bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Type II Pathway for Fatty Acid Biosynthesis Presents Drug Targets in
Plasmodium falciparum
Authors: Waller Ross F. , Ralph Stuart A. , Reed Michael B. , Su Vanessa , Douglas James D. , Minnikin David E. , Cowman Alan F. , Besra Gurdyal S. , McFadden Geoffrey I. 
Published: December 2002

ABSTRACT

It has long been held that the malaria parasite,
Plasmodium
sp., is incapable of de novo fatty acid synthesis. This view has recently been overturned with the emergence of data for the presence of a fatty acid biosynthetic pathway in the relict plastid of
P. falciparum
(known as the apicoplast). This pathway represents the type II pathway common to plant chloroplasts and bacteria but distinct from the type I pathway of animals including humans. Specific inhibitors of the type II pathway, thiolactomycin and triclosan, have been reported to target this
Plasmodium
pathway. Here we report further inhibitors of the plastid-based pathway that inhibit
Plasmodium
parasites. These include several analogues of thiolactomycin, two with sixfold-greater efficacy than thiolactomycin. We also report that parasites respond very rapidly to such inhibitors and that the greatest sensitivity is seen in ring-stage parasites. This study substantiates the importance of fatty acid synthesis for blood-stage parasite survival and shows that this pathway provides scope for the development of novel antimalarial drugs.
Fluconazole Susceptibility of Vaginal Isolates Obtained from Women with Complicated
Candida
Vaginitis: Clinical Implications
Authors: Sobel J. D. , Zervos M. , Reed B. D. , Hooton T. , Soper D. , Nyirjesy P. , Heine M. W. , Willems J. , Panzer H. 
Published: December 2002

ABSTRACT

Despite considerable evidence of azole resistance in oral candidiasis due to
Candida
species, little is known about the azole susceptibilities of the genital tract isolates responsible for vaginitis. The fluconazole susceptibilities of vaginal isolates obtained during a multicenter study of 556 women with complicated
Candida
vaginitis were determined by evaluating two fluconazole treatment regimens. Of 393 baseline isolates of
Candida albicans
, 377 (96%) were highly susceptible to fluconazole (MICs, <8 μg/ml) and 14 (3.6%) were resistant (MICs, ≥64 μg/ml). Following fluconazole therapy, one case of in vitro resistance developed during 6 weeks of monitoring. In accordance with the NCCLS definition, in vitro fluconazole resistance correlated poorly with the clinical response, although a trend of a higher mycological failure rate was found (41 versus 19.6% on day 14). By using an alternative breakpoint of 1 μg/ml, based upon the concentrations of fluconazole achievable in vaginal tissue, no significant differences in the clinical and mycological responses were observed when isolates (
n
= 250) for which MICs were ≤1 μg/ml were compared with isolates (
n
= 30) for which MICs were >1 μg/ml, although a trend toward an improved clinical outcome was noted on day 14 (odds ratio, >2.7; 95% confidence interval, 0.91, 8.30). Although clinical failure was uncommon, symptomatic recurrence or mycological relapse almost invariably occurred with highly sensitive strains (MICs, <1.0 μg/ml). In vitro fluconazole resistance developed in 2 of 18 initially susceptible
C. glabrata
isolates following fluconazole exposure. Susceptibility testing for women with complicated
Candida
vaginitis appears to be unjustified.
Penetration of Dihydroartemisinin into Cerebrospinal Fluid after Administration of Intravenous Artesunate in Severe Falciparum Malaria
Authors: Davis Timothy M. E. , Binh Tran Quang , Ilett Kenneth F. , Batty Kevin T. , Phuöng Hoang Lan , Chiswell Gregory M. , Phuong Vu Duong Bich , Agus Cindy 
Published: December 2002

ABSTRACT
Penetration of cerebrospinal fluid (CSF) by artesunate and DHA was assessed in six adults with cerebral or severe malaria. Lumbar punctures were performed on admission and during convalescence, at 15 min (patient 1), 30 min (patient 2), 45 min (patient 3), 60 min (patient 4), 90 min (patient 5), and 120 min (patient 6) after intravenous administration of 120 mg of artesunate. No artesunate was detectable in CSF. In both studies, DHA levels in CSF increased with time while dihydroartemisinin levels in plasma fell. Dihydroartemisinin might accumulate in CSF during frequent artesunate dosing.
gyrA
Mutations in Ciprofloxacin-Resistant
Bartonella bacilliformis
Strains Obtained In Vitro
Authors: Minnick Michael F. , Wilson Zachary R. , Smitherman Laura S. , Samuels D. Scott 
Published: December 2002

ABSTRACT

We isolated and characterized mutants of
Bartonella bacilliformis
that are resistant to the fluoroquinolone antibiotic ciprofloxacin, which targets the A subunit of DNA gyrase. Mutants had single point mutations in the
gyrA
gene that changed either Asp-90 to Gly or Asp-95 to Asn and had 3- or 16-fold higher resistance, respectively, to ciprofloxacin than did wild-type
B. bacilliformis
. Asp-95 is homologous to Asp-87 of
Escherichia coli
GyrA and is a common residue mutated in fluoroquinolone-resistant strains of other bacteria. This is the first report of a mutation at an Asp-90 homologue, which corresponds to Asp-82 in
E. coli
GyrA.
Flow Cytometric Assessment of Susceptibilities of
Streptococcus pyogenes
to Erythromycin and Rokitamycin
Authors: Braga Pier Carlo , Bovio Cinzia , Culici Maria , Dal Sasso Monica 
Published: December 2002

ABSTRACT

The effects of erythromycin (a 14-membered ring macrolide) and rokitamycin (a 16-membered ring macrolide) on the viability of the
Streptococcus pyogenes
M phenotype were studied by means of flow cytometry and fluorescence microscopy by using a combination of two fluorochromes (syto 9 and propidium iodide) that stains live bacteria green and dead bacteria red. In order to apply the flow cytometry, a bacterial sonication procedure was expressly set up to separate single cells from the long, intralaced
S. pyogenes
chains of up to 30 to 40 cells that have previously prevented the application of flow cytometry to this type of bacteria. The association of flow cytometry using an appropriate sonication procedure, together with a combination of fluorescent probes, offered the possibility of very quickly investigating the different microbiological effects of rokitamycin at 2 μg/ml, which was active on the
S. pyogenes
M phenotype, and of erythromycin at doses of up to 32 μg/ml, which was not.
In Vitro Bactericidal Activities of Linezolid in Combination with Vancomycin, Gentamicin, Ciprofloxacin, Fusidic Acid, and Rifampin against
Staphylococcus aureus
Authors: Grohs Patrick , Kitzis Marie-Dominique , Gutmann Laurent 
Published: December 2002

ABSTRACT

The in vitro activities of linezolid were determined alone and in combination with vancomycin, ciprofloxacin, gentamicin, fusidic acid, or rifampin against five methicillin-susceptible
Staphylococcus aureus
(MSSA) and five methicillin-resistant
S. aureus
(MRSA) strains. Similar responses were obtained against MSSA and MRSA. When combined with fusidic acid, gentamicin, or rifampin, linezolid prevented selection of resistant mutants but showed no synergy. When linezolid was combined with vancomycin and ciprofloxacin, a slight antagonism was observed. While the combination with linezolid may reduce the emergence of mutants resistant to the associated drugs, the absence of synergy, especially in the case of vancomycin and ciprofloxacin, does not argue in favor of such combinations.
Molecular Characterization of Quinolone-Resistant
Neisseria gonorrhoeae
in Hong Kong
Authors: Kam Kai Man , Kam Shirley Sin Yee , Cheung Danny Tze Leung , Tung Viola Wai Na , Au Wai Fun , Cheung May May 
Published: December 2002

ABSTRACT

In Hong Kong, ParC changes among high-level quinolone-resistant
Neisseria gonorrhoeae
(QRNG) isolates at Ser-87→Arg were associated with a higher level of resistance than a Ser-87→Ile alteration. Two previously undescribed mutations in clinical isolates occurring in
gyrA
, conferring Ala-92→Pro and Asp-95→Tyr changes, were detected. Nine different outer membrane lipoprotein (Lip) repeat classes—11 to 19 repeats—were identified, with repeat lengths of 16 and 17 the most common, indicating considerable strain diversity.
Actinomycin D Induces High-Level Resistance to Thymidine Analogs in Replication of Human Immunodeficiency Virus Type 1 by Interfering with Host Cell Thymidine Kinase Expression
Authors: Imamichi Tomozumi , Murphy Michael A. , Adelsberger Joseph W. , Yang Jun , Watkins Catherine M. , Berg Steve C. , Baseler Michael W. , Lempicki Richard A. , Guo Jianhui , Levin Judith G. , Lane H. Clifford 
Published: December 2002

ABSTRACT
Actinomycin D (ActD) is a transcription inhibitor and has been used in the treatment of certain forms of cancer. ActD has been reported to be a potential inhibitor of human immunodeficiency virus type 1 (HIV-1) replication due to its ability to inhibit reverse transcription. In contrast to what was expected, low concentrations of ActD (1 to 10 nM) upregulated HIV-1 replication 8- to 10-fold in MT-2 cells and had no effect on HIV-2 replication or on HIV-1 replication in MT-4, Jurkat, or peripheral blood mononuclear cells. The upregulation of HIV-1 replication was associated with an increase in HIV-1 transcription and a decrease in CD4 and CXCR4 expression. To further evaluate the effects of ActD on emergence of drug resistance in HIV-1 replication, a series of drug resistance assays were performed. Of interest, treatment of MT-2 cells with ActD also led to a high level of resistance to thymidine analogs (>1,000-fold increase in resistance to zidovudine and >250-fold to stavudine) but not to other nucleoside reverse transcriptases (RT), nonnucleoside RT, or protease inhibitors. This resistance appeared to be due to a suppression of host cell thymidine kinase-1 (TK-1) expression. These results indicate that ActD leads to a novel form of thymidine analog resistance by suppressing host cell TK-1 expression. These results suggest that administration of combination drugs to HIV-1-infected patients may induce resistance to antiretroviral compounds via a modification of cellular factors.
Comparing the Ex Vivo Fitness of CCR5-Tropic Human Immunodeficiency Virus Type 1 Isolates of Subtypes B and C
Authors: Ball Sarah C. , Abraha Awet , Collins Kalonji R. , Marozsan Andre J. , Baird Heather , Quiñones-Mateu Miguel E. , Penn-Nicholson Adam , Murray Michael , Richard Nathalie , Lobritz Michael , Zimmerman Peter A. , Kawamura Tatsuyoshi , Blauvelt Andrew , Arts Eric J. 
Published: December 2002

ABSTRACTContinual human immunodeficiency virus type 1 (HIV-1) evolution and expansion within the human population have led to unequal distribution of HIV-1 group M subtypes. In particular, recent outgrowth of subtype C in southern Africa, India, and China has fueled speculation that subtype C isolates may be more fit in vivo. In this study, nine subtype B and six subtype C HIV-1 isolates were added to peripheral blood mononuclear cell cultures for a complete pairwise competition experiment. All subtype C HIV-1 isolates were less fit than subtype B isolates (P< 0.0001), but intrasubtype variations in HIV-1 fitness were not significant. Increased fitness of subtype B over subtype C was also observed in primary CD4+T cells and macrophages from different human donors but not in skin-derived human Langerhans cells. Detailed analysis of the retroviral life cycle during several B and C virus competitions indicated that the efficiency of host cell entry may have a significant impact on relative fitness. Furthermore, phyletic analyses of fitness differences suggested that, for a recombined subtype B/C HIV-1 isolate, higher fitness mapped to the subtype Benvgene rather than the subtype Cgagandpolgenes. These results suggest that subtype B and C HIV-1 may be transmitted with equal efficiency (Langerhans cell data) but that subtype C isolates may be less fit following initial infection (T-cell and macrophage data) and may lead to slower disease progression.
Subgroup B and F Fiber Chimeras Eliminate Normal Adenovirus Type 5 Vector Transduction In Vitro and In Vivo
Authors: Schoggins John W. , Gall Jason G. D. , Falck-Pedersen Erik 
Published: December 2002

ABSTRACT
Altering adenovirus vector (Ad vector) targeting is an important goal for a variety of gene therapy applications and involves eliminating or reducing the normal tropism of a vector and retargeting through a distinct receptor-ligand pathway. The first step of Ad vector infection is high-affinity binding to a target cellular receptor. For the majority of adenoviruses and Ad vectors, the fiber capsid protein serves this purpose, binding to the coxsackievirus and adenovirus receptor (CAR) present on a variety of cell types. In this study we have explored a novel approach to altering Ad type 5 (Ad5) vector targeting based on serotypic differences in fiber function. The subgroup B viruses bind to an unidentified receptor that is distinct from CAR. The subgroup F viruses are the only adenoviruses that express two distinct terminal exons encoding fiber open reading frames. We have constructed chimeric fiber adenoviruses that utilize the tandem fiber arrangement of the subgroup F genome configuration. By taking advantage of serotypic differences in fiber expression, fiber shaft length, and fiber binding efficiency, we have developed a tandem fiber vector that has low binding efficiency for the known fiber binding sites, does not rely on an Ad5-based fiber, and can be grown to high titer using conventional cell lines. Importantly, when characterizing these vectors in vivo, we find the subgroup B system and our optimal tandem fiber system demonstrate reduced liver transduction by over 2 logs compared to an Ad5 fiber vector. These attributes make the tandem fiber vector a useful alternative to conventional strategies for fiber manipulation of adenovirus vectors.
Identification of Protective Epitopes on Ebola Virus Glycoprotein at the Single Amino Acid Level by Using Recombinant Vesicular Stomatitis Viruses
Authors: Takada Ayato , Feldmann Heinz , Stroeher Ute , Bray Mike , Watanabe Shinji , Ito Hiroshi , McGregor Martha , Kawaoka Yoshihiro 
Published: December 2002

ABSTRACT

Ebola virus
causes lethal hemorrhagic fever in humans, but currently there are no effective vaccines or antiviral compounds for this infectious disease. Passive transfer of monoclonal antibodies (MAbs) protects mice from lethal Ebola virus infection (J. A. Wilson, M. Hevey, R. Bakken, S. Guest, M. Bray, A. L. Schmaljohn, and M. K. Hart, Science 287:1664-1666, 2000). However, the epitopes responsible for neutralization have been only partially characterized because some of the MAbs do not recognize the short synthetic peptides used for epitope mapping. To identify the amino acids recognized by neutralizing and protective antibodies, we generated a recombinant vesicular stomatitis virus (VSV) containing the Ebola virus glycoprotein-encoding gene instead of the VSV G protein-encoding gene and used it to select escape variants by growing it in the presence of a MAb (133/3.16 or 226/8.1) that neutralizes the infectivity of the virus. All three variants selected by MAb 133/3.16 contained a single amino acid substitution at amino acid position 549 in the GP2 subunit. By contrast, MAb 226/8.1 selected three different variants containing substitutions at positions 134, 194, and 199 in the GP1 subunit, suggesting that this antibody recognized a conformational epitope. Passive transfer of each of these MAbs completely protected mice from a lethal Ebola virus infection. These data indicate that neutralizing antibody cocktails for passive prophylaxis and therapy of Ebola hemorrhagic fever can reduce the possibility of the emergence of antigenic variants in infected individuals.
Antiviral Effect and Virus-Host Interactions in Response to Alpha Interferon, Gamma Interferon, Poly(I)-Poly(C), Tumor Necrosis Factor Alpha, and Ribavirin in Hepatitis C Virus Subgenomic Replicons
Authors: Lanford Robert E. , Guerra Bernadette , Lee Helen , Averett Devron R. , Pfeiffer Brad , Chavez Deborah , Notvall Lena , Bigger Catherine 
Published: December 2002

ABSTRACTThe recently developed hepatitis C virus (HCV) subgenomic replicon system was utilized to evaluate the efficacy of several known antiviral agents. Cell lines that persistently maintained a genotype 1b replicon were selected. The replicon resident in each cell line had acquired adaptive mutations in the NS5A region that increased colony-forming efficiency, and some replicons had acquired NS3 mutations that alone did not enhance colony-forming efficiency but were synergistic with NS5A mutations. A replicon constructed from the infectious clone of the HCV-1 strain (genotype 1a) was not capable of inducing colony formation even after the introduction of adaptive mutations identified in the genotype 1b replicon. Alpha interferon (IFN-α), IFN-γ, and ribavirin exhibited antiviral activity, while double-stranded RNA (dsRNA) and tumor necrosis factor alpha did not. Analysis of transcript levels for a series of genes stimulated by IFN (ISGs) or dsRNA following treatment with IFN-α, IFN-γ, and dsRNA revealed that both IFNs increased ISG transcript levels, but that some aspect of the dsRNA response pathway was defective in Huh7 cells and replicon cell lines in comparison to primary chimpanzee and tamarin hepatocytes. The colony-forming efficiency of the replicon was reduced or eliminated following replication in the presence of ribavirin, implicating the induction of error-prone replication. The potential role of error-prone replication in the synergy observed between IFN-α and ribavirin in attaining sustained viral clearance is discussed. These studies reveal characteristics of Huh7 cells that may contribute to their unique capacity to support HCV RNA synthesis and demonstrate the utility of the replicon system for mechanistic studies on antiviral agents.
The Adenovirus E3 Promoter Is Sensitive to Activation Signals in Human T Cells
Authors: Mahr Jeffrey A. , Boss Jeremy M. , Gooding Linda R. 
Published: December 2002

ABSTRACTThe group C adenoviruses typically cause acute respiratory disease in young children. In addition, a persistent phase of infection has been observed in which virus may be shed for years without producing overt pathology. Our laboratory recently reported that group C adenovirus DNA can be found in tonsil and adenoid T lymphocytes from the majority of pediatric donors (C. T. Garnett, D. Erdman, W. Xu, and L. R. Gooding, J. Virol. 76:10608-10616, 2002). This finding suggests that immune evasion strategies of human adenoviruses may be directed, in part, toward protection of persistently or latently infected T lymphocytes. Many of the adenoviral gene products implicated in prevention of immune destruction of virus-infected cells are encoded within the E3 transcription unit. In this study, the E3 promoter was evaluated for sensitivity to T-cell activation signals by using a promoter reporter plasmid. Indeed, this promoter is extremely sensitive to T-cell activation, with phorbol myristate acetate (PMA) plus ionomycin increasing E3-directed transcription 100-fold. By comparison, in the same cells E1A expression leads to a 5.5-fold increase in transcription from the E3 promoter. In contrast to induction by E1A, activation by PMA plus ionomycin requires the two E3 NF-κB binding sites. Interestingly, expression of E1A inhibits induction of the E3 promoter in response to T-cell activation while increasing E3 promoter activity in unactivated cells. Collectively, these data suggest that the E3 promoter may have evolved the capacity to respond to T-cell activation in the absence of E1A expression and may act to upregulate antiapoptotic gene expression in order to promote survival of persistently infected T lymphocytes.
Reversion of the M184V Mutation in Simian Immunodeficiency Virus Reverse Transcriptase Is Selected by Tenofovir, Even in the Presence of Lamivudine
Authors: Murry Jeffrey P. , Higgins Joanne , Matthews Timothy B. , Huang Victoria Y. , Van Rompay Koen K. A. , Pedersen Niels C. , North Thomas W. 
Published: December 2002

ABSTRACTThe methionine-to-valine mutation in codon 184 (M184V) in reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) or simian immunodeficiency virus (SIV) confers resistance to (−)-2′-deoxy-3′-thiacytidine (3TC; lamivudine) and increased sensitivity to 9-[2-(phosphonomethoxy)propyl]adenine (PMPA; tenofovir). We have used the SIV model to evaluate the effect of the M184V mutation on the emergence of resistance to the combination of 3TC plus PMPA. A site-directed mutant of SIVmac239 containing M184V (SIVmac239-184V) was used to select for resistance to both 3TC and PMPA by serial passage in the presence of increasing concentrations of both drugs. Under these selection conditions, the M184V mutation reverted in the majority of the selections. Variants resistant to both drugs were found to have the lysine-to-arginine mutation at codon 65 (K65R), which has previously been associated with resistance to PMPA in both SIV and HIV. Similarly, in rhesus macaques infected with SIVmac239-184V for 46 weeks and treated daily with (−)-2′-deoxy-5-fluoro-3′-thiacytidine [(−)-FTC], there was no reversion of M184V, but this mutation reverted to 184 M in all three animals within 24 weeks of treatment with (−)-FTC and PMPA. Although the addition of PMPA to the (−)-FTC therapy induced a decrease in virus loads in plasma, these loads eventually returned to pre-PMPA levels in each case. All animals receiving this combination developed the K65R mutation. These results demonstrate that the combination of PMPA with 3TC or (−)-FTC selects for the K65R mutation and against the M184V mutation in SIV RT.
There Are Two Different Species B Adenovirus Receptors: sBAR, Common to Species B1 and B2 Adenoviruses, and sB2AR, Exclusively Used by Species B2 Adenoviruses
Authors: Segerman Anna , Arnberg Niklas , Erikson Anders , Lindman Kristina , Wadell Göran 
Published: December 2002

ABSTRACT

Unlike most adenovirus (Ad) serotypes, the species B Ads do not use the coxsackie-adenovirus receptor as an attachment receptor. The species B attachment receptor(s) has not yet been identified and is also poorly characterized. Species B Ads can be further divided into species B1 and B2 Ads, and these display different organ tropisms, suggesting a difference in receptor usage. We have studied the receptor interactions of the species B1 serotypes 3p and 7p and the species B2 serotypes 11p and 35 and characterized the properties of the species B receptor(s). Reciprocal blocking experiments using unlabeled Ad11p or Ad3p virions to block the binding to A549 cells of
35
S-labeled 3p, 7p, 11p, and 35 showed that only Ad11p virions efficiently blocked the binding of all the species B Ads studied (≥70%). Thus, there is apparently a common species B Ad receptor (sBAR). However, Ad3p virions only partially (≤30%) blocked the binding of Ad11p and Ad35 to A549 cells. Binding experiments after trypsin treatment of the cells confirmed that the species B2 serotypes address at least two different receptors on A549 and J82 cells, since sBAR is trypsin sensitive but the species B2 Ad receptor (sB2AR) is not. Both receptors are proteins or glycoproteins, since binding of all species B serotypes was abolished after proteinase K or subtilisin treatment of A549 or J82 cells. Furthermore, binding of the species B serotypes to sBAR was abolished with EDTA and restored with Ca
2+
, whereas the binding of Ad11p and Ad35 to SB2AR was independent of divalent cations.