bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antimicrobial Activity and Cell Selectivity of Synthetic and Biosynthetic Cationic Polymers
Authors: Venkatesh Mayandi , Barathi Veluchamy Amutha , Goh Eunice Tze Leng , Anggara Raditya , Fazil Mobashar Hussain Urf Turabe , Ng Alice Jie Ying , Harini Sriram , Aung Thet Tun , Fox Stephen John , Liu Shouping , Yang Liang , Barkham Timothy Mark Sebastian , Loh Xian Jun , Verma Navin Kumar , Beuerman Roger W. , Lakshminarayanan Rajamani 
Published: August 2017

ABSTRACT

The mammalian and microbial cell selectivity of synthetic and biosynthetic cationic polymers has been investigated. Among the polymers with peptide backbones, polymers containing amino side chains display greater antimicrobial activity than those with guanidine side chains, whereas ethylenimines display superior activity over allylamines. The biosynthetic polymer ε-polylysine (εPL) is noncytotoxic to primary human dermal fibroblasts at concentrations of up to 2,000 μg/ml, suggesting that the presence of an isopeptide backbone has greater cell selectivity than the presence of α-peptide backbones. Both εPL and linear polyethylenimine (LPEI) exhibit bactericidal properties by depolarizing the cytoplasmic membrane and disrupt preformed biofilms. εPL displays broad-spectrum antimicrobial properties against antibiotic-resistant Gram-negative and Gram-positive strains and fungi. εPL elicits rapid bactericidal activity against both Gram-negative and Gram-positive bacteria, and its biocompatibility index is superior to those of cationic antiseptic agents and LPEI. εPL does not interfere with the wound closure of injured rabbit corneas. In a rabbit model of bacterial keratitis, the topical application of εPL (0.3%, wt/vol) decreases the bacterial burden and severity of infections caused by
Pseudomonas aeruginosa
and
Staphylococcus aureus
strains.
In vivo
imaging studies confirm that εPL-treated corneas appeared transparent and nonedematous compared to untreated infected corneas. Taken together, our results highlight the potential of εPL in resolving topical microbial infections.
N-Acylated Derivatives of Sulfamethoxazole Block Chlamydia Fatty Acid Synthesis and Interact with FabF
Authors: Mojica Sergio A. , Salin Olli , Bastidas Robert J. , Sunduru Naresh , Hedenström Mattias , Andersson C. David , Núñez-Otero Carlos , Engström Patrik , Valdivia Raphael H. , Elofsson Mikael , Gylfe Åsa 
Published: August 2017

ABSTRACT

The type II fatty acid synthesis (FASII) pathway is essential for bacterial lipid biosynthesis and continues to be a promising target for novel antibacterial compounds. Recently, it has been demonstrated that
Chlamydia
is capable of FASII and this pathway is indispensable for
Chlamydia
growth. Previously, a high-content screen with
Chlamydia trachomatis
-infected cells was performed, and acylated sulfonamides were identified to be potent growth inhibitors of the bacteria.
C. trachomatis
strains resistant to acylated sulfonamides were isolated by serial passage of a wild-type strain in the presence of low compound concentrations. Results from whole-genome sequencing of 10 isolates from two independent drug-resistant populations revealed that mutations that accumulated in
fabF
were predominant. Studies of the interaction between the FabF protein and small molecules showed that acylated sulfonamides directly bind to recombinant FabF
in vitro
and treatment of
C. trachomatis
-infected HeLa cells with the compounds leads to a decrease in the synthesis of
Chlamydia
fatty acids. This work demonstrates the importance of FASII for
Chlamydia
development and may lead to the development of new antimicrobials.
Avibactam Restores the Susceptibility of Clinical Isolates of Stenotrophomonas maltophilia to Aztreonam
Authors: Mojica Maria F. , Papp-Wallace Krisztina M. , Taracila Magdalena A. , Barnes Melissa D. , Rutter Joseph D. , Jacobs Michael R. , LiPuma John J. , Walsh Thomas J. , Vila Alejandro J. , Bonomo Robert A. 
Published: August 2017

ABSTRACT

Stenotrophomonas maltophilia
is an emerging opportunistic pathogen, classified by the World Health Organization as one of the leading multidrug-resistant organisms in hospital settings. The need to discover novel compounds and/or combination therapies for
S. maltophilia
is urgent. We demonstrate the
in vitro
efficacy of aztreonam-avibactam (ATM-AVI) against
S. maltophilia
and kinetically characterize the inhibition of the L2 β-lactamase by avibactam. ATM-AVI overcomes aztreonam resistance in selected clinical strains of
S. maltophilia
, addressing an unmet medical need.
In Vitro
Susceptibility to Closthioamide among Clinical and Reference Strains of Neisseria gonorrhoeae
Authors: Miari Victoria F. , Solanki Priya , Hleba Yonek , Stabler Richard A. , Heap John T. 
Published: August 2017

ABSTRACT

Neisseria gonorrhoeae
is one of the leading antimicrobial resistance threats worldwide. This study determined the MICs of closthioamide to be 0.008 to 0.5 mg/liter for clinical
N. gonorrhoeae
strains and related species. Cross-resistance with existing antimicrobial resistance was not detected, indicating that closthioamide could be used to treat drug-resistant
N. gonorrhoeae
.
Pharmacokinetics of the Protein Microbicide 5P12-RANTES in Sheep following Single-Dose Vaginal Gel Administration
Authors: McBride John W. , Dias Nicola , Cameron David , Offord Robin E. , Hartley Oliver , Boyd Peter , Kett Vicky L. , Malcolm R. Karl 
Published: August 2017

ABSTRACT

5P12-RANTES, a chemokine analogue that potently blocks the HIV CCR5 coreceptor, is being developed as both a vaginal and rectal microbicide for prevention of sexual transmission of HIV. Here, we report the first pharmacokinetic data for 5P12-RANTES following single-dose vaginal gel administration in sheep. Aqueous gel formulations containing low (1.24-mg/ml), intermediate (6.18-mg/ml), and high (32.0-mg/ml; suspension-type gel) concentrations of 5P12-RANTES were assessed via rheology, syringeability, and
in vitro
release testing. Following vaginal gel administration to sheep, 5P12-RANTES concentrations were measured in vaginal fluid, vaginal tissue, and serum over a 96-h period. All gels showed non-Newtonian pseudoplastic behavior, with the high-concentration gels exhibiting a greater viscosity and cohesive structure than the intermediate- and low-concentration gels. In
in vitro
release testing, >90% 5P12-RANTES was released from the low- and intermediate-concentration gels after 72 h. For the high-concentration gel, ∼50% 5P12-RANTES was detected, attributed to protein denaturation during lyophilization and/or subsequent solvation of the protein within the gel matrix. In sheep, 5P12-RANTES concentrations in vaginal fluid, vaginal tissue, and serum increased in a dose-dependent manner. The highest concentrations were measured in vaginal fluid (10
5
to 10
7
ng/ml), followed by vaginal tissue (10
4
to 10
6
ng/ml). Both of these concentration ranges are several orders of magnitude above the reported half-maximal inhibitory concentrations. The lowest concentration was measured in serum (<10
2
ng/ml). The 5P12-RANTES pharmacokinetic data are similar to those reported previously for other candidate microbicides. These data, coupled with 5P12-RANTES's potency at picomolar concentrations, its strong barrier to resistance, and the full protection that it was observed to provide in a rhesus macaque vaginal challenge model, support the continued development of 5P12-RANTES as a microbicide.
Pharmacokinetics of Cefuroxime in Synovial Fluid
Authors: Schwameis R. , Syré S. , Marhofer D. , Appelt A. , Burau D. , Sarahrudi K. , Kloft C. , Zeitlinger M. 
Published: August 2017

ABSTRACT

Cefuroxime is frequently used as preoperative antibiotic prophylaxis and may be used for the treatment of septic arthritis. A prerequisite for successful treatment of septic arthritis is the ability of an antibiotic agent to penetrate into the target site. Therefore, the concentration of cefuroxime in synovial fluid was evaluated. Ten patients who underwent elective knee arthroscopy were included in this study. Patients were treated with a single dose of 1,500 mg cefuroxime intravenously, and subsequently, the concentrations in plasma, the interstitial fluid of muscle tissue, and synovial fluid were measured by using microdialysis. Pharmacokinetic/pharmacodynamic calculations to predict bacterial killing were performed using the epidemiologically defined MIC
90
for clinical isolates and CLSI breakpoints. Cefuroxime penetrated excellently into muscle tissue (ratio of the area under the concentration-time curve [AUC] for muscle tissue/AUC for free plasma, 1.79) and synovial fluid (ratio of the AUC for synovial fluid/AUC for free plasma, 1.94). The cefuroxime concentration was greater than the MIC
90
for
Staphylococcus aureus
and
S. epidermidis
strains (≤2 mg/liter) over the complete dosing interval (the percentage of the dosing interval during which the free cefuroxime concentration exceeded the MIC for the pathogen [
fT
MIC
]). CLSI defines staphylococci with MICs of ≤8 mg/liter to be susceptible to cefuroxime. For staphylococci with MICs of ≤8 mg/liter, the
fT
MIC
in plasma was 52.5%, while the
fT
MIC
in muscle tissue and synovial fluid was 93.6% and 96.3%, respectively. Cefuroxime may be used to treat septic arthritis caused by susceptible bacterial strains (MIC ≤ 8 mg/liter). The activity of cefuroxime in septic arthritis might be underestimated when relying exclusively on plasma concentrations.
The Fluorocycline TP-271 Is Efficacious in Models of Aerosolized Bacillus anthracis Infection in BALB/c Mice and Cynomolgus Macaques
Authors: Grossman Trudy H. , Anderson Michael S. , Drabek Lindsay , Gooldy Melanie , Heine Henry S. , Henning Lisa N. , Lin Winston , Newman Joseph V. , Nevarez Rene , Siefkas-Patterson Kaylyn , Radcliff Anne K. , Sutcliffe Joyce A. 
Published: August 2017

ABSTRACT

The fluorocycline TP-271 was evaluated in mouse and nonhuman primate (NHP) models of inhalational anthrax. BALB/c mice were exposed by nose-only aerosol to
Bacillus anthracis
Ames spores at a level of 18 to 88 lethal doses sufficient to kill 50% of exposed individuals (LD
50
). When 21 days of once-daily dosing was initiated at 24 h postchallenge (the postexposure prophylaxis [PEP] study), the rates of survival for the groups treated with TP-271 at 3, 6, 12, and 18 mg/kg of body weight were 90%, 95%, 95%, and 84%, respectively. When 21 days of dosing was initiated at 48 h postchallenge (the treatment [Tx] study), the rates of survival for the groups treated with TP-271 at 6, 12, and 18 mg/kg TP-271 were 100%, 91%, and 81%, respectively. No deaths of TP-271-treated mice occurred during the 39-day posttreatment observation period. In the NHP model, cynomolgus macaques received an average dose of 197 LD
50
of
B. anthracis
Ames spore equivalents using a head-only inhalation exposure chamber, and once-daily treatment of 1 mg/kg TP-271 lasting for 14 or 21 days was initiated within 3 h of detection of protective antigen (PA) in the blood. No (0/8) animals in the vehicle control-treated group survived, whereas all 8 infected macaques treated for 21 days and 4 of 6 macaques in the 14-day treatment group survived to the end of the study (56 days postchallenge). All survivors developed toxin-neutralizing and anti-PA IgG antibodies, indicating an immunologic response. On the basis of the results obtained with the mouse and NHP models, TP-271 shows promise as a countermeasure for the treatment of inhalational anthrax.
Fatal Pertussis in the Neonatal Mouse Model Is Associated with Pertussis Toxin-Mediated Pathology beyond the Airways
Authors: Scanlon Karen M. , Snyder Yael G. , Skerry Ciaran , Carbonetti Nicholas H. 
Published: August 2017

ABSTRACT

In infants,
Bordetella pertussis
can cause severe disease, manifested as pronounced leukocytosis, pulmonary hypertension, and even death. The exact cause of death remains unknown, and no effective therapies for treating fulminant pertussis exist. In this study, a neonatal mouse model of critical pertussis is characterized, and a central role for pertussis toxin (PT) is described. PT promoted colonization, leukocytosis, T cell phenotypic changes, systemic pathology, and death in neonatal but not adult mice. Surprisingly, PT inhibited lung inflammatory pathology in neonates, a result which contrasts dramatically with observed PT-promoted pathology in adult mice. Infection with a PT-deficient strain induced severe pulmonary inflammation but not mortality in neonatal mice, suggesting that death in these mice was not associated with impaired lung function. Dissemination of infection beyond the lungs was also detected in neonatal mice, which may contribute to the observed systemic effects of PT. We propose that it is the systemic activity of pertussis toxin and not pulmonary pathology that promotes mortality in critical pertussis. In addition, we observed transmission of infection between neonatal mice, the first report of
B. pertussis
transmission in mice. This model will be a valuable tool to investigate causes of pertussis pathogenesis and identify potential therapies for critical pertussis.
17β-Estradiol Dysregulates Innate Immune Responses to Pseudomonas aeruginosa Respiratory Infection and Is Modulated by Estrogen Receptor Antagonism
Authors: Abid Shadaan , Xie ShangKui , Bose Moumita , Shaul Philip W. , Terada Lance S. , Brody Steven L. , Thomas Philip J. , Katzenellenbogen John A. , Kim Sung Hoon , Greenberg David E. , Jain Raksha 
Published: August 2017

ABSTRACT

Females have a more severe clinical course than males in terms of several inflammatory lung conditions. Notably, females with cystic fibrosis (CF) suffer worse outcomes, particularly in the setting of
Pseudomonas aeruginosa
infection. Sex hormones have been implicated in experimental and clinical studies; however, immune mechanisms responsible for this sex-based disparity are unknown and the specific sex hormone target for therapeutic manipulation has not been identified. The objective of this study was to assess mechanisms behind the impact of female sex hormones on host immune responses to
P. aeruginosa
. We used wild-type and CF mice, which we hormone manipulated, inoculated with
P. aeruginosa
, and then examined for outcomes and inflammatory responses. Neutrophils isolated from mice and human subjects were tested for responses to
P. aeruginosa
. We found that female mice inoculated with
P. aeruginosa
died earlier and showed slower bacterial clearance than males (
P
< 0.0001). Ovariectomized females supplemented with 17β-estradiol succumbed to
P. aeruginosa
challenge earlier than progesterone- or vehicle-supplemented mice (
P
= 0.0003). 17β-Estradiol-treated ovariectomized female mice demonstrated increased lung levels of inflammatory cytokines, and when rendered neutropenic the mortality difference was abrogated. Neutrophils treated with 17β-estradiol demonstrated an enhanced oxidative burst but decreased
P. aeruginosa
killing and earlier cell necrosis. The estrogen receptor (ER) antagonist ICI 182,780 improved survival in female mice infected with
P. aeruginosa
and restored neutrophil function. We concluded that ER antagonism rescues estrogen-mediated neutrophil dysfunction and improves survival in response to
P. aeruginosa
. ER-mediated processes may explain the sex-based mortality gap in CF and other inflammatory lung illnesses, and the ER blockade represents a rational therapeutic strategy.
Transforming Growth Factor β1/SMAD Signaling Pathway Activation Protects the Intestinal Epithelium from Clostridium difficile Toxin A-Induced Damage
Authors: Tinoco-Veras Christianne Maria , Santos Ana Angélica Q. A. , Stipursky Joice , Meloni Marcelo , Araujo Ana Paula Bérgamo , Foschetti Danielle Abreu , López-Ureña Diana , Quesada-Gómez Carlos , Leitão Renata F. C. , Gomes Flávia Carvalho Alcantara , Brito Gerly Anne de Castro 
Published: August 2017

ABSTRACT

Clostridium difficile
, the main cause of diarrhea in hospitalized patients, produces toxins A (TcdA) and B (TcdB), which affect intestinal epithelial cell survival, proliferation, and migration and induce an intense inflammatory response. Transforming growth factor β (TGF-β) is a pleiotropic cytokine affecting enterocyte and immune/inflammatory responses. However, it has been shown that exposure of intestinal epithelium to a low concentration of TcdA induces the release of TGF-β1, which has a protective effect on epithelial resistance and a TcdA/TGF-β signaling pathway interaction. The activation of this pathway
in vivo
has not been elucidated. The aim of this study was to investigate the role of the TGF-β1 pathway in TcdA-induced damage in a rat intestinal epithelial cell line (IEC-6) and in a mouse model of an ileal loop. TcdA increased the expression of TGF-β1 and its receptor, TβRII,
in vitro
and
in vivo
. TcdA induced nuclear translocation of the transcription factors SMAD2/3, a hallmark of TGF-β1 pathway activation, both in IEC cells and in mouse ileal tissue. The addition of recombinant TGF-β1 (rTGF-β) prevented TcdA-induced apoptosis/necrosis and restored proliferation and repair activity in IEC-6 cells in the presence of TcdA. Together, these data show that TcdA induces TGF-β1 signaling pathway activation and suggest that this pathway might play a protective role against the effect of
C. difficile
-toxin.
Adaptations to a Loss-of-Function Mutation in the Betaproteobacterium Aromatoleum aromaticum: Recruitment of Alternative Enzymes for Anaerobic Phenylalanine Degradation
Authors: Schmitt G. , Arndt F. , Kahnt J. , Heider J. 
Published: August 2017

ABSTRACT

Anaerobic phenylalanine (Phe) degradation in the betaproteobacterium
Aromatoleum aromaticum
involves transamination and decarboxylation to phenylacetaldehyde, followed by oxidation to phenylacetate. The latter reaction is catalyzed simultaneously by two enzymes, a highly specific phenylacetaldehyde dehydrogenase (PDH) and a rather unspecific tungsten-dependent aldehyde oxidoreductase (AOR). Attempting to establish increased synthesis of AOR, we constructed a mutant lacking the gene for PDH. This mutant still grew on phenylalanine, exhibiting increased AOR activities on medium containing tungstate. In the absence of tungstate, the mutant showed initially severe growth deficiency, but it resumed growth on Phe after longer incubation times. Moreover, the growth rates of the mutant increased during several reinoculation cycles on either tungstate-proficient or -deficient media, reaching the same values as recorded in wild-type strains. We confirmed AOR as the major alternative enzyme serving Phe degradation under tungstate-supplied conditions and identified and characterized the alternative NAD-dependent aldehyde dehydrogenase AldB taking over the function under tungstate-deficient conditions. Sequence analysis of the respective genes from adapted cultures under either growth condition revealed a mutation in the upstream region of the
aor
operon and a mutation within the coding region of
aldB
, which are likely involved in the observed adaptation of the deletion mutant to regain fast growth on Phe.

IMPORTANCE
The betaproteobacterium
Aromatoleum aromaticum
degrades many aromatic compounds under denitrifying conditions. One of the steps of phenylalanine degradation is catalyzed by two simultaneously induced enzymes, a NAD(P)-dependent phenylacetaldehyde dehydrogenase and a W-containing aldehyde oxidoreductase. We report here that the latter fully complements a constructed deletion mutant lacking the gene for phenylacetaldehyde dehydrogenase and is overproduced after several reinoculations. Moreover, an alternative NAD-dependent dehydrogenase is recruited to resume growth in tungstate-free medium, which does not allow the production of aldehyde oxidoreductase. This alternative enzyme is overproduced and seems to have acquired a point mutation in the active center. Our research illustrates the flexibility of environmentally important bacteria in adapting their metabolic pathways to new challenges within only a few generations.
Roles of Transcriptional and Translational Control Mechanisms in Regulation of Ribosomal Protein Synthesis in Escherichia coli
Authors: Burgos Hector L. , O'Connor Kevin , Sanchez-Vazquez Patricia , Gourse Richard L. 
Published: August 2017

ABSTRACTBacterial ribosome biogenesis is tightly regulated to match nutritional conditions and to prevent formation of defective ribosomal particles. InEscherichia coli, most ribosomal protein (r-protein) synthesis is coordinated with rRNA synthesis by a translational feedback mechanism: when r-proteins exceed rRNAs, specific r-proteins bind to their own mRNAs and inhibit expression of the operon. It was recently discovered that the second messenger nucleotide guanosine tetra and pentaphosphate (ppGpp), which directly regulates rRNA promoters, is also capable of regulating many r-protein promoters. To examine the relative contributions of the translational and transcriptional control mechanisms to the regulation of r-protein synthesis, we devised a reporter system that enabled us to genetically separate thecis-acting sequences responsible for the two mechanisms and to quantify their relative contributions to regulation under the same conditions. We show that the synthesis of r-proteins from the S20 and S10 operons is regulated by ppGpp following shifts in nutritional conditions, but most of the effect of ppGpp required the 5′ region of the r-protein mRNA containing the target site for translational feedback regulation and not the promoter. These results suggest that most regulation of the S20 and S10 operons by ppGpp following nutritional shifts is indirect and occurs in response to changes in rRNA synthesis. In contrast, we found that the promoters for the S20 operon were regulated during outgrowth, likely in response to increasing nucleoside triphosphate (NTP) levels. Thus, r-protein synthesis is dynamic, with different mechanisms acting at different times.IMPORTANCEBacterial cells have evolved complex and seemingly redundant strategies to regulate many high-energy-consuming processes. InE. coli, synthesis of ribosomal components is tightly regulated with respect to nutritional conditions by mechanisms that act at both the transcription and translation steps. In this work, we conclude that NTP and ppGpp concentrations can regulate synthesis of ribosomal proteins, but most of the effect of ppGpp is indirect as a consequence of translational feedback in response to changes in rRNA levels. Our results illustrate how effects of seemingly redundant regulatory mechanisms can be separated in time and that even when multiple mechanisms act concurrently their contributions are not necessarily equivalent.