bluuebunny/crossref_metadata_2025_split huggingface dataset:
Caspofungin Kills Candida albicans by Causing both Cellular Apoptosis and Necrosis
Authors: Hao Binghua , Cheng Shaoji , Clancy Cornelius J. , Nguyen M. Hong 
Published: November 2012

ABSTRACT

Caspofungin exerts candidacidal activity by inhibiting cell wall (1,3)-β-
d
-glucan synthesis. We investigated the physiologic mechanisms of caspofungin-induced
Candida albicans
cell death. Apoptosis (programmed cell death) and necrosis were studied after
C. albicans
SC5314 cells were exposed to caspofungin at 0.06, 0.125, and 0.5 μg/ml (0.5×, 1×, and 4× the MIC, respectively) for 3 h. Caspofungin at 0.125 and 0.5 μg/ml reduced cellular viability by >50%, as measured by colony counts and methylene blue exclusion. Apoptosis and necrosis were demonstrated by annexin V and propidium iodide staining for phosphatidylserine externalization and loss of membrane integrity, respectively. At all concentrations of caspofungin, 20 to 25% and 5 to 7% of
C. albicans
cells exhibited early apoptosis and late apoptosis/necrosis, respectively (
P
value was not significant [NS]). Necrosis, on the other hand, was significantly greater at 0.125 (43%) and 0.5 (48%) μg/ml than at 0.06 μg/ml (26%) (
P
values of 0.003 and 0.003, respectively). The induction of apoptosis at concentrations less than or equal to the MIC was corroborated by dihydrorhodamine 123 (DHR-123) and dihydroethidium (DHE) staining (reactive oxygen species production), JC-1 staining (mitochondrial membrane potential dissipation), and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) and 4′,6-diamidino-2-phenylindole dihydrochloride (DAPI) staining (DNA damage and nuclear fragmentation). Moreover, electron microscopy of cells exposed to 0.125 μg/ml of caspofungin showed hallmark apoptotic features like chromatin margination and condensation and nuclear blebs. Apoptosis was associated with metacaspase 1 activation, as demonstrated by D2R staining. Caspofungin exerts activity against
C. albicans
by directly killing cells (resulting in necrosis) and causing others to undergo programmed cell death (apoptosis). Apoptosis is initiated at subinhibitory concentrations, suggesting that strategies to target this process may augment the benefits of antifungal agents.
Benznidazole-Related Adverse Drug Reactions and Their Relationship to Serum Drug Concentrations in Patients with Chronic Chagas Disease
Authors: Pinazo María-Jesús , Guerrero Laura , Posada Elizabeth , Rodríguez Elena , Soy Dolors , Gascon Joaquim 
Published: November 2012

ABSTRACT

For treating Chagas disease (CD), a current worldwide health problem, only benznidazole and nifurtimox have been approved to be used. In both cases, unwanted drug-related adverse events (ADRs) are frequent when these drugs are used in adults in the chronic stage. The main objective of this study was to establish benznidazole ADRs and their relationship to serum concentrations in patients with chronic
Trypanosoma cruzi
infection in order to perform more accurate dosages to minimize ADRs. A total of 54 patients were recruited over 12 months. Of these 54 patients, 53 (98%) experienced at least one ADR during follow-up, and the overall average ADR incidence was 2.4 episodes/patient/month. Benznidazole treatment was discontinued in 11 patients, 7 among them due to severe adverse effects. The mean duration of treatment before withdrawal was 11 days. Benznidazole serum concentrations were recorded on days 15, 30, 45, and 60 of follow-up and evaluated according to clinical and epidemiological variables and ADR severity. No relationship was found between the benznidazole serum concentration and the ADRs. The mean (standard deviation) trough serum benznidazole concentrations (all below 20 mcg/ml) on days 15, 30, 45, and 60 were 6.4 (1.9), 6.1 (1.8), 6.2 (2.2), and 5.7 (1.7) μg/ml, respectively. Benznidazole serum concentrations do not appear to be related to the appearance of serious ADRs. Further, well-controlled studies are necessary to establish the optimal regimen for benznidazole in adults with chronic CD.
Highly Variable Plasma Concentrations of Voriconazole in Pediatric Hematopoietic Stem Cell Transplantation Patients
Authors: Bartelink Imke H. , Wolfs Tom , Jonker Martine , de Waal Marjolein , Egberts Toine C. G. , Ververs Tessa T. , Boelens Jaap J. , Bierings Marc 
Published: November 2012

ABSTRACT

Invasive fungal infections are of great concern in pediatric hematopoietic stem cell transplantation (HSCT) recipients. Voriconazole is usually the drug of first choice for treating or preventing invasive aspergillosis. Optimum trough levels (
C
trough
s) are between 1 and 5 mg/liter. It is unclear whether these levels are reached with currently advised pediatric dosing schedules. Between 2007 and 2011, 11 patients <2 years of age, 31 between 2 and 12 years, and 20 between 12 and 20 years were (prophylactically or therapeutically) treated with voriconazole in the HSCT unit of UMC Utrecht. For children <2 years of age, the dosage recommended for 2 to 12 years was used. In 34% of children who started with the recommended dose, an adequate
C
trough
was reached irrespective of age or administration route. After therapeutic drug monitoring (TDM)-based dose adjustments, adequate
C
trough
s were reached in 80% of the patients at median doses of 31.5 (age, <2 years), 16 (age, 2 to 12 years), and 9.4 mg/kg of body weight/day (age, >12 years) (
P
= 0.034). The intrapatient variability in
C
trough
ranged between 1 and 238%. Voriconazole was discontinued in six patients due to toxicity. These patients had a median
C
trough
of 0.5 mg/liter at the initial dose (ranging from 0.5 to 2.6 mg/liter), and a medium maximal concentration of 4 mg/liter was reached. Inter- and intrapatient variability is a major concern in voriconazole treatment and necessitates therapeutic drug monitoring of dosing, especially in young children.
An Improved Small-Molecule Inhibitor of FtsZ with Superior
In Vitro
Potency, Drug-Like Properties, and
In Vivo
Efficacy
Authors: Stokes Neil R. , Baker Nicola , Bennett James M. , Berry Joanne , Collins Ian , Czaplewski Lloyd G. , Logan Alastair , Macdonald Rebecca , MacLeod Leanne , Peasley Hilary , Mitchell Jeffrey P. , Nayal Narendra , Yadav Anju , Srivastava Anil , Haydon David J. 
Published: November 2012

ABSTRACT

The bacterial cell division protein FtsZ is an attractive target for small-molecule antibacterial drug discovery. Derivatives of 3-methoxybenzamide, including compound PC190723, have been reported to be potent and selective antistaphylococcal agents which exert their effects through the disruption of intracellular FtsZ function. Here, we report the further optimization of 3-methoxybenzamide derivatives towards a drug candidate. The
in vitro
and
in vivo
characterization of a more advanced lead compound, designated compound 1, is described. Compound 1 was potently antibacterial, with an average MIC of 0.12 μg/ml against all staphylococcal species, including methicillin- and multidrug-resistant
Staphylococcus aureus
and
Staphylococcus epidermidis
. Compound 1 inhibited an
S. aureus
strain carrying the G196A mutation in FtsZ, which confers resistance to PC190723. Like PC190723, compound 1 acted on whole bacterial cells by blocking cytokinesis. No interactions between compound 1 and a diverse panel of antibiotics were measured in checkerboard experiments. Compound 1 displayed suitable
in vitro
pharmaceutical properties and a favorable
in vivo
pharmacokinetic profile following intravenous and oral administration, with a calculated bioavailability of 82.0% in mice. Compound 1 demonstrated efficacy in a murine model of systemic
S. aureus
infection and caused a significant decrease in the bacterial load in the thigh infection model. A greater reduction in the number of
S. aureus
cells recovered from infected thighs, equivalent to 3.68 log units, than in those recovered from controls was achieved using a succinate prodrug of compound 1, which was designated compound 2. In summary, optimized derivatives of 3-methoxybenzamide may yield a first-in-class FtsZ inhibitor for the treatment of antibiotic-resistant staphylococcal infections.
Molecular Identification, Antifungal Susceptibility Profile, and Biofilm Formation of Clinical and Environmental Rhodotorula Species Isolates
Authors: Nunes Jorge Meneses , Bizerra Fernando César , Ferreira Renata Carmona e , Colombo Arnaldo Lopes 
Published: November 2012

ABSTRACT

Rhodotorula
species are emergent fungal pathogens capable of causing invasive infections, primarily fungemia. They are particularly problematic in immunosuppressed patients when using a central venous catheter. In this study, we evaluated the species distribution of 51 clinical and 8 environmental
Rhodotorula
species isolates using the ID32C system and internal transcribed spacer (ITS) sequencing. Antifungal susceptibility testing and biofilm formation capability using a crystal violet staining assay were performed. Using ITS sequencing as the gold standard, the clinical isolates were identified as follows: 44
R. mucilaginosa
isolates, 2
R. glutinis
isolates, 2
R. minuta
isolates, 2
R. dairenensis
isolates, and 1
Rhodosporidium fluviale
isolate. The environmental isolates included 7
R. mucilaginosa
isolates and 1
R. slooffiae
isolate. Using the ID32C system, along with a nitrate assimilation test, only 90.3% of the isolates tested were correctly identified. In the biofilm formation assay,
R. mucilaginosa
and
R. minuta
exhibited greater biofilm formation ability compared to the other
Rhodotorula
species; the clinical isolates of
R. mucilaginosa
showed greater biofilm formation compared to the environmental isolates (
P
= 0.04). Amphotericin B showed good
in vitro
activity (MIC ≤ 1 μg/ml) against planktonic cells, whereas voriconazole and posaconazole showed poor activity (MIC
50
/MIC
90
, 2/4 μg/ml). Caspofungin and fluconazole MICs were consistently high for all isolates tested (≥64 μg/ml and ≥ 4 μg/ml, respectively). In this study, we emphasized the importance of molecular methods to correctly identify
Rhodotorula
species isolates and non-
R. mucilaginosa
species in particular. The antifungal susceptibility profile reinforces amphotericin B as the antifungal drug of choice for the treatment of
Rhodotorula
infections. To our knowledge, this is the first study evaluating putative differences in the ability of biofilm formation among different
Rhodotorula
species.
Complete Nucleotide Sequences of
bla
KPC-4
- and
bla
KPC-5
-Harboring IncN and IncX Plasmids from Klebsiella pneumoniae Strains Isolated in New Jersey
Authors: Chen Liang , Chavda Kalyan D. , Fraimow Henry S. , Mediavilla José R. , Melano Roberto G. , Jacobs Michael R. , Bonomo Robert A. , Kreiswirth Barry N. 
Published: November 2012

ABSTRACT

Klebsiella pneumoniae
carbapenemase (KPC)-producing
Enterobacteriaceae
have emerged as major nosocomial pathogens.
bla
KPC
, commonly located on Tn
4401
, is found in Gram-negative bacterial strains, with the two most common variants,
bla
KPC-2
and
bla
KPC-3
, identified in plasmids with diverse genetic backgrounds. In this study, we examined
bla
KPC-4
- and
bla
KPC-5
-bearing plasmids recovered from two
K. pneumoniae
strains, which were isolated from a single New Jersey hospital in 2005 and 2006, respectively. IncN plasmid pBK31551 is 84 kb in length and harbors
bla
KPC-4
,
bla
TEM-1
,
qnrB2
,
aac
(
3
)
-Ib
,
aph
(
3′
)
-I
,
qacF
,
qacE
Δ
1
,
sul1
, and
dfrA14
, which confer resistance to β-lactams, quinolones, aminoglycosides, quaternary ammonium compounds, and co-trimoxazole. The conserved regions within pBK31551 are similar to those of other IncN plasmids. Surprisingly, analysis of the Tn
4401
sequence revealed a large IS
110
- and Tn
6901
-carrying element (8.3 kb) inserted into the
istA
gene, encoding glyoxalase/bleomycin resistance, alcohol dehydrogenase, and
S
-formylglutathione hydrolase. Plasmid pBK31567 is 47 kb in length and harbors
bla
KPC-5
,
dfrA5
,
qacE
Δ
1
, and
sul1
. pBK31567 belongs to a novel IncX subgroup (IncX5) and possesses a highly syntenic plasmid backbone like other IncX plasmids; however, sequence similarity at the nucleotide level is divergent. The
bla
KPC-5
gene is carried on a Tn
4401
element and differs from the genetic environment of
bla
KPC-5
described in
Pseudomonas aeruginosa
strain P28 from Puerto Rico. This study underscores the genetic diversity of multidrug-resistant plasmids involved in the spread of
bla
KPC
genes and highlights the mobility and plasticity of Tn
4401
. Comparative genomic analysis provides new insights into the evolution and dissemination of KPC plasmids belonging to different incompatibility groups.
Clonal Structure, Extended-Spectrum β-Lactamases, and Acquired AmpC-Type Cephalosporinases of Escherichia coli Populations Colonizing Patients in Rehabilitation Centers in Four Countries
Authors: Izdebski R. , Baraniak A. , Fiett J. , Adler A. , Kazma M. , Salomon J. , Lawrence C. , Rossini A. , Salvia A. , Vidal Samso J. , Fierro J. , Paul M. , Lerman Y. , Malhotra-Kumar S. , Lammens C. , Goossens H. , Hryniewicz W. , Brun-Buisson C. , Carmeli Y. , Gniadkowski M. 
Published: November 2012

ABSTRACT

The prospective project MOSAR was conducted in five rehabilitation units: the Berck Maritime Hôpital (Berck, France), Fondazione Santa Lucia (Rome, Italy), Guttmann Institute (GI; Barcelona, Spain), and Loewenstein Hospital and Tel-Aviv Souraski Medical Center (TA) (Tel-Aviv, Israel). Patients were screened for carriage of
Enterobacteriaceae
resistant to expanded-spectrum cephalosporins (ESCs) from admission until discharge. The aim of this study was to characterize the clonal structure, extended-spectrum β-lactamases (ESBLs), and acquired AmpC-like cephalosporinases in the
Escherichia coli
populations collected. A total of 376 isolates were randomly selected. The overall number of sequence types (STs) was 76, including 7 STs that grouped at least 10 isolates from at least three centers each, namely, STs 10, 38, 69, 131, 405, 410, and 648. These clones comprised 65.2% of all isolates, and ST131 alone comprised 41.2%. Of 54 STs observed only in one center, some STs played a locally significant role, like ST156 and ST393 in GI or ST372 and ST398 in TA. Among 16 new STs, five arose from evolution within the ST10 and ST131 clonal complexes. ESBLs and AmpCs accounted for 94.7% and 5.6% of the ESC-hydrolyzing β-lactamases, respectively, being dominated by the CTX-M-like enzymes (79.9%), followed by the SHV (13.5%) and CMY-2 (5.3%) types. CTX-M-15 was the most prevalent β-lactamase overall (40.6%); other ubiquitous enzymes were CTX-M-14 and CMY-2. Almost none of the common clones correlated strictly with one β-lactamase; although 58.7% of ST131 isolates produced CTX-M-15, the clone also expressed nine other enzymes. A number of clone variants with specific pulsed-field gel electrophoresis and ESBL types were spread in some locales, potentially representing newly emerging
E. coli
epidemic strains.
Effects of Etravirine on the Pharmacokinetics of the Integrase Inhibitor S/GSK1265744
Authors: Ford Susan L. , Gould Elizabeth , Chen Shuguang , Lou Yu , Dumont Etienne , Spreen William , Piscitelli Stephen 
Published: November 2012

ABSTRACT
HIV integrase inhibitors such as raltegravir and elvitegravir halt HIV progression, but treatment-emergent resistance and cross-resistance have been observed. The nonnucleoside reverse transcriptase inhibitor etravirine (ETR) may be used in combination with integrase inhibitors in patients with drug resistance. This single-center, open-label, two-period, single-sequence crossover study evaluated the effects of ETR coadministration on the pharmacokinetic profile of S/GSK1265744, an investigational integrase inhibitor in phase 2 studies. Healthy subjects received 30 mg of S/GSK1265744 alone once daily for 10 days (period 1) and in combination with 200 mg of ETR twice daily for 14 days (period 2). Serial plasma samples for pharmacokinetic analyses were collected on day 10 during period 1 and on day 14 during period 2. All treatments were well tolerated. Etravirine had no effects on S/GSK1265744 geometric mean ratios of the area under the curve from time zero until the end of the dosing interval (1.01; 90% confidence interval [CI], 0.956 to 1.06), of the maximum observed plasma concentration (1.04; 90% CI, 0.987 to 1.09), or of the plasma concentration at the end of the dosing interval (0.999; 90% CI, 0.942 to 1.06). Etravirine pharmacokinetics (PK) parameters observed following coadministration with S/GSK1265744 were in the range of historical values reported for ETR alone in healthy subjects. These results indicate that 30 mg of S/GSK1265744 for 10 days as monotherapy followed by an additional 14 days in combination with ETR was well tolerated in healthy subjects and that no dose adjustment of S/GSK1265744 is required when it is coadministered with ETR.
Antimicrobial Properties of 8-Hydroxyserrulat-14-en-19-oic Acid for Treatment of Implant-Associated Infections
Authors: Nowakowska Justyna , Griesser Hans J. , Textor Marcus , Landmann Regine , Khanna Nina 
Published: November 2012

ABSTRACT

Treatment options are limited for implant-associated infections (IAI) that are mainly caused by biofilm-forming staphylococci. We report here on the activity of the serrulatane compound 8-hydroxyserrulat-14-en-19-oic acid (EN4), a diterpene isolated from the Australian plant
Eremophila neglecta
. EN4 elicited antimicrobial activity toward various Gram-positive bacteria but not to Gram-negative bacteria. It showed a similar bactericidal effect against logarithmic-phase, stationary-phase, and adherent
Staphylococcus epidermidis
, as well as against methicillin-susceptible and methicillin-resistant
S. aureus
with MICs of 25 to 50 μg/ml and MBCs of 50 to 100 μg/ml. The bactericidal activity of EN4 was similar against
S. epidermidis
and its Δ
ica
mutant, which is unable to produce polysaccharide intercellular adhesin-mediated biofilm. In time-kill studies, EN4 exhibited a rapid and concentration-dependent killing of staphylococci, reducing bacterial counts by >3 log
10
CFU/ml within 5 min at concentrations of >50 μg/ml. Investigation of the mode of action of EN4 revealed membranolytic properties and a general inhibition of macromolecular biosynthesis, suggesting a multitarget activity.
In vitro
-tested cytotoxicity on eukaryotic cells was time and concentration dependent in the range of the MBCs. EN4 was then tested in a mouse tissue cage model, where it showed neither bactericidal nor cytotoxic effects, indicating an inhibition of its activity. Inhibition assays revealed that this was caused by interactions with albumin. Overall, these findings suggest that, upon structural changes, EN4 might be a promising pharmacophore for the development of new antimicrobials to treat IAI.
Biochemical Characterization of Cardiolipin Synthase Mutations Associated with Daptomycin Resistance in Enterococci
Authors: Davlieva Milya , Zhang Wanna , Arias Cesar A. , Shamoo Yousif 
Published: November 2012

ABSTRACT

Daptomycin (DAP) resistance in enterococci has been linked to mutations in genes that alter the cell envelope stress response (CESR) (
liaFSR
) and changes in enzymes that directly affect phospholipid homeostasis, and these changes may alter membrane composition, such as that of cardiolipin synthase (Cls). While Cls substitutions are observed in response to DAP therapy, the effect of these mutations on Cls activity remains obscure. We have expressed, purified, and characterized Cls enzymes from both
Enterococcus faecium
S447 (residues 52 to 482; Cls447a) and
Enterococcus faecalis
S613 (residues 53 to 483; Cls613a) as well as Cls variants harboring a single-amino-acid change derived from DAP-resistant isolates of
E. faecium
.
E. faecium
Cls447a and
E. faecalis
Cls613a are tightly associated with the membrane and copurify with their substrate, phosphatidylglycerol (PG), and product, cardiolipin (CL). The amount of PG that copurifies with Cls is in molar excess to protein, suggesting that the enzyme localizes to PG-rich membrane regions. Both Cls447a
H215R
and Cls447a
R218Q
showed an increase in
V
max
(μM CL/min/μM protein) from 0.16 ± 0.01 to 0.26 ± 0.02 and 0.26 ± 0.04, respectively, indicating that mutations associated with adaptation to DAP increase Cls activity. Modeling of Cls447a to
Streptomyces
sp. phospholipase D indicates that the adaptive mutations Cls447a
H215R
and Cls447a
R218Q
are proximal to the phospholipase domain 1 (PLD1) active site and near the putative nucleophile H217. As mutations to Cls are part of a larger genomic adaptation process, increased Cls activity is likely to be highly epistatic with other changes to facilitate DAP resistance.
Detection of Francisella tularensis-Specific Antibodies in Patients with Tularemia by a Novel Competitive Enzyme-Linked Immunosorbent Assay
Authors: Sharma Neekun , Hotta Akitoyo , Yamamoto Yoshie , Fujita Osamu , Uda Akihiko , Morikawa Shigeru , Yamada Akio , Tanabayashi Kiyoshi 
Published: November 2012

ABSTRACT

A novel competitive enzyme-linked immunosorbent assay (cELISA) was developed and evaluated for detection of antibodies against
Francisella tularensis
in humans. The assay is based on the ability of serum antibodies to inhibit the binding of monoclonal antibodies (MAbs) directed against
F. tularensis
lipopolysaccharide antigens. The assay was evaluated using serum samples of tularemia patients, inactivated
F. tularensis
-immunized rabbits, and
F. tularensis
-infected mice. Antibodies against
F. tularensis
were successfully detected in serum samples of tularemia patients as well as the immunized and infected animals. The cELISA method was compared to indirect ELISA (iELISA) and the commonly used microagglutination test (MA) using serum samples of 19 tularemia patients and 50 healthy individuals. The sensitivity and specificity of cELISA were 93.9 and 96.1%, respectively, in comparison to the iELISA. MA was less sensitive than cELISA with a sensitivity and specificity of only 81.8 and 98.0%, respectively. A high degree of correlation (
R
2
= 0.8226) was observed between cELISA and iELISA results. The novel cELISA developed in this study appears to be highly sensitive and specific for serodiagnosis of human tularemia. The potential of the MAb-based cELISA to be used in both human and animal samples emphasizes its usefulness for serological survey of tularemia among multiple animal species.