bluuebunny/crossref_metadata_2025 huggingface dataset:
A multidisciplinary approach to understanding carbonate deposition under tectonically controlled hydrothermal circulation: A case study from a recent travertine mound in the Euganean hydrothermal system, northern Italy
Authors: Pola Marco , Gandin Anna , Tuccimei Paola , Soligo Michele , Deiana Rita , Fabbri Paolo , Zampieri Dario
Published: July 2013

A multidisciplinary study was carried out on an Upper Pleistocene travertine mound (Montirone Hill; Abano Terme, south of Padova, Veneto, Italy) with the aim of developing a comprehensive understanding of the processes interacting in structurally controlled thermal springs and the consequent deposition of thermal limestones. The sedimentology, geochemistry, structural characteristics and hydrogeology of the mound, which is associated with the Euganean geothermal field and the related complex structural framework of the Schio‐Vicenza fault system, were investigated. A palaeo‐environmental model of the deposit has been reconstructed clarifying the connection between the travertine deposition and the regional structural setting. Calcium‐rich thermal waters rose from spring orifices (estimated temperature from 54°C to 61°C based on geochemical calculations) and produced a mound made of coalescent shield‐like bodies. The dominant lime‐mudstone facies resulted from the accumulation of lime mud at the bottom of shallow crater‐like basins located on top of stacked cones. Soft sediment deformations affecting the lime mud sediment were most probably produced by the recurrent uprising of gas bubbles. The overlying crystalline crusts were deposited on the flanks of the mound by waters overflowing from the vents with laminar flux. A deep hydrothermal circuit with a long period of water–rock interaction is supported by geochemical analyses. Furthermore, a local extensional regime, enhancing the migration of thermal fluids to the surface, is inferred based on the results of the structural analysis carried out on the fault/fracture mesh that affects the mound. These results corroborate the well‐established relation among travertine deposits, hydrothermal systems and fault systems, and substantiate the structurally controlled conceptual model of the Euganean hydrothermal system, suggesting that both the thermal and the fault systems were active at least since 34 ka.
Successful medical treatment for globe penetration following tooth extraction in a dog
Authors: Guerreiro Cleo E. , Appelboam Helen , Lowe Robert C.
Published: July 2013

A five‐year‐old entire male Tibetan Terrier was referred for left‐sided periorbital swelling and blepharospasm 4 days following ipsilateral maxillary tooth extraction. Examination of the left eye revealed mild exophthalmos, pain on retropulsion, and absent menace response and pupillary light reflexes. Examination of the posterior segment was not possible owing to the anterior segment pathology. Differential diagnoses considered were iatrogenic globe penetration and peribulbar abscess/cellulitis. Ocular ultrasound was consistent with a penetrating wound to the globe. Treatment with systemic prednisolone and marbofloxacin, and topical atropine sulfate 1%, prednisolone acetate, and brinzolamide was started. Marked clinical improvement allowed visual confirmation of the perforation. Oral prednisolone was tapered over the following 10 weeks. At final re‐examination (10 months), the patient was visual, and fundic examination revealed an additional chorioretinal scar, most likely an exit wound that was obscured by vitreal debris on initial examinations. Neither scar was associated with retinal detachment. To the authors' knowledge, this is the first reported case of successful medical management of iatrogenic globe penetration following exodontic procedures.
Spinal TNFα is necessary for inactivity‐induced phrenic motor facilitation
Authors: Broytman Oleg , Baertsch Nathan A. , Baker‐Herman Tracy L.
Published: July 2013

Key points

A central neural apnoea in the absence of hypoxia elicits a form of respiratory plasticity known as inactivity‐induced phrenic motor facilitation (iPMF), a rebound increase in phrenic burst amplitude when central respiratory neural activity is restored.

iPMF requires spinal atypical protein kinase C (aPKC) activity in spinal segments encompassing the phrenic motor nucleus.

Here, we report novel findings that tumour necrosis factor‐α (TNFα) signalling in or near the phrenic motor pool is necessary and sufficient for iPMF as: (1) spinal TNFα inhibition inhibits iPMF; and (2) spinal TNFα elicits long‐lasting increases in phrenic burst amplitude via an aPKC‐dependent mechanism.

These data are consistent with the hypothesis that local mechanisms operating within or near the phrenic motor pool sense and respond to reduced respiratory neural activity, and suggest that TNFα‐induced activation of aPKC near phrenic motor neurons forms part of the core cellular pathway giving rise to iPMF.

Abstract  A prolonged reduction in central neural respiratory activity elicits a form of plasticity known as inactivity‐induced phrenic motor facilitation (iPMF), a ‘rebound’ increase in phrenic burst amplitude apparent once respiratory neural activity is restored. iPMF requires atypical protein kinase C (aPKC) activity within spinal segments containing the phrenic motor nucleus to stabilize an early transient increase in phrenic burst amplitude and to form long‐lasting iPMF following reduced respiratory neural activity. Upstream signal(s) leading to spinal aPKC activation are unknown. We tested the hypothesis that spinal tumour necrosis factor‐α (TNFα) is necessary for iPMF via an aPKC‐dependent mechanism. Anaesthetized, ventilated rats were exposed to a 30 min neural apnoea; upon resumption of respiratory neural activity, a prolonged increase in phrenic burst amplitude (42 ± 9% baseline; P < 0.05) was apparent, indicating long‐lasting iPMF. Pretreatment with recombinant human soluble TNF receptor 1 (sTNFR1) in the intrathecal space at the level of the phrenic motor nucleus prior to neural apnoea blocked long‐lasting iPMF (2 ± 8% baseline; P > 0.05). Intrathecal TNFα without neural apnoea was sufficient to elicit long‐lasting phrenic motor facilitation (pMF; 62 ± 7% baseline; P < 0.05). Similar to iPMF, TNFα‐induced pMF required spinal aPKC activity, as intrathecal delivery of a ζ‐pseudosubstrate inhibitory peptide (PKCζ‐PS) 35 min following intrathecal TNFα arrested TNFα‐induced pMF (28 ± 8% baseline; P < 0.05). These data demonstrate that: (1) spinal TNFα is necessary for iPMF; and (2) spinal TNFα is sufficient to elicit pMF via a similar aPKC‐dependent mechanism. These data are consistent with the hypothesis that reduced respiratory neural activity elicits iPMF via a TNFα‐dependent increase in spinal aPKC activity.
Myths and realities of the cardiac vagus
Authors: Coote J. H.
Published: July 2013

Abstract  There is continuing belief that cardiac parasympathetic postganglionic fibres are sparse or absent from the ventricles. This review of the literature shows that the supposition is a myth. Early studies considered that fine silver‐stained fibres coursing amongst ventricle myocardial cells were most likely cardiac parasympathetic postganglionic fibres. The conclusions were later supported by acetyl cholinesterase staining using a method that appeared not to be associated with noradrenaline nerve fibres. The conclusion is critically examined in the light of several recent histological studies using the acetyl cholinesterase method and also a more definitive technique (CHAT), that suggest a widespread location of parasympathetic ganglia and a relatively dense parasympathetic innervation of ventricular muscle in a range of mammals including man. The many studies demonstrating acetylcholine release in the ventricle on vagal nerve stimulation and a high density of acetylcholine M2 receptors is in accord with this as are tests of ventricular performance from many physiological studies. Selective control of cardiac functions by anatomically segregated parasympathetic ganglia is discussed. It is argued that the influence of vagal stimulation on ventricular myocardial action potential refractory period, duration, force and rhythm is evidence that vagal fibres have close apposition to myocardial fibres. This is supported by clear evidence of accentuated antagonism between sympathetic activity and vagal activity in the ventricle and also by direct effects of vagal activity independent of sympathetic activity. The idea of differential control of atrial and ventricular physiology by vagal C and vagal B preganglionic fibres is examined as well as differences in chemical phenotypes and their function. The latter is reflected in medullary and supramedullary control. Reference is made to the importance of this knowledge to understanding the normal physiology of cardiac autonomic control and significance to pathology.
Mechanisms of retroaxonal barrage firing in hippocampal interneurons
Authors: Sheffield Mark E. J. , Edgerton Gabrielle B. , Heuermann Robert J. , Deemyad Tara , Mensh Brett D. , Spruston Nelson
Published: July 2013

Key points

Persistent firing can be triggered in a population of inhibitory interneurons found in the hippocampus and neocortex. Repeated stimulation eventually triggers an autonomous barrage of spikes that is generated and maintained in the axon, followed by antidromic propagation to the soma.

This barrage of spikes is generated and maintained in the axon, followed by antidromic propagation to the soma. The mechanisms underlying this ‘retroaxonal barrage firing’ are unknown.

We find that retroaxonal barrage firing is Ca2+ dependent, is inhibited by the L‐type Ca2+ channel blockers cadmium, nifedipine and verapamil, and does not require synaptic transmission. Loading the stimulated interneuron with BAPTA did not block barrage firing, suggesting that the required Ca2+ entry may occur in other cells.

Retroaxonal barrage firing was observed in mice lacking the Cx36 isoform (most common neuronal isoform), indicating that this particular isoform is not required.

Abstract  We recently described a new form of neural integration and firing in a subset of interneurons, in which evoking hundreds of action potentials over tens of seconds to minutes produces a sudden barrage of action potentials lasting about a minute beyond the inciting stimulation. During this persistent firing, action potentials are generated in the distal axon and propagate retrogradely to the soma. To distinguish this from other forms of persistent firing, we refer to it here as ‘retroaxonal barrage firing’, or ‘barrage firing’ for short. Its induction is blocked by chemical inhibitors of gap junctions and curiously, stimulation of one interneuron in some cases triggers barrage firing in a nearby, unstimulated interneuron. Beyond these clues, the mechanisms of barrage firing are unknown. Here we report new results related to these mechanisms. Induction of barrage firing was blocked by lowering extracellular calcium, as long as normal action potential threshold was maintained, and it was inhibited by blocking L‐type voltage‐gated calcium channels. Despite its calcium dependence, barrage firing was not prevented by inhibiting chemical synaptic transmission. Furthermore, loading the stimulated/recorded interneuron with BAPTA did not block barrage firing, suggesting that the required calcium entry occurs in other cells. Finally, barrage firing was normal in mice with deletion of the primary gene for neuronal gap junctions (connexin36), suggesting that non‐neuronal gap junctions may be involved. Together, these findings suggest that barrage firing is probably triggered by a multicellular mechanism involving calcium signalling and gap junctions, but operating independently of chemical synaptic transmission.
How LeuT shapes our understanding of the mechanisms of sodium‐coupled neurotransmitter transporters
Authors: Penmatsa Aravind , Gouaux Eric
Published: July 2013

Neurotransmitter transporters are ion‐coupled symporters that drive the uptake of neurotransmitters from neural synapses. In the past decade, the structure of a bacterial amino acid transporter, leucine transporter (LeuT), has given valuable insights into the understanding of architecture and mechanism of mammalian neurotransmitter transporters. Different conformations of LeuT, including a substrate‐free state, inward‐open state, and competitive and non‐competitive inhibitor‐bound states, have revealed a mechanistic framework for the transport and transport inhibition of neurotransmitters. The current review integrates our understanding of the mechanistic and pharmacological properties of eukaryotic neurotransmitter transporters obtained through structural snapshots of LeuT.
Identification of Extended-Spectrum-β-Lactamase-Positive Klebsiella pneumoniae Urinary Tract Isolates Harboring KPC and CTX-M β-Lactamases in Nonhospitalized Patients
Authors: Kopacz Joanna , Mariano Noriel , Colon-Urban Rita , Sychangco Paul , Wehbeh Wehbeh , Segal-Maurer Sorana , Urban Carl
Published: July 2013

Forty-seven extended-spectrum-β-lactamase-positive
Klebsiella pneumoniae
urinary tract isolates from nonhospitalized patients were identified, and 79% harbored KPC and/or CTX-M β-lactamases. Approximately 90% of the isolates were resistant to trimethoprim-sulfamethoxazole and levofloxacin, and 40% were resistant to a carbapenem, while 92% were susceptible to polymyxin B, 87% were susceptible to tigecycline, and 79% were susceptible to fosfomycin. Increased use of broader-spectrum antibiotics may help to prevent their dissemination and reduce the risk of progression to invasive disease.
Cyclic AMP Effectors in African Trypanosomes Revealed by Genome-Scale RNA Interference Library Screening for Resistance to the Phosphodiesterase Inhibitor CpdA
Authors: Gould Matthew K. , Bachmaier Sabine , Ali Juma A. M. , Alsford Sam , Tagoe Daniel N. A. , Munday Jane C. , Schnaufer Achim C. , Horn David , Boshart Michael , de Koning Harry P.
Published: July 2013

One of the most promising new targets for trypanocidal drugs to emerge in recent years is the cyclic AMP (cAMP) phosphodiesterase (PDE) activity encoded by
TbrPDEB1
and
TbrPDEB2
. These genes were genetically confirmed as essential, and a high-affinity inhibitor, CpdA, displays potent antitrypanosomal activity. To identify effectors of the elevated cAMP levels resulting from CpdA action and, consequently, potential sites for adaptations giving resistance to PDE inhibitors, resistance to the drug was induced. Selection of mutagenized trypanosomes resulted in resistance to CpdA as well as cross-resistance to membrane-permeable cAMP analogues but not to currently used trypanocidal drugs. Resistance was not due to changes in cAMP levels or in
PDEB
genes. A second approach, a genome-wide RNA interference (RNAi) library screen, returned four genes giving resistance to CpdA upon knockdown. Validation by independent RNAi strategies confirmed resistance to CpdA and suggested a role for the identified
cA
MP
R
esponse
P
roteins (CARPs) in cAMP action. CARP1 is unique to kinetoplastid parasites and has predicted cyclic nucleotide binding-like domains, and RNAi repression resulted in >100-fold resistance. CARP2 and CARP4 are hypothetical conserved proteins associated with the eukaryotic flagellar proteome or with flagellar function, with an orthologue of CARP4 implicated in human disease. CARP3 is a hypothetical protein, unique to
Trypanosoma
. CARP1 to CARP4 likely represent components of a novel cAMP signaling pathway in the parasite. As cAMP metabolism is validated as a drug target in
Trypanosoma brucei
, cAMP effectors highly divergent from the mammalian host, such as
CARP1
, lend themselves to further pharmacological development.
Combination of Pantothenamides with Vanin Inhibitors as a Novel Antibiotic Strategy against Gram-Positive Bacteria
Authors: Jansen Patrick A. M. , Hermkens Pedro H. H. , Zeeuwen Patrick L. J. M. , Botman Peter N. M. , Blaauw Richard H. , Burghout Peter , van Galen Peter M. , Mouton Johan W. , Rutjes Floris P. J. T. , Schalkwijk Joost
Published: July 2013

The emergence of resistance against current antibiotics calls for the development of new compounds to treat infectious diseases. Synthetic pantothenamides are pantothenate analogs that possess broad-spectrum antibacterial activity
in vitro
in minimal media. Pantothenamides were shown to be substrates of the bacterial coenzyme A (CoA) biosynthetic pathway, causing cellular CoA depletion and interference with fatty acid synthesis. In spite of their potential use and selectivity for bacterial metabolic routes, these compounds have never made it to the clinic. In the present study, we show that pantothenamides are not active as antibiotics in the presence of serum, and we found that they were hydrolyzed by ubiquitous pantetheinases of the vanin family. To address this further, we synthesized a series of pantetheinase inhibitors based on a pantothenate scaffold that inhibited serum pantetheinase activity in the nanomolar range. Mass spectrometric analysis showed that addition of these pantetheinase inhibitors prevented hydrolysis of pantothenamides by serum. We found that combinations of these novel pantetheinase inhibitors and prototypic pantothenamides like N5-Pan and N7-Pan exerted antimicrobial activity
in vitro
, particularly against Gram-positive bacteria (
Staphylococcus aureus
,
Staphylococcus epidermidis
,
Streptococcus pneumoniae
, and
Streptococcus pyogenes
) even in the presence of serum. These results indicate that pantothenamides, when protected against degradation by host pantetheinases, are potentially useful antimicrobial agents.
Synchrotron X-Ray Fluorescence Microscopy of Gallium in Bladder Tissue following Gallium Maltolate Administration during Urinary Tract Infection
Authors: Ball Katherine R. , Sampieri Francesca , Chirino Manuel , Hamilton Don L. , Blyth Robert I. R. , Sham Tsun-Kong , Dowling Patricia M. , Thompson Julie
Published: July 2013

A mouse model of cystitis caused by uropathogenic
Escherichia coli
was used to study the distribution of gallium in bladder tissue following oral administration of gallium maltolate during urinary tract infection. The median concentration of gallium in homogenized bladder tissue from infected mice was 1.93 μg/g after daily administration of gallium maltolate for 5 days. Synchrotron X-ray fluorescence imaging and X-ray absorption spectroscopy of bladder sections confirmed that gallium arrived at the transitional epithelium, a potential site of uropathogenic
E. coli
infection. Gallium and iron were similarly but not identically distributed in the tissues, suggesting that at least some distribution mechanisms are not common between the two elements. The results of this study indicate that gallium maltolate may be a suitable candidate for further development as a novel antimicrobial therapy for urinary tract infections caused by uropathogenic
E. coli
.
Susceptibility to Alternative Oral Antimicrobial Agents in Relation to Sequence Type ST131 Status and Coresistance Phenotype among Recent Escherichia coli Isolates from U.S. Veterans
Authors: Johnson James R. , Drawz Sarah M. , Porter Stephen , Kuskowski Michael A.
Published: July 2013

The rising prevalence of resistance to first-line antimicrobial agents in
Escherichia coli
, which has paralleled the emergence of
E. coli
sequence type ST131, has created a need for alternative oral options for use in treating outpatients with infections such as cystitis and chronic prostatitis. Accordingly, we determined susceptibility to six alternative oral agents (azithromycin, chloramphenicol, doxycycline, fosfomycin, minocycline, and rifampin) by Etest or disk diffusion for 120 recently obtained
E. coli
clinical isolates from Veterans Affairs Medical Centers across the United States. Isolates were randomly selected in three subgroups of 40 isolates each based on coresistance to fluoroquinolones with and without extended-spectrum cephalosporins (ESCs). Results were stratified according to trimethoprim-sulfamethoxazole (TMP-SMZ) phenotype. Overall, the prevalence of susceptible (or susceptible plus intermediate) isolates varied by agent, with rifampin being lowest (0%), fosfomycin highest (98 to 99%), and others in the mid-range (37 to 88%). Substantial proportions of isolates (15 to 27%) yielded intermediate results for azithromycin, chloramphenicol, doxycycline, and minocycline. Among isolates resistant (versus susceptible) to fluoroquinolones with or without ESCs, susceptibility to the above four agents declined significantly among non-ST131 isolates but not ST131 isolates. In contrast, in the presence of resistance to TMP-SMZ, susceptibility to azithromycin, doxycycline, and minocycline was significantly reduced among both ST131 and non-ST131 isolates. These findings identify potential alternative oral agents for use with
E. coli
isolates resistant to fluoroquinolones, ESCs, and/or TMP-SMZ and suggest that determination of ST131 status could help guide initial antimicrobial selection, pending susceptibility results.
Field-Based Flow Cytometry for
Ex Vivo
Characterization of Plasmodium vivax and P. falciparum Antimalarial Sensitivity
Authors: Russell B. , Malleret B. , Suwanarusk R. , Anthony C. , Kanlaya S. , Lau Y. L. , Woodrow C. J. , Nosten F. , Renia L.
Published: July 2013

Ex vivo
antimalarial sensitivity testing in human malaria parasites has largely depended on microscopic determination of schizont maturation. While this microscopic method is sensitive, it suffers from poor precision and is laborious. The recent development of portable, low-cost cytometers has allowed us to develop and validate a simple, field-optimized protocol using SYBR green and dihydroethidium for the accurate and objective determination of antimalarial drug sensitivity in freshly isolated
Plasmodium vivax
and
Plasmodium falciparum
.
Mutation of RNA Polymerase β-Subunit Gene Promotes Heterogeneous-to-Homogeneous Conversion of β-Lactam Resistance in Methicillin-Resistant Staphylococcus aureus
Authors: Aiba Yoshifumi , Katayama Yuki , Hishinuma Tomomi , Murakami-Kuroda Hiroko , Cui Longzhu , Hiramatsu Keiichi
Published: July 2013

Three types of phenotypic expression of β-lactam resistance have been reported in methicillin-resistant
Staphylococcus aureus
(MRSA): heterogeneous, homogeneous, and Eagle-type resistance. Heterogeneous-to-homogeneous conversion of β-lactam resistance is postulated to be caused by a chromosomal mutation (
chr*
) in addition to the expression of the
mecA
gene. Eagle-type resistance is a unique phenotype of
chr*
occurring in pre-MRSA strain N315 whose
mecA
gene expression is strongly repressed by an intact
mecI
gene. We here report that certain mutations of the
rpoB
gene, encoding the RNA polymerase β subunit, belong to
chr*
. We studied homogeneous MRSA (homo-MRSA) strain N315ΔIP-H5 (abbreviated as ΔIP-H5), which was obtained from hetero-MRSA strain N315ΔIP by selection with 8 mg/liter imipenem. Whole-genome sequencing of ΔIP-H5 revealed the presence of a unique mutation in the
rpoB
gene,
rpoB
(N967I), causing the amino acid replacement of Asn by Ile at position 967 of RpoB. The effect of the
rpoB
(N967I) mutation was confirmed by constructing a revertant H5
rpoB
(I967N) strain as well as an N315-derived mutant, N315
rpoB
(N967I). H5
rpoB
(I967N) regained the hetero-resistance phenotype, and the N315
rpoB
(N967I) strain showed an Eagle-type phenotype similar to that of the typical Eagle-type MRSA strain N315h4. Furthermore, subsequent whole-genome sequencing revealed that N315h4 also had a missense mutation of
rpoB
(R644H). Introduction of the
rpoB
(N967I) mutation was accompanied by decreased autolysis, prolonged doubling time, and tolerance to bactericidal concentrations of methicillin. We consider that
rpoB
mutations are the major cause for heterogeneous-to-homogeneous phenotypic conversion of β-lactam resistance in MRSA strain N315 and its derived strains.
Head-to-Head Comparison of Inhibitory and Fungicidal Activities of Fluconazole, Itraconazole, Voriconazole, Posaconazole, and Isavuconazole against Clinical Isolates of Trichosporon asahii
Authors: Hazirolan Gulsen , Canton Emilia , Sahin Selma , Arikan-Akdagli Sevtap
Published: July 2013

Treatment of disseminated
Trichosporon
infections still remains difficult. Amphotericin B frequently displays inadequate fungicidal activity and echinocandins have no meaningful antifungal effect against this genus. Triazoles are currently the drugs of choice for the treatment of
Trichosporon
infections. This study evaluates the inhibitory and fungicidal activities of five triazoles against 90 clinical isolates of
Trichosporon asahii
. MICs (μg/ml) were determined according to Clinical and Laboratory Standards Institute microdilution method M27-A3 at 24 and 48 h using two endpoints, MIC-2 and MIC-0 (the lowest concentrations that inhibited ∼50 and 100% of growth, respectively). Minimum fungicidal concentrations (MFCs; μg/ml) were determined by seeding 100 μl of all clear MIC wells (using an inoculum of 10
4
CFU/ml) onto Sabouraud dextrose agar. Time-kill curves were assayed against four clinical
T. asahii
isolates and the
T. asahii
ATCC 201110 strain. The MIC-2 (∼50% reduction in turbidity compared to the growth control well)/MIC-0 (complete inhibition of growth)/MFC values that inhibited 90% of isolates at 48 h were, respectively, 8/32/64 μg/ml for fluconazole, 1/2/8 μg/ml for itraconazole, 0.12/0.5/2 μg/ml for voriconazole, 0.5/2/4 μg/ml for posaconazole, and 0.25/1/4 μg/ml for isavuconazole. The MIC-0 endpoints yielded more consistent MIC results, which remained mostly unchanged when extending the incubation to 48 h (98 to 100% agreement with 24-h values) and are easier to interpret. Based on the time-kill experiments, none of the drugs reached the fungicidal endpoint (99.9% killing), killing activity being shown but at concentrations not reached in serum. Statistical analysis revealed that killing rates are dose and antifungal dependent. The lowest concentration at which killing activity begins was for voriconazole, and the highest was for fluconazole. These results suggest that azoles display fungistatic activity and lack fungicidal effect against
T. asahii
. By rank order, the most active triazole is voriconazole, followed by itraconazole ∼ posaconazole ∼ isavuconazole > fluconazole.
ComparativeIn VitroActivities of SMT19969, a New Antimicrobial Agent, against Clostridium difficile and 350 Gram-Positive and Gram-Negative Aerobic and Anaerobic Intestinal Flora Isolates
Authors: Goldstein Ellie J. C. , Citron Diane M. , Tyrrell Kerin L. , Merriam C. Vreni
Published: July 2013

The comparativein vitroactivity of SMT19969, a novel, narrow-spectrum, nonabsorbable agent, was studied against 50 ribotype-definedClostridium difficilestrains, 174 Gram-positive and 136 Gram-negative intestinal anaerobes, and 40 Gram-positive aerobes. SMT19969 was one dilution more active againstC. difficileisolates (MIC range, 0.125 to 0.5 μg/ml; MIC90, 0.25 μg/ml), including ribotype 027 strains, than fidaxomicin (range, 0.06 to 1 μg/ml; MIC90, 0.5 μg/ml) and two to six dilutions lower than either vancomycin or metronidazole. SMT19969 and fidaxomicin were generally less active against Gram-negative anaerobes, especially theBacteroides fragilisgroup species, than vancomycin and metronidazole, suggesting that SMT19969 has a lesser impact on the normal intestinal microbiota that maintain colonization resistance. SMT19969 showed limited activity against other Gram-positive anaerobes, includingBifidobacteriaspecies,Eggerthella lenta,Finegoldia magna, andPeptostreptococcus anaerobius, with MIC90s of >512, >512, 64, and 64 μg/ml, respectively.Clostridiumspecies showed various levels of susceptibility, withC. innocuumbeing susceptible (MIC90, 1 μg/ml) andC. ramosumandC. perfringensbeing nonsusceptible (MIC90, >512 μg/ml). Activity againstLactobacillusspp. (range, 0.06 to >512 μg/ml; MIC90, >512 μg/ml) was comparable to that of fidaxomicin and varied by species and strain. Gram-positive aerobic cocci (Staphylococcus aureus,Enterococcus faecalis,E. faecium, and streptococci) showed high SMT19969 MIC90values (128 to >512 μg/ml).
Effect of Nitroxides on Swarming Motility and Biofilm Formation, Multicellular Behaviors in Pseudomonas aeruginosa
Authors: de la Fuente-Núñez César , Reffuveille Fany , Fairfull-Smith Kathryn E. , Hancock Robert E. W.
Published: July 2013

The ability of nitric oxide (NO) to induce biofilm dispersion has been well established. Here, we investigated the effect of nitroxides (sterically hindered nitric oxide analogues) on biofilm formation and swarming motility in
Pseudomonas aeruginosa
. A transposon mutant unable to produce nitric oxide endogenously (
nirS
) was deficient in swarming motility relative to the wild type and the complemented strain. Moreover, expression of the
nirS
gene was upregulated by 9.65-fold in wild-type swarming cells compared to planktonic cells. Wild-type swarming levels were substantially restored upon the exogenous addition of nitroxide containing compounds, a finding consistent with the hypothesis that NO is necessary for swarming motility. Here, we showed that nitroxides not only mimicked the dispersal activity of NO but also prevented biofilms from forming in flow cell chambers. In addition, a
nirS
transposon mutant was deficient in biofilm formation relative to the wild type and the complemented strain, thus implicating NO in the formation of biofilms. Intriguingly, despite its stand-alone action in inhibiting biofilm formation and promoting dispersal, a nitroxide partially restored the ability of a
nirS
mutant to form biofilms.
Neisseria Prophage Repressor Implicated in Gonococcal Pathogenesis
Authors: Daou Nadine , Yu Chunxiao , Mcclure Ryan , Gudino Cynthia , Reed George W. , Genco Caroline A.
Published: July 2013

Neisseria gonorrhoeae
, the causative agent of the sexually transmitted disease gonorrhea, can infect and colonize multiple mucosal sites in both men and women. The ability to cope with different environmental conditions requires tight regulation of gene expression. In this study, we identified and characterized a gonococcal transcriptional regulatory protein (Neisseria phage repressor [Npr]) that was previously annotated as a putative gonococcal phage repressor protein. Npr was found to repress transcription of NGNG_00460 to NGNG_00463 (NGNG_00460-00463), an operon present within the phage locus NgoΦ4. Npr binding sites within the NGNG_00460-00463 promoter region were found to overlap the −10 and −35 promoter motifs. A gonococcal
npr
mutant demonstrated increased adherence to and invasion of human endocervical epithelial cells compared to a wild-type gonococcal strain. Likewise, the gonococcal
npr
mutant exhibited enhanced colonization in a gonococcal mouse model of mucosal infection. Analysis of the gonococcal
npr
mutant using RNA sequence (RNA-seq) analysis demonstrated that the Npr regulon is limited to the operon present within the phage locus. Collectively, our studies have defined a new gonococcal phage repressor protein that controls the transcription of genes implicated in gonococcal pathogenesis.
Inflammation-Induced Acid Tolerance Genes
gadAB
in Luminal Commensal Escherichia coli Attenuate Experimental Colitis
Authors: Tchaptchet Sandrine , Fan Ting-Jia , Goeser Laura , Schoenborn Alexi , Gulati Ajay S. , Sartor R. Balfour , Hansen Jonathan J.
Published: July 2013

Dysregulated immune responses to commensal intestinal bacteria, including
Escherichia coli
, contribute to the development of inflammatory bowel diseases (IBDs) and experimental colitis. Reciprocally,
E. coli
responds to chronic intestinal inflammation by upregulating expression of stress response genes, including
gadA
and
gadB
. GadAB encode glutamate decarboxylase and protect
E. coli
from the toxic effects of low pH and fermentation acids, factors present in the intestinal lumen in patients with active IBDs. We hypothesized that
E. coli
upregulates
gadAB
during inflammation to enhance its survival and virulence. Using real-time PCR, we determined
gadAB
expression in luminal
E. coli
from ex-germfree wild-type (WT) and interleukin-10 (IL-10) knockout (KO) (IL-10
−/−
) mice selectively colonized with a commensal
E. coli
isolate (NC101) that causes colitis in KO mice in isolation or in combination with 7 other commensal intestinal bacterial strains.
E. coli
survival and host inflammatory responses were measured in WT and KO mice colonized with NC101 or a mutant lacking the
gadAB
genes (NC101Δ
gadAB
). The susceptibility of NC101 and NC101Δ
gadAB
to killing by host antimicrobial peptides and their translocation across intestinal epithelial cells were evaluated using bacterial killing assays and transwell experiments, respectively. We show that expression of
gadAB
in luminal
E. coli
increases proportionately with intestinal inflammation in KO mice and enhances the susceptibility of NC101 to killing by the host antimicrobial peptide cryptdin-4 but decreases bacterial transmigration across intestinal epithelial cells, colonic inflammation, and mucosal immune responses. Chronic intestinal inflammation upregulates acid tolerance pathways in commensal
E. coli
isolates, which, contrary to our original hypothesis, limits their survival and colitogenic potential. Further investigation of microbial adaptation to immune-mediated inflammation may provide novel insights into the pathogenesis and treatment of IBDs.
Emetic Potentials of Newly Identified Staphylococcal Enterotoxin-Like Toxins
Authors: Omoe Katsuhiko , Hu Dong-Liang , Ono Hisaya K. , Shimizu Satoru , Takahashi-Omoe Hiromi , Nakane Akio , Uchiyama Takehiko , Shinagawa Kunihiro , Imanishi Ken'ichi
Published: July 2013

Staphylococcal enterotoxins (SEs) are a common causative agent of food poisoning. Recently, many new SE-like (SEl) toxins have been reported, although the role of SEls in food poisoning remains unclear. In this study, the emetic potentials of SElK, SElL, SElM, SElN, SElO, SElP, and SElQ were assessed using a monkey-feeding assay. All the SEls that were tested induced emetic reactions in monkeys at a dose of 100 μg/kg, although the numbers of affected monkeys were significantly smaller than the numbers that were affected after consuming SEA or SEB. This result suggests that these new SEs may play some role in staphylococcal food poisoning.
Virulent Shigella flexneri Affects Secretion, Expression, and Glycosylation of Gel-Forming Mucins in Mucus-Producing Cells
Authors: Sperandio Brice , Fischer Natalie , Chevalier-Curt Marie Joncquel , Rossez Yannick , Roux Pascal , Robbe Masselot Catherine , Sansonetti Philippe J.
Published: July 2013

Mucin glycoproteins are secreted in large amounts by the intestinal epithelium and constitute an efficient component of innate immune defenses to promote homeostasis and protect against enteric pathogens. In this study, our objective was to investigate how the bacterial enteropathogen
Shigella flexneri
, which causes bacillary dysentery, copes with the mucin defense barrier. We report that upon
in vitro
infection of mucin-producing polarized human intestinal epithelial cells, virulent
S. flexneri
manipulates the secretion of gel-forming mucins. This phenomenon, which is triggered only by virulent strains, results in accumulation of mucins at the cell apical surface, leading to the appearance of a gel-like structure that favors access of bacteria to the cell surface and the subsequent invasion process. We identify MUC5AC, a gel-forming mucin, as a component of this structure. Formation of this gel does not depend on modifications of electrolyte concentrations, induction of trefoil factor expression, endoplasmic reticulum stress, or response to unfolded proteins. In addition, transcriptional and biochemical analyses of infected cells reveal modulations of mucin gene expression and modifications of mucin glycosylation patterns, both of which are induced by virulent bacteria in a type III secretion system-dependent manner. Thus,
S. flexneri
has developed a dedicated strategy to alter the mucus barrier by targeting key elements of the gel-forming capacity of mucins: gene transcription, protein glycosylation, and secretion.
The p38 MAPK and JNK Pathways Protect Host Cells against Clostridium perfringens Beta-Toxin
Authors: Nagahama Masahiro , Shibutani Masahiro , Seike Soshi , Yonezaki Mami , Takagishi Teruhisa , Oda Masataka , Kobayashi Keiko , Sakurai Jun
Published: July 2013

Clostridium perfringens
beta-toxin is an important agent of necrotic enteritis and enterotoxemia. Beta-toxin is a pore-forming toxin (PFT) that causes cytotoxicity. Two mitogen-activated protein kinase (MAPK) pathways (p38 and c-Jun N-terminal kinase [JNK]-like) provide cellular defense against various stresses. To investigate the role of the MAPK pathways in the toxic effect of beta-toxin, we examined cytotoxicity in five cell lines. Beta-toxin induced cytotoxicity in cells in the following order: THP-1 = U937 > HL-60 > BALL-1 = MOLT-4. In THP-1 cells, beta-toxin formed oligomers on lipid rafts in membranes and induced the efflux of K
+
from THP-1 cells in a dose- and time-dependent manner. The phosphorylation of p38 MAPK and JNK occurred in response to an attack by beta-toxin. p38 MAPK (SB203580) and JNK (SP600125) inhibitors enhanced toxin-induced cell death. Incubation in K
+
-free medium intensified p38 MAPK activation and cell death induced by the toxin, while incubation in K
+
-high medium prevented those effects. While streptolysin O (SLO) reportedly activates p38 MAPK via reactive oxygen species (ROS), we showed that this pathway did not play a major role in p38 phosphorylation in beta-toxin-treated cells. Therefore, we propose that beta-toxin induces activation of the MAPK pathway to promote host cell survival.
Heme Uptake Mediated by LHR1 Is Essential for Leishmania amazonensis Virulence
Authors: Miguel Danilo C. , Flannery Andrew R. , Mittra Bidyottam , Andrews Norma W.
Published: July 2013

The protozoan parasite
Leishmania amazonensis
is a heme auxotroph and must acquire this essential factor from the environment. Previous studies showed that
L. amazonensis
incorporates heme through the transmembrane protein LHR1 (L
eishmania H
eme
R
esponse 1).
LHR1
-null promastigotes were not viable, suggesting that the transporter is essential for survival. Here, we compared the growth, differentiation, and infectivity for macrophages and mice of wild-type,
LHR1
-single-knockout (
LHR1/
Δ
lhr1
), and
LHR1
-complemented (
LHR1/
Δ
lhr1
plus
LHR1
)
L. amazonensis
strains.
LHR1/
Δ
lhr1
promastigotes replicated poorly in heme-deficient media and had lower intracellular heme content than wild-type parasites.
LHR1/
Δ
lhr1
promastigotes were also less effective in reducing ferric iron to ferrous iron, a reaction mediated by the heme-containing parasite enzyme LFR1 (
Leishmania Ferric Reductase
1).
LHR1/
Δ
lhr1
parasites differentiated normally into aflagellated forms expressing amastigote-specific markers but were not able to replicate intracellularly after infecting macrophages. Importantly, the intracellular growth of
LHR1/
Δ
lhr1
amastigotes was fully restored when macrophages were allowed to phagocytose red blood cells prior to infection.
LHR1/
Δ
lhr1
parasites were also severely defective in the development of cutaneous lesions in mice. All phenotypes observed in
LHR1/
Δ
lhr1
L. amazonensis
were rescued by expression of episomal
LHR1
. Our results reveal the importance of efficient heme uptake for
L. amazonensis
replication and vertebrate host infectivity, reinforcing the potential usefulness of LHR1 as a target for new antileishmanial drugs.
Toxin Inhibition of Antimicrobial Factors Induced by Bacillus anthracis Peptidoglycan in Human Blood
Authors: Barua Soumitra , Iyer Janaki K. , Larabee Jason L. , Raisley Brent , Hughes Molly A. , Coggeshall K. Mark , Ballard Jimmy D.
Published: July 2013

Here, we describe the capacity of
Bacillus anthracis
peptidoglycan (BaPGN) to trigger an antimicrobial response in human white blood cells (WBCs). Analysis of freshly isolated human blood cells found that monocytes and neutrophils, but not B and T cells, were highly responsive to BaPGN and produced a variety of cytokines and chemokines. This BaPGN-induced response was suppressed by anthrax lethal toxin (LT) and edema toxin (ET), with the most pronounced effect on human monocytes, and this corresponded with the higher levels of anthrax toxin receptor 1 (ANTXR1) in these cells than in neutrophils. The supernatant from BaPGN-treated cells altered the growth of
B. anthracis
Sterne, and this effect was blocked by LT, but not by ET. An FtsX mutant of
B. anthracis
known to be resistant to the antimicrobial effects of interferon-inducible Glu-Leu-Arg (ELR)-negative CXC chemokines was not affected by the BaPGN-induced antimicrobial effects. Collectively, these findings describe a system in which BaPGN triggers expression of antimicrobial factors in human WBCs and reveal a distinctive role, not shared with ET, in LT's capacity to suppress this response.
Haemorrhagic stroke or hyperglycaemia?
Authors: Jalota Leena , Luber Sarah , Shrestha Rijesh , Patel Arti
Published: July 2013

A 56-year-old woman with no medical history was admitted with acute onset hemiballistic-choreiform movements of right extremity. On admission, her serum glucose and osmolality were elevated. Her glycosylated haemoblobin (HbA1c) was 17.9 with average blood sugars of 467 mg/dL. A CT scan of the brain revealed unilateral hyperintensities in the basal ganglia. A complete stroke work-up, including MRI and MR angiography of brain was otherwise unrevealing. Subcutaneous insulin was instituted, which led to complete resolution of her symptoms within 48 h of hospital admission. She was readmitted 4 weeks after her initial discharge for similar, but less severe, symptoms. This time her HbA1c was 13.9 with an average blood sugar of 352 mg/dL. A repeat MRI demonstrated a persistent abnormal signal within the left basal ganglia without infarct. She was started on subcutaneous insulin. Her symptoms improved but did not resolve. Haloperidol and gabapentin were initiated and she was again discharged after stabilisation to a rehabilitation centre as per physiotherapy recommendations.
Association between childhood adversities and adulthood depressive symptoms in South Korea: results from a nationally representative longitudinal study
Authors: Kim Seung-Sup , Jang Hyobum , Chang Hyoung Yoon , Park Young Su , Lee Dong-Woo
Published: July 2013

Objective

To examine how childhood adversity (ie, parental death, parental divorce, suspension of school education due to financial strain or being raised in a relative's house due to financial strain) is associated with prevalence and incidence of adulthood depressive symptoms and whether this association differs by gender and by age in South Korea.

Design

Prospective cohort design.

Setting

Nationally representative longitudinal survey in South Korea.

Participants

11 526 participants in South Korea.

Outcome measure

Prevalence and incidence of adulthood depressive symptoms were assessed as a dichotomous variable using the Centers for Epidemiologic Studies Depression (CES-D) Scale in 2006 and 2007.

Results

In the prevalence analysis, each of the four childhood adversities was significantly associated with a higher prevalence of adulthood depressive symptoms. The higher incidence of depressive symptoms was associated with suspension of school education (OR 1.55, 95% CI 1.32 to 1.82) and parental divorce (OR 1.65, 95% CI 1.00 to 2.71). In the age-stratified analyses, prevalence of depressive symptoms was associated with all CAs across different adulthoods, except for parental divorce and late adulthood depressive symptoms. After being stratified by gender, the association was significant for parental divorce (OR 3.76, 95% CI 2.34 to 6.03) in the prevalence analysis and for being raised in a relative’s house (OR 1.89, 95% CI 1.21 to 2.94) in the incidence analysis only among women.

Conclusions

This study suggests that childhood adversity may increase prevalence and incidence of adulthood depressive symptoms, and the impact of parental divorce or being raised in a relative's house due to financial strain on adulthood depressive symptoms may differ by gender.
Search and rescue helicopter-assisted transfer of ST-elevation myocardial infarction patients from an island in the Baltic Sea: results from over 100 rescue missions
Authors: Schoos Mikkel Malby , Kelbæk Henning , Pedersen Frants , Kjærgaard Benedict , Trautner Sven , Holmvang Lene , Jørgensen Erik , Helqvist Steffen , Saunamäki Kari , Engstrøm Thomas , Clemmensen Peter
Published: July 2013

Background

Since 2005, ST-elevation myocardial infarction (STEMI) patients from the island of Bornholm in the Baltic Sea have been transferred for primary percutaneous coronary intervention (pPCI) by an airborne service. We describe the result of pPCI as part of the Danish national reperfusion strategy offered to a remote island population.

Methods

In this observational study, patients from Bornholm (n=101) were compared with patients from the mainland (Zealand) (n=2495), who were grouped according to time intervals (<120, 121–180, >180 min). The primary endpoint was all-cause 30-day mortality. Individual-level data from the Central Population Registry provided outcome that was linked to our inhospital PCI database.

Results

Treatment delay was longer in patients from Bornholm (349 min (IQR 267–446)) vs Zealand (211 (IQR 150–315)) (p<0.001). In patients from Zealand, 30-day mortality did not increase with time intervals (p=0.176), whereas, long-term mortality did (∼3 years) (p=0.007). Thirty-day mortality was similar for Bornholm and the overall Zealand group (5.9% vs 6.2% p=0.955). Early presenters (<180 min) from Zealand (37%) had similar 30-day (5.3% vs 5.9% p=0.789), but numerically reduced long-term mortality compared with Bornholm (12.8% vs 15.8% p=0.387). Age, female gender, diabetes, Killipclass >2 and preprocedural thrombolysis in myocardial infarction (TIMI) flow 0/1 independently predicted 30-day mortality, however, treatment delay did not. Postprocedural TIMI flow 3 predicted improved survival.

Conclusions

In this small population of STEMI patients from a remote island, airborne transfer appears feasible and safe, and their 30-day mortality after pPCI comparable with that of the mainland population despite inherent reperfusion delay exceeding guidelines.
Regional analgesia in the emergency department for hip fractures: survey of current UK practice and its impact on services in a teaching hospital
Authors: Rashid Anwar , Beswick Eleanor , Galitzine Svetlana , Fitton Laurence
Published: July 2013

Introduction

While the benefits of regional analgesia (RA) for preoperative pain relief in hip fracture (HF) in elderly patients are well recognised, this service is yet to be established in many UK emergency departments (EDs). We set out to discover how widely RA is adopted in the UK EDs.

Methods

In April–July 2010, we conducted a postal survey of 218 UK EDs, followed up with fax reminders for non-respondents.

Results

A total of 147/218 (67%) EDs completed the survey. Sixty five (44%) respondents reported use of RA blocks for HF. The commonest stated reasons for not using RA were lack of trained staff (36%) or appropriate equipment (22%). RA users practiced femoral nerve block most widely (60% of EDs) followed by fascia iliaca compartment block (FICB) (22%).

Discussion

It is more a lack of trained staff and suitable equipment that prevents RA blocks being widely adopted in the UK. We advocate FICB in HF patients, which is an easy landmark-based block that can be safely performed by ED doctors. Our survey initiated multidisciplinary consultation and development of a protocol for preoperative FICB in HFs in our teaching hospital ED.

Conclusions

RA for HFs is not widely used in UK EDs, proving that there is room for improvement .The finding that RA blocks are performed by the ED medical staff in 84% of the responding EDs practising RA was reassuring for developing the service in our hospital. FICB should be considered as an alternative to parenteral analgesia in adult patients with HF.