bluuebunny/crossref_metadata_2025_split huggingface dataset:
The mobility of an alkali promoter as probed in situ during a catalytic reaction: Li in the CO oxidation on Pt
Authors: Suchorski Y. , Beben J. , Frac A. , Medvedev V. K. , Weiss H. 
Published: January 2007

AbstractFluctuations of the local ion rate of Li+ ions emitted during in situ monitoring of the catalytic CO oxidation on the nanofacets of a Pt field emitter tip with a lithium field desorption‐microscope (Li‐FDM) are utilized to study the Li surface diffusion. The ‘virtual probe‐hole’ approach, which is based on the digitization of the Li‐FDM video images, is used. This allows to analyze simultaneously the local fluctuations of ions originating from arbitrarily user‐defined probed surface regions of nanometer size. The anisotropy of the Li diffusion on the spatially inhomogeneous Pt surface is directly proved and a slowing effect of the coadsorbed CO on the Li diffusion is observed. Copyright © 2007 John Wiley & Sons, Ltd.
In vitroeffects of ghrelin on gastric H+-K+-ATPase and pepsin activity and mRNA expression of gastrin, somatostatin, receptors for GH and IGF-1 in cultured gastric mucosal cells of weanling piglets
Authors: Du G.-M. , Liu M.-J. , Shi Z.-M. , Zhang L. , Wei X.-H. , Zhao R.-Q. 
Published: January 2007

AbstractThe present study was conducted to investigate the effects of ghrelin on gastric acid and pepsin secretion, as well as the mRNA expression of gastrin, somatostatin (SS) and receptors for growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in gastric mucosal cells in vitro. Gastric mucosal cells were isolated from 5-week-old weanling piglets and exposed for 4 h to 3×10−2, 3×10−1, 3, 3×10 and 3×102nmol/l of h-ghrelin, respectively after 30-h incubation in DMEM/F-12. Pepsin activity in culture medium, cell viability and H+-K+-ATPase activity, as well as mRNA expression of gastrin, SS, GHR and IGF-1R in gastric mucosal cells were determined as response criteria. The experiment was repeated three times. Ghrelin significantly (P<0·05) increased H+-K+-ATPase activity of gastric mucosal cells at 3×10−1, 3 and 3×10 nmol/l of h-ghrelin. However, no significant changes were observed either in pepsin activity or the cell viability after ghrelin treatment. The mRNA expression of gastrin and SS was significantly increased in gastric mucosal cells exposed to h-ghrelin at 3×10−1and 3 nmol/l (P<0·05). H-ghrelin significantly increased IGF-1R but not GHR mRNA expression at 3×10−1, 3 and 3×10 nmol/l of h-ghrelin (P<0·05). Ghrelin acts on gastric mucosal cells from weanling piglets to regulate the H+-K+-ATPase activity and mRNA expression of gastrin, SS, and IGF-1Rin vitro.
Dynamic Topology of Biological Networks
Authors: Iyengar Ravi 
Published: January 2007

AbstractThe mammalian cell can be represented as a large modular network that consists of a central signal network that interacts with and regulates multiple cellular machines that are responsible for phenotypic behavior. We have used graph-theory approaches to analyze signal flow through a network representing the hippocampal neuron and find that signal-induced connectivity results in the formation of many regulatory motifs. Information flow through the central signaling network is initiated by extra-cellular signals such as hormones binding to their receptors. The flow of information through the signaling network results in the appearance of regulatory motifs such as feedback loops, feedforward and bifan motifs. Within the large cellular networks, these regulatory motifs are juxtaposed next to each other in several formats such as the stacked configuration or the nested configuration. We have studied the dynamics of regulatory motifs by biochemical computation using ordinary differential equation models. Positive feedback loops can function as bistable switches. Nested feed-forward motifs can give rise to two emergent properties: coincidence detection and prolonged outputs for short inputs. Bifan motifs can control response times, with some configurations working as delays and others promoting rapid responses. Bifan motifs can also act as filters. Feed-forward motifs lead to signal prolongation and thus function as a switch to alter cell state. The functional consequences of organization of motifs within networks as well as the properties of feedback, feedforward and bifans motifs are presented.
Comparative molecular dynamics analysis of tapasin‐dependent and ‐independent MHC class I alleles
Authors: Sieker Florian , Springer Sebastian , Zacharias Martin 
Published: January 2007

AbstractMHC class I molecules load antigenic peptides in the endoplasmic reticulum and present them at the cell surface. Efficiency of peptide loading depends on the class I allele and can involve interaction with tapasin and other proteins of the loading complex. Allele HLA‐B*4402 (Asp at position 116) depends on tapasin for efficient peptide loading, whereas HLA‐B*4405 (identical to B*4402 except for Tyr116) can efficiently load peptides in the absence of tapasin. Both alleles adopt very similar structures in the presence of the same peptide. Comparative unrestrained molecular dynamics simulations on the α1/α2 peptide binding domains performed in the presence of bound peptides resulted in structures in close agreement with experiments for both alleles. In the absence of peptides, allele‐specific conformational changes occurred in the first segment of the α2‐helix that flanks the peptide C‐terminal binding region (F‐pocket) and contacts residue 116. This segment is also close to the proposed tapasin contact region. For B*4402, a shift toward an altered F‐pocket structure deviating significantly from the bound form was observed. Subsequent free energy simulations on induced F‐pocket opening in B*4402 confirmed a conformation that deviated significantly from the bound structure. For B*4405, a free energy minimum close to the bound structure was found. The simulations suggest that B*4405 has a greater tendency to adopt a peptide receptive conformation in the absence of peptide, allowing tapasin‐independent peptide loading. A possible role of tapasin could be the stabilization of a peptide‐receptive class I conformation for HLA‐B*4402 and other tapasin‐dependent alleles.
Progesterone and environmental tobacco smoke act synergistically to exacerbate the development of allergic asthma in a mouse model
Authors: Mitchell V. L. , Gershwin L. J. 
Published: January 2007

SummaryBackground
Asthma affects males and females differently. Females have a higher incidence than males after the onset of puberty. This suggests a hormonal component to the development of the disease. Progesterone, a female hormone, has previously been shown to illicit a T‐helper type 2 (TH2) immune response similar to that seen in allergic asthma. Previous studies performed by our laboratory have shown that exposure to environmental tobacco smoke (ETS) enhances the immune response to allergens.Objective
To determine if the combination of exposure to ETS and progesterone would further exacerbate the immune response in a mouse model of allergic asthma.Methods
Female mice were ovariectomized and then implanted with time‐release progesterone pellets. Mice were housed in either filtered air (FA) or ETS chambers and half were exposed to aerosolized house dust mite allergen (HDMA). Bronchoalveolar lavage was performed for cell differentials; lung and spleen cells were harvested to compare IL‐4 and IFN‐γ production by ELISPOT.Results
Progesterone pellet implantation resulted in increased serum progesterone levels (28.3±8.43 vs. 13.5±7.22 ng/mL in placebo‐treated mice, P<0.0001). Serum total IgE levels were significantly greater in progesterone vs. non‐progesterone treated animals that were also exposed to HDMA. ETS exposure enhanced total IgE levels as well. Lung homogenate cells from HDMA/progesterone‐treated animals stimulated with Concavalin A produced significantly more IL‐4 compared with HDMA/placebo‐treated animals (200±17.6 vs. 146±17.5 spots/well, P<0.01 in ETS exposed animals and 221±28.9 vs. 167±23.4 spots/well, P<0.01 in animals housed in FA). HDMA/ETS‐treated animals had higher eosinophilia in lavage than all other groups.Conclusion
Increased serum progesterone levels exacerbate the allergic asthmatic phenotype in a mouse model. These effects are further exacerbated by the addition of environmental tobacco smoke. Progesterone provides a major contribution to the gender differences seen in the development and elicitation of the asthmatic response.
Contrasting patterns of population subdivision and historical demography in three western Mediterranean lizard species inferred from mitochondrial DNA variation
Authors: PINHO C. , HARRIS D. J. , FERRAND N. 
Published: January 2007

AbstractPleistocene climatic oscillations were a major force shaping genetic variability in many taxa. We analyse the relative effects of the ice ages across a latitudinal gradient in the Western Mediterranean region, testing two main predictions: (i) species with historical distributions in northern latitudes should have experienced greater loss of suitable habitat, resulting in higher extinction of historical lineages than species distributed in southern latitudes, where the effects of the ice ages were not as drastic. This would be reflected in the observation of lower diversity and number of differentiated lineages in northern areas. (ii) a signature of demographic expansion following the climate amelioration should be obvious in northern species, whereas in the south evidence of long‐term effective population size stability should be observed. We used as models three species of wall lizards (Podarcis bocagei, Podarcis carbonelliandPodarcis vaucheri) that replace each other along the study area. We investigated the patterns of mitochondrial DNA diversity and subdivision and obtained demographic parameter estimates for each species. Our results suggest thatP. bocagei, the northernmost species, bears low genetic diversity, a shallow coalescent history and marks of a demographic expansion. In contrast,P. vaucheri, the species with a southernmost distribution, shows deeper coalescence events, complex geographical substructure and no evidence for population growth. The species with an intermediate distribution,P. carbonelli, shows average levels of diversity, substructure and population growth. Taken together, these results conform to our main predictions and are explained by a differential influence of the ice ages on distinct latitudes.
Aetiology of Bovine Abortion in Switzerland from 1986 to 1995 – A Retrospective Study with Emphasis on Detection ofNeospora caninumandToxoplasma gondiiby PCR
Authors: Reitt K. , Hilbe M. , Voegtlin A. , Corboz L. , Haessig M. , Pospischil A. 
Published: January 2007

SummaryIn a retrospective study, covering the period from 1986 to 1995, tissues of aborted fetuses were re‐examined. A total of 347 cases were tested immunohistochemically, among them samples of 223 brains were examined forNeospora caninum,Toxoplasma gondiiand Bovine Virus Diarrhoea Virus (BVDV), and 249 placentae for Chlamydiaceae. Two real‐time PCR assays, one forN. caninum, and one forT. gondii, were developed. These potential abortion‐inducing agents were detected – and confirmed by PCR, except for BVDV – in 16.1% (N. caninum), 0% (T. gondii), 9.9% (BVDV) and 0.8% (Chlamydiales) of the cases examined. Immunohistochemistry proved to be inadequate for the detection of the protozoal epitopes, whereas it was confirmed as a very useful tool for the detection of BVDV. In abortion material, PCR is considered to be more suitable for the detection of protozoa andChlamydophila abortus, an adequate sampling presupposed.
Spinal cord plasticity in acquisition and maintenance of motor skills
Authors: Wolpaw J. R. 
Published: January 2007

AbstractThroughout normal life, activity‐dependent plasticity occurs in the spinal cord as well as in brain. Like other central nervous system (CNS) plasticity, spinal cord plasticity can occur at numerous neuronal and synaptic sites and through a variety of mechanisms. Spinal cord plasticity is prominent early in life and contributes to mastery of standard behaviours like locomotion and rapid withdrawal from pain. Later in life, spinal cord plasticity has a role in acquisition and maintenance of new motor skills, and in compensation for peripheral and central changes accompanying ageing, disease and trauma. Mastery of the simplest behaviours is accompanied by complex spinal and supraspinal plasticity. This complexity is necessary, in order to preserve the complete behavioural repertoire, and is also inevitable, due to the ubiquity of activity‐dependent CNS plasticity. Explorations of spinal cord plasticity are necessary for understanding motor skills. Furthermore, the spinal cord's comparative simplicity and accessibility makes it a logical starting point for studying skill acquisition. Induction and guidance of activity‐dependent spinal cord plasticity will probably play an important role in realization of effective new rehabilitation methods for spinal cord injuries, cerebral palsy and other motor disorders.
Continuous Performance Test (CPT) of College Students With ADHD, Psychiatric Disorders, Cognitive Deficits, or No Diagnosis
Authors: Advokat Claire , Martino Leslie , Hill B D , Gouvier William 
Published: January 2007

Objective/Method: The Conner’s Continuous Performance Test (CPT) was administered to four groups of adult college students who self-referred for comprehensive psychoeducational evaluation and received either no diagnosis ( n = 30) or a diagnosis of ADHD ( n = 26), a psychiatric disorder ( n = 17), or various cognitive deficits ( n = 22). Results: The groups did not differ with respect to age, sex, race, or IQ. Although the ADHD group made more CPT errors of omission, had longer response times, and showed greater variability in responding than the other three groups, these differences did not reach statistical significance when analyzed parametrically using standard scores. But when the pattern of scores across the groups was analyzed nonparametrically, significant and interpretable results emerged. Conclusion: The CPT reliably differentiated between individuals with ADHD and both normal college students and individuals with psychiatric diagnoses but not persons with learning/cognitive disorders.
Clinical Predictors of Occult Pneumonia in the Febrile Child
Authors: Murphy Charles G. , Van De Pol Alma C. , Harper Marvin B. , Bachur Richard G. 
Published: January 2007

Background: The utility of chest radiographs (CXRs) for detecting occult pneumonia (OP) among pediatric patients without lower respiratory tract signs has been previously studied, but no predictors other than white blood cell count (WBC) and height of fever have been investigated. Objectives: To identify predictors of OP in pediatric patients in the postconjugate pneumococcal vaccination era. Methods: This was a retrospective cross sectional study that was conducted in a large urban pediatric hospital. Physician records of emergency department (ED) patients of age 10 years or less who presented with fever (≥38°C) and had a CXR obtained for suspected pneumonia were reviewed. Patients were classified into two groups: “signs of pneumonia” and “no signs of pneumonia” on the basis of the presence or absence of respiratory distress, tachypnea, or lower respiratory tract findings. Occult pneumonia was defined as radiographic pneumonia in a patient without signs of pneumonia. Results: Two thousand one hundred twenty‐eight patients were studied. Among patients categorized as having no signs of pneumonia (n = 1,084), 5.3% (95% CI = 4.0% to 6.8%) had OP. Presence of cough and longer duration of cough (greater than 10 days) had positive likelihood ratios (LR+) of 1.24 (95% CI = 1.15 to 1.33) and 2.25 (95% CI = 1.21 to 4.20), respectively. Absence of cough had a negative likelihood ratio (LR−) of 0.19 (95% CI = 0.05 to 0.75). The likelihood of OP increased with increasing duration of fever (LR+ for more than three days and more than five days of fever, respectively: 1.62; 95% CI = 1.13 to 2.31 and 2.24; 95% CI = 1.35 to 3.71). When obtained (56% of patients), WBC was a predictor of OP, with a LR+ of 1.76 (95% CI = 1.40 to 2.22) and 2.17 (95% CI = 1.58 to 2.96) for WBC of >15,000/mm3 and >20,000/mm3, respectively. Conclusions: Occult pneumonia was found in 5.3% of patients with fever and no lower respiratory tract findings, tachypnea, or respiratory distress. There is limited utility in obtaining a CXR in febrile children without cough. The likelihood of pneumonia increased with longer duration of cough or fever or in the presence of leukocytosis.
A More Explicit Grading Scale Decreases Grade Inflation in a Clinical Clerkship
Authors: Weaver Christopher S. , Humbert Aloysius J. , Besinger Bart R. , Graber James A. , Brizendine Edward J. 
Published: January 2007

Objectives: The medical education literature contains few publications about the phenomenon of grade inflation. The authors' clinical clerkship grading scale suffered from apparent inflation relative to the recommended university distribution. The investigators hypothesized that a simple change of the shift grading cards, using explicit criteria, would decrease this grade inflation and aid to redistribute the shift evaluations. Methods: This was a before‐and‐after study examining medical student shift evaluation grades. Evaluators and students were blinded to the purpose of the card change and were unaware that a study was being conducted. Beginning June 1, 2005, the authors altered the shift evaluation cards from the previous four choices of honors, high pass, pass, or fail to five choices of upper 5%, upper 25%, expected, below expected, or far below expected, and explicit grading criteria were provided. No other interventions to alter the grade distribution occurred. Data were collected on all evaluations from June 1, 2004, to March 31, 2005 (before change), and compared with data on all evaluations from June 1, 2005, to March 31, 2006 (after change). Results: A total of 3,349 evaluations were analyzed: 1,612 before the card change and 1,737 after the change. The grade distribution before the card change was as follows: honors, 22.6%; high pass, 49.0%; pass, 28.4%; and fail, 0%. This compared with the following ratings after the card change: upper 5%, 9.8%; upper 25%, 41.2%; expected, 46.2%; below expected, 2.8%; and far below expected, 0% (p < 0.001). Conclusions: A simple change in shift evaluation cards to include more explicit grading criteria resulted in a significant change in grade distribution and greatly decreased grade inflation.
Iron Supplementation for Postoperative Anaemia Following Major Paediatric Orthopaedic Surgery
Authors: Lau Kelvin KW , Utukuri Murali M , Ramachandran Manoj , Jones David Ha 
Published: January 2007

INTRODUCTION There is increasing evidence that the anaemia of surgery is not iron deficient and is, therefore, unresponsive to iron supplementation. Oral iron is best avoided postoperatively, particularly in children, due to its dose-dependent side effects. We undertook a national survey of major paediatric orthopaedic surgical units in the UK to investigate the current management of postoperative anaemia with particular reference to iron supplementation. MATERIALS AND METHODS Middle-grade doctors and charge nurses at 23 major paediatric orthopaedic units in the UK were contacted by telephone and a structured questionnaire was used to determine the management of postoperative anaemia in major hip, pelvic and spinal surgery. RESULTS Only one (4.3%) of the units surveyed had a formally established protocol for the management of postoperative anaemia. Only 10 out of 23 units (43.5%) did not routinely prescribe iron postoperatively. Of the remaining units, 11 commenced iron based on the postoperative haemoglobin level while only 2 used iron supplementation after investigation of serum haematinics for iron deficiency. One unit used erythropoietin in the treatment of postoperative anaemia. CONCLUSIONS Iron supplementation continues to be used in major paediatric orthopaedic surgery in the treatment of postoperative anaemia in the absence of iron deficiency. Given the current available evidence, we call for an end to the practice of routine iron supplementation for postoperative anaemia following major paediatric orthopaedic surgery in the UK.
Efficacy of preloading combined with prefabricated vertical band drains in improving a clayey silt stratum in situ
Authors: Chakravarthi V. K. , Phanikumar B. R. 
Published: January 2007

This paper presents a detailed field study of a soft clayey silt stratum improved in situ with preloading combined with prefabricated vertical band drains (PVDs). The clayey silt stratum was to support a warehouse in a chemical plant. As the bearing capacity of the soil was much lower than the load it was to support, the subsoil condition was improved by installing PVDs in combination with preloading. Thus the rate of consolidation of the clay stratum was increased. The band drains were installed up to a depth of 14·2 m at a spacing of 1·6 m. The intensity of preloading applied was 52 kPa. For preloading, the surcharge fill was placed up to a height of 3·10 m from the natural ground level. The area of both preloading and band drains was 15% greater than that of the floor of the warehouse for more effective improvement of the ground. Preloading was done for 60 days. Settlements were monitored using settlement gauges. The settlements observed across the entire area indicated that the preloading operation was uniform all through. The amount of settlement was large up to the point of filling the surcharge, but thereafter it did not show a significant increase.Cet exposé présente l'étude de terrain détaillée d'une strate tendre de limon argileux améliorée par précharge et drains en bande préfabriqués verticaux (PVDs). La strate de limon argileux devait porter un entrepzô t dans une usine chimique. Comme la capacité porteuse du sol était bien plus basse que la charge qu'elle devait recevoir, la condition du sous-sol a été améliorée en installant des PVD avec la précharge. Ainsi le taux de consolidation de la strate argileuse a augmenté. Des drains en bande ont été installés jusqu'à une profondeur de 14,2 m avec un espacement de 1,6 m. L'intensité de la précharge appliquée était de 52 kPa. Pour la précharge, un remplissage de surcharge a été placé jusqu'à une hauteur de 3,10 m à partir du niveau du sol naturel. Pour avoir une amélioration plus efficace du sol, la surface de la zone de précharge et de drains é tait de 15% plus é tendue que celle du sol de l'entrepô t. La précharge a été appliquée pendant 60 jours. Les affaissements ont été contrôlés en utilisant des jauges de tassement. Les tassements observés à travers toute la zone ont indiqué que l'opération de précharge était uniforme. Le volume de tassement é tait important jusqu'au point de remplissage mais après, il n'a montré aucune augmentation significative.