bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of plane Couette–Poiseuille flow of shear-thinning fluid
Authors: Nouar Chérif , Frigaard Ian
Published: June 2009

A linear stability analysis of the combined plane Couette and Poiseuille flow of shear-thinning fluid is investigated. The rheological behavior of the fluid is described using the Carreau model. The linearized stability equations and their boundary conditions result in an eigenvalue problem that is solved numerically using a Chebyshev collocation method. A parametric study is performed in order to assess the roles of viscosity stratification and the Couette component. First of all, it is shown that for shear-thinning fluid, the critical Reynolds number for a two-dimensional perturbation is less than for a three dimensional. Therefore, it is sufficient to deal only with a modified Orr–Sommerfeld equation for the normal velocity component. The influence of the velocity of the moving wall on the critical conditions is qualitatively similar to that for a Newtonian fluid. Concerning the effect of the shear thinning, the computational results indicate that this behavior leads to a decrease in the phase velocity of the traveling waves and an increase in stability, when an appropriate viscosity is used in the definition of the Reynolds number. Using a long-wave version of the Orr–Sommerfeld equation, the cutoff velocity is derived. The mechanisms responsible for the changes in the flow stability are discussed in terms of the location of the critical layers, Reynolds stress distribution, and the exchange of energy between the base flow and the disturbance.
Control of domain nucleation in glass covered amorphous microwires
Authors: Chizhik A. , Zhukov A. , Gonzalez J. , Blanco J. M.
Published: June 2009

We report investigations on the control of the magnetic domain nucleation and domain wall motion performed in glass covered amorphous microwires using the magneto-optical Kerr effect. The conditions of the acceleration, deceleration, and suppression of the domain nucleation have been determined. It was found that the combination of the dc electric current flowing along the wire and the phase shift in the nucleation coil permits to control the direction of the domain wall motion.
Directional emission and universal far-field behavior from semiconductor lasers with limaçon-shaped microcavity
Authors: Yan Changling , Wang Qi Jie , Diehl Laurent , Hentschel Martina , Wiersig Jan , Yu Nanfang , Pflügl Christian , Capasso Federico , Belkin Mikhail A. , Edamura Tadataka , Yamanishi Masamichi , Kan Hirofumi
Published: June 2009

We report experimental demonstration of directional light emission from limaçon-shaped microcavity semiconductor lasers. Quantum cascade lasers (QCLs) emitting at λ≈10 μm are used as a model system. Both ray optics and wave simulations show that for deformations in the range 0.37<ε<0.43, these microcavities support high quality-factor whispering gallerylike modes while having a directional far-field profile with a beam divergence θ∥≈30° in the plane of the cavity. The measured far-field profiles are in good agreement with simulations. While the measured spectra show a transition from whispering gallerylike modes to a more complex mode structure at higher pumping currents, the far field is insensitive to the pumping current demonstrating the predicted “universal far-field behavior” of this class of chaotic resonators. Due to their relatively high quality factor, our microcavity lasers display reduced threshold current densities compared to conventional ridge lasers with millimeter-long cavities. The performance of the limaçon-shaped QCLs is robust with respect to variations of the deformation near its optimum value of ε=0.40.
Oscillatory shear induced droplet deformation and breakup in immiscible polymer blends
Authors: Janpaen Vitsarut , Niamlang Sumonman , Lerdwijitjarud Wanchai , Sirivat Anuvat
Published: June 2009

Deformation and breakup of droplets in polybutadiene/polydimethylsiloxane blends subject to oscillatory shear flow were investigated experimentally using an optical shear flow cell. The apparent major axis (a∗) and the minor axis (c) in the vorticity direction of the droplets were measured as functions of time. From the time series of a∗ and c and the deformation parameter, (a∗−c)/(a∗+c), we define the deformation amplitudes as one-half the differences between the maximum and minimum values. The deformation amplitude parameters generally decrease with increasing viscosity ratio, time scale ratio, and droplet elasticity. The dependences of the deformation amplitude parameters on capillary number are generally linear up to a certain value for Newtonian droplets regardless of viscosity ratio and time scale ratio. The dependences become totally nonlinear with increasing droplet elasticity. Droplet viscosity and elasticity generally impede breakup under oscillatory shear. Critical capillary number for breakup, the number of resultant daughter droplets, and the number of cycle required for breakup to occur increase with time scale ratio. The apparent breakup pattern changes from the dumbbell type to the end-pinching type as time scale ratio increases.
Efficient solution of the self-consistent field theory for block copolymer fluids displaying Schulz–Flory polydispersity
Authors: Woodward Clifford E. , Forsman Jan
Published: June 2009

We develop a new formulation of polymer self-consistent field theory for polydisperse copolymer fluids satisfying the Schulz–Flory distribution. The result we obtain is remarkably simple and quickly solved numerically. The computational effort scales inversely with the width of the Schulz–Flory distribution. This suggests a significant saving in computational effort when compared with existing approximate solutions of the polymer self-consistent field equations for polydispersed systems.
Local opening of a large bandgap in metallic single-walled carbon nanotubes induced by tunnel injection of low-energy electrons
Authors: Yamada Kenta , Sato Hiroaki , Komaguchi Tetsuya , Mera Yutaka , Maeda Koji
Published: June 2009

Probing with a tip of scanning tunneling microscopy (STM) of metallic single-walled carbon nanotubes (SWCNT) was found to induce defects in the tubes. The primary defect formation by probing was enhanced with a rate proportional to tunnel-injected electron current above a sample-bias threshold of around +4 V. Scanning tunneling spectroscopic measurements of local density of states revealed that the defects imaged by STM, presumably secondary defects stabilized at the test temperature (95 K), are accompanied by a localized bandgap of 0.7 eV, which may account for the reported metal-semiconductor conversion in SWCNT-based field-effect transistor that is induced by low-energy electron irradiation.
Structure and interaction of flexible dendrimers in concentrated solution
Authors: Rosenfeldt S. , Ballauff M. , Lindner P. , Harnau L.
Published: June 2009

We study the influence of mutual interaction on the conformation of flexible poly(propyleneamine) dendrimers of fourth generation in concentrated solution. Mixtures of dendrimers with protonated and deuterated end groups are investigated by small-angle neutron scattering up to volume fractions of 0.23. This value is in the range of the overlap concentration of the dendrimers. The contrast between the solute and the solvent was varied by using mixtures of protonated and deuterated solvents. This allows us to investigate the partial structure factors of the deuterated dendrimers in detail. An analysis of the measured scattering intensities reveals that the shape of the flexible dendrimers is practically independent of the concentration in contrast to the pronounced conformational changes in flexible linear polymers.
Iterative optimization of plasmon resonant nanostructures
Authors: Pavaskar Prathamesh , Cronin Stephen B.
Published: June 2009

We perform finite difference time domain simulations of two-dimensional clusters of metal nanoparticles with incident planewave irradiation. An iterative optimization algorithm is used to determine the configuration of the nanoparticles that gives the maximum electric field intensity at the center of the cluster. The optimum configurations of these clusters have mirror symmetry about the axis of planewave propagation, but are otherwise nonsymmetric and nonintuitive. The maximum field intensity is found to increase monotonically with the number of nanoparticles in the cluster, producing intensities that are five times larger than linear chains of nanoparticles and 2500 times larger than the incident electromagnetic field.
Magnetism of semiconductor-based magnetic tunnel junctions under electric field from first principles
Authors: Kan Erjun , Xiang Hongjun , Yang Jinlong , Whangbo Myung-Hwan
Published: June 2009

Semiconductor magnetic tunnel junctions (MTJs), composed of diluted magnetic semiconductors (DMSs) sandwiching a semiconductor barrier, have potential applications in spintronics but their development has been slow due to the difficulty of controlling the magnetism of DMSs. In terms of density functional calculations for model semiconductor MTJs, (Zn,Co)O/ZnO/(Zn,Co)O and (Ga,Mn)N/GaN/(Ga,Mn)N, we show that the magnetic coupling between the transition metal ions in each DMS electrode of such semiconductor MTJs can be switched from ferromagnetic to antiferromagnetic, or vice versa, under the application of external electric field across the junctions. Our results suggest a possible avenue for the application of semiconductor MTJs.
Femtosecond laser induced plasma diffraction gratings in air as photonic devices for high intensity laser applications
Authors: Suntsov S. , Abdollahpour D. , Papazoglou D. G. , Tzortzakis S.
Published: June 2009

The creation of volume plasma density gratings in air by temporally overlapped high-intensity IR femtosecond laser pulses is demonstrated experimentally. Through the diffraction of various probe beams the plasma grating properties are recovered including its thickness and refractive index modulation, as well as its decay dynamics. The diffraction properties of these plasma photonic devices suggest that they can be used in applications involving high intensity lasers, such as filamentation, where no physical objects can be placed in the path of the laser beams.
A standing-wave thermoacoustic engine with gas-liquid coupling oscillation
Authors: Tang K. , Lei T. , Jin T. , Lin X. G. , Xu Z. Z.
Published: June 2009

A thermoacoustic engine usually uses either gas or liquid as the working fluid. However, an analysis based on acoustic-electric analogy indicates that gas-liquid coupling oscillation may lead to lower resonant frequency and larger pressure amplitude. A standing-wave thermoacoustic engine containing a water column was fabricated and tested. Compared with the same apparatus using nitrogen gas, the introduction of a 1.5 kg water column resulted in a drop of resonant frequency by 79.0% and a rise of pressure amplitude by 157.4%, while for the case of helium gas, a drop by 91.4% and a rise by 208.3% were observed, respectively.
Valence electron energy-loss spectroscopy of nanoporous MgO
Authors: Jiang N. , Su D. , Spence J. C. H. , Howie A.
Published: June 2009

This work reports experimental evidence for a redshift in the main peak in the valence electron energy loss spectrum of nanoporous MgO. An interpretation is given based on effective-medium response theory. We find that the main peak energy depends on the density of nanopores within the illuminated area. As a result, by combining electron energy loss spectroscopy with transmission electron microscopy imaging, the loss peak position may be used to measure the porosity of nanoporous materials.
Quantum electron transport through SrTiO3: Effects of dopants on conductance channel
Authors: Wang Zhongchang , Tsukimoto Susumu , Saito Mitsuhiro , Ikuhara Yuichi
Published: June 2009

Combining nonequilibrium Green’s function technique with density functional theory, electronic structure and quantum transport of Pt–SrTiO3–Pt heterostructures are investigated with special focus on effects of dopants. We find that intrinsically closed conductance channel in SrTiO3 opens after doping substitutional atoms of higher valency for Sr or Ti, resulting in enhancement in electron transmission at Fermi level and drastic increase in current with bias. The switch of channel is suggested to be due to the redistribution of density of states on orbitals of channel atoms.
Subpicosecond quantum dot saturable absorber mode-locked semiconductor disk laser
Authors: Wilcox Keith G. , Butkus Mantas , Farrer Ian , Ritchie David A. , Tropper Anne , Rafailov Edik U.
Published: June 2009

We report the generation of subpicosecond pulses from a passively mode locked, optically pumped quantum well semiconductor disk laser using a quantum dot semiconductor saturable absorber mirror (SESAM). We obtained 870 fs pulses at a repetition rate of 895 MHz with average output power of 45 mW at 1027.5 nm. The mode locking operation was insensitive to SESAM temperature over the range of −10 to 85 °C, with the pulse duration variation thought to be dominated by the temperature dependence of the group delay dispersion.
Synthesis and magnetic properties of Al doped Zn0.995Mn0.005O powers
Authors: Li Xiang , Yu Zhou , Long Xue , Lin Pengtin , Cheng Xingwang , Liu Ying , Cao Chuanbao , Zhang Hongwei , Wu Guangheng , Yu Richeng
Published: June 2009

Chemical method was employed to synthesize Mn and Al codoped ZnO, namely, Zn0.995−xMn0.005AlxO with the nominal composition of x=0, 0.005, and 0.02. Structural, optical, and magnetic properties of the produced samples were studied. The results indicated that introduce Al as additional dopants induces in an enhancement of the ferromagnetism in Zn0.995Mn0.005O. The enhanced ferromagnetism (FM) in (Mn,Al) codoped sample can be understood in view of that introducing of Al could promote spinodal decomposition and lead to Mn rich regions. The Mn rich regions could be responsibility for the observed enhancement of FM at room temperature.
Venous and Arterial Leg Ulceration
Authors: Irving Greg , Hargreaves Simon
Published: June 2009

Chronic leg ulceration is a major health problem in the UK costing the NHS up to £600 million per annum. In Western countries, 1–2% of the population is likely to have a chronic leg ulcer at any one time; this increases to 3% in those over 65 years old. Studies have found that 60–80% of chronic leg ulcers have a venous component and 10–30% are associated with arterial insufficiency. The natural history of the disease is a continuous cycle of breakdown and healing over decades. As a result, ulcer healing rates can be poor with up to 50% of venous ulcers open and unhealed for 9 months. Most of the clinical management falls to primary care with over 80% of leg ulcer cared for in the community.
Diagnostic Criteria for Eosinophilic Esophagitis: A 5‐year Retrospective Review in a Pediatric Population
Authors: Lai Anita L , Girgis Safwat , Liang Yuanyuan , Carr Stuart , Huynh Hien Q
Published: June 2009

Background:

The diagnostic criterion based on the number of eosinophils (Eos) per high‐power field (HPF) does not appear to capture all patients with eosinophilic esophagitis (EE).

Objectives:

To determine whether EE has been underrecognized at our institution, clinical variables predicting EE, and whether the Luna eosinophil granule (LEG) stain detects eosinophils better than hematoxylin and eosin (HE).

Materials and Methods:

Esophageal biopsies of 202 children younger than 18 years old from 2000 to 2004 were reviewed and Eos/HPF was recorded. Clinical variables from charts were reviewed and a marginal logit model was used to determine significance. LEG stains for 60 randomly selected patients were prepared and compared to HE originals.

Results:

EE diagnoses have risen from none in 2000 to 23 in 2004. The clinically significant variables that predicted EE were improvement from EE treatment (160 times more likely to have EE; P < 0.0005), final endoscopic diagnosis of EE (31 times; P = 0.004), absence of vascular pattern on endoscopy (20 times; P = 0.008), and vertical furrows on endoscopy (29 times; P = 0.039). LEG stain appeared to be superior to HE in detecting low Eos/HPF (mean 24.82 and 38.53, respectively). Peak counts of eosinophils in the most involved HPF significantly correlated with highest average count of eosinophils per HPF in the most involved specimen (Pearson correlation 0.958).

Conclusions:

Misdiagnosed EE cases decreased but prevalence appeared to increase. LEG potentially can be a more sensitive stain. The key variables that predict EE were typical endoscopic findings and improvement from specific EE treatment.
Lymphocytic Leiomyositis and Myenteric Ganglionitis Are Intrinsic Features of Cystic Fibrosis: Studies in Distal Intestinal Obstruction Syndrome and Meconium Ileus
Authors: Smith Virpi V , Schäppi Michela G , Bisset W Michael , Kiparissi Fevronia , Jaffe Adam , Milla Peter J , Lindley Keith J
Published: June 2009

Background:

Cystic fibrosis (CF) is a multisystem disorder intrinsically associated with inflammation of mucosal surfaces. Because inflammation can result in enteric neuromuscular dysfunction we hypothesized that terminal ileitis in patients with CF may predispose to distal ileal obstruction syndrome (DIOS).

Methods and Patients:

Full‐thickness terminal ileal tissues from 6 children with CF and severe DIOS, 6 infants with complicated meconium ileus (MI), and 6 children with non‐CF intestinal atresia were studied.

Results:

Lymphocyte‐predominant mucosal and transmural ileal inflammation was present in 6 of 6 patients with DIOS. Lymphocytic ganglionitis was present in 4 of 6 although numbers of myenteric neurons were not decreased (5/5). Myocyte proteins were preserved (6/6). Mild submucosal fibrosis was common in DIOS (5/6) and transformation of submucosal fibroblasts to a myofibroblastic phenotype was noted in 4 of 6. Inflammatory changes were distinct from those described in fibrosing colonopathy. Antroduodenal manometry in an individual who had experienced MI/DIOS was consistent with a neuropathic pseudo‐obstructive process. Submucosal or transmural lymphocyte predominant inflammation was also present in 6 of 6 infants with complicated MI, which, when coupled with submucosal myofibroblast proliferation (5/6), appeared highly predictive of CF rather than non‐CF atresia. Histological findings at birth were similar, although milder, than those seen in DIOS, suggesting that these changes are a primary abnormality in CF.

Conclusions:

Submucosal or transmural inflammation of the ileum is common in newborns with CF and MI and older children with DIOS. Severe recurrent DIOS should be investigated with seromuscular and mucosal biopsy of the ileum to seek a transmural ileitis potentially amenable to anti‐inflammatory therapies.
Colonic Volvulus in Children With Intestinal Motility Disorders
Authors: Altaf Muhammad A , Werlin Steven L , Sato Thomas T , Rudolph Colin D , Sood Manu R
Published: June 2009

Background:

Chronic intestinal pseudo‐obstruction (CIP) is a condition characterized by symptoms of bowel obstruction in the absence of an anatomical cause. Patients with CIP and chronic intractable constipation (CIC) can also develop anatomical obstruction, and the presenting symptoms mimic those of underlying pseudo‐obstruction.

Objectives:

Our objectives were to evaluate the incidence, clinical presentation, and diagnostic investigations of colonic volvulus in children with intestinal motility disorders and to differentiate these episodes of colonic volvulus from the underlying motility disorder based on clinical presentation and imaging techniques.

Materials and Methods:

Patients records of children with colonic volvulus cared for at our institution over the previous 20 years were retrospectively reviewed. We identified 8 patients who were between 2 and 22 years of age at the time of diagnosis with colonic volvulus who also had CIP and CIC.

Results:

The mean age ± SD at presentation with colonic volvulus was 13.2 ± 5.05 years. All patients presented with worsening of abdominal distension and pain. The mean duration of symptoms of colonic volvulus before seeking medical help was 4.2 days (range 1–7 days). Water‐soluble contrast enema was the single most useful investigation for confirming the diagnosis. All patients required surgery. There was no mortality associated with colonic volvulus.

Conclusions:

Clinicians should be vigilant and include volvulus in the differential diagnosis of the acute onset of abdominal distension and pain in patients with CIP and CIC. Delay in diagnosis can result in bowel ischemia and perforation.
Effect of Maternal Diabetes on Postnatal Development of Brush Border Enzymes and Transport Functions in Rat Intestine
Authors: Sharma Ruchi , Kaur Jyotdeep , Mahmood Akhtar
Published: June 2009

Aims/Hypothesis:

The effect of alloxan‐induced maternal diabetes has been studied on the postnatal development of brush border enzymes in rat intestine.

Materials and Methods:

Diabetes was induced by injecting alloxan in rat mothers on day 3 of gestation.

Results:

There was no change in gestational period (22 days) in control and diabetic groups; however, the litter size was reduced (P < 0.001) in diabetic mothers compared with controls. Body weight of pups born to diabetic mothers was significantly low up to 45 days of postnatal age compared with controls. Analysis of brush border enzymes revealed elevated levels of lactase (76%), sucrase (46%), maltase (25%), trehalase (38%), alkaline phosphatase (57%), and leucine aminopeptidase (56%) up to 21 days of postnatal age in diabetic group compared with controls. However, in 30‐ to 45‐day‐old animals, the enzyme levels were either reduced in diabetic group or there was no change compared with controls. Western blot analysis corroborated the enzyme analysis data in purified brush borders. Also, 45 days after birth, the intestinal uptake of D‐glucose and glycine was significantly high (30%–61%) in pups from diabetic dams compared with controls.

Conclusions:

These findings indicate that alloxan‐induced maternal diabetes influences the postnatal development of intestine and the expression of various brush border enzymes and transport functions in rat intestine. This could affect the growth and development of the offspring during the postnatal period.
Chromosome Instability in Lymphocytes of Children With Coeliac Disease
Authors: Martin‐Arruti Maialen , Irastorza Inaki , de Prado Elena , Martin‐Sanchez Esperanza , Martin‐Guerrero Idoia , Ballesteros Javier , Vitoria Juan Carlos , Garcia‐Orad Africa
Published: June 2009

Undiagnosed individuals with celiac disease (CD) or those who do not comply with gluten‐free diet (GFD) are at a higher risk of developing malignancies. A possible origin of chromosomal alteration in autoimmune reaction could be mistakes in the rearrangement of V(D)J of the IgH gene. Our aim was to verify whether higher genomic instability was found in coeliac individuals and whether GFD reduced it. As marker of genomic instability we analysed the frequency of 2 translocations, t(14;18) and t(11;14), in peripheral blood by nested PCR, in 37 patients with CD at diagnosis, 27 patients with CD after 2 years on GFD, and 36 control individuals. No significant differences were found.
Diet‐dependent Mucosal Colonization and Interleukin‐1β Responses in Preterm Pigs Susceptible to Necrotizing Enterocolitis
Authors: Van Haver Els R , Sangild Per T , Oste Marijke , Siggers Jayda LA , Weyns Andre LM , Van Ginneken Christa J
Published: June 2009

Objectives:

Intestinal colonization challenges the neonatal innate immune system, especially in newborns with an immature immune response lacking the supportive bioactive components from mother's milk. Accordingly, formula‐fed preterm pigs frequently show bacterial overgrowth, mucosal atrophy, and gut lesions reflecting necrotizing enterocolitis (NEC) within the first days after birth. We hypothesized that NEC development is related to a diet‐dependent bacterial adherence and a subsequent proinflammatory cytokine response in the gut mucosa immediately after introduction of enteral food.

Materials and Methods:

Premature piglets (92% gestation) received 2 to 3 days of total parenteral nutrition followed by 0, 8, or 17 hours of enteral formula or sow's colostrum feeding.

Results:

Following 8 hours, but not 17 hours, of colostrum feeding, a reduced number of intestinal samples with adherent bacteria (both Gram‐negative and Gram‐positive bacteria) was counted compared with 0 or 8 hours of formula feeding. Besides a more dense colonization, formula feeding leads to higher intestinal interleukin‐1β (IL‐1β) levels and more NEC‐like lesions from 8 hours onward. The load of adherent bacteria was especially high in NEC lesions. Toll‐like receptor 4 was detected in enteroendocrine, neuronal, and smooth muscle cells, potentially mediating the increase in IL‐1β levels by Gram‐negative bacteria.

Conclusions:

Formula feeding facilitates bacterial adherence and the development of a proinflammatory state of the intestine, which may be among the key factors that predispose formula‐fed preterm neonates to NEC.
Age‐ and Sex‐related Reference Ranges of Alanine Aminotransferase Levels in Children: European Paediatric HCV Network
Authors: England Kirsty , Thorne Claire , Pembrey Lucy , Tovo Pier‐Angelo , Newell Marie‐Louise
Published: June 2009

Background:

Serum alanine aminotransferase (ALT) levels are commonly used to indicate liver damage. Although elevated levels indicate possible liver injury, abnormalities, or disease, some patients with “normal” ALT levels have minimal to mild liver disease. Recently, ALT reference ranges for adults were queried and revised ranges proposed with lower upper limits of normality. The appropriateness of current paediatric ALT reference ranges is unclear.

Material and Methods:

Hepatitis C virus (HCV)–uninfected children from the European Paediatric HCV Network represent a large population of healthy children born to HCV‐infected mothers, with ALT observations collected prospectively from birth. Linear regression identified factors associated with ALT levels while accounting for within‐child repeated measurements. ALT centiles stratified by sex were calculated using maximum penalized likelihood methods and LMS software.

Results:

A total of 1293 HCV‐uninfected children had 5011 ALT measurements during follow‐up. ALT levels significantly decreased with increasing age, whilst ALT levels were significantly lower in girls than boys. Reference cutoffs representing the 95th centiles before 18 months of age were 60 U/L for boys and 55 U/L for girls, decreasing to 40 U/L for boys and 35 U/L for girls after 18 months of age.

Conclusions:

These reference ranges represent a unique investigation of ALT levels in a healthy child population. We show lower and more detailed age‐related cutoffs of normality than available. Additionally, we demonstrate a significant effect of sex on ALT reference ranges, which has not previously been described in children younger than 5 years of age.
Isolation, Identification, and Characterization of Small Bioactive Peptides From Lactobacillus GG Conditional Media That Exert Both Anti‐Gram‐negative and Gram‐positive Bactericidal Activity
Authors: Lu Ruiliang , Fasano Serena , Madayiputhiya Nandakumar , Morin Nicholas P , Nataro James , Fasano Alessio
Published: June 2009

Objectives:

Diarrheal diseases remain a major human plague that still claim millions of lives every year. Probiotics, including Lactobacillus GG (LGG), are known to have a beneficial effect on diarrheal diseases, but their mechanism of action has not yet been completely established. Therefore, the main objective of this work was to identify and characterize moieties elaborated by LGG that exert antibacterial activity.

Materials and Methods:

Lactobacillus GG conditional media was subjected to liquid chromatography/mass spectrometry. The identified peptides were synthesized by Symphony peptide synthesizer and purified by HPLC using Dynamax reverse‐phase C18 column. Using A600 measurement and tested for their antibacterial activity.

Results:

We identified 7 small peptides from LGG cultured media, 2 of which are NPSRQERR and PDENK, retained the antibacterial activity detected with LGG conditional media. The antibacterial activity was exerted against both Gram‐negative (Escherichia coli EAEC 042 and Salmonella typhi) and, with less potency, Gram‐positive (Staphylococcus aureus) bacteria.

Conclusions:

Lactobacillus GG elaborates small peptides showing various degrees of antibacterial activity. NPSRQERR showed the most potent antibacterial effect that was detected both in Gram‐negative and Gram‐positive microorganisms. These synthetic peptides may represent novel tools for the treatment of bacterial infectious diseases.
Antibodies Against Deamidated Gliadin as New and Accurate Biomarkers of Childhood Coeliac Disease
Authors: Prause Christian , Ritter Maria , Probst Christian , Daehnrich Cornelia , Schlumberger Wolfgang , Komorowski Lars , Lieske Ruediger , Richter Thomas , Hauer Almuthe C , Stern Martin , Uhlig Holm H , Laass Martin W , Zimmer Klaus‐Peter , Mothes Thomas
Published: June 2009

Objectives:

Assays of tissue transglutaminase antibodies (anti‐tTG) represent the cornerstone of serological coeliac disease (CD) diagnostics. Assays of antibodies against native gliadin (anti‐nGli) lost importance due to low validity. We investigated the performance of new assays for antibodies against deamidated gliadin (anti‐dGli) in childhood CD.

Methods:

We retrospectively compared children (142 with active CD and 160 without CD, diagnosis confirmed or excluded by intestinal biopsy) concerning (immunoglobulin [Ig] G and IgA) anti‐nGli, anti‐tTG, and 2 different anti‐dGli assays.

Results:

IgG‐anti‐dGli1, IgG‐anti‐dGli2, and IgA‐anti‐tTG performed similarly. Area under the receiver‐operating characteristic curve (AUC) was 98.6%, 98.9%, and 97.9%; accuracy was 94.7%, 95.7%, and 96.7%. Anti‐dGli1 and anti‐dGli2 (IgG and IgA) and IgA‐anti‐tTG performed significantly better than IgA‐anti‐nGli and IgG‐anti‐nGli. Both IgG‐anti‐dGli showed higher AUC and accuracy than IgA‐anti‐dGli and IgG‐anti‐tTG. Combined evaluation of IgA‐anti‐tTG with one of the IgG‐anti‐dGli tests reduced the rate of falsely classified patients. At enhanced cutoff (specificity >99%), sensitivity was above 67% for both IgG‐anti‐dGli and IgA‐anti‐tTG. If IgA‐anti‐tTG assay was combined with one of the IgG‐anti‐dGli tests, then the fraction of patients identified with more than 99% specificity as coeliacs increased significantly above 84.5%. Combined evaluation of the 2 IgG‐anti‐dGli tests did not improve the performance.

Conclusions:

The new IgA and IgG‐anti‐dGli tests outperform conventional anti‐nGli assays. The validity of IgG‐anti‐dGli cannot be distinguished from IgA‐anti‐tTG. It should be studied prospectively whether antibody assays could replace biopsy in diagnosis of CD in a substantial segment of children.
Enteral Glutamine and/or Arginine Supplementation Have Favorable Effects on Oxidative Stress Parameters in Neonatal Rat Intestine
Authors: Kul Mustafa , Vurucu Sabahattin , Demirkaya Erkan , Tunc Turan , Aydinoz Seçil , Meral Cihan , Kesik Vural , Alpay Faruk
Published: June 2009

Objective:

To investigate and compare the effects of enteral glutamine and arginine supply on lipid peroxidation and antioxidant enzyme levels in the small intestine of healthy breast‐fed rats.

Materials and Methods:

The study comprised 40 newborn Sprague‐Dawley rats born to 5 mother rats. Newborn rats were randomly divided into 4 groups. Starting from day 1 until day 21, group I received only breast milk; group II received breast milk and 200 mg/kg/day oral glutamine; group III received breast milk and 200 mg/kg/day oral arginine; and group IV received breast milk, 200 mg/kg/day glutamine, and 200 mg/kg/day arginine. Malondialdehyde levels and glutathione peroxidase (GPx) and superoxide dismutase activities were measured.

Results:

The lowest malondialdehyde levels were found in group II (P = 0.0001). Superoxide dismutase activity was found to be significantly higher in group II than group I (P < 0.001). Of the 4 groups, GPx activity was highest in group IV. GPx activity in group II was significantly higher than in group I (P = 0.001) or group III (P = 0.001). GPx activity was higher in group IV than in group I (P = 0.001) or group III (P = 0.001).

Conclusions:

Enteral glutamine alone or in the presence of arginine has favorable effects on oxidative stress not only in experimental models of hypoxia‐reoxygenation, but also in healthy newborn rats. This suggests that in premature neonates with insufficient oxidative resistance, glutamine and arginine supplementation may help prevent necrotizing enterocolitis.
Prevalence of Subclinical Vitamin K Deficiency in Cholestatic Liver Disease
Authors: Strople Jennifer , Lovell Glenda , Heubi James
Published: June 2009

Background and Objective:

Prothrombin time (PT), a surrogate marker of vitamin K deficiency, may underestimate the prevalence of vitamin K deficiency in cholestatic liver disease. This study investigated the frequency of vitamin K deficiency in children and adults with cholestatic liver disease by determining plasma protein induced in vitamin K absence II (PIVKA‐II), and assessed the relation between plasma PIVKA‐II levels and markers of cholestasis, measured PT, international normalized ratio (INR), serum undercarboxylated osteocalcin (ucOC), serum vitamins A and E, and serum 25‐hydroxyvitamin D levels.

Patients and Methods:

Blood was collected from patients with cholestatic liver disease for liver biochemistries, PT, INR, bile acids, 25‐hydroxyvitamin D, vitamin A, vitamin E, ucOC, and PIVKA‐II.

Results:

Thirty‐one patients were enrolled (age range 0.5–54 years, median age 5.7 years, 17 females). Nine patients (29%) had increased INRs, whereas 21 (68%) had elevated plasma PIVKA‐II levels. All patients with increased INRs had increased plasma PIVKA‐II. Fifteen of 21 patients with increased plasma PIVKA‐II were receiving supplemental vitamin K therapy (range 7.8–700 μg/kg/day). Plasma PIVKA‐II levels were positively correlated with serum conjugated bilirubin, bile acids, aspartate aminotransferase, alanine aminotransferase, PT, INR, and serum ucOC (P ≤ 0.02) and negatively correlated with serum 25‐hydroxyvitamin D levels (P = 0.01). Twenty‐two patients (71%) had vitamin D deficiency, 9 patients (29%) had vitamin A deficiency, and 2 patients (6%) had vitamin E deficiency.

Conclusions:

Despite vitamin K supplementation, elevation of plasma PIVKA‐II suggesting ongoing vitamin K deficiency is common in cholestatic liver disease. Better strategies for vitamin K supplementation and dosing guidelines are needed.
Intestinal Stem Cells
Authors: Garrison Aaron P , Helmrath Michael A , Dekaney Christopher M
Published: June 2009

The epithelial cell lining of the gastrointestinal tract is the most rapidly proliferating tissue in the body. The constant state of renewal of differentiated epithelial cells is sustained by a continual supply of progeny from multipotent progenitors that originate from stem cells located within the intestinal crypts. In addition to supporting normal epithelial homeostasis, intestinal stem cells (ISC) are thought to play an important role in the rapid expansion of the gut during development, tissue regeneration following injury or surgical loss, and malignancy. Because of the lack of specific ISC markers required to isolate and characterize these cells, our current knowledge of the biology of ISC results largely from indirect measures of their behavior published during the past 40 years. The recent description of several potential ISC markers and the use of transgenic mice, both as a tool to lineage trace and to isolate specific cells expressing these markers, have provided a tremendous advancement to our current understanding of these cells. This brief review provides a general historical overview of our understanding of ISC and the tools available to study their behavior in the context of normal and pathological conditions, as well as potential future clinical applications that may result from this exciting area of research.
Antitumor effects of 2‐oxoglutarate through inhibition of angiogenesis in a murine tumor model
Authors: Matsumoto Ken , Obara Naoshi , Ema Masatsugu , Horie Masaki , Naka Ayano , Takahashi Satoru , Imagawa Shigehiko
Published: June 2009

Hypoxia‐inducible factor 1 (HIF‐1) plays essential roles in tumor angiogenesis and growth by regulating the transcription of several key genes in response to hypoxic stress and growth factors. HIF‐1 is a heterodimeric transcriptional activator consisting of inducible α and constitutive β subunits. In oxygenated cells, proteins containing the prolyl hydroxylase domain (PHD) directly sense intracellular oxygen concentrations. PHDs tag HIF‐1α subunits for polyubiquitination and proteasomal degradation by prolyl hydroxylation using 2‐oxoglutarate (2‐OX) and dioxygen. Our recent studies showed that 2‐OX reduces HIF‐1α, erythropoietin, and vascular endothelial growth factor (VEGF) expression in the hepatoma cell line Hep3B when under hypoxic conditions in vitro. Here, we report that similar results were obtained in Lewis lung cancer (LLC) cells in in vitro studies. Furthermore, 2‐OX showed potent antitumor effects in a mouse dorsal air sac assay and a murine tumor xenograft model. In the dorsal air sac assay, 2‐OX reduced the numbers of newly formed vessels induced by LLC cells. In a murine tumor xenograft model, intraperitoneal injection of 2‐OX significantly inhibited tumor growth and angiogenesis in tumor tissues. Moreover, 5‐fluorouracil combined with 2‐OX significantly inhibited tumor growth in this model, which was accompanied by reduction of Vegf gene expression and inhibited angiogenesis in tumor tissues. These results suggest that 2‐OX is a promising anti‐angiogenic therapeutic agent. (Cancer Sci 2009; 100: 1639–1647)
Role of oxidation‐triggered activation of JNK and p38 MAPK in black tea polyphenols induced apoptotic death of A375 cells
Authors: Bhattacharya Udayan , Halder Babli , Mukhopadhyay Sibabrata , Giri Ashok K.
Published: June 2009

Theaflavins (TF) and thearubigins (TR) are the major polyphenols of black tea. Our previous study revealed that TF‐ and TR‐induced apoptosis of human malignant melanoma cells (A375) is executed via a mitochondria‐mediated pathway. In our present study we observed the role of the three most important MAPK (ERK, JNK, and p38) in TF‐ and TR‐induced apoptosis. TF and TR treatment of A375 cells led to sustained activation of JNK and p38 MAPK but not ERK, suggesting that JNK and p38 are the effector molecules in this polyphenol‐induced cell death. This idea was further supported by subsequent studies in which JNK and p38 activation was inhibited by specific inhibitors. Significant inhibition was found in TF‐ and TR‐treated A375 cell death pretreated with JNK‐ or p38‐specific inhibitors only. Further, we have found that TF and TR treatment induces a time‐dependent increase in intracellular reactive oxygen species generation in A375 cells. Interestingly, treatment with the antioxidant N‐acetyl cystein inhibits TF‐ and TR‐induced JNK and p38 activation as well as induction of cell death in A375 cells. We also provide evidence demonstrating the critical role of apoptosis signal‐regulating kinase 1 in TF‐ and TR‐induced apoptosis in A375 cells. Taken together our results strongly suggest that TF and TR induce apoptotic death of A375 cells through apoptosis signal‐regulating kinase 1, MAPK kinase, and the JNK–p38 cascade, which is triggered by N‐acetyl cystein intracellular oxidative stress. (Cancer Sci 2009; 100: 1971–1978)
Emphasizing interpersonal factors: an extension of the Witkiewitz and Marlatt relapse model
Authors: Hunter‐Reel Dorian , McCrady Barbara , Hildebrandt Thomas
Published: June 2009

Aim  Recently, Witkiewitz & Marlatt reformulated the Marlatt & Gordon relapse model to account for current research findings. The present paper aims to extend this model further to incorporate social variables more fully.

Methods  The social‐factors and alcohol‐relapse literatures were reviewed within the framework of the reformulated relapse model.

Results  The literature review found that the number of social network members, investment of the individual in the social network, levels of general and alcohol‐specific support available within the social network and specific behaviors of network members all predict drinking outcomes. However, little is known about the mechanisms by which these social variables influence outcomes. The authors postulate that social variables influence outcomes by affecting intra‐individual factors central to the reformulated relapse prevention model, including processes (e.g. self‐efficacy, outcome expectancies, craving, motivation, negative affective states) and behaviors (e.g. coping and substance use). The authors suggest specific hypotheses and discuss methods that can be used to study the impact of social factors on the intra‐individual phenomena that contribute to relapse.

Conclusion  The proposed extension of the relapse model provides testable hypotheses that may guide future alcohol‐relapse research.
Adolescent smoking and depression: evidence for self‐medication and peer smoking mediation
Authors: Audrain‐McGovern Janet , Rodriguez Daniel , Kassel Jon D.
Published: June 2009

Aims  The nature of the relationship between adolescent smoking and depression is unclear and the mechanisms that account for the comorbidity have received little investigation. The present study sought to clarify the temporal precedence for smoking and depression and to determine whether these variables are linked indirectly through peer smoking.

Participants  The sample was composed of 1093 adolescents participating in a longitudinal study of the behavioral predictors of smoking adoption.

Design and measurements  In this prospective cohort study, smoking, depression, peer smoking and other covariates were measured annually from mid‐adolescence (9th grade; age 14) to late adolescence (12th grade, age 18).

Findings  Parallel processes latent growth curve models supported a bidirectional relationship between adolescent smoking and depression, where higher depression symptoms in mid‐adolescence (age 14) predicted adolescent smoking progression from mid‐ to late adolescence (ages 14–18). A significant indirect effect indicated that higher depression symptoms across time predicted an increase in the number of smoking peers, which in turn predicted smoking progression from mid‐adolescence to late adolescence. In addition, smoking progression predicted a deceleration of depression symptoms from mid‐ to late adolescence. A significant indirect effect indicated that greater smoking at baseline predicted a deceleration in the number of smoking peers across time, which predicted a deceleration in depression symptoms from mid‐adolescence to late adolescence.

Conclusions  The current study provides the first evidence of bidirectional self‐medication processes in the relationship between adolescent smoking and depression and highlights peer smoking as one explanation for the comorbidity.
Opioid agonist pharmacotherapy in New South Wales from 1985 to 2006: patient characteristics and patterns and predictors of treatment retention
Authors: Burns Lucy , Randall Deborah , Hall Wayne D. , Law Matthew , Butler Tony , Bell James , Degenhardt Louisa
Published: June 2009

Aims  The aims of this study were to: examine the number and characteristics of patients entering and re‐entering opioid replacement treatment between 1985 and 2006, to examine select demographic and treatment correlates of leaving treatment between 1985 and 2000, and to compare retention rates in methadone and buprenorphine maintenance treatment from 2001 to 2006.

Design  A retrospective cohort study using register data from the Pharmaceutical Drugs of Addiction System.

Setting  Opioid substitution treatment in New South Wales (NSW), Australia.

Participants  A total of n = 42 690 individuals prescribed opioid replacement treatment between 1985 and 2006 in NSW.

Measurements  Client characteristics over time, retention in days in first treatment episode, number of episodes of treatment and proportion switching medication.

Findings  Overall, younger individuals were significantly more likely to leave their first treatment episode than older individuals. In 2001–06, after controlling for age, sex and first administration point, the hazard of leaving treatment was 1.9 times for those on buprenorphine relative to those on methadone. Retention in treatment varied somewhat across historical time, with those entering during 1995–2000 more likely to leave at an earlier stage than those who entered before that time.

Conclusions  Retention in treatment appears to fluctuate in inverse proportion to the availability of heroin. Individuals in contemporary treatment are older users with a lengthy treatment history. This study has provided population‐level evidence to suggest that retention in methadone and buprenorphine differ in routine clinical practice. Future work might investigate ways in which patient adherence and retention may be improved.
Factors associated with the use of aids to cessation in English smokers
Authors: Kotz Daniel , Fidler Jenny , West Robert
Published: June 2009

Aims  To assess factors associated with the use of smoking cessation aids among smokers trying to quit in a country where these aids are widely available and free or cheap to access.

Design  Cross‐sectional household survey, the ‘Smoking Toolkit Study’.

Setting  England.

Participants  A total of 3767 respondents who smoked and made at least one serious quit attempt in the past 12 months were interviewed from November 2006 to April 2008.

Measurements  We analysed differences across socio‐demographic and smoking characteristics in the use of nicotine replacement therapy (NRT) over the counter or on prescription, bupropion, varenicline, telephone support and the National Health Service Stop Smoking Service (NHS‐SSS) which combines behavioural support with medication.

Findings  More than half of smokers trying to quit (51.2%) had used any kind of treatment; 48.4% had used some form of medication but only 6.2% had used the NHS‐SSS. The use of some form of smoking cessation treatment was higher in female than in male smokers [odds ratio (OR): 1.24, 95% confidence interval (CI): 1.08, 1.43] and increased with age (OR: 1.19, 95% CI: 1.14,1.25) and cigarettes smoked per day (OR = 1.05, 95% CI = 1.04,1.06). There was no association with social grade. Smokers who planned their quit attempt were more likely to have used all types of smoking cessation treatments, except for telephone support.

Conclusions  In England, half of all attempts to quit smoking are aided by some form of pharmacological or behavioural treatment. However, the use of the most effective treatment option (the NHS‐SSS) is low, despite it being free of charge. Factors associated with an increased use of aids to cessation were female sex, older age, more cigarettes smoked per day and planning a quit attempt. Research is needed into how to increase utilization rates, particularly among males and younger smokers.