bluuebunny/crossref_metadata_2025 huggingface dataset:
Secondary seed dispersal by dung beetles in an Amazonian forest fragment of Colombia: influence of dung type and edge effect
Authors: SANTOS‐HEREDIA Carolina , ANDRESEN Ellen , STEVENSON Pablo
Published: December 2011

Seeds of many plant species are secondarily dispersed by dung beetles, but the outcome of this interaction is highly context‐specific. Little is known about how certain anthropogenic disturbances affect this plant–animal interaction. The aims of this study were to assess the effect of dung type on secondary dispersal by dung beetles in a forest fragment, and to determine whether this interaction is affected by edge effects. Using pitfall traps, we captured dung beetles attracted to dung of 2 frugivorous mammals: woolly monkeys and howler monkeys. We found differences between both dung beetle assemblages, but these differences were not consistent in time. Using seeds surrounded by both dung types, we carried out a field experiment using seeds of 2 plant species. We found that the probability of secondary dispersal by dung beetles was higher for seeds placed in woolly monkey dung. Finally, we carried out a field experiment using plastic beads as seed mimics to assess edge effects. We found that secondary seed dispersal by dung beetles was negatively affected by edges. The disruption of plant–animal interactions along anthropogenic forest edges could have long‐term negative effects on forest dynamics by affecting processes of regeneration.
Mental health literacy in higher education students
Authors: Reavley Nicola J. , McCann Terence V. , Jorm Anthony F.
Published: December 2011

Aim: With approximately 50% of young people aged 18–24 in tertiary education, these are potential settings for programmes to improve mental health literacy. A survey was carried out with students and staff of a tertiary education institution to investigate recognition of depression, help‐seeking intentions, beliefs about interventions and stigmatizing attitudes.

Methods: Students of an Australian metropolitan university (with staff as a comparison group) participated in a telephone interview. They answered questions relating to mental health literacy.

Results: Of the completed interviews, 774 (65%) were students and 422 (35%) were staff. Over 70% of students and staff were able to recognize depression in a vignette, with greater likelihood of recognition in students associated with older age, female gender, being born in Australia and a higher level of education. Over 80% of respondents said they would seek help if they had a problem similar to that of the vignette. However, rates of specific help‐seeking intentions for students were relatively low, with only 26% nominating a general practitioner and only 10% nominating a student counsellor. Factors associated with stigmatizing attitudes included male gender, younger age, lower level of education, being born outside Australia and lack of recognition of depression.

Conclusions: There is a need for mental health literacy interventions targeted at students, particularly those who are younger, male, born outside Australia and of a lower level of education. As rates of specific help‐seeking intentions for students were relatively low, there is a need for further exploration of the barriers to help seeking from professional sources.
Biological indicators of illness risk in offspring of bipolar parents: targeting the hypothalamic‐pituitary‐adrenal axis and immune system
Authors: Duffy Anne , Lewitzka Ute , Doucette Sarah , Andreazza Ana , Grof Paul
Published: December 2011

Aim: The study aims to provide a selective review of the literature pertaining to the hypothalamic‐pituitary‐adrenal (HPA) axis and immune abnormalities as informative biological indicators of vulnerability in bipolar disorder (BD).

Method: We summarize key findings relating to HPA axis and immunological abnormalities in bipolar patients and their high‐risk offspring. Findings derive from a review of selected original papers published in the literature, and supplemented by papers identified through bibliography review. Neurobiological findings are discussed in the context of emergent BD in those at genetic risk and synthesized into a neurodevelopmental model of illness onset and progression.

Results: BD is associated with a number of genetic and possibly epigenetic abnormalities associated with neurotransmitter, hormonal and immunologically mediated neurobiological pathways. Data from clinical and high‐risk studies implicate HPA axis and immune system abnormalities, which may represent inherited vulnerabilities important for the transition to illness onset. Post‐mortem and clinical studies implicate intracellular signal transduction processes and disturbance in energy metabolism associated with established BD. Specifically, long‐standing maladaptive alterations such as changes in neuronal systems may be mediated through changes in intracellular signalling pathways, oxidative stress, cellular energy metabolism and apoptosis associated with substantial burden of illness.

Conclusions: Prospective longitudinal studies of endophenotypes and biomarkers such as HPA axis and immune abnormalities in high‐risk offspring will be helpful to understand genetically mediated biological pathways associated with illness onset and progression. A clinical staging model describing emergent illness in those at genetic risk should facilitate this line of investigation.
Selective nodal irradiation of regionally advanced non‐small‐cell lung cancer with proton therapy and IMRT: A dosimetric comparison
Authors: Nichols Jr. Romaine C. , Huh Soon H. , Henderson Randal H. , Li Zuofeng , Flampouri Stella , D'Agostino Harry J. , Cury James D. , Pham Dat C. , Mendenhall Nancy P. , Hoppe Bradford S.
Published: December 2011

Objectives:  Evaluate the dosimetric impact of selective/elective nodal treatment with dose‐escalated radiotherapy for regionally advanced non‐small‐cell lung cancer (NSCLC) using proton therapy (PT) or intensity‐modulated radiotherapy (IMRT).

Methods:  Five consecutive patients with regionally advanced NSCLC underwent treatment planning for high‐dose involved‐field (IF) treatment (positron emission tomography‐positive gross disease) with or without selective/elective nodal irradiation, defined as the extended field (EF). Four treatment plans were developed for each patient: i) IMRT to treat IF to 74 Gy (IFrT); ii) IMRT to treat high‐risk nodes to 44 Gy and IF to 74 Gy (EFrT); iii) PT to treat IF to 74CGE (IFpT); and iv) PT to treat high‐risk nodes to 44CGE and IF to 74CGE (EFpT). High‐risk nodes were defined as mediastinal, hilar, and supraclavicular lymph node stations adjacent to foci of PET‐positive gross disease. The IMRT and PT plans were isoeffective. Dose to organs at risk (OARs), including the lung, esophagus, heart and spinal cord, were evaluated.

Results:  The average IF clinical target volume (CTV) was 397 cc (344–428), while the average EF CTV was 642 cc (530–753 cc). Comparing IMRT with PT, mean lung dose reduced 3.4 Gy/CGE and 3.7 Gy/CGE; lung V20 reduced 4% and 5% for EF and IF, respectively.

Conclusions:  Selective/elective nodal irradiation with protons reduces normal‐lung exposure compared to selective/elective nodal irradiation with IMRT.
The role of endobronchial ultrasound in central early lung cancer
Authors: Sanz‐Santos José , Andreo Felipe , Serra Pere , Monsó Eduard , Ruiz‐Manzano Juan
Published: December 2011

Central early lung cancers (CELC) are tumors arising from the central airways, roentgenographically occult, which are usually diagnosed by bronchoscopy after a positive sputum cytology. Most CELCs are undetectable for conventional white light bronchoscopy (WLB) but can be identified under autofluorescence bronchoscopy (AFB). Although AFB increases the sensitivity of WLB in detecting CELC, its low specificity remains a problem. Surgery has been the most accepted treatment for CELCs; however 20–30% of patients suffering CELC tend to have multicentricities and usually present with poor cardiopulmonary status. Therefore, surgery is not suitable in most of the cases and other therapeutic options such as bronchoscopic treatments should be considered. Because most endoscopic treatments are unlikely to be curative if the tumor has spread beyond the bronchial cartilage, accurate evaluation of CELC bronchial wall invasion is critical before selecting a bronchoscopic treatment. Endobronchial ultrasound (EBUS) is a relatively new technique that has proven to be useful in the evaluation of the normal and cancer‐invaded bronchial wall. Some authors have demonstrated that after adding EBUS assessment to AFB in autofluorescence‐positive lesions the specificity increases from 50 to 90%. Other studies have focused on the ability of EBUS to detect bronchial wall invasion in patients with CELCs. They compared the EBUS images with pathological findings of surgical specimens of patients that underwent surgery; in most of the cases the correlation between EBUS and pathological findings increased over 90%. Furthermore, in patients not eligible for surgery, EBUS has proven to predict patients expected response to endoscopic treatments.
CcpA regulates biofilm formation and competence in Streptococcus gordonii
Authors: Zheng L. , Chen Z. , Itzek A. , Herzberg M.C. , Kreth J.
Published: December 2011

Streptococcus gordonii is an important member of the oral biofilm community. As an oral commensal streptococcus, S. gordonii is considered beneficial in promoting biofilm homeostasis. CcpA is known as the central regulator of carbon catabolite repression in Gram‐positive bacteria and is also involved in the control of virulence gene expression. To further establish the role of CcpA as central regulator in S. gordonii, the effect of CcpA on biofilm formation and natural competence of S. gordonii was investigated. These phenotypic traits have been suggested to be important to oral streptococci in coping with environmental stress. Here we demonstrate that a CcpA mutant was severely impaired in its biofilm‐forming ability, showed a defect in extracellular polysaccharide production and reduced competence. The data suggest that CcpA is involved in the regulation of biofilm formation and competence development in S. gordonii.
Locally analytic vectors of some crystabelian representations of GL2(ℚp)
Authors: Liu Ruochuan
Published: December 2011

For V a two-dimensional p-adic representation of Gℚp, we denote by B(V ) the admissible unitary representation of GL2(ℚp) attached to V under the p-adic local Langlands correspondence of GL2(ℚp) initiated by Breuil. In this paper, building on the works of Berger–Breuil and Colmez, we determine the locally analytic vectors B(V )an of B (V ) when V is irreducible, crystabelian and Frobenius semisimple with distinct Hodge–Tate weights; this proves a conjecture of Breuil. Using this result, we verify Emerton’s conjecture that dim Ref η⊗ψ (V )=dim Exp η∣⋅∣⊗xψ (B (V )an ⊗(x∣⋅∣∘det )) for those V which are irreducible, crystabelian and Frobenius semisimple.
Acid‐sensing ion channel subtype 3 function and immunolabelling increases in skeletal muscle sensory neurons following femoral artery occlusion
Authors: Xing Jihong , Lu Jian , Li Jianhua
Published: December 2011

Non‐technical summary  Limb ischaemia commonly occurs in peripheral artery disease and blood pressure response to stimulation of muscle afferent nerves during exercise activity is augmented in this disease; however, the mechanisms responsible for this physiological process are not well‐known. In this report, expression and function of acid‐sensing ion channels subtype 3 (ASIC3) in muscle afferent nerves were examined following the hindlimb ischaemia induced by femoral artery occlusion. The data provided here suggest that femoral artery occlusion increases ASIC3 expression and responsiveness in muscle sensory neurons. The results help us better understand why the blood pressure response to exercise is exaggerated in patients with peripheral artery disease.
Gut microbiota, epithelial function and derangements in obesity
Authors: Raybould Helen E.
Published: December 2011

Abstract  The gut epithelium is a barrier between the ‘outside’ and ‘inside’ world. The major function of the epithelium is to absorb nutrients, ions and water, yet it must balance these functions with that of protecting the ‘inside’ world from potentially harmful toxins, irritants, bacteria and other pathogens that also exist in the gut lumen. The health of an individual depends upon the efficient digestion and absorption of all required nutrients from the diet. This requires sensing of meal components by gut enteroendocrine cells, activation of neural and humoral pathways to regulate gastrointestinal motor, secretory and absorptive functions, and also to regulate food intake and plasma levels of glucose. In this way, there is a balance between the delivery of food and the digestive and absorptive capacity of the intestine. Maintenance of the mucosal barrier likewise requires sensory detection of pathogens, toxins and irritants; breakdown of the epithelial barrier is associated with gut inflammation and may ultimately lead to inflammatory bowel disease. However, disruption of the barrier alone is not sufficient to cause frank inflammatory bowel disease. Several recent studies have provided compelling new evidence to suggest that changes in epithelial barrier function and inflammation are associated with and may even lead to altered regulation of body weight and glucose homeostasis. This article provides a brief review of some recent evidence to support the hypothesis that changes in the gut microbiota and alteration of gut epithelial function will perturb the homeostatic humoral and neural pathways controlling food intake and body weight.
G protein‐coupled receptor signalling in the cardiac nuclear membrane: evidence and possible roles in physiological and pathophysiological function
Authors: Tadevosyan Artavazd , Vaniotis George , Allen Bruce G. , Hébert Terence E. , Nattel Stanley
Published: December 2011

Abstract  G protein‐coupled receptors (GPCRs) play key physiological roles in numerous tissues, including the heart, and their dysfunction influences a wide range of cardiovascular diseases. Recently, the notion of nuclear localization and action of GPCRs has become more widely accepted. Nuclear‐localized receptors may regulate distinct signalling pathways, suggesting that the biological responses mediated by GPCRs are not solely initiated at the cell surface but may result from the integration of extracellular and intracellular signalling pathways. Many of the observed nuclear effects are not prevented by classical inhibitors that exclusively target cell surface receptors, presumably because of their structures, lipophilic properties, or affinity for nuclear receptors. In this topical review, we discuss specifically how angiotensin‐II, endothelin, β‐adrenergic and opioid receptors located on the nuclear envelope activate signalling pathways, which convert intracrine stimuli into acute responses such as generation of second messengers and direct genomic effects, and thereby participate in the development of cardiovascular disorders.
Cav2 channels mediate low and high voltage‐activated calcium currents in Drosophila motoneurons
Authors: Ryglewski Stefanie , Lance Kimberly , Levine Richard B. , Duch Carsten
Published: December 2011

Key points 

Neurons in the brain express a diversity of ion channels to impart specialized functional properties.

At least three distinct voltage gated calcium channel gene families are known, each of which is thought to produce calcium channels with unique properties, which in turn, differently affect neuronal function.

Here we use a genetic model system to determine which genes are responsible for the calcium currents in an identified motoneuron.

Surprisingly, the same ion channel gene encodes two distinct currents with fundamentally different properties, and the data also suggest that the normal function of this calcium channel gene is affected by the expression of another one.

The results provide insights into the relationship between gene expression and ionic currents, and thus, into the regulation of normal neuronal function.
A novel method for spatially complex diffraction‐limited photoactivation and photobleaching in living cells
Authors: Shkryl Vyacheslav M. , Maxwell Joshua T. , Blatter Lothar A.
Published: December 2011

Key points 

For the contraction of a cardiac cell the liberation of calcium ions (Ca2+) from an intracellular Ca2+ storing compartment is required.

This release of Ca2+ ions occurs through groups (clusters) of Ca2+ release channels that can be activated by cellular signalling molecules such as Ca2+ itself or the messenger molecule inositol‐1,4,5‐trisphosphate (IP3).

Here we present a new technique that allows activation of individual release sites or groups of channels in a highly localized manner in living cells and the study of their structural and functional details with high precision.
Platelets: a critical link between inflammation and microvascular dysfunction
Authors: Stokes Karen Y. , Granger D. Neil
Published: December 2011

Abstract  Inflammation is an underlying feature of a variety of human diseases. An important manifestation of this pathophysiological response is microvascular dysfunction, which includes the activation of vascular endothelial cells, and circulating leucocytes and platelets. While endothelial cells and leucocytes are widely accepted as critical players in the microvascular alterations induced by inflammation, recent attention has focused on the modulatory role of platelets, which act both as effector and target cells in inflamed microvessels. Evidence is presented to demonstrate the capacity for ‘cross‐talk’ between platelets and other cells (endothelial cells, leucocytes) that contribute to an inflammatory response, and to illustrate the pathophysiological consequences of these interactions of platelets with other cells within the microvasculature.
Numerical Study on Creeping Flow of Burgers’ Fluids through a Peristaltic Tube
Authors: Tripathi Dharmendra
Published: December 2011

Motivated by the objective of improving an understanding of the complex rheological fluid dynamics in fluid engineering and biomedical engineering, we consider the creeping flow of Burgers’ fluid with a fractional model through a peristaltic tube in the present article. Homotopy analysis method is used to solve the problem and obtain the approximate analytical solution in terms of axial velocity, volumetric flow rate, pressure gradient, stream function and mechanical efficiency under the long wavelength approximation. It is assumed that the cross-section of the tube varies sinusoidally along the length of tube. The impacts of fractional parameters, material constants, time and amplitude on the pressure difference, frictional force across one wavelength and trapping, are depicted numerically. It is found that the second material constant helps the flow pattern, whereas the other three material constants resist it through the peristaltic tube. The effects of fractional parameters on flow pattern are found to be opposite to each other.
Impaired Fitness and Transmission of Macrolide-Resistant Campylobacter jejuni in Its Natural Host
Authors: Luangtongkum Taradon , Shen Zhangqi , Seng Virginia W. , Sahin Orhan , Jeon Byeonghwa , Liu Peng , Zhang Qijing
Published: December 2011

Campylobacter jejuni
is a major zoonotic pathogen transmitted to humans via the food chain and is prevalent in chickens, a natural reservoir for this pathogenic organism. Due to the importance of macrolide antibiotics in clinical therapy of human campylobacteriosis, development of macrolide resistance in
Campylobacter
has become a concern for public health. To facilitate the control of macrolide-resistant
Campylobacter
, it is necessary to understand if macrolide resistance affects the fitness and transmission of
Campylobacter
in its natural host. In this study we conducted pairwise competitions and comingling experiments in chickens using clonally related and isogenic
C. jejuni
strains, which are either susceptible or resistant to erythromycin (Ery). In every competition pair, Ery-resistant (Ery
r
)
Campylobacter
was consistently outcompeted by the Ery-susceptible (Ery
s
) strain. In the comingling experiments, Ery
r
Campylobacter
failed to transmit to chickens precolonized by Ery
s
Campylobacter
, while isogenic Ery
s
Campylobacter
was able to transmit to and establish dominance in chickens precolonized by Ery
r
Campylobacter
. The fitness disadvantage was linked to the resistance-conferring mutations in the 23S rRNA. These findings clearly indicate that acquisition of macrolide resistance impairs the fitness and transmission of
Campylobacter
in chickens, suggesting that the prevalence of macrolide-resistant
C. jejuni
will likely decrease in the absence of antibiotic selection pressure.
Battacin (Octapeptin B5), a New Cyclic Lipopeptide Antibiotic from Paenibacillus tianmuensis Active against Multidrug-Resistant Gram-Negative Bacteria
Authors: Qian Chao-Dong , Wu Xue-Chang , Teng Yi , Zhao Wen-Peng , Li Ou , Fang Sheng-Guo , Huang Zhao-Hui , Gao Hai-Chun
Published: December 2011

Hospital-acquired infections caused by drug-resistant bacteria are a significant challenge to patient safety. Numerous clinical isolates resistant to almost all commercially available antibiotics have emerged. Thus, novel antimicrobial agents, specifically those for multidrug-resistant Gram-negative bacteria, are urgently needed. In the current study, we report the isolation, structure elucidation, and preliminary biological characterization of a new cationic lipopeptide antibiotic, battacin or octapeptin B5, produced from a
Paenibacillus tianmuensis
soil isolate. Battacin kills bacteria
in vitro
and has potent activity against Gram-negative bacteria, including multidrug-resistant and extremely drug-resistant clinical isolates. Hospital strains of
Escherichia coli
and
Pseudomonas aeruginosa
are the pathogens most sensitive to battacin, with MICs of 2 to 4 μg/ml. The ability of battacin to disrupt the outer membrane of Gram-negative bacteria is comparable to that of polymyxin B, the last-line therapy for infections caused by antibiotic-resistant Gram-negative bacteria. However, the capacity of battacin to permeate bacterial plasma membranes is less extensive than that of polymyxin B. The bactericidal kinetics of battacin correlate with the depolarization of the cell membrane, suggesting that battacin kills bacteria by disrupting the cytoplasmic membrane. Other studies indicate that battacin is less acutely toxic than polymyxin B and has potent
in vivo
biological activity against
E. coli
. Based on the findings of the current study, battacin may be considered a potential therapeutic agent for the treatment of infections caused by antibiotic-resistant Gram-negative bacteria.
In Vitro
Activities of CB-183,315, Vancomycin, and Metronidazole against 556 Strains of Clostridium difficile, 445 Other Intestinal Anaerobes, and 56 Enterobacteriaceae Species
Authors: Citron Diane M. , Tyrrell Kerin L. , Merriam C. Vreni , Goldstein Ellie J. C.
Published: December 2011

MICs of CB-183,315, a novel lipopeptide antibiotic, vancomycin, and metronidazole were determined for intestinal anaerobes and
Enterobacteriaceae
. The MIC
90
s for Gram-negative anaerobes were >8,192, 8,192, and 4 μg/ml for CB-183,315, vancomycin, and metronidazole, respectively. Against
Enterobacteriaceae
, the MIC
90
s were >8,192 μg/ml, 1,024 μg/ml, and 1,024 μg/ml, respectively. The CB-183,315 MIC
90
for
Clostridium difficile
was 0.5 μg/ml. Its lack of activity against normal fecal organisms makes it a promising new agent for treating
C. difficile
.
Distribution of the Multidrug Resistance Gene
cfr
in Staphylococcus Species Isolates from Swine Farms in China
Authors: Wang Yang , Zhang Wanjiang , Wang Juan , Wu Congming , Shen Zhangqi , Fu Xiao , Yan Yang , Zhang Qijing , Schwarz Stefan , Shen Jianzhong
Published: December 2011

A total of 149 porcine
Staphylococcus
isolates with florfenicol MICs of ≥16 μg/ml were screened for the presence of the multiresistance gene
cfr
, its location on plasmids, and its genetic environment. In total, 125 isolates carried either
cfr
(16 isolates),
fexA
(92 isolates), or both genes (17 isolates). The 33
cfr
-carrying staphylococci, which included isolates of the species
Staphylococcus cohnii
,
S. arlettae
, and
S. saprophyticus
in which the
cfr
gene has not been described before, exhibited a wide variety of SmaI pulsed-field gel electrophoresis patterns. In 18 cases, the
cfr
gene was located on plasmids. Four different types of
cfr
-carrying plasmids—pSS-01 (
n
= 2; 40 kb), pSS-02 (
n
= 3; 35.4 kb), pSS-03 (
n
= 10; 7.1 kb), and pBS-01 (
n
= 3; 16.4 kb)—were differentiated on the basis of their sizes, restriction patterns, and additional resistance genes. Sequence analysis revealed that in plasmid pSS-01, the
cfr
gene was flanked in the upstream part by a complete
aacA-aphD
-carrying Tn
4001
-like transposon and in the downstream part by a complete
fexA
-carrying transposon Tn
558
. In plasmid pSS-02, an insertion sequence IS
21-558
and the
cfr
gene were integrated into transposon Tn
558
and thereby truncated the
tnpA
and
tnpB
genes. The smallest
cfr
-carrying plasmid pSS-03 carried the macrolide-lincosamide-streptogramin B resistance gene
erm
(C). Plasmid pBS-01, previously described in
Bacillus
spp., harbored a Tn
917
-like transposon, including the macrolide-lincosamide-streptogramin B resistance gene
erm
(B) in the
cfr
downstream region. Plasmids, which in part carry additional resistance genes, seem to play an important role in the dissemination of the gene
cfr
among porcine staphylococci.
Innate Immunity against Granulibacter bethesdensis, an Emerging Gram-Negative Bacterial Pathogen
Authors: Zarember Kol A. , Marshall-Batty Kimberly R. , Cruz Anna R. , Chu Jessica , Fenster Michael E. , Shoffner Adam R. , Rogge Larissa S. , Whitney Adeline R. , Czapiga Meggan , Song Helen H. , Shaw Pamela A. , Nagashima Kunio , Malech Harry L. , DeLeo Frank R. , Holland Steven M. , Gallin John I. , Greenberg David E.
Published: December 2011

Acetic acid bacteria were previously considered nonpathogenic in humans. However, over the past decade, five genera of
Acetobacteraceae
have been isolated from patients with inborn or iatrogenic immunodeficiencies. Here, we describe the first studies of the interactions of the human innate immune system with a member of this bacterial family,
Granulibacter bethesdensis
, an emerging pathogen in patients with chronic granulomatous disease (CGD). Efficient phagocytosis of
G. bethesdensis
by normal and CGD polymorphonuclear leukocytes (CGD PMN) required heat-labile serum components (e.g., C3), and binding of C3 and C9 to
G. bethesdensis
was detected by immunoblotting. However, this organism survived in human serum concentrations of ≥90%, indicating a high degree of serum resistance. Consistent with the clinical host tropism of
G. bethesdensis
, CGD PMN were unable to kill this organism, while normal PMN, in the presence of serum, reduced the number of CFU by about 50% after a 24-h coculture. This finding, together with the observations that
G. bethesdensis
was sensitive to H
2
O
2
but resistant to LL-37, a human cationic antimicrobial peptide, suggests an inherent resistance to O
2
-independent killing. Interestingly, 10 to 100 times greater numbers of
G. bethesdensis
were required to achieve the same level of reactive oxygen species (ROS) production induced by
Escherichia coli
in normal PMN. In addition to the relative inability of the organism to elicit production of PMN ROS,
G. bethesdensis
inhibited both constitutive and FAS-induced PMN apoptosis. These properties of reduced PMN activation and resistance to nonoxidative killing mechanisms likely play an important role in
G. bethesdensis
pathogenesis.
The Antibacterial Activity of LL-37 against Treponema denticola Is Dentilisin Protease Independent and Facilitated by the Major Outer Sheath Protein Virulence Factor
Authors: Rosen Graciela , Sela Michael N. , Bachrach Gilad
Published: December 2011

Host defense peptides are innate immune effectors that possess both bactericidal activities and immunomodulatory functions. Deficiency in the human host defense peptide LL-37 has previously been correlated with severe periodontal disease.
Treponema denticola
is an oral anaerobic spirochete closely associated with the pathogenesis of periodontal disease. The
T. denticola
major surface protein (MSP), involved in adhesion and cytotoxicity, and the dentilisin serine protease are key virulence factors of this organism. In this study, we examined the interactions between LL-37 and
T. denticola
. The three
T. denticola
strains tested were susceptible to LL-37. Dentilisin was found to inactivate LL-37 by cleaving it at the Lys, Phe, Gln, and Val residues. However, dentilisin deletion did not increase the susceptibility of
T. denticola
to LL-37. Furthermore, dentilisin activity was found to be inhibited by human saliva. In contrast, a deficiency of the
T. denticola
MSP increased resistance to LL-37. The MSP-deficient mutant bound less fluorescently labeled LL-37 than the wild-type strain. MSP demonstrated specific, dose-dependent LL-37 binding. In conclusion, though capable of LL-37 inactivation, dentilisin does not protect
T. denticola
from LL-37. Rather, the rapid, MSP-mediated binding of LL-37 to the treponemal outer sheath precedes cleavage by dentilisin. Moreover,
in vivo
, saliva inhibits dentilisin, thus preventing LL-37 restriction and ensuring its bactericidal and immunoregulatory activities.
Chronic kidney disease: a large-scale population-based study of the effects of introducing theCKD-EPIformula for eGFR reporting
Authors: O'Callaghan Christopher A , Shine Brian , Lasserson Daniel S
Published: December 2011

Objective

To evaluate the effects of introducing theChronic Kidney Disease-Epidemiology Collaboration (CKD-EPI)formula for estimated glomerular filtration rate (eGFR) reporting in the adult population in routine clinical practice with clinician-directed testing.

Design

Retrospective study of all creatinine measurements and calculation of eGFRs using Modification of Diet in Renal Disease (MDRD) andCKD-EPIformulae.

Setting

General population, Oxfordshire, UK.

Participants

An unselected population of around 660 000.

Interventions

Reporting of eGFRs using MDRD orCKD-EPIformulae.

Primary and secondary outcome measures

Evaluation of the effects of theCKD-EPIformula on the prevalence of different stages of chronic kidney disease (CKD).

Results

TheCKD-EPIformula reduced the prevalence of CKD (stages 2–5) by 16.4% in patients tested in primary care. At the important stage 2–stage 3 cut-off, there was a relative reduction of 7.5% in the prevalence of CKD stages 3–5 from 15.7% to 14.5%. TheCKD-EPIformula reduced the prevalence of CKD stages 3–5 in those aged <70 but increased it at ages >70. Above 70 years, the prevalence of stages 3–5 was similar with both equations for women (around 41.2%) but rose in men from 33.3% to 35.5%. CKD stages 4–5 rose by 15% due exclusively to increases in the over 70s, which could increase specialist referral rates. The CKD classification of 18.3% of all individuals who had a creatinine measurement was altered by a change from the MDRD to theCKD-EPIformula. In the UK population, the classification of up to 3 million patients could be altered, the prevalence of CKD could be reduced by up to 1.9 million and the prevalence of CKD stages 3–5 could fall by around 200 000.

Conclusions

Introduction of theCKD-EPIformula for eGFR reporting will reduce the prevalence of CKD in a primary care setting with current testing practice but will raise the prevalence in the over 70s age group. This has implications for clinical practice, healthcare policy and current prevalence-based funding arrangements.
Factors associated with depressive state in patients with myasthenia gravis: a multicentre cross-sectional study
Authors: Suzuki Yasushi , Utsugisawa Kimiaki , Suzuki Shigeaki , Nagane Yuriko , Masuda Masayuki , Kabasawa Chiaki , Shimizu Yuko , Utsumi Hiroya , Uchiyama Shinichiro , Fujihara Kazuo , Suzuki Norihiro
Published: December 2011

Objectives

The objective of this study was to examine clinical factors associated with depressive state in patients with myasthenia gravis (MG).

Design

Cross-sectional study.

Setting and participants

We evaluated 287 consecutive cases of MG seen at six neurological centres located in Eastern Japan.

Outcome measures

All MG patients completed the Japanese version of the Beck Depression Inventory–Second Edition (BDI-II). Disease severity was determined according to the MG Foundation of America (MGFA) quantitative MG score, MG activities of daily living scale and MG composite scale (MG composite). Clinical state following treatment was categorised according to MGFA postintervention status. Associations between detailed clinical parameters of MG and BDI-II score were then examined statistically.

Results

Mean BDI-II score for patients with MG (11.0±8.1) did not differ substantially from and overlapped with that reported as the Japanese standard (8.7±6.4). The mean +2 SDs for the Japanese standard is 21.5, approximately equal to the cut-off level indicative of moderate or worse depression (>20 points) in the original English version. We thus defined BDI-II >21.5 as depressive state, with a frequency of 13.6% in patients with MG. Multivariate logistic regression analysis revealed current dose of oral prednisolone (OR 1.09, 95% CI 1.02 to 1.17; p=0.01), unchanged MGFA postintervention status (OR 3.55, 95% CI 1.18 to 10.71; p=0.02), time since onset (OR 0.93, 95% CI 0.87 to 0.99; p=0.03) and MG composite (OR 1.16, 95% CI 1.00 to 1.34; p=0.046) as factors independently associated with depressive state in MG.

Conclusions

Dose of oral corticosteroids appears to represent the major factor associated with depressive state in MG. Unchanged status despite treatment and early disease stage are also significant background factors for depressive state, along with disease severity.
Republished research: Helminths: an unrecognised disease burden prevalent among migrants in the gastroenterology clinic
Authors: Smith P J , Theis B , McCartney S , Brown M
Published: December 2011

Objective

To estimate the prevalence of, and implement a diagnostic strategy for, imported helminth infection in the gastroenterology clinic.

Design

A retrospective study of eosinophil count and probable tropical exposure (phase I) followed by a prospective study of parasitological investigation (phase II).

Setting

Gastroenterology service of an inner London hospital.

Patients

Adult patients newly attending general gastroenterology and inflammatory bowel disease clinics.

Interventions

In phase I, evidence of undiagnosed helminth infection was sought by analysing patient records for associations between eosinophil count and ethnicity. In phase II, a UK guideline for investigation of eosinophilia in migrants was implemented and diagnostic yield determined.

Main outcome measures

In phase I, prevalence of eosinophilia was determined; in phase II, helminth prevalence and degree of eosinophilia before and after treatment were reported. Information on symptomatic response to treatment was recorded. Ethnicity was used as a proxy measure for tropical exposure.

Results

426 new patients attended in a 12 month period. Eosinophilia was present in 27 (6.3%). 10/27 (37.0%) patients with eosinophilia were of African or Asian ethnicity whereas only 20% (85/426) of patients overall were from these ethnic groups (χ2=5.27, p=0.02). Following implementation of the protocol, 25/36 migrants with eosinophilia attended for parasitological investigations. Helminth infection was diagnosed in 10/25 (40%). Strongyloidiasis (six patients) and schistosomiasis (three patients) were the most common diagnoses. Median eosinophil count was 1.06×109/l in those with helminths and 0.58×109/l in those without (p=0.004). Eosinophil counts normalised in, and symptomatic improvement was reported by, most patients after treatment.

Conclusions

Eosinophilia is associated with African or Asian ethnicity in an inner city gastroenterology service. This association is probably explained by imported helminths, which are prevalent in this setting, may be a cause of gastrointestinal symptoms and is easily diagnosed and treated by standard protocols.
A new theoretical method to evaluate the internal stability of granular soils
Authors: Moraci Nicola , Mandaglio Maria Clorinda , Ielo Domenico
Published: December 2011

The geotextile filter design is particularly complex when granular base soils are internally unstable. In these conditions, the design criteria available in literature are not always reliable. This paper deals with a new theoretical method developed to evaluate the internal stability of granular soils. To simulate, theoretically, the filtration process inside these soils, a set of spherical particles and different soil relative densities have been considered. The soil has been represented by means of a sequence of parallel layers, containing constrictions and particles, placed upon each other at a distance, in the direction of hydraulic flow, which is a function of the soil relative density. The movement of the fine particles through the different soil layers has been simulated by means of a mechanism that compares each particle contained in the i layer with the constrictions contained in the next i + 1 layer. The results of the numerical simulations were used to evaluate the internal stability of the analyzed granular soil and the corresponding critical diameter of suffusion, Dc. Finally, the reliability of the proposed theoretical method was evaluated by means of the results of experimental long-term filtration tests performed using a rigid-wall permeameter on different unstable granular soils.
Active pressure on gravity walls supporting purely frictional soils
Authors: Loukidis D. , Salgado R.
Published: December 2011

The active earth pressure used in the design of gravity walls is calculated based on the internal friction angle of the retained soil or backfill. However, the friction angle of a soil changes during the deformation process. For drained loading, the mobilized friction angle varies between the peak and critical-state friction angles, depending on the level of shear strain in the retained soil. Consequently, there is not a single value of friction angle for the retained soil mass, and the active earth pressure coefficient changes as the wall moves away from the backfill and plastic shear strains in the backfill increase. In this paper, the finite element method is used to study the evolution of the active earth pressure behind a gravity retaining wall, as well as the shear patterns developing in the backfill and foundation soil. The analyses relied on use of a two-surface plasticity constitutive model for sands, which is based on critical-state soil mechanics.
Deep cavity flow mechanism of pipe penetration in clay
Authors: Tho Kee Kiat , Leung Chun Fai , Chow Yean Khow , Palmer Andrew Clennel
Published: December 2011

The evolution of penetration resistance as a function of penetration depth of a pipe into a cohesive seabed is of practical importance, particularly in the areas of pipeline on-bottom stability assessment and T-bar penetrometer data interpretation. In the past, this subject was addressed primarily in a discontinuous manner by separating the penetration response into two broad regimes of shallow and deep penetrations followed by deriving plasticity solutions assuming a simplified “wished-in-place” configuration. In this manner, the effects of evolving seabed topology and the progressive transition from a shallow failure mechanism to a deep failure mechanism are neglected. This paper aims to provide greater insights into the transition zone, which is especially important for the interpretation of T-bar test data at shallow depths. In this study, the penetration response of a smooth pipe over a wide range of normalized clay strengths is numerically simulated. A deep cavity flow mechanism where the bearing capacity factor is 12% less than the conventional full-flow mechanism is identified and found to be operative up to a depth of 10 pipe diameters under a certain combination of material properties. An analysis method is proposed to predict the load–penetration response for a given set of clay strengths and pipe diameters.
HIGH EFFICIENCY KA-BAND MMIC SSPA POWER COMBINER FOR NASA'S SPACE COMMUNICATIONS
Authors: SIMONS RAINEE N. , WINTUCKY EDWIN G. , FREEMAN JON C. , CHEVALIER CHRISTINE T.
Published: December 2011

In this paper, we will review the design, construction and performance of the two-way Ka -band waveguide branch-line and asymmetric magic- T based unequal power combiners. The manufactured combiners were designed to combine input signals that are equal in phase and with an amplitude ratio of two. Next, the design, construction and performance of a three-way branch-line unequal power combiner, achieved by serially interconnecting two 2-way branch-line hybrids and optimizing the dimensions using software tools, is presented. The application of the two-way and three-way combiners for combining the output from two or three MMIC PAs was demonstrated. The observed efficiencies for all three power combining configurations are 90 percent or greater at Ka -band (31.8 to 32.3 GHz).
CRYOGENIC OPERATION OF GaN SCHOTTKY RECTIFIERS
Authors: NAIK HARSH , MARRON TOM , CHOW T. PAUL
Published: December 2011

We report for the first time operation of GaN Schottky rectifiers under cryogenic temperatures. A 600V, 4A GaN Schottky rectifiers from Velox Semiconductors has been used for the characterization. Forward conduction and reverse blocking performance was measured down to 77K. Two Schottky barrier heights have been noticed at low temperatures and a tunneling limited reverse leakage current was observed for the rectifier.
LIMITS OF INFRARED IMAGING
Authors: TENNANT W. E.
Published: December 2011

The background photon shot noise, induced by the signal itself and all other in-band surroundings, provides the fundamental infrared imaging sensitivity limit (background limited performance or BLIP). Optical diffraction constrains resolution angle to values greater than the ratio of the detection wavelength to the optics diameter. Imaging technology tries to attain BLIP at spatial frequencies approaching the diffraction limit while minimizing system size, weight, power, and life-cycle cost.

To minimize costs, detector array technology must raise the detector operating temperature while keeping dark currents and other noise mechanisms below background shot noise. This requires reducing material and process defects. Recently HgCdTe has seen the MWIR-LWIR device dark currents to be limited only by fundamental mechanisms over a wide range of temperatures and wavelengths. Novel materials systems (e.g. Type-II superlattices) in theory have even lower fundamental limits than HgCdTe , but as yet lag in demonstrated performance. At least for now HgCdTe provides a convenient well-characterized benchmark and gives insight into further improvement possibilities

Infrared imaging technology must also exploit advanced processing and packaging techniques to reduce detector pitch to a few wavelengths of detected light. Mid- and long-wave infrared imaging arrays with ~15μm detector dimensions are now approaching this goal.
ELECTROMAGNETIC COMPOSITE-BASED REFLECTING TERAHERTZ WAVEPLATES
Authors: STRIKWERDA ANDREW C. , AVERITT RICHARD D. , FAN KEBIN , ZHANG XIN , METCALFE GRACE D. , WRABACK MICHAEL
Published: December 2011

We have created a low profile, high efficiency half waveplate for operation at terahertz (THz) frequencies. The waveplate is a periodic gold/polyimide composite with a physical thickness of λ/10. Our reflection based waveplate has an intensity throughput of 80% at the design frequency of 350 GHz. This is quite high in comparison to transmissive THz components which typically suffer a large insertion loss due to Fresnel reflections. Simulations suggest a halfwave rotation of over 99% of the reflected THz radiation from 320 – 372 GHz. Experiments at 350 GHz confirm the basic operation of our electromagnetic composite as a functional half waveplate.
SPATIAL WAVEFUNCTION-SWITCHED (SWS)-FET: A NOVEL DEVICE TO PROCESS MULTIPLE BITS SIMULTANEOUSLY WITH SUB-PICOSECOND DELAYS
Authors: JAIN F. C. , CHANDY J. , MILLER B. , HASANEEN E-S. , HELLER E.
Published: December 2011

Spatial Wavefunction-Switched (SWS) Field-Effect Transistors (FETs) consist of inversion layers comprising two or more coupled quantum wells (QWs). Carriers can be localized in any of the wells and vertically transferred between them by changing the gate voltage. In addition, carriers can also be laterally transferred between adjacent SWSFET devices by the manipulation of the gate voltages (Vg). This enables processing of two more bits simultaneously by changing the spatial location of the carrier ensemble wavefunction, which in turn determines the state of the device [e.g., electrons in well W2 (01), in W1 (10), in both (11), in neither (00)]. Experimentally, the capacitance-voltage data, having a distinct peak, has been presented in InGaAs - AlInAs two-quantum well structures. The peak(s) are attributed to the appearance of carriers, first in the lower well and subsequently their transfer to the upper well. Use of multiple channels allows for CMOS-like configuration with both transistors having n -channel mobilities. Simulation of an InGaAs SWS inverter computes a gate delay of 0.24ps. A cut-off frequency in excess of 8THz is computed for 12nm channel length InGaAs SWSFETs. Examples, including logic gates and a 3-bit full-adder, are presented to show the reduction of device count when SWS-FETs are employed.
CHARACTERIZATION OF CONDUCTION MECHANISMS RELEVANT TO DEVICE PERFORMANCE IN NANOPERFORATED GRAPHENE
Authors: SAFRON NATHANIEL S. , ARNOLD MICHAEL S.
Published: December 2011

We have recently reported on the synthesis and characterization of a new form of nanostructured graphene that we call "nanoperforated graphene". Nanoperforated graphene is fabricated by etching a periodic array of nanoscale holes into atomic membranes of graphene to create an ultrathin superlattice-like structure. Nanoperforated graphene demonstrates semiconductor-like behavior and we have realized room-temperature field-induced conductance modulation as high as 450 (compared with < 10 for unpatterned graphene) with field-effect mobilities of ~ 1 cm2V-1s-1. Here, we discuss the conduction mechanisms in nanoperforated graphene and the relevance of this new material for field-effect transistor devices. In nanoperforated graphene with 15 nm nanoconstrictions, we observe that the low-bias mobility is independent of temperature, consistent with elastic scattering-limited conduction. At low temperatures, a transport gap limits conduction in the sub-threshold regime and affects the threshold voltage for band conduction. We show that the high-bias electrical characteristics of nanoperforated graphene are similar to "artificial solids," a class of materials made of 2D arrays of Coulomb islands, consistent with observed Coulomb Blockade features in the sub-threshold regime. Currently, the device characteristics of the nanopatterned graphene material are found to be suitable for large-area, thin-film transistor applications. Future higher-performance applications are expected.