bluuebunny/crossref_metadata_2025 huggingface dataset:
Density functional theory study of self-association of N-methylformamide and its effect on intramolecular and intermolecular geometrical parameters and the cis/trans population
Authors: García Martínez A. , Teso Vilar E. , García Fraile A. , Martínez-Ruiz P.
Published: June 2006

The single-point total energy (E) of several acyclic and cyclic oligomers of N-methylformamide (NMF) was computed by the first time without any geometrical restriction, using the B3LYP∕6-31G* method of the density functional theory in order to determine the effect of self-association on intramolecular geometrical parameters of cis- and trans-NMF, the intermolecular distances of the hydrogen-bonding chains formed by NMF as well as intermolecular association energies including couterpoise corrections. It is concluded that liquid NMF exists mainly as polymers formed by self-association of trans-NMF units, whereas the cis-NMF isomer occurs as isolated units inserted along the chains. These computational results are in accordance with the experimentally determined predominance (ca. 90%) of trans-NMF population by means of H1- NMR and other spectroscopic techniques, but in severe contradiction with a recent interpretation of x-ray diffraction data on liquid NMF, postulating a cyclic trimer of cis-NMF (c-C3) as the predominating species. The counterpoise-corrected values of the association energy, ΔE(CP), calculated for cyclic oligomers, increase with the polymerization degree (n) revealing a high grade of cooperative effect for amidic hydrogen-bonded chains. Noteworthy, the difference between the ΔE(CP) values of the cyclic cis- and trans-homooligomers of NMF is positive for n=2 and 3 but negative for n⩾4.
Phonon driven proton transfer in crystals with short strong hydrogen bonds
Authors: Fontaine-Vive F. , Johnson M. R. , Kearley G. J. , Cowan J. A. , Howard J. A. K. , Parker S. F.
Published: June 2006

Recent work on understanding why protons migrate with increasing temperature in short, strong hydrogen bonds is extended here to three more organic, crystalline systems. Inelastic neutron scattering and density functional theory based simulations are used to investigate structure, vibrations, and dynamics of these systems as functions of temperature. The mechanism determined in a previous work on urea phosphoric acid of low frequency vibrations stabilizing average crystal structures, in which the potential energy well of the hydrogen bond has its minimum shifted towards the center of the bond, is found to be valid here. The new feature of the N–H⋯O hydrogen bonds studied in this work is that the proton is transferred from the donor atom to the acceptor atom. Molecular dynamics simulations show that in an intermediate temperature regime, in which the proton is not completely transferred, the proton is bistable, jumping from one side of the hydrogen bond to the other. In the case of 3,5-pyridine dicarboxylic acid, which has been studied in most detail, specific phonons are identified, which influence the potential energy surface of the proton in the short, strong hydrogen bond.
On a singularity-free pair-polarizability anisotropy model for atomic gases
Authors: Chrysos M. , Dixneuf S. , Rachet F.
Published: June 2006

We present a collision-induced light scattering spectrum of Ne2 and analyze it, together with an induced spectrum of Ar2, in terms of a model for the pair-polarizability anisotropy β of an atomic gas. This model, which is in essence a slight modification of one introduced by Ceccherini et al. [J. Chem. Phys. 111, 6316 (1999)], is shown to describe the measured spectra much farther into the wings than does the original model. The agreement of our measurements with quantum-mechanical spectra from the most reliable, now available, ab initio computation methods for β produces evidence in support of the data and counters criticism of our experiment.
Oldest true orb-weaving spider (Araneae: Araneidae)
Authors: Penney David , Ortuño Vicente M
Published: June 2006

The aerial orb web woven by spiders of the family Araneidae typifies these organisms to laypersons and scientists alike. Here we describe the oldest fossil species of this family, which is preserved in amber from Álava, Spain and represents the first record of Araneidae from the Lower Cretaceous. The fossils provide direct evidence that all three major orb web weaving families: Araneidae, Tetragnathidae and Uloboridae had evolved by this time, confirming the antiquity of the use of this remarkable structure as a prey capture strategy by spiders. Given the complex and stereotyped movements that all orb weavers use to construct their webs, there is little question regarding their common origin, which must have occurred in the Jurassic or earlier. Thus, various forms of this formidable prey capture mechanism were already in place by the time of the explosive Cretaceous co-radiation of angiosperms and their flying insect pollinators. This permitted a similar co-radiation of spider predators with their flying insect prey, presumably without the need for a ‘catch-up lag phase’ for the spiders.
Magnetic iron compounds in the human brain: a comparison of tumour and hippocampal tissue
Authors: Brem Franziska , Hirt Ann M , Winklhofer Michael , Frei Karl , Yonekawa Yasuhiro , Wieser Heinz-Gregor , Dobson Jon
Published: June 2006

Iron is a central element in the metabolism of normal and malignant cells. Abnormalities in iron and ferritin expression have been observed in many types of cancer. Interest in characterizing iron compounds in the human brain has increased due to advances in determining a relationship between excess iron accumulation and neurological and neurodegenerative diseases. In this work, four different magnetic methods have been employed to characterize the iron phases and magnetic properties of brain tumour (meningiomas) tissues and non-tumour hippocampal tissues. Four main magnetic components can be distinguished: the diamagnetic matrix, nearly paramagnetic blood, antiferromagnetic ferrihydrite cores of ferritin and ferrimagnetic magnetite and/or maghemite. For the first time, open hysteresis loops have been observed on human brain tissue at room temperature. The hysteresis properties indicate the presence of magnetite and/or maghemite particles that exhibit stable single-domain (SD) behaviour at room temperature. A significantly higher concentration of magnetically ordered magnetite and/or maghemite and a higher estimated concentration of heme iron was found in the meningioma samples. First-order reversal curve diagrams on meningioma tissue further show that the stable SD particles are magnetostatically interacting, implying high-local concentrations (clustering) of these particles in brain tumours. These findings suggest that brain tumour tissue contains an elevated amount of remanent iron oxide phases.
Cheating can stabilize cooperation in mutualisms
Authors: Foster Kevin R , Kokko Hanna
Published: June 2006

Mutualisms present a challenge for evolutionary theory. How is cooperation maintained in the face of selection for selfishness and cheating? Both theory and data suggest that partner choice, where one species preferentially directs aid to the more cooperative members of the other species, is central to cooperation in many mutualisms. However, the theory has only so far considered the evolutionary effects of partner choice on one of the species in a mutualism in isolation. Here, we investigate the co-evolution of cooperation and choice in a choosy host and its symbiont. Our model reveals that even though choice and cooperation may be initially selected, it will often be unstable. This is because choice reduces variation in the symbiont and, therefore, tends to remove the selective incentive for its own maintenance (a scenario paralleled in the lek paradox in female choice and policing in within-species cooperation). However, we also show that when variability is reintroduced into symbionts each generation, in the form of less cooperative individuals, choice is maintained. This suggests that the presence of cheaters and cheater species in many mutualisms is central to the maintenance of partner choice and, paradoxically, cooperation itself.
Best squirrels trade a long life for an early reproduction
Authors: Descamps Sébastien , Boutin Stan , Berteaux Dominique , Gaillard Jean-Michel
Published: June 2006

Age at primiparity plays a crucial role in population dynamics and life-history evolution. Long-term data on female North American red squirrels were analysed to study the fitness consequences of delaying first reproduction. Early breeders were born earlier, had a higher breeding success and achieved a higher lifetime reproductive success than females who delayed their first reproduction, which suggests a higher quality of early breeders. However, early breeders had similar mass when tagged, and similar number of food caches available at one year of age as late breeders. Nevertheless, we found evidence of survival costs of early primiparity. Early breeders had a lower survival between one and two years of age than late breeders and a lower lifespan. Our study points out that two reproductive tactics co-occurred in this population: a tactic based on early maturity at the cost of a lower survival versus a tactic based on delayed maturity and long lifespan. High quality individuals express the most profitable tactic by breeding early whereas low quality individuals do the best of a bad job by delaying their first reproduction.
The role of the central melanocortin system in the regulation of food intake and energy homeostasis: lessons from mouse models
Authors: Ellacott Kate L.J , Cone Roger D
Published: June 2006

A little more than a decade ago, the molecular basis of the lipostat was largely unknown. At that time, many laboratories were at work attempting to clone the genes encoding the
obesity
,
diabetes
,
fatty
,
tubby
and
agouti
loci, with the hope that identification of these obesity genes would help shed light on the process of energy homeostasis, appetite and energy expenditure. Characterization of
obesity
and
diabetes
elucidated the nature of the adipostatic hormone leptin and its receptor, respectively, while cloning of the
agouti
gene eventually led to the identification and characterization of one of the key neural systems upon which leptin acts to regulate intake and expenditure. In this review, we describe the neural circuitry known as the central melanocortin system and discuss the current understanding of its role in feeding and other processes involved in energy homeostasis.
Heterologous Expression and Biochemical Characterization of a Polyamine Oxidase from Arabidopsis Involved in Polyamine Back Conversion
Authors: Tavladoraki Paraskevi , Rossi Marianna Nicoletta , Saccuti Giuseppe , Perez-Amador Miguel Angel , Polticelli Fabio , Angelini Riccardo , Federico Rodolfo
Published: June 2006

Polyamine oxidase (PAO) is a flavin adenine dinucleotide-dependent enzyme involved in polyamine catabolism. Animal PAOs oxidize spermine (Spm), spermidine (Spd), and/or their acetyl derivatives to produce H2O2, an aminoaldehyde, and Spd or putrescine, respectively, thus being involved in a polyamine back-conversion pathway. On the contrary, plant PAOs that have been characterized to date oxidize Spm and Spd to produce 1,3-diaminopropane, H2O2, and an aminoaldehyde and are therefore involved in the terminal catabolism of polyamines. A database search within the Arabidopsis (Arabidopsis thaliana) genome sequence showed the presence of a gene (AtPAO1) encoding for a putative PAO with 45% amino acid sequence identity with maize (Zea mays) PAO. The AtPAO1 cDNA was isolated and cloned in a vector for heterologous expression in Escherichia coli. The recombinant protein was purified by affinity chromatography on guazatine-Sepharose 4B and was shown to be a flavoprotein able to oxidize Spm, norspermine, and N1-acetylspermine with a pH optimum at 8.0. Analysis of the reaction products showed that AtPAO1 produces Spd from Spm and norspermidine from norspermine, demonstrating a substrate oxidation mode similar to that of animal PAOs. To our knowledge, AtPAO1 is the first plant PAO reported to be involved in a polyamine back-conversion pathway.
Salicylic Acid, an Ambimobile Molecule Exhibiting a High Ability to Accumulate in the Phloem
Authors: Rocher Françoise , Chollet Jean-François , Jousse Cyril , Bonnemain Jean-Louis
Published: June 2006

The ability of exogenous salicylic acid (SA) to accumulate in castor bean (Ricinus communis) phloem was evaluated by HPLC and liquid scintillation spectrometry analyses of phloem sap collected from the severed apical part of seedlings. Time-course experiments indicated that SA was transported to the root system via the phloem and redistributed upward in small amounts via the xylem. This helps to explain the peculiarities of SA distribution within the plant in response to biotic stress and exogenous SA application. Phloem loading of SA at 1, 10, or 100 μm was dependent on the pH of the cotyledon incubating solution, and accumulation in the phloem sap was the highest (about 10-fold) at the most acidic pH values tested (pH 4.6 and 5.0). As in animal cells, SA uptake still occurred at pH values close to neutrality (i.e. when SA is only in its dissociated form according to the calculations made by ACD LogD suite software). The analog 3,5-dichlorosalicylic acid, which is predicted to be nonmobile according to the models of Bromilow and Kleier, also moved in the sieve tubes. These discrepancies and other data may give rise to the hypothesis of a possible involvement of a pH-dependent carrier system translocating aromatic monocarboxylic acids in addition to the ion-trap mechanism.
‘Romantisch‐komisch’: zu einem literarischen Modus in der deutschen Literatur zwischen Frühaufklärung und Klassik (Jacobi – Michaelis – Wieland)
Authors: Gelzer Florian
Published: June 2006

Der Beitrag möchte den Begriff des ‘Romantisch‐Komischen’ als Bezeichnung für einen bestimmten Schreibmodus des 18. Jahrhunderts einführen. Er soll es ermöglichen, üblicherweise getrennt behandelte Texte aus dem Gebiet des Singspiels und der Verserzählung als unmittelbar zusammengehörig zu verstehen: als einen Versuch der damaligen Autoren, das Stoffreservoir des ‘Roman(t)ischen’ für eine anspruchsvolle Form von Unterhaltungsliteratur fruchtbar zu machen. Als Beispiele dienen eine Reihe von weitgehend unbekannten Texten aus dem Umfeld des Halberstädter Freundschaftskreises von Johann Wilhelm Ludwig Gleim. Die Untersuchung dieser Versdichtungen, poetischen Briefe und Singspiele von Johann Georg Jacobi, Johann Benjamin Michaelis und Christoph Martin Wieland soll aufzeigen, wie auch bedeutende ‘klassische’ Werke wie Wielands Oberon oder Alceste auf der hier umrissenen Tradition des ‘Romantisch‐Komischen’ beruhen.
Newer cyclo‐oxygenase‐2 selective inhibitors, other non‐steroidal anti‐inflammatory drugs and the risk of acute pancreatitis
Authors: SØRENSEN H. T. , JACOBSEN J. , NØRGAARD M. , PEDERSEN L. , JOHNSEN S. P. , BARON J. A.
Published: June 2006

Background

Case reports have suggested that the use of newer cyclo‐oxygenase‐2 selective inhibitors may cause acute pancreatitis, but there has been no formal study of the association.

Aim

To assess the relationship between the use of cyclo‐oxygenase‐2 inhibitors and other non‐steroidal anti‐inflammatory drugs, and risk of acute pancreatitis.

Methods

A population‐based case–control study was conducted using hospital discharge and prescription data from Denmark. Using conditional logistic regression with adjustment for multiple covariates, we estimated the relative risk of acute pancreatitis for use of the cyclo‐oxygenase‐2 inhibitors celecoxib and rofecoxib and for other non‐steroidal anti‐inflammatory drugs.

Results

A total of 3083 cases of acute pancreatitis and 30 830 population controls were identified. For current use the relative risk estimate for celecoxib was 1.4 (95% CI: 0.8–2.3) and for rofecoxib was 1.3 (95% CI: 0.7–2.3). The overall relative risk for other non‐steroidal anti‐inflammatory drugs was 2.7 (95% CI: 2.4–3.0) with a substantial variation in risk between the individual drugs. The highest relative risk was for diclofenac (odds ratio 5.0, 95% CI: 4.2–5.9) and the lowest for naproxen (odds ratio 1.1, 95% CI: 0.7–1.7).

Conclusion

Cyclo‐oxygenase‐2 selective inhibitors are associated with a lower risk of acute pancreatitis than most other non‐steroidal anti‐inflammatory drugs.
The epidemiology of pancreatic cancer in the United States: changes below the surface
Authors: SHAIB Y. H. , DAVILA J. A. , EL‐SERAG H. B.
Published: June 2006

Background

Pancreatic cancer is the fourth leading cause of cancer death in the United States.

Aim

To examine temporal changes in the incidence and survival of patients with pancreatic adenocarcinoma.

Methods

Using data from nine registries of the Surveillance, Epidemiology and End Results programme, age‐adjusted incidence rates per 100 000 and survival rates were calculated for pancreatic cancer between 1977 and 2001.

Results

We identified 58 655 cases of pancreatic cancer. The age‐adjusted incidence rate remained stable during the study period (11.3 in 1977–1981 and 10.9 in 1997–2001). Overall, men were 30% more affected than women (age‐adjusted incidence rate of 13.0 in men and 9.8 in women). The age‐adjusted incidence rates were almost 50% higher among Blacks (16.4) than Whites (10.8) and people of other races (9.8). Over time the proportions of patients with localized disease decreased from 12.3% to 7.4% and those with regional disease increased from 18.6% to 25.8%, while metastatic disease remained stable (52.5% vs. 49.8%). The 1‐year relative survival increased from 15.2% in 1977–1981 to 21.6% in 1997–2001.

Conclusions

The incidence of pancreatic cancer is stable. A shift from localized to regional disease was observed over time. The overall survival remains poor despite important improvements among patients with early stage disease.
Maternal cultural participation and child health status in a Middle Eastern context: evidence from an urban health study
Authors: Khawaja M. , Barazi R. , Linos N.
Published: June 2006

Background  The negative effect of poverty on child health has been well established. However, rapid urbanization in developing countries prompts new research questions relating to socio‐cultural practices and other related variables in these settings.

Objective  To examine the association between maternal cultural participation and child health status in impoverished neighbourhoods of Beirut, Lebanon.

Methods  A cross‐sectional survey of 1241 mothers with children aged less than 5 years was conducted from randomly selected households in three impoverished neighbourhoods of diverse ethnic and religious make‐up. The outcome variable was child health status (good/bad) as assessed by the mother. Maternal variables, including cultural participation, education, demographic and environmental/structural factors, were studied. Descriptive statistics and bivariate associations were provided using Pearson’s chi‐square tests. Unadjusted and adjusted odds ratios were then obtained from binary logistic regression models.

Results  Two indicators of maternal cultural participation, namely watching entertaining television and attending movies/art exhibitions, were found to be significantly associated with child health status after controlling for other risk factors. The quality of water, the quality of local health services and maternal education were also significantly associated with child health status. Household income, child gender and household dampness had no significant association with child health status in this context.

Conclusion  Maternal cultural participation was a significant predictor of child health status in impoverished urban communities. Improving child health through culturally focused interventions for mothers, especially in deprived areas, may be greatly important.
Dendritic cells as potential adjuvant for immunotherapy in adrenocortical carcinoma
Authors: Papewalis Claudia , Fassnacht Martin , Willenberg Holger S. , Domberg Julia , Fenk Roland , Rohr Ulrich‐Peter , Schinner Sven , Bornstein Stefan R. , Scherbaum Werner A. , Schott Matthias
Published: June 2006

Objective  Adrenocortical carcinoma (ACC) is a rare malignancy associated with a dismal prognosis. Dendritic cells (DCs) are professional antigen‐presenting cells leading to an antitumour immune response. The aim of this study was to elaborate two methods of antigen delivery to DCs and to evaluate an immunotherapy protocol in ACC patients.

Design/patients  Autologous DCs were pulsed with autologous tumour lysate (TL). Fusion of DCs with tumour cells was based on a polyethylene glycol method. Two patients with metastasized hypersecretory ACC were vaccinated twice.

Measurements  In vitro data were quantified by measurement of PBMC (peripheral blood mononuclear cell) responses and cytokine secretion and by flow cytometry analyses. Clinical response was monitored by CT scan of tumour mass and measurement of angiogenic factors.

Results  The maximum loading of TL was obtained at 24 h as 48·2% (± 26·8%) of DCs were TL‐positive. The DC/tumour cell fusion efficacy was ∼45% as shown by double positive staining for ACTH receptor and DC‐specific CD83. In vivo DC vaccination resulted in positive delayed‐type hypersensitivity skin reactions reflecting specific memory T‐lymphocyte reaction. In vitro analyses revealed specific T‐cell proliferation in patient 1 (stimulation index: 5·7 compared to pretreatment) and induction of cytotoxic granzyme B secreting T cells in patient 2 (0·41% CD8 + cells vs. 0·06% pretreatment) as indicators of specific cytotoxic T cells. Although angiogenic serum markers could be stabilized, no impact on tumour growth could be observed.

Conclusion  Our data demonstrate that autologous dendritic cells induce antigen‐specific Th1 immunity in adrenocortical carcinoma. The clinical outcome, however, was not improved in the patients studied here.
Objective investigation of the sleep–wake cycle in adults with intellectual disabilities and autistic spectrum disorders
Authors: Hare D. J. , Jones S. , Evershed K.
Published: June 2006

Background  Disturbances in circadian rhythm functioning, as manifest in abnormal sleep–wake cycles, have been postulated to be present in people with autistic spectrum disorders (ASDs). To date, research into the sleep–wake cycle in people with ASDs has been primarily dependant on third‐party data collection.

Method  The utilization of non‐invasive objective recording technologies such as actigraphy permits investigation of both sleep and circadian rhythm functioning in people with ASDs, together with the collection of data on daytime activity.

Results  Data were collected from 31 participants with intellectual disabilities living in supported community‐based residential provision aged between 20 and 58 years, of whom 14 had an ASD. Analysis indicated that there were no significant differences in sleep patterns and circadian rhythm function between those participants with an ASD and those without.

Conclusions  The mean scores of the participants as a whole indicated abnormalities in the two key circadian rhythm parameters of interdaily stability and intradaily variability. The implications of these findings for both clinical practice and theory are discussed.
Characteristics and experiences of children and young people with severe intellectual disabilities and challenging behaviour attending 52‐week residential special schools
Authors: Pilling N. , McGill P. , Cooper V.
Published: June 2006

Background  This study sought to gather information about the characteristics and experiences of children and young people with severe intellectual disabilities and severe challenging behaviour attending 52‐week residential special schools.

Method  Staff of nine schools completed postal questionnaires on the characteristics and experiences of 156 pupils.

Results  Those attending residential schools are predominantly male, teenagers and in long‐term placements. Most have limited communication skills and autistic spectrum disorders. All display high numbers of challenging behaviours, many of them serious. Children have a greater range and complexity of needs than pupils at day severe learning difficulties (SLD) schools, albeit with some overlap.

Conclusions  Children at 52‐week residential schools present needs that both families and local services struggle to meet. Residential placement may provide the intensity of educational input and social support that is required, but may increase the vulnerability of the children. Local alternatives to residential schools should be investigated.
Cytotoxic CD4+ T cells in viral hepatitis
Authors: Aslan N. , Yurdaydin C. , Wiegand J. , Greten T. , Ciner A. , Meyer M. F. , Heiken H. , Kuhlmann B. , Kaiser T. , Bozkaya H. , Tillmann H. L. , Bozdayi A. M. , Manns M. P. , Wedemeyer H.
Published: June 2006

Summary.  CD4+ T cells are thought to contribute to antiviral immune responses by secretion of cytokines thereby providing help to CD8+ T and B cells. However, perforin‐positive cytotoxic CD4+ T cells have been described in human immunodeficiency virus‐positive patients suggesting a role not only of CD8+ but also of CD4+ T cells for killing virus‐infected cells. We investigated 76 patients with viral hepatitis [15 hepatitis B virus (HBV), 22 HBV/hepatitis D virus and 17 hepatitis C virus (HCV)] for cytotoxic CD4+ T cells. The frequency of perforin‐positive CD4+ T cells in viral hepatitis was highly variable ranging from <1% to more than 25%. Perforin‐positive CD4+ T cells displayed the phenotype of terminally differentiated effector cells (CD28−, CD27−). The highest frequencies of CD4+ cytotoxic T lymphocytes (CTLs) were found in patients with delta hepatitis (P = 0.04 vs HBV and HCV patients), and the presence of CD4+ CTLs was associated with elevated aspartate aminotransferase levels (P = 0.01) and decreased platelet counts (P = 0.03). Perforin‐positive CD4+ T cells decreased in two individuals during spontaneous clearance of acute hepatitis C. Significant associations were found between the frequency of perforin‐expressing CD4+ cells and age (P = 0.04), perforin‐positive CD8+ cells (P < 0.001) and perforin‐positive CD4−/CD8− lymphoid cells (P = 0.002). Differentiated CD27− effector CD4+ CTLs can be detected in patients with viral hepatitis. In particular in patients with more advanced liver disease, the accumulation of perforin‐positive T cells with age could be one correlate for the more severe course of viral hepatitis in elderly individuals.
Philopatry and reproductive success in Bornean orang‐utans (Pongo pygmaeus)
Authors: GOOSSENS B. , SETCHELL J. M. , JAMES S. S. , FUNK S. M. , CHIKHI L. , ABULANI A. , ANCRENAZ M. , LACKMAN‐ANCRENAZ I. , BRUFORD M. W.
Published: June 2006

Behavioural observations suggest that orang‐utans are semi‐solitary animals with females being philopatric and males roaming more widely in search of receptive partners, leading to the prediction that females are more closely related than males at any given site. In contrast, our study presents evidence for male and female philopatry in the orang‐utan. We examined patterns of relatedness and parentage in a wild orang‐utan population in Borneo using noninvasively collected DNA samples from animals observed to defecate, and microsatellite markers to assess dispersal and mating strategies. Surprisingly, resident females were equally as related to other resident females (mean rxy = 0.303) as resident males were to other resident males (mean rxy = 0.305). Moreover, resident females were more related to each other and to the resident males than they were to nonresident females, and resident males were more related to each other (and resident females) than they were to nonresident males. We assigned genetic mothers to 12 individuals in the population, while sires could be identified for eight. Both flanged males and unflanged males achieved paternity, similar to findings reported for Sumatran orang‐utans.
Threshold of sediment motion under unidirectional currents
Authors: MILLER M. C. , McCAVE I. N. , KOMAR P. D.
Published: June 2006

Carefully selected data for the threshold of sediment movement under unidirectional flow conditions have been utilized to re‐examine the various empirical curves that are commonly employed to predict this threshold. After a review of the existing data, we employed only that data obtained from open channel flumes with parallel sidewalls where flows were uniform and steady over flattened beds of unigranular, rounded sediments. Without these restrictions, an unmanageable amount of scatter is introduced.

This selected data is used to develop a modified Shields‐type threshold diagram that extends the limits of the original diagram by three orders of magnitude in the grain‐Reynolds number. The equally general but more easily employed Yalin diagram for sediment threshold is also examined. Although the Shields and Yalin diagrams are general in that they apply to a wide range of different liquids, in both cases somewhat different curves are obtained for threshold under air than for the liquids.

The often used empirical curves of the friction velocity u*, the velocity 100 cm above the bed u100, the bottom stress θt, and Shields’ relative stress θt, all versus the grain diameter D, are limited in their ranges of application to certain combinations of grain density, fluid density, fluid viscosity and gravity. These conditions must be selected before the curves are generated from either the more general Shields or Yalin curves. For example, on the basis of the data selected for use in this paper, empirical threshold relationships for quartz density material in water are

image

where the velocity u100 measured 100 cm above the sediment bed is given in cm/sec and the grain diameter D is in cm.

The limitations on any of the threshold relationships are severe. These limitations should be properly understood so that the empirical curves and relationships are not improperly employed.
Invasion dynamics and potential spread of the invasive alien plant speciesAgeratina adenophora(Asteraceae) in China
Authors: Wang Rui , Wang Yin‐Zheng
Published: June 2006

Ageratina adenophora(Sprengel) R. King & H. Robinson (=Eupatorium adenophorumSprengel) is one of the worst invasive alien species in China. SinceA.adenophorawas first noticed in Yunnan Province of China in the 1940s, its rapid spread has caused an ecological problem in south‐western China. Understanding its historical invasion pattern and its potential for further spread is needed to plan the management of the species. We reconstructed the historical process of its invasion and analysed its ecological preferences in the invaded region. After a lag phase of 20 years (1940–60),A.adenophoraspread rapidly throughout the south and middle subtropical zones in Yunnan, Guizhou, Sichuan, and Guangxi, China, with an average expansion rate of 20 km per year. It spread relatively slowly in north subtropical areas, with an average expansion rate of 6.8 km per year. It has not established in warm temperate areas within the invaded regions. Although range expansion in Yunnan stopped after 1990, the expansion of its range into neighbouring provinces indicates thatA.adenophorahas not reached the full potential of its distribution and its range is still rapidly expanding within China. We applied ecological niche modelling (GARP — Genetic Algorithm for Rule‐set Prediction) to predict potential invasion areas in mainland China on the basis of occurrence points within colonized areas whereA.adenophorahas reached equilibrium. The predictions, confirmed by the range of values of four key environmental parameters, generally match the parameters of the geography and ecology in the invaded region. Southern and south‐central China have climatic conditions suggestive of a high potential for invasion byA.adenophora. Climatic conditions in northern and western China appear unsuitable forA.adenophora. Urgent measures should be taken to prevent this species from further spreading into the vast areas of potential habitat in southern and south‐central China.
Biotic indirect effects: a neglected concept in invasion biology
Authors: White Eve M. , Wilson John C. , Clarke Anthony R.
Published: June 2006

Indirect effects involve more than two species and are defined as how one species alters the effect that another species has on a third. These complex interactions are often overlooked in studies of interactions between alien and native species, and their role in influencing biological invasions has been rarely considered. Based on a comprehensive review of the invasion biology literature, we examine the evidence for the occurrence of four of the most commonly documented indirect effects (apparent competition, indirect mutualism/commensalism, exploitative competition, and trophic cascades) in the invasion process. Studies investigating indirect effects in the context of invasion biology are relatively rare, but have been increasing in recent years, and there are sufficient examples to indicate that this kind of interaction is likely to be more common than is currently recognized. Whether indirect interactions are mediated by an alien or a native species, and whether they occur between ecologically similar or dissimilar alien and native species, depends in part on the type of interaction considered and no predictable patterns were detected in the literature. Further empirical studies will help to elucidate such patterns. At this stage, the inherent unpredictability of indirect interactions means that their impacts in relation to invasions are particularly challenging for land managers to deal with, and their role in invasions is a complex, but is a valuable area of investigation for researchers.
Branching Patterns of the Left Main Coronary Artery in the Dog Demonstrated by the Use of Corrosion Casting Technique
Authors: Noestelthaller A. , Probst A. , König H. E.
Published: June 2006

As many investigators use dogs as experimental models in catheterization‐, ligation‐, and collateral flow studies, knowledge and awareness of the canine left coronary artery anatomical variation is vital for differentiation between canine and human coronary arterial patterns and canine and human coronary congenital anomalies with or without circulatory importance. The present study was performed to examine and review the various principal subdivisions of the canine left main coronary artery (LMCA) in vascular casts of 20 hearts obtained from cadavers of clinically normal dogs of various ages, breeds and of either sex. A corrosion casting technique using an acrylic resin called Tensol Cement No. 70 and a lower‐viscosity acrylic resin called Mercox®were used to produce a three‐dimensional model of the canine coronary arteries. In our study, all dog hearts were left preponderant and the patterns of the principal subdivisions of the LMCA were grouped into three types: Type 1 occurred in seven of the 20 dogs (35%), Type 2 in 12 of 20 dogs (60%) and Type 3 in one instance (5%). A comparison between the canine divisional patterns of the LMCA in the vascular casts and those reported in the literature showed major agreement.
Antifungal susceptibility testing by flow cytometry: is it the future?
Authors: Vale‐Silva Luís André , Buchta Vladimír
Published: June 2006

The current increase in the number and significance of fungal infections, the expanding armamentarium of antifungal agents, and the emergence of the problem of antifungal drug resistance have been intensifying the importance of antifungal susceptibility testing (AST). The Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) in the United States and the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antimicrobial Susceptibility Testing (AFST‐EUCAST) published standard methodologies in order to achieve higher reproducibility and allow direct inter‐laboratory comparison of the susceptibility results. Nevertheless, several problems remain unresolved and the methods depend on long incubation periods of a minimum of 24 h (EUCAST) or even 48 h (CLSI). Over the last 15 years, successful applications of flow cytometric techniques to AST of both yeast and moulds have been reported. These techniques are based on the analysis of a great number of fungal cells individually and frequently rely on short incubation times of no more than a few hours. Considering these attributes, flow cytometry (FC) seems to have the potential to achieve clinical usefulness in the near future. The collection of data on the reproducibility of the results and on the correlation with clinical outcomes has barely started, however. Practical validation of the experimental methodologies is not granted before a significant amount of data addressing those questions is available.
Epidemiology of tinea capitis in Ceyhan district, Adana in Çukurova region, Turkey
Authors: Gümüsay Türker , Ilkit Macit
Published: June 2006

This study was conducted on the primary school students in Ceyhan district of Adana, Turkey between May and June 2002 to determine the clinical form, causative agents and prevalence of tinea capitis. A total of 9576 students, with a male‐to‐female ratio of 50.6–49.4% were screened in 24 primary schools. Tinea capitis superficialis was diagnosed in seven cases, and kerion Celsi in one. Among eight cases, there were seven boys and one girl. Trichophyton violaceum was the most frequent causative agent, followed by T. tonsurans, T. mentagrophytes, Microsporum canis and M. gypseum.
Efficacy of rifabutin‐based triple therapy in Helicobacter pylori infected patients after two standard treatments
Authors: González Carro Pedro , Pérez Roldán Francisco , De Pedro Esteban Aurora , Legaz Huidobro Maria L. , Soto Fernández Susana , Roncero Garcia Escribano Oscar , Esteban López‐Jamar Jose M. , Pedraza Martin Carmen , Ruíz Carrillo Francisco
Published: June 2006

Background and Aim:  Even with the current most effective treatment regimens for Helicobacter pylori infection, a considerable number of patients will be resistant to eradication. The aim of the present study was to evaluate the H. pylori eradication rate in patients resistant to standard therapies when treated with a triple therapy of pantoprazole, rifabutin and amoxicillin.

Methods:  Ninety‐two consecutive patients diagnosed with H. pylori infection resistant to two previous treatment regimens were treated with pantoprazole, rifabutin and amoxicillin for 10 days. The persistence or eradication of H. pylori was determined by a 13C‐urea breath test performed 4 weeks after the treatment.

Results:  Per protocol eradication was achieved in 62.2% of patients and the intention‐to‐treat eradication was 60.8%. Only two patients were excluded for adverse events related to the treatment.

Conclusions:  The eradication rate is acceptable as a third‐line therapy, particularly in centers with high cure rate for first line therapy. Another important value of this study is the good tolerance for the treatment observed in our patients. It is possible that rifabutin‐based triple therapy may be of use in hospital centers that do not have disposable culture and susceptibility methods against H. pylori.
Ameliorating effect of saporin‐conjugated anti‐CD11b monoclonal antibody in a murine T‐cell‐mediated chronic colitis
Authors: Kanai Takanori , Uraushihara Koji , Totsuka Teruji , Nemoto Yasuhiro , Fujii Rei , Kawamura Takahiro , Makita Shin , Sawada Daisuke , Yagita Hideo , Okumura Ko , Watanabe Mamoru
Published: June 2006

Background:  Crohn’s disease (CD) is an inflammatory bowel disease that is associated with several changes in the immune system, including an increased number of infiltrating macrophages. These macrophages release a variety of pro‐inflammatory cytokines, such as tumor necrosis factor‐α (TNF‐α) which are critically involved in the onset and the development of CD. The present study was performed to explore the initial involvement of macrophages in the development of T‐cell‐mediated chronic colitis.

Methods:  The effects were evaluated of saporin‐conjugated anti‐CD11b monoclonal antibody (mAb) on the development of chronic colitis in severe combined immunodeficiency (SCID) mice induced by adoptive transfer of CD4+CD45RBhigh T cells as an animal model of CD.

Results:  Significantly increased CD11b‐expressing macrophages as well as CD4+ T cells were found in inflamed colon from colitic mice. Administration of saporin‐conjugated anti‐CD11b mAb markedly ameliorated the clinical and histopathological disease. In vivo treatment with saporin‐conjugated anti‐CD11b mAb decreased CD4+ T‐cell infiltration in the colon and suppressed inferferon‐γ (IFN‐γ) and TNF‐α production by lamina propria CD4+ T cells.

Conclusions:  Collectively, the present results suggest an initial role of macrophages in the pathogenesis of T‐cell‐mediated chronic colitis. Furthermore, the macrophage‐specific targeting may be a promising strategy for therapeutic intervention in CD.
Distribution of signal transducer and activator of transcription 6 gene G2964A polymorphism in Chinese patients with ulcerative colitis
Authors: Zhu Jianbo , Xia Bing , Guo Qiusha , Cheng Hong , Li Jin , Ye Mei , Hu Zhengguo , Zhang Xiaolian , Tan Jingquan
Published: June 2006

Background and Aims:  The signal transducer and activator of transcription 6 (STAT6) gene is located on chromosome 12q13.3–14.1 just within the IBD2 region and is a key transcription factor involved in interleukin (IL)‐4 and IL‐13‐mediated Th2 response. The aim of the present study was to determine distribution of the STAT6 gene polymorphism in Chinese patients with ulcerative colitis.

Methods:  The G2964A polymorphism in the 3′ untranslated region of the STAT6 gene was studied in 84 unrelated Chinese patients with ulcerative colitis and 176 healthy controls by PCR and the amplification created restriction site method. The results were then compared with those from a Dutch study published previously.

Result:  Significant differences in genotype and allele frequencies of the STAT6 G2964A polymorphism were not found between patients with ulcerative colitis and healthy controls. Subgroups of the patients with ulcerative colitis classified according to the age at onset, sex and location of disease did not differ significantly in the distribution of this polymorphism. However, the genotypes (P < 0.0001, chi‐squared = 75.332) and allele frequencies (P < 0.0001, odds ratio = 4.298, 95% confidence interval = 3.070–6.018) were significantly different between the Chinese and Dutch populations.

Conclusion:  The STAT6 G2964A polymorphism is not involved in the genetic susceptibility to ulcerative colitis in Chinese patients.
Estimation of standard liver volume in Japanese living liver donors
Authors: Hashimoto Takuya , Sugawara Yasuhiko , Tamura Sumihito , Hasegawa Kiyoshi , Kishi Yoji , Kokudo Norihiro , Makuuchi Masatoshi
Published: June 2006

Background:  Standard liver volume (SLV) is an important concept in adult living liver donor transplantation. The purpose of this study was to re‐evaluate and modify the authors’ previous formula for predicting total liver volume (TLV).

Methods:  The TLV of 301 Japanese living donors was measured by computed tomography. This TLV was then compared with the liver volume calculated using established formulas. The correlation between TLV and several factors including body surface area (BSA) were analyzed and a new equation (SLVn) to better approximate TLV was determined. Factors related to the difference between TLV and SLVn were examined.

Results:  Average TLV was 1196.3 ± 221.0 cm3. Urata’s formula underestimated TLV by 17.6 cm3 and the other formulas overestimated it by 120.4–244.9 cm3. TLV could be approximated by BSA; SLVn (cm3) = −404.8 + 961.3 × BSA (m2, R2 = 0.58). SLVn tended to overestimate the TLV of older donors and to underestimate TLV of thin donors.

Conclusions:  A new simple formula is presented that might be a better fit for calculating TLV in Japanese adults. This formula might be useful for evaluating the size of an adequate graft.
Relationship between molecular markers and endoscopic findings in laterally spreading tumors
Authors: Hashimoto Shinichi , Higaki Shingo , Amano Ayaka , Harada Katsunori , Nishikawa Jun , Yoshida Tomoharu , Okita Kiwamu , Sakaida Isao
Published: June 2006

Background and Aim:  Characteristic clinicopathological features of laterally spreading tumors (LSTs) have been reported by endoscopists; however, only a few studies have been conducted on the biological features. These studies were not fully associated with the endoscopic findings of LSTs. The aim of this study was to estimate the biological features of each type of endoscopic finding of LST using two molecular markers, matrix metalloproteinase‐7 (MMP‐7) and β‐catenin.

Methods:  Expression of the molecular markers and the endoscopic findings were compared in 22 LSTs and 14 subpedunculated polyps. MMP‐7 and β‐catenin were immunostained. Three types of representative endoscopic findings of LST were defined as segments in LSTs. They were 15 granular segments, seven large nodular segments, and seven flat segments that corresponded to the area composed of aggregates of similar size granules, large nodules of diameter more than 10 mm, and a flat surface with no granule, respectively.

Results:  Expression of MMP‐7 and coexpression of MMP‐7 and β‐catenin were higher in large nodular segments than in granular segments (P < 0.0167). Among the three types of segments, flat segments showed the highest expression densities of β‐catenin accumulated in the nucleus. Large nodular segments and subpedunculated polyps showed similar expression patterns for the molecular markers.

Conclusions:  This study provides new and important information on the relationship between the molecular markers and endoscopic findings of LSTs.
Cost‐effectiveness of peginterferon alfa‐2a compared to lamivudine treatment in patients with hepatitis B e antigen positive chronic hepatitis B in Taiwan
Authors: Sullivan Sean D , Veenstra David L , Chen Pei‐Jer , Chang Ting‐Tsung , Chuang Wan‐Long , Tsai Chiaming , Patel Kavita
Published: June 2006

Background:  Peginterferon alfa‐2a (40KD), a new treatment option for patients with chronic hepatitis B (CHB), offers improved efficacy with a defined treatment duration compared with lamivudine, but at a higher cost. We undertook an economic evaluation of peginterferon alfa‐2a from the perspective of the Taiwan Bureau of National Health Insurance to assess the clinical outcomes and costs of 48 weeks of peginterferon alfa‐2a for the treatment of patients with hepatitis B e antigen (HBeAg)‐positive CHB, compared to lamivudine treatment for 48 weeks.

Methods:  We performed a cost‐effectiveness analysis using a state‐transition Markov model simulating the natural history of HBeAg‐positive CHB. Efficacy data were obtained from a randomized clinical trial of 820 patients (87% were Asian) comparing peginterferon alfa‐2a to lamivudine. We modeled a hypothetical cohort of 32‐year‐old patients with HBeAg‐positive CHB. Life expectancy, quality‐adjusted life expectancy, lifetime costs ($NTD) and incremental cost‐effectiveness ratios (ICER) were estimated. One‐way sensitivity analyses were performed on all parameters in the model to evaluate uncertainty.

Results:  Treatment with peginterferon alfa‐2a compared to lamivudine resulted in higher total costs, but longer quality‐adjusted life expectancy, yielding an ICER of $NTD 381 000 ($US 12 000) per quality‐adjusted life year (QALY) gained. Although there is uncertainty associated with the prognosis of HBeAg‐positive CHB, the ICER did not exceed $NTD 485 000 ($US 15 000) per QALY gained despite variation in the parameters used in the analysis.

Conclusions:  Our analysis suggests that 48‐week treatment with peginterferon alfa‐2a compared to 48‐week treatment with lamivudine in HBeAg‐positive patients offers life expectancy and quality of life benefits at a favorable cost‐effectiveness ratio.