bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plectasin Shows Intracellular Activity against
Staphylococcus aureus
in Human THP-1 Monocytes and in a Mouse Peritonitis Model
Authors: Brinch Karoline Sidelmann , Sandberg Anne , Baudoux Pierre , Van Bambeke Françoise , Tulkens Paul M. , Frimodt-Møller Niels , Høiby Niels , Kristensen Hans-Henrik 
Published: September 2009

ABSTRACT

Antimicrobial therapy of infections with
Staphylococcus aureus
can pose a challenge due to slow response to therapy and recurrence of infection. These treatment difficulties can partly be explained by intracellular survival of staphylococci, which is why the intracellular activity of antistaphylococcal compounds has received increased attention within recent years. The intracellular activity of plectasin, an antimicrobial peptide, against
S. aureus
was determined both in vitro and in vivo. In vitro studies using THP-1 monocytes showed that some intracellular antibacterial activity of plectasin was maintained (maximal relative efficacy [
E
max
], 1.0- to 1.3-log reduction in CFU) even though efficacy was inferior to that of extracellular killing (
E
max
, >4.5-log CFU reduction). Animal studies included a novel use of the mouse peritonitis model, exploiting extra- and intracellular differentiation assays, and assessment of the correlations between activity and pharmacokinetic (PK) parameters. The intracellular activity of plectasin was in accordance with the in vitro studies, with an
E
max
of a 1.1-log CFU reduction. The parameter most important for activity was
fC
peak
/MIC, where
fC
peak
is the free peak concentration. These findings stress the importance of performing studies of extra- and intracellular activity since these features cannot be predicted from traditional MIC and killing kinetic studies. Application of both the THP-1 and the mouse peritonitis models showed that the in vitro results were similar to findings in the in vivo model with respect to demonstration of intracellular activity. Therefore the in vitro model was a good screening model for intracellular activity. However, animal models should be applied if further information on activity, PK/pharmacodynamic parameters, and optimal dosing regimens is required.
Antimicrobial Susceptibilities of
Mycoplasma genitalium
Strains Examined by Broth Dilution and Quantitative PCR
Authors: Hamasuna Ryoichi , Jensen Jørgen Skov , Osada Yukio 
Published: September 2009

ABSTRACT

Only limited information regarding the antimicrobial susceptibilities of
Mycoplasma genitalium
is available because of difficulties in isolating
M. genitalium
strains from clinical specimens. Antimicrobial susceptibilities of 15 clinical isolates, 7 ATCC strains, and an early passage of the M30 strain were examined by the broth dilution method. Azithromycin, clarithromycin, sitafloxacin, and moxifloxacin were the most active drugs against
M. genitalium
, and their MIC
90
s were 0.002, 0.008, 0.125, and 0.125 mg/liter, respectively.
Structures of Triacetyloleandomycin and Mycalamide A Bind to the Large Ribosomal Subunit of
Haloarcula marismortui
Authors: Gürel Güliz , Blaha Gregor , Steitz Thomas A. , Moore Peter B. 
Published: September 2009

ABSTRACT

Structures have been obtained for the complexes that triacetyloleandomycin and mycalamide A form with the large ribosomal subunit of
Haloarcula marismortui
. Triacetyloleandomycin binds in the nascent peptide tunnel and inhibits the activity of ribosomes by blocking the growth of the nascent peptide chain. Mycalamide A binds to the E site and inhibits protein synthesis by occupying the space normally occupied by the CCA end of E-site-bound tRNAs.
In Vitro Activities of Three New Dihydrofolate Reductase Inhibitors against Clinical Isolates of Gram-Positive Bacteria
Authors: Bowker Karen E. , Caspers Patrick , Gaucher Bérengère , MacGowan Alasdair P. 
Published: September 2009

ABSTRACTBAL0030543, BAL0030544, and BAL0030545 are dihydrophthalazine inhibitors with in vitro potency against gram-positive pathogens. The MIC50s for methicillin (meticillin)-sensitiveStaphylococcus aureus, methicillin-resistantStaphylococcus aureus, hetero-vancomycin-resistantStaphylococcus aureus, and vancomycin-resistantStaphylococcus aureus(VISA) range from 0.015 to 0.25 μg/ml (MIC90s ≤ 0.5 μg/ml). MIC50s for beta-hemolytic streptococci range from 0.03 to 0.06 μg/ml, MIC50s forStreptococcus pneumoniaerange from 0.06 to 0.12 μg/ml, MIC50s forListeria monocytogenesrange from 0.015 to 0.06 μg/ml, and MIC50s forStreptococcus mitisare ≤0.015 μg/ml. These three dihydrophthalazine antifolates have improved potency compared to that of trimethoprim and activity against gram-positive pathogens resistant to other drug classes. (This work was presented in part at the 48th Interscience Conference on Antimicrobial Agents and Chemotherapy, Washington, DC, 2008 [1].)
Effect of Varying Amounts of a Liquid Nutritional Supplement on the Pharmacokinetics of Posaconazole in Healthy Volunteers
Authors: Krishna Gopal , Ma Lei , Vickery Donna , Yu Xin , Wu Irene , Power Edward , Beresford Eric , Komjathy Steven 
Published: September 2009

ABSTRACTThe aim of this single-center, phase 1, randomized, 5 by 5 crossover, open-label study was to determine the effects of varying amounts of a nutritional supplement (Boost Plus) on the pharmacokinetics of posaconazole in 30 healthy volunteers. After an overnight fast, subjects were administered a single dose of 400 mg posaconazole oral suspension alone or following Boost Plus (8 fluid ounces [oz] [240 ml], 4 oz [120 ml], 2 oz [60 ml], or 1 oz [30 ml]). Subjects were randomized to receive all five treatments in different sequences, with a 14-day washout between treatments. Primary pharmacokinetic variables—area under the concentration-time curve from time zero to the time of the final quantifiable sample (AUCtf), maximum observed plasma concentration (Cmax), time toCmax(Tmax), and relative bioavailability—were assessed up to 5 days postdose. Safety assessments included testing for adverse events, clinical laboratory tests, measurement of vital signs, physical examinations, and electrocardiograms. Posaconazole bioavailability increased almost linearly with increasing amounts of Boost Plus. Based on log-transformed data, the relative bioavailabilities (AUCs) of posaconazole were 35% (fasting), 48% (1 oz), 60% (2 oz), and 77% (4 oz) of the level reached in the presence of 8 oz Boost Plus, whereasTmaxwas unaffected. Compared with the levels reached under fasting conditions, posaconazoleCmaxand AUC values increased 3.5- and 2.9-fold, respectively, when given with 8 oz Boost Plus. Single doses of posaconazole at 400 mg alone and with 1, 2, 4, or 8 oz Boost Plus were safe and well tolerated in healthy subjects.
Pharmacodynamic Profile of Tigecycline against Methicillin-Resistant
Staphylococcus aureus
in an Experimental Pneumonia Model
Authors: Koomanachai Pornpan , Crandon Jared L. , Banevicius Mary Anne , Peng Li , Nicolau David P. 
Published: September 2009

ABSTRACT

Tigecycline (TGC) is an extended-spectrum antibiotic with activity against
Staphylococcus aureus
, including methicillin (meticillin)-resistant
S. aureus
strains, which are well-recognized pathogens in nosocomial pneumonia. The objective of this study was to characterize the exposure-response relationship for TGC against
S. aureus
in an immunocompromised BALB/c murine pneumonia model. Six
S. aureus
isolates were studied, and the TGC MICs for those isolates ranged from 0.125 to 0.5 mg/liter. The pharmacokinetics (PK) of TGC in serum and bronchoalveolar lavage (BAL) fluid were evaluated, as was the level of protein binding of the compound in this murine species. Administration of TGC at 1.56 to 150 mg/kg of body weight/day in single or two to three divided doses was used in the efficacy studies. TGC displayed linear PK and had a mean half-life of 10.9 ± 2.5 h. Efficacy was highly correlated with the area under the free concentration-time curve (
f
AUC)/MIC (
r
2
= 0.93). The 80% and 50% effective exposure indexes and the stasis exposure index were similar between the isolates (means ± standard deviations, 3.04 ± 1.12, 1.84 ± 1.3, and 1.9 ± 1.5, respectively). Maximal efficacy was predicted at a 2.85-log
10
-CFU reduction. TGC appeared to accumulate in the interstitial space, as the ratios of the
f
AUC from 0 to 8 h of epithelial lining fluid to plasma were 7.02, 15.11, and 23.95 for doses of 12.5, 25, and 50 mg/kg, respectively. TGC was highly effective in this murine pneumonia model. In light of current MIC distributions, the
f
AUC/MIC targets that we defined against
S. aureus
are readily achievable in humans given conventional doses of TGC.
The O Antigen Is a Critical Antigen for the Development of a Protective Immune Response to
Bordetella parapertussis
Authors: Zhang Xuqing , Goebel Elizabeth M. , Rodríguez Maria Eugenia , Preston Andrew , Harvill Eric T. 
Published: September 2009

ABSTRACT

Despite excellent vaccine coverage in developed countries, whooping cough is a reemerging disease that can be caused by two closely related pathogens,
Bordetella pertussis
and
B. parapertussis
. The two are antigenically distinct, and current vaccines, containing only
B. pertussis
-derived antigens, confer efficient protection against
B. pertussis
but not against
B. parapertussis
.
B. pertussis
does not express the O antigen, while
B. parapertussis
retains it as a dominant surface antigen. Since the O antigen is a protective antigen for many pathogenic bacteria, we examined whether this factor is a potential protective antigen for
B. parapertussis
. In a mouse model of infection, immunization with wild-type
B. parapertussis
elicited a strong antibody response to the O antigen and conferred efficient protection against a subsequent
B. parapertussis
challenge. However, immunization with an isogenic mutant lacking the O antigen,
B. parapertussis
Δ
wbm
, induced antibodies that recognized other antigens but did not efficiently mediate opsonophagocytosis of
B. parapertussis
. The passive transfer of sera raised against
B. parapertussis
, but not
B. parapertussis
Δ
wbm
, reduced
B. parapertussis
loads in the lower respiratory tracts of mice. The addition of 10 μg of purified
B. parapertussis
lipopolysaccharide (LPS), which contains the O antigen, but not
B. parapertussis
Δ
wbm
LPS drastically improved the efficacy of the acellular vaccine Adacel against
B. parapertussis
. These data suggest that the O antigen is a critical protective antigen of
B. parapertussis
and its inclusion can substantially improve whooping cough vaccine efficacy against this pathogen.
Electropositive Charge in α-Defensin Bactericidal Activity: Functional Effects of Lys-for-Arg Substitutions Vary with the Peptide Primary Structure
Authors: Llenado R. Alan , Weeks Colby S. , Cocco Melanie J. , Ouellette André J. 
Published: September 2009

ABSTRACT

Cationic amino acids contribute to α-defensin bactericidal activity. Curiously, although Arg and Lys have equivalent electropositive charges at neutral pH, α-defensins contain an average of nine Arg residues per Lys residue. To investigate the role of high α-defensin Arg content, all Arg residues in mouse Paneth cell α-defensin cryptdin 4 (Crp4) and rhesus myeloid α-defensin 4 (RMAD-4) were replaced with Lys to prepare (R/K)-Crp4 and (R/K)-RMAD-4, respectively. Lys-for-Arg replacements in Crp4 attenuated bactericidal activity and slowed the kinetics of
Escherichia coli
ML35 cell permeabilization, and (R/K)-Crp4 required longer exposure times to reduce
E. coli
cell survival. In marked contrast, Lys substitutions in RMAD-4 improved microbicidal activity against certain bacteria and permeabilized
E. coli
more effectively. Therefore, Arg→Lys substitutions attenuated activity in Crp4 but not in RMAD-4, and the functional consequences of Arg→Lys replacements in α-defensins are dependent on the peptide primary structure. In addition, the bactericidal effects of (R/K)-Crp4 and (R/K)-RMAD-4 were more sensitive to inhibition by NaCl than those of the native peptides, suggesting that the high Arg content of α-defensins may be under selection to confer superior microbicidal function under physiologic conditions.
Immunoproteomic Analysis of the Development of Natural Immunity in Subjects Colonized by
Neisseria meningitidis
Reveals Potential Vaccine Candidates
Authors: Williams Jeannette N. , Skipp Paul J. , O'Connor C. David , Christodoulides Myron , Heckels John E. 
Published: September 2009

ABSTRACT
The potential protective effect of existing vaccines against serogroup B meningococci, based on outer membrane proteins, is limited by strain restriction and apparent short duration of immune responses. In contrast, meningococcal colonization is known to stimulate the production of cross-protective antibodies as defined by the development of serum bactericidal activity (SBA) against heterologous serogroup B strains. In the current study, a resource of human serum samples and meningococcal carriage strains from studies of longitudinal carriage has been subjected to immunoproteomic analysis to investigate the outer membrane protein antigens associated with the development of SBA to both homologous and heterologous meningococcal serogroup B strains. Proteins from outer membranes of homologous and heterologous strains were separated by two-dimensional electrophoresis and reacted with paired sera which showed an increase in SBA following colonization. Individuals showed differing patterns of reactivity upon colonization, with an increase in SBA being associated with increases in the number of spots detected before and after colonization and/or with increases in the intensity of individual spots. Analysis of immunoreactive spots by mass spectrometry resulted in the identification of 43 proteins potentially associated with the development of SBA against both homologous and heterologous strains. The list of protein immunogens generated included not only well-established antigens but also novel proteins that represent potentially new candidates for inclusion in defined, multicomponent serogroup B vaccines.
Toxin-Mediated Effects on the Innate Mucosal Defenses: Implications for Enteric Vaccines
Authors: Glenn Gregory M. , Francis David H. , Danielsen E. Michael 
Published: September 2009

ABSTRACTRecent studies have confirmed older observations that the enterotoxins enhance enteric bacterial colonization and pathogenicity. How and why this happens remains unknown at this time. It appears that toxins such as the heat-labile enterotoxin (LT) fromEscherichia colican help overcome the innate mucosal barrier as a key step in enteric pathogen survival. We review key observations relevant to the roles of LT and cholera toxin in protective immunity and the effects of these toxins on innate mucosal defenses. We suggest either that toxin-mediated fluid secretion mechanically disrupts the mucus layer or that toxins interfere with innate mucosal defenses by other means. Such a breach gives pathogens access to the enterocyte, leading to binding and pathogenicity by enterotoxigenicE. coli(ETEC) and other organisms. Given the common exposure to LT+ETEC by humans visiting or residing in regions of endemicity, barrier disruption should frequently render the gut vulnerable to ETEC and other enteric infections. Conversely, toxin immunity would be expected to block this process by protecting the innate mucosal barrier. Years ago, Peltola et al. (Lancet 338:1285-1289, 1991) observed unexpectedly broad protective effects against LT+ETEC and mixed infections when using a toxin-based enteric vaccine. If toxins truly exert barrier-disruptive effects as a key step in pathogenesis, then a return to classic toxin-based vaccine strategies for enteric disease is warranted and can be expected to have unexpectedly broad protective effects.
Entry ofPorphyromonas gingivalisOuter Membrane Vesicles into Epithelial Cells Causes Cellular Functional Impairment
Authors: Furuta Nobumichi , Takeuchi Hiroki , Amano Atsuo 
Published: September 2009

ABSTRACTPorphyromonas gingivalis, a periodontal pathogen, secretes outer membrane vesicles (MVs) that contain major virulence factors, including proteases termed gingipains (Arg-gingipain [Rgp] and Lys-gingipain [Kgp]). We recently showed thatP. gingivalisMVs swiftly enter host epithelial cells via an endocytosis pathway and are finally sorted to lytic compartments. However, it remains unknown whether MV entry impairs cellular function. Herein, we analyzed cellular functional impairment following entry ofP. gingivalisinto epithelial cells, including HeLa and immortalized human gingival epithelial (IHGE) cells. After being taken up by endocytic vacuoles, MVs degraded the cellular transferrin receptor (TfR) and integrin-related signaling molecules, such as paxillin and focal adhesion kinase (FAK), which resulted in depletion of intracellular transferrin and inhibition of cellular migration. Few Rgp-null MVs entered the cells, and these negligibly degraded TfR, whereas paxillin and FAK degradation was significant. In contrast, Kgp-null MVs clearly entered the cells and degraded TfR, while they scarcely degraded paxillin and FAK. In addition, both wild-type and Kgp-null MVs significantly impaired cellular migration, whereas the effect of Rgp-null MVs was limited. Our findings suggest that, following entry ofP. gingivalisMVs into host cells, MV-associated gingipains degrade cellular functional molecules such as TfR and paxillin/FAK, resulting in cellular impairment, indicating thatP. gingivalisMVs are potent vehicles for transmission of virulence factors into host cells and are involved in the etiology of periodontitis.
Parental occupational exposure to organic solvents and anencephaly in Mexico
Authors: Aguilar-Garduño C , Lacasaña M , Blanco-Muñoz J , Borja-Aburto V Hugo , García A M 
Published: September 2009

Objective:To assess the relationship between parental occupational exposure to organic solvents, and the risk of anencephaly in Mexico.Methods:A case-control study was conducted based on the registers of the Epidemiological Surveillance System for Neural Tube Defects in Mexico; 151 cases of anencephaly of ⩾20 weeks’ gestation were included. A control, born alive and without any apparent congenital malformations at birth, was selected for each case in the same maternity service in which the case was born. Information on occupational exposures, lifestyle habits, reproductive history, use of medicines, supplementation with multivitamins and folic acid, was obtained by a general questionnaire; a food frequency questionnaire was also applied to obtain information of daily intake of folate and other B vitamins. Occupational exposure to organic solvents was based on job title as a proxy for exposure and analysed considering two critical periods around conception.Results:In logistic regression analysis, the odds of having a child with anencephaly was higher if the mother or the father was occupationally exposed to organic solvents during the periconceptional period, or when both parents or at least one of them were occupationally exposed during this period with an adjusted odds ratio of 2.97 (95% CI 1.36 to 6.52).Conclusions:The results support the hypothesis that both maternal and paternal occupational exposure to organic solvents can increase the probability of having a child with anencephaly.
Incidence of metabolic syndrome among night-shift healthcare workers
Authors: Pietroiusti A , Neri A , Somma G , Coppeta L , Iavicoli I , Bergamaschi A , Magrini A 
Published: September 2009

Objective:Night-shift work is associated with ischaemic cardiovascular disorders. It is not currently known whether it may be causally linked to metabolic syndrome (MS), a risk condition for ischaemic cardiovascular disorders. The syndrome presents with visceral obesity associated with mild alterations in glucidic and lipidic homeostasis, and in blood pressure. The aim of this study was to assess whether a causal relationship exists between night-shift work and the development of MS.Methods:Male and female nurses performing night shifts, free from any component of MS at baseline, were evaluated annually for the development of the disorder during a 4-year follow-up. Male and female nurses performing daytime work only, visited during the same time period, represented the control group.Results:The cumulative incidence of MS was 9.0% (36/402) among night-shift workers, and 1.8% (6/336) among daytime workers (relative risk (RR) 5.0, 95% CI − 2.1 to 14.6). The annual rate of incidence of MS was 2.9% in night-shift workers and 0.5% in daytime workers. Kaplan–Meier survival curves of the two groups were significantly different (log-rank test; p<0.001). Multiple Cox regression analysis (forward selection method based on likelihood ratio) showed that among selected variables (age, gender, smoking, alcohol intake, familiar history, physical activity, and work schedule) the only predictors of occurrence of MS were sedentariness (hazard ratio (HR) 2.92; 95% CI 1.64 to 5.18; p = 0.017), and night-shift work (HR 5.10; 95% CI 2.15 to 12.11; p<0.001).Conclusions:The risk of developing MS is strongly associated with night-shift work in nurses. Medical counselling should be promptly instituted in night-shift workers with the syndrome, and in case of persistence or progression, a change in work schedule should be considered.
Melanoma Proteoglycan Modifies Gene Expression to Stimulate Tumor Cell Motility, Growth, and Epithelial-to-Mesenchymal Transition
Authors: Yang Jianbo , Price Matthew A. , Li Gui Yuan , Bar-Eli Menashe , Salgia Ravi , Jagedeeswaran Ramasamy , Carlson Jennifer H. , Ferrone Soldano , Turley Eva A. , McCarthy James B. 
Published: September 2009

Abstract
Melanoma chondroitin sulfate proteoglycan (MCSP) is a plasma membrane–associated proteoglycan that facilitates the growth, motility, and invasion of tumor cells. MCSP expression in melanoma cells enhances integrin function and constitutive activation of Erk1,2. The current studies were performed to determine the mechanism by which MCSP expression promotes tumor growth and motility. The results show that MCSP expression in radial growth phase, vertical growth phase, or metastatic cell lines causes sustained activation of Erk1,2, enhanced growth, and motility which all require the cytoplasmic domain of the MCSP core protein. MCSP expression in a radial growth phase cell line also promotes an epithelial-to-mesenchymal transition based on changes in cell morphology and the expression of several epithelial-to-mesenchymal transition markers. Finally, MCSP enhances the expression of c-Met and hepatocyte growth factor, and inhibiting c-Met expression or activation limits the increased growth and motility of multiple melanoma cell lines. The studies collectively show the importance of MCSP in promoting progression by an epigenetic mechanism and they indicate that MCSP could be targeted to delay or inhibit tumor progression in patients. [Cancer Res 2009;69(19):7538–47]