazole (MIC90s, 2 μg/ml), and itraconazole (MIC90s, 4 μg/ml). The MICs of terbinafine, amphotericin B, and the two formulations of nystatin (for which no statistically significant differences in antifungal activities were found for the two species) forS. apiospermumisolates were high. Cross-resistance was observed among all the azoles except posaconazole and among all the polyenes except the lipid formulation. A distribution analysis was performed with the MICs of each drug and for each species. Bimodal and skewed MIC distributions were obtained, and cutoffs indicating the borders of different MIC subpopulations of the distributions were determined on the basis of the normal plot technique. These cutoffs were in many cases reproducible between 48 and 72 h.
Potent Efficacy of Entecavir (BMS-200475) in a Duck Model of Hepatitis B Virus Replication
Authors: Marion Patricia L. , Salazar Felix H. , Winters Mark A. , Colonno Richard J. 
Published: July 2002

ABSTRACT

The ability of entecavir (ETV) to inhibit
Duck hepatitis B virus
(DHBV) infection in duck hepatocytes and ducklings was examined using lamivudine (3TC) as a comparator drug. ETV exhibited antiviral activity (50% effective concentration [EC
50
], 0.13 nM) in DHBV-infected duck hepatocytes that was >1,000-fold more potent than that of 3TC (EC
50
, 138 nM). A 21-day treatment of ducklings with 1 mg of ETV per kg of body weight per day by oral gavage resulted in a mean reduction of log
10
3.1 in serum DHBV DNA levels. Daily treatment with 0.1 mg of ETV/kg was nearly as effective, achieving an average viral DNA level decrease of log
10
2.1. Reducing the daily dose of ETV to only 0.01 mg/kg resulted in an average viral DNA level decrease of log
10
0.97. Daily treatment with 25 mg of 3TC/kg resulted in an average viral DNA level decrease of log
10
0.66, compared to the log
10
0.20 drop seen for ducklings given the vehicle alone. ETV was also more effective in decreasing the DHBV DNA levels in duck livers after 21 days of treatment, causing average drops of log
10
1.41, log
10
0.76, and log
10
0.26 for dose levels of 1.0, 0.1, and 0.01 mg/kg, respectively, compared to a decrease of log
10
0.06 for 3TC at a dose level of 25 mg/kg. Levels of viral covalently closed circular DNA in the treatment group receiving 1 mg of ETV/kg were reduced compared to those in the vehicle-treated group. ETV and 3TC were both well tolerated in all treated animals. These results show that ETV is a highly potent and effective antiviral in the DHBV duck model.
Grepafloxacin, a Dimethyl Derivative of Ciprofloxacin, Acts Preferentially through Gyrase in
Streptococcus pneumoniae
: Role of the C-5 Group in Target Specificity
Authors: Morris Julia E. , Pan Xiao-Su , Fisher L. Mark 
Published: July 2002

ABSTRACT

Grepafloxacin, a 5-
methyl
-7-piperazinyl-3"-
methyl
analogue of ciprofloxacin, was used to obtain stepwise-selected mutants of
Streptococcus pneumoniae
7785. Analysis of the quinolone resistance-determining regions of the
gyrA
,
gyrB
,
parC
, and
parE
genes in these mutants revealed that
gyrA
mutations preceded those in
parC
. Given that ciprofloxacin (5-
H
,7-piperazinyl) and AM-1121 (5-
H
,7-piperazinyl-3"-
methyl
) both act through topoisomerase IV, we conclude that the 5-
methyl
group of grepafloxacin favors gyrase in
S. pneumoniae
.
Doxycycline Induces Expression of P Glycoprotein in MCF-7 Breast Carcinoma Cells
Authors: Mealey Katrina L. , Barhoumi Rola , Burghardt Robert C. , Safe Stephen , Kochevar Deborah T. 
Published: July 2002

ABSTRACT

P-glycoprotein (P-gp) overexpression by tumor cells imparts resistance to multiple antineoplastic chemotherapeutic agents (multiple drug resistance). Treatment of tumor cells with chemotherapeutic agents such as anthracyclines, epipodophyllotoxins, and
Vinca
alkaloids results in induction of P-gp expression. This study was performed to determine if clinically relevant antimicrobial drugs (i.e., drugs that are used to treat bacterial infections in cancer patients) other than antineoplastic agents can induce expression of P-gp in MCF-7 breast carcinoma cells. Expression of P-gp and
MDR1
mRNA was determined in samples from MCF-7 cells that were treated in culture with doxorubicin (positive control) and the antimicrobial drugs doxycycline, piperacillin, and cefoperazone. The functional status of P-gp was assessed using laser cytometry to determine intracellular doxorubicin concentrations. The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay was used to determine if the cytotoxicity of experimental drugs was related to their ability to induce P-gp expression. MCF-7 cells treated with doxycycline (MCF-7/doxy) were stimulated to overexpress P-gp, whereas cells treated with piperacillin and cefoperazone did not overexpress P-gp. MCF-7/doxy cells were compared to a positive-control subline, MCF-7/Adr, previously selected for doxorubicin resistance, and to MCF-7 cells treated with doxorubicin (MCF-7/doxo). All three sublines overexpressed P-gp and
MDR1
mRNA and accumulated less intracellular doxorubicin than did control MCF-7 cells. P-gp expression was induced only by experimental drugs that were cytotoxic (doxorubicin and doxycycline). Doxycycline, a drug that has been used for treatment of bacterial infections in cancer patients, can induce functional P-gp expression in cancer cells, resulting in multidrug resistance.
Expression of Efflux Pump Gene
pmrA
in Fluoroquinolone-Resistant and -Susceptible Clinical Isolates of
Streptococcus pneumoniae
Authors: Piddock Laura J. V. , Johnson Maggie M. , Simjee S. , Pumbwe L. 
Published: July 2002

ABSTRACT

Thirty-four ciprofloxacin-resistant (MIC ≥ 2 μg/ml) and 12 ciprofloxacin-susceptible clinical isolates of
Streptococcus pneumoniae
were divided into four groups based upon susceptibility to norfloxacin and the effect of reserpine (20 μg/ml). The quinolone-resistance-determining regions of
parC
,
parE
,
gyrA
, and
gyrB
of all ciprofloxacin-resistant clinical isolates were sequenced, and the activities of eight other fluoroquinolones, acriflavine, ethidium bromide, chloramphenicol, and tetracycline in the presence and absence of reserpine were determined. Despite a marked effect of reserpine upon the activity of norfloxacin, there were only a few isolates for which the activity of another fluoroquinolone was enhanced by reserpine. For most isolates the MICs of acriflavine and ethidium bromide were lowered in the presence of reserpine despite the lack of effect of this efflux pump inhibitor on fluoroquinolone activity. The strains that were most resistant to the fluoroquinolones were predominantly those with mutations in three genes. Expression of the gene encoding the efflux pump PmrA was examined by Northern blotting (quantified by quantitative competitive reverse transcriptase PCR) and compared with that of
S
.
pneumoniae
R6 and R6N. Within each group there were isolates that had high-, medium-, and low-level expression of this gene; however, increased expression was not exclusively associated with those isolates with a phenotype suggestive of an efflux mutant. These data suggest that there is another reserpine-sensitive efflux pump in
S
.
pneumoniae
that extrudes ethidium bromide and acriflavine but not fluoroquinolones.
Human Immunodeficiency Virus (HIV) Type 1 Reverse Transcriptase Resistance Mutations in Hepatitis B Virus (HBV)-HIV-Coinfected Patients Treated for HBV Chronic Infection Once Daily with 10 Milligrams of Adefovir Dipivoxil Combined with Lamivudine
Authors: Delaugerre Constance , Marcelin Anne-Geneviève , Thibault Vincent , Peytavin Gilles , Bombled Tony , Bochet Marie-Valérie , Katlama Christine , Benhamou Yves , Calvez Vincent 
Published: July 2002

ABSTRACT
Adefovir dipivoxil (ADV) at a suboptimal concentration for human immunodeficiency virus type 1 (HIV-1) (10 mg once daily) can be used to treat hepatitis B virus (HBV) infection in HIV-1-HBV-coinfected patients and does not, even in the case of uncontrolled HIV-1 replication, select for either ADV mutations at codons 65 and 70 or any other particular HIV-1 reverse transcriptase resistance profile.
Identification of Major Glucan-Associated Cell Wall Proteins of
Candida albicans
and Their Role in Fluconazole Resistance
Authors: Angiolella Letizia , Micocci Mia M. , D'Alessio Simona , Girolamo Antonietta , Maras Bruno , Cassone Antonio 
Published: July 2002

ABSTRACT

Identification of major glucan-associated proteins (GAPs) of the cell wall of a number of
Candida albicans
isolates susceptible or resistant to fluconazole (FLC) was addressed by direct sequencing of the protein bands resolved by unidimensional gel electrophoresis. Changes in the GAP compositions of the different strains grown in the presence of the drug were also investigated. In the FLC-susceptible strains, the major (more abundant) GAPs were enolase (46 kDa), two isoforms of phosphoglyceromutase (32 and 29 kDa), and two β-(1-3)-exoglucanases (44 and 34 kDa), one of which (the 34-kDa component) was glycosylated. When these strains were grown in the presence of FLC there were substantial decreases in the intensities of the two enzymes of the glycolytic pathway (enolase and the phosphoglyceromutases), which were apparently replaced by enhancement of the exoglucanase constituents, particularly the 44-kDa one. This GAP pattern closely mimicked that observed in the FLC-resistant strains whether they were grown in the presence or in the absence of the drug. Both the enolase and the exoglucanase constituents were detected in the culture supernatants of FLC-treated cells, together with substantial amounts of highly glycosylated, probably mannoprotein secretory material, suggesting that FLC may cause marked alterations of GAP incorporation into the cell wall. Altogether, we were able to identify all major GAP constituents and monitor their distributions in the cell wall of
C. albicans
during treatment with FLC. The near equivalence of the GAP profile for the FLC-susceptible strain grown in the presence of FLC to that for the FLC-resistant strain suggests that the effects of the drug on GAPs may be stably incorporated into the cell wall of the fungus upon acquisition of resistance.
Concentration and Detection of Caliciviruses in Water Samples by Reverse Transcription-PCR
Authors: Huang P. W. , Laborde D. , Land V. R. , Matson D. O. , Smith A. W. , Jiang X. 
Published: July 2002

ABSTRACT
Human caliciviruses (HuCVs) cause waterborne outbreaks of gastroenteritis. Standard indicators of a safe water supply do not adequately predict contamination of water by viruses, including HuCVs. We developed a method to concentrate and detect HuCVs in water samples by using a cultivable primate calicivirus (Pan-1) as a model. Viable Pan-1 was seeded in different types of water and then filtered with a 1MDS filter, eluted with beef extract (BE), and reconcentrated by polyethylene glycol (PEG) precipitation. The viruses in the final samples were tested by plaque assay or by reverse transcription (RT)-PCR following extraction of the RNA with Trizol. Pan-1 was more sensitive to high-pH treatment than poliovirus was; a pH 9.0 BE solution was found to recover 35% more viable Pan-1 than a pH 9.5 BE solution recovered. Pan-1 was recovered from small volumes of deionized, finished, ground, and surface waters at efficiencies of 94, 73, 67, and 64%, respectively, when samples were assayed after elution without further concentration. When larger volumes of water (up to 40 liters) were tested after elution and concentration with PEG, 38, 19, and 14% of the seeded Pan-1 were recovered from finished, ground, and surface waters, respectively. The limit of detection of Pan-1 by RT-PCR was estimated to be 0.75 to 1.5 PFU in 40 liters of finished water. This method may be adapted for monitoring HuCVs in drinking water and other types of water for public health safety.
Phenylacetyl-Coenzyme A Is the True Inducer of the Phenylacetic Acid Catabolism Pathway in
Pseudomonas putida
U
Authors: García Belén , Olivera Elías R. , Miñambres Baltasar , Carnicero David , Muñiz Carmen , Naharro Germán , Luengo José M. 
Published: July 2002

ABSTRACT

Aerobic degradation of phenylacetic acid in
Pseudomonas putida
U is carried out by a central catabolism pathway (phenylacetyl-coenzyme A [CoA] catabolon core). Induction of this route was analyzed by using different mutants specifically designed for this objective. Our results revealed that the true inducer molecule is phenylacetyl-CoA and not other structurally or catabolically related aromatic compounds.
Photosynthetic Bradyrhizobia Are Natural Endophytes of the African Wild Rice
Oryza breviligulata
Authors: Chaintreuil Clémence , Giraud Eric , Prin Yves , Lorquin Jean , Bâ Amadou , Gillis Monique , de Lajudie Philippe , Dreyfus Bernard 
Published: July 2002

ABSTRACT

We investigated the presence of endophytic rhizobia within the roots of the wetland wild rice
Oryza breviligulata
, which is the ancestor of the African cultivated rice
Oryza glaberrima
. This primitive rice species grows in the same wetland sites as
Aeschynomene sensitiva
, an aquatic stem-nodulated legume associated with photosynthetic strains of
Bradyrhizobium
. Twenty endophytic and aquatic isolates were obtained at three different sites in West Africa (Senegal and Guinea) from nodal roots of
O. breviligulata
and surrounding water by using
A. sensitiva
as a trap legume. Most endophytic and aquatic isolates were photosynthetic and belonged to the same phylogenetic
Bradyrhizobium/Blastobacter
subgroup as the typical photosynthetic
Bradyrhizobium
strains previously isolated from
Aeschynomene
stem nodules. Nitrogen-fixing activity, measured by acetylene reduction, was detected in rice plants inoculated with endophytic isolates. A 20% increase in the shoot growth and grain yield of
O. breviligulata
grown in a greenhouse was also observed upon inoculation with one endophytic strain and one
Aeschynomene
photosynthetic strain. The photosynthetic
Bradyrhizobium
sp. strain ORS278 extensively colonized the root surface, followed by intercellular, and rarely intracellular, bacterial invasion of the rice roots, which was determined with a
lacZ
-tagged mutant of ORS278. The discovery that photosynthetic
Bradyrhizobium
strains, which are usually known to induce nitrogen-fixing nodules on stems of the legume
Aeschynomene
, are also natural true endophytes of the primitive rice
O. breviligulata
could significantly enhance cultivated rice production.
Improved Direct Viable Count Procedure for Quantitative Estimation of Bacterial Viability in Freshwater Environments
Authors: Yokomaku Daisaku , Yamaguchi Nobuyasu , Nasu Masao 
Published: July 2002

ABSTRACT
A direct viable count (DVC) procedure was developed which clearly and easily discriminates the viability of bacterial cells. In this quantitative DVC (qDVC) procedure, viable cells are selectively lysed by spheroplast formation caused by incubation with antibiotics and glycine. This glycine effect leads to swollen cells with a very loose cell wall. The viable cells then are lysed easily by a single freeze-thaw treatment. The number of viable cells was obtained by subtracting the number of remaining cells after the qDVC procedure from the total cell number before the qDVC incubation. This improved procedure should provide useful information about the metabolic potential of natural bacterial communities.
Interspecific Transfer of
Streptomyces
Giant Linear Plasmids in Sterile Amended Soil Microcosms
Authors: Ravel Jacques , Wellington Elizabeth M. H. , Hill Russell T. 
Published: July 2002

ABSTRACT

The interspecific transfer of two giant linear plasmids was investigated in sterile soil microcosms. Plasmids pRJ3L (322 kb) and pRJ28 (330 kb), both encoding mercury resistance, were successfully transferred in amended soil microcosms from their streptomycete hosts, the isolates CHR3 and CHR28, respectively, to a plasmidless and mercury-sensitive strain,
Streptomyces lividans
TK24. Transconjugants of
S. lividans
TK24 were first observed after 2 to 3 days of incubation at 30°C, which corresponded to the time taken for the formation of mycelia in soil. Transfer frequencies were 4.8 × 10
−4
and 3.6 × 10
−5
CFU/donor genome for pRJ3L and pRJ28, respectively. Transconjugants were analyzed by pulsed-field gel electrophoresis for the presence of plasmids, and plasmid identity was confirmed by restriction digests. Total genomic DNA digests confirmed that transconjugants were
S. lividans
TK24. The mercury resistance genes were shown to be on the plasmid in the transconjugants by hybridization analysis and were still functional. This is the first demonstration of transfer of giant linear plasmids in sterile soil microcosms. Giant linear plasmids were detected in many
Streptomyces
spp. isolated from mercury-contaminated sediments from Boston Harbor (United States), Townsville Harbor (Australia), and the Sali River (Tucuman, Argentina). Mercury resistance genes were shown to be present on some of these plasmids. Our findings that giant linear plasmids can be transferred between
Streptomyces
spp. and are common in environmental
Streptomyces
isolates suggest that these plasmids are important in gene transfer between streptomycetes in the environment.