bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gallium Disrupts Iron Uptake by Intracellular and ExtracellularFrancisellaStrains and Exhibits Therapeutic Efficacy in a Murine Pulmonary Infection Model
Authors: Olakanmi Oyebode , Gunn John S. , Su Shengchang , Soni Shilpa , Hassett Daniel J. , Britigan Bradley E. 
Published: November 2009

ABSTRACTFrancisella tularensisrequires iron (Fe) for growth, but the biologic sources of Fe for this organism are largely unknown. We found thatFrancisellasp. growing in broth culture or within human macrophages can acquire Fe from the two major host Fe-binding proteins, lactoferrin (Lf) and transferrin (Tf). Fe acquisition is a potential target for novel therapies. Gallium (Ga) is a transition metal that interferes with cellular Fe metabolism by competing with Fe for uptake/utilization. Growth of eitherF. tularensislive vaccine strain (LVS) orFrancisella novicidawas inhibited by ≥2 μM Ga chelated to Tf or Lf, with GaLf being somewhat more potent.Francisellaspp. express two Fe-containing antioxidant enzymes, catalase (KatG) and Fe cofactored superoxide dismutase (FeSOD). Growth of LVS with 10 μM GaTf or GaLf led to a dramatic decrease in bacterial catalase activity and in FeSOD activity that was associated with an increased susceptibility to H2O2. Ga also protected mice from intranasal challenge withF. novicida. Whereas 100% of theF. novicida-infected mice died by day 9, 75% of the mice receiving Ga continued to survive to at least day 15. Thus, a single intranasal dose of Ga followed by daily intraperitoneal Ga at a dose tolerated by the animals resulted in prolonged survival. These data support the potential utility of Ga as a therapy forF. tularensisinfection of the lung.
Structure-Microbicidal Activity Relationship of Synthetic Fragments Derived from the Antibacterial α-Helix of Human Lactoferrin
Authors: Håversen L. , Kondori N. , Baltzer L. , Hanson L. Å. , Dolphin G. T. , Dunér K. , Mattsby-Baltzer I. 
Published: November 2009

ABSTRACT

There is a need for new microbicidal agents with therapeutic potential due to antibiotic resistance in bacteria and fungi. In this study, the structure-microbicidal activity relationship of amino acid residues 14 to 31 (sequence 14-31) from the N-terminal end, corresponding to the antibacterial α-helix of human lactoferrin (LF), was investigated by downsizing, alanine scanning, and substitution of amino acids. Microbicidal analysis (99% killing) was performed by a microplate assay using
Escherichia coli
,
Staphylococcus aureus
, and
Candida albicans
as test organisms. Starting from the N-terminal end, downsizing of peptide sequence 14-31 showed that the peptide sequence 19-31 (KCFQWQRNMRKVR, HL9) was the optimal length for antimicrobial activity. Furthermore, HL9 bound to lipid A/lipopolysaccharide, as shown by neutralizing endotoxic activity in a
Limulus
assay. Alanine scanning of peptide sequence 20-31 showed that Cys20, Trp23, Arg28, Lys29, or Arg31 was important for expressing full killing activity, particularly against
C. albicans
. Substituting the neutral hydrophilic amino acids Gln24 and Asn26 for Lys and Ala (HLopt2), respectively, enhanced microbicidal activity significantly against all test organisms compared to the amino acids natural counterpart, also, in comparison with HL9, HLopt2 had more than 10-fold-stronger fungicidal activity. Furthermore, HLopt2 was less affected by metallic salts than HL9. The microbicidal activity of HLopt2 was slightly reduced only at pH 7.0, as tested in the pH range of 4.5 to 7.5. The results showed that the microbicidal activity of synthetic peptide sequences, based on the antimicrobial α-helix region of LF, can be significantly enhanced by optimizing the length and substitution of neutral amino acids at specific positions, thus suggesting a sequence lead with therapeutic potential.
Efficacy Profiles of Daptomycin for Treatment of Invasive and Noninvasive Pulmonary Infections with
Streptococcus pneumoniae
Authors: Henken Stefanie , Bohling Jennifer , Martens-Lobenhoffer Jens , Paton James C. , Ogunniyi A. David , Briles David E. , Salisbury Vyvyan C. , Wedekind Dirk , Bode-Böger Stefanie M. , Welsh Thomas , Bange Franz C. , Welte Tobias , Maus Ulrich A. 
Published: November 2009

ABSTRACT

Daptomycin is a novel lipopeptide antibiotic with excellent activity against Gram-positive bacterial pathogens, but its therapeutic value for the treatment of invasive pneumococcal disease compared to that for the treatment of pneumococcal pneumonia is incompletely defined. We investigated the efficacy of daptomycin in two models of
Streptococcus pneumoniae
-induced lung infection, i.e., pneumococcal pneumonia and septic pneumococcal disease. Mice were infected with a bioluminescent, invasive serotype 2
S. pneumoniae
strain or a less virulent serotype 19
S. pneumoniae
strain and were then given semitherapeutic or therapeutic daptomycin or ceftriaxone. Readouts included survival; bacterial loads; and septic disease progression, as determined by biophotonic imaging. Semitherapeutic daptomycin treatment fully protected the mice against the progression of septic disease induced by serotype 2
S. pneumoniae
, while therapeutic treatment of the mice with daptomycin or ceftriaxone led to ∼70% or ∼60% survival, respectively. In contrast, mice infected with serotype 19
S. pneumoniae
developed severe pneumonia and lung leakage even in the presence of increased intra-alveolar daptomycin levels, resulting in only 40% survival, whereas the ceftriaxone-treated mice had 100% survival. Together, although daptomycin demonstrates little efficacy in the treatment of pneumococcal pneumonia, daptomycin is highly effective in preventing
S. pneumoniae
-induced septic death, thus possibly offering a therapeutic option for patients with life-threatening septic pneumococcal disease.
Interaction of Ceftobiprole with the Low-Affinity PBP 5 of
Enterococcus faecium
Authors: Henry Xavier , Amoroso Ana , Coyette Jacques , Joris Bernard 
Published: November 2009

ABSTRACT

Ceftobiprole is a new cephalosporin that exhibits a high level of affinity for methicillin-resistant
Staphylococcus aureus
PBP 2a. It was reported that ceftobiprole did not interact with a mutated form of the low-affinity protein
Enterococcus faecium
PBP 5 (PBP 5fm) that, when overexpressed, confers a β-lactam resistance phenotype to the bacterium. Our results show that ceftobiprole binds to unmutated PBP 5fm to form a stable acyl-enzyme and that ceftobiprole is able to efficiently kill a penicillin-resistant
Enterococcus faecium
strain that produces this protein.
Escherichia coli
Sequence Type ST131 as an Emerging Fluoroquinolone-Resistant Uropathogen among Renal Transplant Recipients
Authors: Johnson James R. , Johnston Brian , Clabots Connie , Kuskowski Michael A. , Pendyala Swaroop , DebRoy Chitrita , Nowicki Bogdan , Rice James 
Published: November 2009

ABSTRACT

Among 40
Escherichia coli
urine isolates from renal transplant recipients (Galveston, TX, 2003 to 2005), sequence type ST131 (O25:H4) was highly prevalent (representing 35% of isolates overall and 60% of fluoroquinolone-resistant isolates), virulent appearing, antimicrobial resistant (but extended-spectrum-cephalosporin susceptible), and associated with black race. Pulsotypes were diverse; some were linked to other locales. ST131 emerged significantly during the study period. These findings suggest that
E. coli
ST131 may constitute an important new multidrug-resistant threat to renal transplant recipients.
In Vitro
and
In Vivo
Efficacies of Teicoplanin-Loaded Calcium Sulfate for Treatment of Chronic Methicillin-Resistant
Staphylococcus aureus
Osteomyelitis
Authors: Jia Wei-Tao , Luo Shi-Hua , Zhang Chang-Qing , Wang Jian-Qiang 
Published: November 2009

ABSTRACT

The
i
n vitro
and
in vivo
therapeutic efficacies of teicoplanin-loaded calcium sulfate (TCS; 10% [wt] teicoplanin) were investigated in a rabbit model of chronic methicillin-resistant
Staphylococcus aureus
(MRSA) osteomyelitis. The
in vitro
elution characteristics of teicoplanin from TCS pellets were realized by carrying out an evaluation of the release kinetics, recovery rate, and antibacterial activity of the released teicoplanin. Chronic osteomyelitis was induced by inoculating 10
7
CFU of a MRSA strain into the tibial cavity of rabbits. After 3 weeks, the animals were treated by debridement followed by implantation of TCS pellets in group 1, calcium sulfate (CS) pellets alone in group 2, and intravenous (i.v.) teicoplanin (6 mg/kg of body weight every 12 h for three doses and then every 24 h up to 4 weeks) in group 3. Animals in group 4 were left untreated. After 6 weeks, the efficacy of the osteomyelitis treatment was evaluated by hematological, radiological, microbiological, and histological examinations.
In vitro
elution studies showed sustained release of teicoplanin at a therapeutic level over a time period of 3 weeks. The released teicoplanin maintained its antibacterial activity.
In vivo
, the best therapeutic effect was observed in animals treated with TCS pellets, resulting in significantly lower radiological and histological scores, lower positive rates of MRSA culture and bacterial load, and excellent bone regeneration compared with those treated by CS alone or i.v. teicoplanin, without any local or systemic adverse effects. TCS pellets are an effective alternative to i.v. teicoplanin for the treatment of chronic MRSA osteomyelitis, particularly because teicoplanin is delivered locally while the TCS pellets simultaneously promote bone defect repair.
Panel of Prototypical Raltegravir-Resistant Infectious Molecular Clones in a Novel Integrase-Deleted Cloning Vector
Authors: Reuman Elizabeth C. , Bachmann Michael H. , Varghese Vici , Fessel W. Jeffrey , Shafer Robert W. 
Published: November 2009

ABSTRACT
We created an HIV-1 cloning vector, pNL4.3ΔIN, to generate recombinant infectious molecular clones for analysis of patient-derived HIV-1 integrase coding regions. Using this vector, we constructed a panel of clinically derived viruses with the canonical patterns of raltegravir resistance mutations and submitted the panel to the NIH AIDS Research and Reference Reagent Program. Investigational integrase inhibitors with activity against these clones are likely to retain activity against the most clinically relevant raltegravir-resistant variants.
Waging War against UropathogenicEscherichia coli: Winning Back the Urinary Tract
Authors: Sivick Kelsey E. , Mobley Harry L. T. 
Published: November 2009

ABSTRACTUrinary tract infection (UTI) caused by uropathogenicEscherichia coli(UPEC) is a substantial economic and societal burden—a formidable public health issue. Symptomatic UTI causes significant discomfort in infected patients, results in lost productivity, predisposes individuals to more serious infections, and usually necessitates antibiotic therapy. There is no licensed vaccine available for prevention of UTI in humans in the United States, likely due to the challenge of targeting a relatively heterogeneous group of pathogenic strains in a unique physiological niche. Despite significant advances in the understanding of UPEC biology, mechanistic details regarding the host response to UTI and full comprehension of genetic loci that influence susceptibility require additional work. Currently, there is an appreciation for the role of classic innate immune responses—from pattern receptor recognition to recruitment of phagocytic cells—that occur during UPEC-mediated UTI. There is, however, a clear disconnect regarding how factors involved in the innate immune response to UPEC stimulate acquired immunity that facilitates enhanced clearance upon reinfection. Unraveling the molecular details of this process is vital in the development of a successful vaccine for prevention of human UTI. Here, we survey the current understanding of host responses to UPEC-mediated UTI with an eye on molecular and cellular factors whose activity may be harnessed by a vaccine that stimulates lasting and sterilizing immunity.
Fibrin network structure and clot mechanical properties are altered by incorporation of erythrocytes
Authors: Gersh Kathryn , Nagaswami Chandrasekaran , Weisel John 
Published: November 2009

SummaryAlthough many in vitro fibrin studies are performed with plasma, in vivo clots and thrombi contain erythrocytes, or red blood cells (RBCs).To determine the effects of RBCs on fibrin clot structure and mechanical properties, we compared plasma clots without RBCs to those prepared with low (2 vol%), intermediate (5-10 vol%), or high (≥20 vol%) numbers of RBCs. By confocal microscopy, we found that low RBC concentrations had little effect on clot structure. Intermediate RBC concentrations caused heterogeneity in the fiber network with pockets of densely packed fibers alongside regions with few fibers. With high levels of RBCs, fibers arranged more uniformly but loosely around the cells. Scanning electron micrographs demonstrated an uneven distribution of RBCs throughout the clot and a significant increase in fiber diameter upon RBC incorporation. While permeability was not affected by RBC addition, at 20% or higher RBCs, the ratio of viscous modulus (G′′) to elastic modulus (G′) increased significantly over that of a clot without any RBCs. RBCs triggered variability in the fibrin network structure, individual fiber characteristics, and overall clot viscoelasticity compared to the absence of cells. These results are important for understanding in vivo clots and thrombi.
Chlamydia pneumoniae adversely modulates vascular cell properties by direct interaction with signalling cascades
Authors: Kern Jan , Maass Viola , Maass Matthias 
Published: November 2009

SummaryDue to its dependence on intracellular development Chlamydia pneumoniae has developed numerous strategies to create an adequate environment within its host cells ensuring both chlamydial reproduction and target cell survival. The bacterium that has been related to atherogenesis due to its presence in vascular tissue is able to enter a persistent state of chronic infection in the vasculature that escapes antibiotic targeting. Ingestion of the bacterium results in severe modifications and reprogramming of signalling pathways and the metabolism of the host cell. Processes range from the prevention of direct lysosomal destruction of chlamydial inclusions to the inhibition of host cell apoptosis and an enhanced cellular glucose uptake to maintain energy-consuming mechanisms. Furthermore, infection regularly causes the development of a proinflammatory and proproliferative phenotype in the host cell in vitro, ex vivo and in vivo and own new findings suggest a detrimental proliferative loop within vascular cells upon a modified endothelin-1 axis demonstrating a potential for proatherosclerotic processes in early and progressed atherosclerosis. This review displays crucial mechanisms of Chlamydia pneumoniae-induced interactions with vascular host cell signalling cascades with an emphasis on mitogenic and inflammatory processes as well as target cell activation.
Thrombin generation as an intermediate phenotype for venous thrombosis
Authors: Segers Olivier , Oerle René van , Cate Hugo ten , Rosing Jan , Castoldi Elisabetta 
Published: November 2009

Summary
In vitro thrombin generation, which reflects an individual’s plasma coagulation potential and has been shown to correlate with the risk of venous thromboembolism (VTE), might represent a useful intermediate phenotype for the genetic dissection of VTE. As a proof of principle, we have investigated whether the thrombin generation assay can detect changes in the haemostatic balance associated with common genetic variation affecting the level or function of coagulation factors and inhibitors. The study population consisted of 140 healthy individuals. Plasma levels of coagulation factors and inhibitors and thrombin generation parameters determined at low tissue factor (TF) ± thrombomodulin (TM) and at high TF ± activated protein C (APC) were available from a previous study. All individuals were genotyped for F5 Leiden, F2 G20210A and 19 additional single nucleotide polymorphisms (SNPs) in haemostasis-related genes. The association of each SNP with plasma levels of the corresponding proteins and with thrombin generation parameters (lag time, peak height and endogenous thrombin potential [ETP]) was evaluated by statistical analysis. Not only F5 Leiden and F2 G20210A, but also several other common SNPs, significantly affected thrombin generation parameters. In particular, FGA A1069G (Thr312Ala) decreased the ETP-APC, F2 A19911G increased the ETP-APC, F10 IVS2 C+517G decreased the ETP+APC, F12 C-46T decreased peak height at low TF, and TFPI T-287C and TFPI IVS7 T-33C decreased the ETP+APC. These results indicate that the thrombin generation assay is sensitive to genetic variation in haemostasis-related genes, which makes it a promising tool to identify novel genetic risk factors of VTE.
The influence of variation in the P2Y12 receptor gene on in vitro platelet inhibition with the direct P2Y12 antagonist cangrelor
Authors: van Werkum Jochem , Rude Goran , Leebeek Frank , Kruit Adrian , Hackeng Christian , ten Berg Jurriën , de Maat Moniek , Ruven Henk , Bouman Heleen 
Published: November 2009

SummaryNovel P2Y12 inhibitors are in development to overcome the occurrence of atherothrombotic events associated with poor responsiveness to the widely used P2Y12 inhibitor clopidogrel. Cangrelor is an intravenously administered P2Y12 inhibitor that does not need metabolic conversion to an active metabolite for its antiplatelet action, and as a consequence exhibits a more potent and consistent antiplatelet profile as compared to clopidogrel. It was the objective of this study to determine the contribution of variation in the P2Y12 receptor gene to platelet aggregation after in vitro partial P2Y12 receptor blockade with the direct antagonist cangrelor. Optical aggregometry was performed at baseline and after in vitro addition of 0.05 and 0.25 μM cangrelor to the platelet-rich plasma of 254 healthy subjects. Five haplotype-tagging (ht)-SNPs covering the entire P2Y12 receptor gene were genotyped (rs6798347C>t, rs6787801T>c, rs9859552C>a, rs6801273A>g and rs2046934T>c [T744C]) and haplotypes were inferred. The minor c allele of SNP rs6787801 was associated with a 5% lower 20 μM ADP-induced peak platelet aggregation (0.05 μM cangrelor, p<0.05). Aa homozygotes for SNP rs9859552 showed 20% and 17% less inhibition of platelet aggregation with cangrelor when compared to CC homozygotes (0.05 and 0.25 μM cangrelor respectively; p<0.05). Results of the haplotype analyses were consistent with those of the single SNPs. Polymorphisms of the P2Y12 receptor gene contribute significantly to the interindividual variability in platelet inhibition after partial in vitro blockade with the P2Y12 antagonist cangrelor.
Hydration does not prevent orthostatic hypercoagulability
Authors: Brenner Benjamin , Masoud Muhannad , Sarig Galit , Jacob Giris 
Published: November 2009

SummaryProlonged standing activates the coagulation cascade by the activation of endothelial cells, and probably the haemoconcentration effect contributes to this "orthostatic hypercoagulability". It was the objective of this study to assess whether rehydration (haemodilution) prevents or attenuates orthostatic induced thrombin formation. Twelve healthy young subjects were studied during two separate visits. Haematocrit (Hct), total plasma protein, coagulation profile tests, including endothelial activation related factors, and protein C global pathway were studied at rest supine, and while standing at 15 and 30 minutes (min). During the second visit the study was repeated after intravenous 1.5 liter 0.9% saline. While in supine posture, intravenous rehydration resulted in Hct reduction of 14.2 ± 2% (haemodilution), a decrease of 11.5 ± 1.3% in total protein, as well as a significant dilutional effect on most of the coagulation parameters. Still standing for 30 min, with and without rehydration caused a comparable increase in tissue factor by 49.83 ± 13.6%, and 35.34 ± 8.55% (p>0.05), respectively and in von Willebrand factor (vWF) 9.5 ± 2.4% and 13.59 ± 2.17% (p>0.05), respectively. At 30 min standing, after intravenous rehydration, factor V and VIII activities, and fibrinogen rose by 22 ± 1.9%, 31.2 ± 6.2%, 9.15 ± 2.64%, (p<0.002 for all), respectively. Prothrombin fragments 1+2 elevated by 84.84 ± 15.3% (p<0.001). Comparable results were obtained with and without the rehydration. Additionally, protein C assay results decreased by 19.4 ±1.7% and 17.5 ± 2.6%, with and without fluids (p<0.05 for both). In healthy subjects, intravenous prophylactic rehydration with normal saline resulted in a haemodilution of all the coagulation parameters, but did neither attenuate nor prevent the orthostatic hypercoagulability.
The contribution of systems biology and reverse genetics to the understanding of Kaposi’s sarcoma-associated herpesvirus pathogenesis in endothelial cells
Authors: Konrad Andreas , Alkharsah Khaled , Jochmann Ramona , Thurau Mathias , Marquardt Gaby , Stürzl Michael , Schulz Thomas 
Published: November 2009

SummaryKaposi’s sarcoma-associated herpesvirus (KSHV) / human herpesvirus-8 is the causative agent of the endothelial cell-derived tumour Kaposi’s sarcoma. Herpesviruses possess large complex genomes which provide many options to regulate cellular physiology during the viral life cycle and in the course of tumourigenicity. Novel techniques of systems biology and reverse genetics are increasingly applied to dissect the complex interaction of KSHV with endothelial cells. This review will outline novel results and pitfalls of these technologies in the elucidation of KSHV pathogenicity.
Venous thromboembolism during pregnancy, postpartum or during contraceptive use
Authors: Blanco-Molina Ángeles , Rota Lidia , Micco Pierpaolo Di , Brenner Benjamin , Trujillo-Santos Javier , Ruiz-Gamietea Angeles , Monreal Manuel ,   the RIETE Investigators
Published: November 2009

SummaryVenous thromboembolism (VTE) is a leading cause of maternal death during pregnancy or postpartum, and in women using hormonal contraceptives. However, important issues concerning its natural history and therapy remain unsolved, and most of the protocols for treatment of VTE in this patient population are based on data extrapolated from other populations. RIETE is an ongoing registry of consecutive patients with objectively confirmed, symptomatic, acute VTE. We examined the clinical characteristics and three-month outcome of all enrolled women with pregnancy, postpartum or using hormonal contraceptives. As of December 2008, 173 pregnant women, 135 postpartum, and 798 contraceptive users were enrolled. Of these, 438 (40%) presented with pulmonary embolism (PE) and 668 with deep-vein thrombosis (DVT). Most women with acute PE had dyspnea (72%) or chest pain (75%), but only 2.0% had hypoxaemia. During the three-month study period, five women (0.45%; 95% CI: 0.17–1.00) died (3 had fatal PE), 13 (1.18%; 95% CI: 0.66–1.95) had VTE recurrences, and seven (0.63%; 95% CI: 0.28–1.25) major bleeding. Two of the three women with fatal PE died during the first few hours after arriving at the emergency ward, with no time to start any therapy. The outcome of pregnant or postpartum women with VTE is similar to that in contraceptive users, even though the treatment is different. The non-specific nature of PE signs may have caused some delay in PE diagnosis.
Endothelium, venous thromboembolism and ischaemic cardiovascular events
Authors: Momi Stefania , Migliacci Rino , Gresele Paolo 
Published: November 2009

SummaryThe association between venous thromboembolism and arterial thrombosis has emerged as consistent clinical observation in the last few years. While several experimental, epidemiological and pharmacologic studies support this association, the initial pathophysiological mechanism linking these two clinical conditions remains to be established. This review discusses the pathophysiological bases and a number of experimental and clinical observations suggesting that the common link between venous thromboembolism and arterial thrombosis is represented by a dysfunctional endothelium.