bluuebunny/crossref_metadata_2025_split huggingface dataset:
Amiodarone and Miltefosine Act Synergistically against
Leishmania mexicana
and Can Induce Parasitological Cure in a Murine Model of Cutaneous Leishmaniasis
Authors: Serrano-Martín Xenón , Payares Gilberto , De Lucca Marisel , Martinez Juan Carlos , Mendoza-León Alexis , Benaim Gustavo 
Published: October 2009

ABSTRACT

Leishmaniasis is parasitic disease that is an important problem of public health worldwide. Intramuscularly administered glucantime and pentostam are the most common drugs used for treatment of this disease, but they have significant limitations due to toxicity and increasing resistance. A recent breakthrough has been the introduction of orally administered miltefosine for the treatment of visceral, cutaneous, and mucocutaneous leishmaniasis, but the relative high cost and concerns about teratogenicity have limited the use of this drug. Searching for alternative drugs, we previously demonstrated that the antiarrhythmic drug amiodarone is active against
Leishmania mexicana
promastigotes and intracellular amastigotes, acting via disruption of intracellular Ca
2+
homeostasis (specifically at the mitochondrion and the acidocalcisomes of these parasites) and through inhibition of the parasite's de novo sterol biosynthesis (X. Serrano-Martín, Y. García-Marchan, A. Fernandez, N. Rodriguez, H. Rojas, G. Visbal, and G. Benaim, Antimicrob. Agents Chemother.
53:
1403-1410, 2009). In the present work, we found that miltefosine also disrupts the parasite's intracellular Ca
2+
homeostasis, in this case by inducing a large increase in intracellular Ca
2+
levels, probably through the activation of a plasma membrane Ca
2+
channel. We also investigated the in vitro and in vivo activities of amiodarone and miltefosine, used alone or in combination, on
L. mexicana
. It was found that the drug combination had synergistic effects on the proliferation of intracellular amastigotes growing inside macrophages and led 90% of parasitological cures in a murine model of leishmaniasis, as revealed by a PCR assay using a novel DNA sequence specific for
L. mexicana
.
Polyamine Transport as a Target for Treatment ofPneumocystisPneumonia
Authors: Liao Chung-Ping , Phanstiel Otto , Lasbury Mark E. , Zhang Chen , Shao Shoujin , Durant Pamela J. , Cheng Bi-Hua , Lee Chao-Hung 
Published: October 2009

ABSTRACTPolyamine levels are greatly increased in alveolar macrophages (AMs) duringPneumocystispneumonia (PCP), leading to increased production of H2O2, which causes AMs to undergo apoptosis. One of the mechanisms by which polyamine levels in AMs are elevated is enhanced uptake of exogenous polyamines. In this study, the possibility of targeting polyamine uptake as a treatment for PCP was examined. Four anthracene- and one benzene-polyamine conjugates that are potential polyamine transport inhibitors, includingN1-anthracen-9-ylmethyl-butane-1,4-diamine;N-(4-aminobutyl)-N-anthracen-9-ylmethylbutane-1,4-diamine;N-[4-(4-aminobutylamino)butyl]-N-anthracen-9-ylmethylbutane-1,4-diamine;N-(4-amino-butyl)-N′-(10-{[4-(4-amino-butylamino)butylamino]-methyl}anthracen-9-ylmethyl)butane-1,4-diamine (44-Ant-44); and benzene-polyamine conjugateN-(4-amino-butyl)-N′-(4-{[4-(4-amino-butylamino)butylamino]-methyl}benzyl)butane-1,4-diamine (44-Bn-44), were tested. Compounds 44-Ant-44 and 44-Bn-44 were found to have a very low toxicity to AMs in vitro and were evaluated for their therapeutic effect on PCP in vivo. Sprague-Dawley rats infected withP. cariniifor 28 days were intranasally instilled with 50 μl of a 1 mM solution of 44-Bn-44 or 44-Ant-44 every 2 days. Twenty-one days after initiation of the treatment, three to five rats from each group were sacrificed and examined for lung pathology, organism burden, and apoptosis of AMs. Both 44-Bn-44 and 44-Ant-44 reduced organism burdens; however, only 44-Ant-44 decreased the severity of the infection with reduced lung inflammation, increased clearance of exudates, increased air space, and decreased apoptosis of AMs. 44-Ant-44 also significantly prolonged the survival of treated animals. These results suggest that polyamine uptake is a potential target for treatment of PCP.
Novel Antiseptic Urinary Catheters for Prevention of Urinary Tract Infections: Correlation of In Vivo and In Vitro Test Results
Authors: Hachem Ray , Reitzel Ruth , Borne Agatha , Jiang Ying , Tinkey Peggy , Uthamanthil Rajesh , Chandra Jyotsna , Ghannoum Mahmoud , Raad Issam 
Published: October 2009

ABSTRACT

Urinary catheters are widely used for hospitalized patients and are often associated with high rates of urinary tract infection. We evaluated in vitro the antiadherence activity of a novel antiseptic Gendine-coated urinary catheter against several multidrug-resistant bacteria. Gendine-coated urinary catheters were compared to silver hydrogel-coated Foley catheters and uncoated catheters. Bacterial biofilm formation was assessed by quantitative culture and scanning electron microscopy. These data were further correlated to an in vivo rabbit model. We challenged 31 rabbits daily for 4 days by inoculating the urethral meatus with 1.0 × 10
9
CFU streptomycin-resistant
Escherichia coli
per day. In vitro, Gendine-coated urinary catheters reduced the CFU of all organisms tested for biofilm adherence compared with uncoated and silver hydrogel-coated catheters (
P
< 0.004). Scanning electron microscopy analysis showed that a thick biofilm overlaid the control catheter and the silver hydrogel-coated catheters but not the Gendine-coated urinary catheter. Similar results were found with the rabbit model. Bacteriuria was present in 60% of rabbits with uncoated catheters and 71% of those with silver hydrogel-coated catheters (
P
< 0.01) but not in those with Gendine-coated urinary catheters. No rabbits with Gendine-coated urinary catheters had invasive bladder infections. Histopathologic assessment revealed no differences in toxicity or staining. Gendine-coated urinary catheters were more efficacious in preventing catheter-associated colonization and urinary tract infections than were silver hydrogel-coated Foley catheters and uncoated catheters.
Prevalence and Clonal Characterization of
Streptococcus pyogenes
Clinical Isolates with Reduced Fluoroquinolone Susceptibility in Spain
Authors: Montes Milagrosa , Tamayo Esther , Orden Beatriz , Larruskain Julián , Perez-Trallero Emilio 
Published: October 2009

ABSTRACT

The aim of this study was to determine the prevalence and characteristics of non-fluoroquinolone (FQ)-susceptible
Streptococcus pyogenes
isolates and to study their mechanisms of resistance. We performed a prospective prevalence study with 468 isolates collected from 2005 to 2007 and a retrospective study that was based on the examination of existing data collected from 1999 to 2008. The retrospective study included data for isolates with high-level resistance (HR) to ciprofloxacin (MIC ≥ 32 μg/ml) (HR isolates) and isolates with the same
emm
types as those reported in the literature with low-level resistance (LR) to ciprofloxacin (MICs, 2 to 8 μg/ml) (LR isolates,
n
= 205). Genetic characterization of the isolates was performed by means of
emm
typing and multilocus sequence typing. The prevalence of LR ranged from 1.9% in 2005 to 30.8% in 2007. This increase was mainly due to the circulation of an
emm
6 subtype (
emm
6.4) that represented 77.1% of the LR isolates in 2007. Notably, another
emm
6 subtype, also detected in 2007 (
emm
6.37), showed coresistance to 14- and 15-membered macrolides mediated by the
mefA
gene. Only three HR isolates were detected (isolates
emm
68.1/ST247/T3,13,B3264,
emm
77/ST399/T28, and
emm
28/ST52/T28), and all were identified in the retrospective study. Overall, the 673 isolates represented 25
emm
types. All LR isolates were clustered into two
emm
types:
emm
6 (six
emm
6 subtypes) and
emm
75. All the 156
emm
6 isolates had LR, harbored the Ser79/Ala mutation in the
parC
gene product, and had the same sequence type (ST), ST382. Most (21/33) of the
emm
75 isolates had LR, showed the Ser79/Phe plus Asp91/Asn double mutation in the
parC
gene product, and were ST150. The Asp91/Asn mutation by itself did not confer resistance to FQs.
Long-Lasting Enfuvirtide Carrier Pentasaccharide Conjugates with Potent Anti-Human Immunodeficiency Virus Type 1 Activity
Authors: Huet Thierry , Kerbarh Olivier , Schols Dominique , Clayette Pascal , Gauchet Cécile , Dubreucq Guy , Vincent Loïc , Bompais Heidi , Mazinghien Romain , Querolle Olivier , Salvador Arnaud , Lemoine Jérôme , Lucidi Bruno , Balzarini Jan , Petitou Maurice 
Published: October 2009

ABSTRACTEnfuvirtide (also known as Fuzeon, T-20, or DP-178) is an antiretroviral fusion inhibitor which prevents human immunodeficiency virus type 1 (HIV-1) from entering host cells. This linear 36-mer synthetic peptide is indicated, in combination with other antiretroviral agents, for the treatment of HIV-1-infected individuals and AIDS patients with multidrug-resistant HIV infections. Although enfuvirtide is an efficient anti-HIV-1 drug, its clinical use is limited by a short plasma half-life, i.e., approximately 2 h, which requires twice-daily subcutaneous injections, often resulting in skin sensitivity reaction side effects at the injection sites. Ultimately, 80% of patients stop enfuvirtide treatment within 6 months because of these side effects. We report on the development of long-lasting enfuvirtide conjugates by the use of the site-specific conjugation of enfuvirtide to an antithrombin-binding carrier pentasaccharide (CP) through polyethylene glycol (PEG) linkers of various lengths. These conjugates showed consistent and broad anti-HIV-1 activity in the nanomolar range. The coupling of the CP to enfuvirtide only moderately affected the in vitro anti-HIV-1 activity in the presence of antithrombin. Most importantly, one of these conjugates, enfuvirtide-PEG12-CP (EP40111), exhibited a prolonged elimination half-life of more than 10 h in rat plasma compared to the half-life of native enfuvirtide, which was 2.8 h. On the basis of the pharmacokinetic properties of antithrombin-binding pentasaccharides, the anticipated half-life of EP40111 in humans would putatively be about 120 h, which would allow subcutaneous injection once a week instead of twice daily. In conclusion, EP40111 is a promising compound with strong potency as a novel long-lasting anti-HIV-1 drug.
Metronidazole Resistance in
Prevotella
spp. and Description of a New
nim
Gene in
Prevotella baroniae
Authors: Alauzet C. , Mory F. , Teyssier C. , Hallage H. , Carlier J. P. , Grollier G. , Lozniewski A. 
Published: October 2009

ABSTRACT

Nonduplicate clinical isolates of
Prevotella
spp. recovered from patients hospitalized between 2003 and 2006 in two French tertiary-care teaching hospitals were investigated for their susceptibility to metronidazole and the presence of
nim
genes. Of the 188 strains tested, 3 isolates displayed reduced susceptibility to metronidazole after 48 h of incubation, while 27 additional isolates exhibited heterogeneous resistance after prolonged incubation; all 30 of the isolates were
nim
negative. Among the remaining 158 isolates, 7
nim
-positive isolates were detected. All of these strains were identified as
Prevotella baroniae
by 16S rRNA gene sequence analysis and contained a new
nim
gene, named
nimI
, as determined by DNA sequence analysis. Chromosomal localization of this single-copy gene was demonstrated in all clinical isolates as well as in type strain
P. baroniae
DSM 16972 by using Southern hybridization. No known associated insertion sequence elements were detected upstream of the
nimI
gene in any of the
nim
-positive strains by PCR mapping. After prolonged exposure to metronidazole, stable resistant subpopulations could be selected in
nimI
-positive
Prevotella
isolates (
n
= 6) as well as in
nim-
negative
Prevotella
isolates (
n
= 6), irrespective of their initial susceptibility to this antibiotic. This study is the first description of a new nitroimidazole resistance gene in
P. baroniae
which seems to be silent and which might be intrinsic in this species. Moreover, our findings highlight the fact that high-level resistance to metronidazole may be easily induced in both
nim
-positive and
nim
-negative
Prevotella
sp. strains.
Novel Approach for Comparing the Abilities of Quinolones To Restrict the Emergence of Resistant Mutants during Quinolone Exposure
Authors: Malik Muhammad , Hoatam Gerard , Chavda Kalyan , Kerns Robert J. , Drlica Karl 
Published: October 2009

ABSTRACT

An agar-plate assay was adapted to examine aspects of quinolone structure that restrict the emergence of quinolone-mediated quinolone resistance. When
Escherichia coli
was applied to agar containing nalidixic acid, the number of quinolone-resistant mutants arising during incubation was decreased by raising the drug concentration and by mutations expected to block the induction of the SOS response (
recA
,
lexA
); the mutant number was increased by a mutator mutation (
ung
). The examination of four related fluoroquinolones then revealed that a C-8 methoxy group and an
N
-ethyl piperazine substituent at C-7 reduced mutant acquisition more effectively than C-8 H and C-7
C
-ethyl piperazine groups. The fluoroquinolone that was most effective at restricting mutant acquisition was the most active when lethal activity was measured on agar plates or in liquid medium (as minimal bactericidal concentration). It also exhibited the lowest ratio of mutant MIC to wild-type MIC when it was tested with a set of isogenic gyrase mutants, and it had a low mutant prevention concentration (MPC) relative to MIC. However, a low MPC was less likely to be important in restricting the induced mutant accumulation because a fluoroquinolone
N
-ethyl piperazine substituent was more effective than a
C
-ethyl piperazine substituent at reducing mutant accumulation but was less effective at lowering the MPC. An 8-methoxy-quinazoline-2,4-dione was also effective at restricting the accumulation of resistant mutants on agar. Collectively, these data characterize a simple assay for detection of drug-mediated resistance that is sensitive to the structures of GyrA inhibitors. The assay provides a new method for screening quinolones and quinolone-like molecules that complements MPC-based tests for restricting the emergence of resistance.
Inhibition of Erythrocyte Invasion andPlasmodium falciparumMerozoite Surface Protein 1 Processing by Human Immunoglobulin G1 (IgG1) and IgG3 Antibodies
Authors: Lazarou Maria , Patiño José A. Guevara , Jennings Richard M. , McIntosh Richard S. , Shi Jianguo , Howell Steven , Cullen Eilish , Jones Tarran , Adame-Gallegos Jaime R. , Chappel Jonathan A. , McBride Jana S. , Blackman Michael J. , Holder Anthony A. , Pleass Richard J. 
Published: October 2009

ABSTRACTAntigen-specific antibodies (Abs) to the 19-kDa carboxy-terminal region ofPlasmodium falciparummerozoite surface protein 1 (MSP119) play an important role in protective immunity to malaria. Mouse monoclonal Abs (MAbs) 12.10 and 12.8 recognizing MSP119can inhibit red cell invasion by interfering with MSP1 processing on the merozoite surface. We show here that this ability is dependent on the intact Ab since Fab and F(ab′)2fragments derived from MAb 12.10, although capable of binding MSP1 with high affinity and competing with the intact antibody for binding to MSP1, were unable to inhibit erythrocyte invasion or MSP1 processing. The DNA sequences of the variable (V) regions of both MAbs 12.8 and 12.10 were obtained, and partial amino acid sequences of the same regions were confirmed by mass spectrometry. Human chimeric Abs constructed by using these sequences, which combine the original mouse V regions with human γ1 and γ3 constant regions, retain the ability to bind to both parasites and recombinant MSP119, and both chimeric human immunoglobulin G1s (IgG1s) were at least as good at inhibiting erythrocyte invasion as the parental murine MAbs 12.8 and 12.10. Furthermore, the human chimeric Abs of the IgG1 class (but not the corresponding human IgG3), induced significant NADPH-mediated oxidative bursts and degranulation from human neutrophils. These chimeric human Abs will enable investigators to examine the role of human Fcγ receptors in immunity to malaria using a transgenic parasite and mouse model and may prove useful in humans for neutralizing parasites as an adjunct to antimalarial drug therapy.
The Secreted Esterase of Group AStreptococcusIs Important for Invasive Skin Infection and Dissemination in Mice
Authors: Zhu Hui , Liu Mengyao , Sumby Paul , Lei Benfang 
Published: October 2009

ABSTRACTVirulence factors regulated by the CovRS/CsrRS two-component gene regulatory system contribute to the invasive diseases caused by group AStreptococcus(GAS). To determine whether thestreptococcalsecretedesterase (Sse), an antigen that protects against subcutaneous GAS infection, is one of these virulence factors, we investigated the phenotype of a nonpolarssedeletion mutant strain (Δsse). In addition, we examined the effects ofcovSmutation onsseexpression. As assessed using a mouse model of subcutaneous infection, the virulence of the Δssestrain is attenuated and the overall pathology is reduced. Furthermore, GAS was detected in the blood and spleens from mice subcutaneously infected with the parental strain, whereas mice subcutaneously infected with the Δssestrain had no GAS present in their blood and spleens. The ability of the mutant to survive in the subcutis of mice appeared to be compromised. The growth of the Δssestrain in rich and chemically defined media and nonimmune human blood and sera was slower than that of the wild-type strain. Complementation restored the phenotype of the Δssestrain to that of the wild-type strain. The wild-type, Δsse, and complement strains had no detectable SpeB activity. Expression of Sse is negatively controlled by CovRS. These findings suggest that Sse is a CovRS-regulated virulence factor that is important for the virulence of GAS in subcutaneous infection and plays an important role in severe soft tissue infections and systemic dissemination of GAS from the skin.
Saliva Enables the Antimicrobial Activity of LL-37 in the Presence of Proteases of
Porphyromonas gingivalis
Authors: Gutner Michal , Chaushu Stella , Balter Daniela , Bachrach Gilad 
Published: October 2009

ABSTRACT

Proteolysis is a common microbial virulence mechanism that enables the destruction of host tissue and evasion from host defense mechanisms. Antimicrobial peptides, also known as host defense peptides, are effector molecules of the innate immunity that demonstrate a broad range of antimicrobial and immunoregulatory activities. Deficiency of the human LL-37 antimicrobial peptide was previously correlated with severe periodontal disease.
Porphyromonas gingivalis
, the major pathogen associated with periodontitis, is highly proteolytic. In this study,
P. gingivalis
was found capable of degrading LL-37 by utilizing its arginine-specific gingipains. Saliva collected from volunteers with a healthy periodontium protected LL-37 from proteolysis by
P. gingivalis.
Salivary protection of LL-37 was heat resistant and specific and enabled LL-37 to inhibit growth of
Escherichia coli
in the presence of the
P. gingivalis
proteases. Previously, saliva and other body fluids have been shown to inhibit the antimicrobial activity of LL-37. Here we demonstrate that at a cost of a small reduction in the bactericidal activity of LL-37, saliva enables the antibacterial activity of LL-37 despite the presence of proteases secreted by the main periodontopathogen.
Molecular Characterization of EmABP, an Apolipoprotein A-I Binding Protein Secreted by the
Echinococcus multilocularis
Metacestode
Authors: Bernthaler Peter , Epping Kerstin , Schmitz Gerd , Deplazes Peter , Brehm Klaus 
Published: October 2009

ABSTRACT

Cestodes are unable to synthesize de novo most of their own membrane lipids, including cholesterol, and have to take them up from the host during an infection. The underlying molecular mechanisms are so far unknown. Here we report the identification and characterization of a novel gene, Em
abp
, which is expressed by larval stages and adults of the fox tapeworm
Echinococcus multilocularis
. The encoded protein, EmABP, displays significant homologies to apolipoprotein A-I binding protein (AI-BP) of mammalian origin and to metazoan YjeF_N domain proteins. Like mammalian AI-BP, EmABP carries an export-directing signal sequence which is absent in predicted AI-BP orthologs from the related flatworms
Schistosoma japonicum
and
Schmidtea mediterranea
. Using a specific antibody and immunoprecipitation techniques, we demonstrate that EmABP is secreted into the extraparasitic environment and into the hydatid fluid of in vitro-cultivated metacestode vesicles. Furthermore, we show that apolipoprotein A-I (apoA-I), a major constituent of cholesterol-transporting high-density lipoproteins, is present in hydatid fluid. By pulldown experiments, we demonstrate that recombinantly expressed, purified EmABP interacts with purified human apoA-I and is able to precipitate apoA-I from human serum. On the basis of these features and the suggested function of AI-BP in cholesterol transport in higher eukaryotes, we propose a role for EmABP in cholesterol and lipid uptake mechanisms of larval
E. multilocularis
.
The Long-Lived Nature of
Clostridium perfringens
Iota Toxin in Mammalian Cells Induces Delayed Apoptosis
Authors: Hilger Hanna , Pust Sascha , von Figura Guido , Kaiser Eva , Stiles Bradley G. , Popoff Michel R. , Barth Holger 
Published: October 2009

ABSTRACT

Mono-ADP ribosylation of actin by bacterial toxins, such as
Clostridium perfringens
iota or
Clostridium botulinum
C2 toxins, results in rapid depolymerization of actin filaments and cell rounding. Here we report that treatment of African green monkey kidney (Vero) cells with iota toxin resulted in delayed caspase-dependent death. Unmodified actin did not reappear in toxin-treated cells, and enzyme-active toxin was detectable in the cytosol for at least 24 h. C2 toxin showed comparable, long-lived effects in cells, while a C2 toxin control lacking ADP-ribosyltransferase activity did not induce cell death. To address whether the remarkable stability of the iota and C2 toxins in cytosol was crucial for inducing cell death, we treated cells with C/SpvB, the catalytic domain of
Salmonella enterica
SpvB. Although C/SpvB also mono-ADP ribosylates actin as do the iota and C2 toxins, cells treated with a cell-permeating C/SpvB fusion toxin became rounded but recovered and remained viable. Moreover, unmodified actin reappeared in these cells, and ADP-ribosyltransferase activity due to C/SpvB was not detectable in the cytosol after 24 h, a result most likely due to degradation of C/SpvB. Repeated application of C/SpvB prevented recovery of cells and reappearance of unmodified actin. In conclusion, a complete but transient ADP ribosylation of actin was not sufficient to trigger apoptosis, implying that long-term stability of actin-ADP-ribosylating toxins, such as iota and C2, in the cytosol is crucial for inducing delayed, caspase-dependent cell death.