bluuebunny/crossref_metadata_2025 huggingface dataset:
Nutrient-responsive mTOR signalling grows on Sterile ground
Authors: Cook Simon J. , Morley Simon J.
Published: March 2007

The control of cell growth, that is cell size, is largely controlled by mTOR (the mammalian target of rapamycin), a large serine/threonine protein kinase that regulates ribosome biogenesis and protein translation. mTOR activity is regulated both by the availability of growth factors, such as insulin/IGF-1 (insulin-like growth factor 1), and by nutrients, notably the supply of certain key amino acids. The last few years have seen a remarkable increase in our understanding of the canonical, growth factor-regulated pathway for mTOR activation, which is mediated by the class I PI3Ks (phosphoinositide 3-kinases), PKB (protein kinase B), TSC1/2 (the tuberous sclerosis complex) and the small GTPase, Rheb. However, the nutrient-responsive input into mTOR is important in its own right and is also required for maximal activation of mTOR signalling by growth factors. Despite this, the details of the nutrient-responsive signalling pathway(s) controlling mTOR have remained elusive, although recent studies have suggested a role for the class III PI3K hVps34. In this issue of the Biochemical Journal, Findlay et al. demonstrate that the protein kinase MAP4K3 [mitogen-activated protein kinase kinase kinase kinase-3, a Ste20 family protein kinase also known as GLK (germinal centre-like kinase)] is a new component of the nutrient-responsive pathway. MAP4K3 activity is stimulated by administration of amino acids, but not growth factors, and this is insensitive to rapamycin, most likely placing MAP4K3 upstream of mTOR. Indeed, MAP4K3 is required for phosphorylation of known mTOR targets such as S6K1 (S6 kinase 1), and overexpression of MAP4K3 promotes the rapamycin-sensitive phosphorylation of these same targets. Finally, knockdown of MAP4K3 levels causes a decrease in cell size. The results suggest that MAP4K3 is a new component in the nutrient-responsive pathway for mTOR activation and reveal a completely new function for MAP4K3 in promoting cell growth. Given that mTOR activity is frequently deregulated in cancer, there is much interest in new strategies for inhibition of this pathway. In this context, MAP4K3 looks like an attractive drug target since inhibitors of this enzyme should switch off mTOR, thereby inhibiting cell growth and proliferation, and promoting apoptosis.
Field emission from gadolinium silicide prepared by ion implantation with electron beam annealing
Authors: Duan H. G. , Xie E. Q. , Ye F.
Published: March 2007

A silicon-based field emission cathode, the rare earth silicide GdSi2 was prepared by implanting Gd ions into silicon using a metal vapor vacuum arc ion source and subsequently annealed by electron beam. For as-implanted samples, turn-on field was about 21V∕μm at a current density of 1μA∕cm2 and a field emission current density of 1mA∕cm2 was reached at an applied field of 34V∕μm. After annealing, the turn-on field could be as low as 9V∕μm and the current density of 1mA∕cm2 can be reached at an applied field of 14V∕μm. X-ray diffraction with x-ray photoelectron spectroscopy analyses and atomic force microscopy were used to characterize microstructure changes of the samples. The results showed that these excellent field emission characteristics were attributed to the GdSi2 compounds formed in the samples. The field emission mechanism was discussed in terms of Fowler-Nordheim (FN) theory. It was found that FN plots could be divided into two segments obviously, and this was perhaps because of the thermal effect in the process of field emission.
Switching speed distribution of spin-torque-induced magnetic reversal
Authors: He J. , Sun J. Z. , Zhang S.
Published: March 2007

The switching probability of a single-domain ferromagnet under spin-current excitation is evaluated using the Fokker-Planck equation (FPE). In the case of uniaxial anisotropy, the FPE reduces to an ordinary differential equation in which the lowest eigenvalue λ1 determines the slowest switching events. We have calculated λ1 using both analytical and numerical methods. It is found that the previous model based on thermally distributed initial magnetization states [J. Z. Sun et al., Proc. SPIE 5359, 445 (2004)] can be accurately justified in some useful limiting conditions.
Ion heating in the presheath
Authors: Meige Albert , Sutherland Orson , Smith Helen B. , Boswell Rod W.
Published: March 2007

A one-dimensional model of a small plasma ion source (10cm long) is studied. A hybrid simulation where ions are treated as particles and electrons as a fluid obeying the Boltzmann relation is used to investigate ion heating in the plasma presheath. At low pressure (below a few mTorr), the ion velocity distribution is Maxwellian in the bulk and becomes a drifting Maxwellian distribution while transiting the presheath. The distribution remains essentially isotropic as the ions are accelerated through the presheath to satisfy the Bohm criterion. At intermediate pressures (around 10mTorr), ion-neutral collisions scatter a significant part of the ion kinetic energy from the parallel direction to the perpendicular direction, leading to a net heating of the ions. In addition, the ion velocity distribution becomes distinctly anisotropic. At higher pressure (above a few tens of mTorr), ion heating is still observed, but yields isotropic ion velocity distributions.
Effects of grains’ features in surface roughness scaling
Authors: Oliveira T. J. , Reis F. D. A. Aarão
Published: March 2007

We study the local and global roughness scaling in growth models with grains at the film surfaces. The local roughness, measured as a function of window size r, shows a crossover at a characteristic length rc, from a rapid increase with exponent α1 to a slower increase with exponent α2. The result α1≈1 is explained by the large height differences in the borders of the grains when compared to intragrain roughness, and must not be interpreted as a consequence of a diffusion dominated intragrain dynamics. This exponent shows a weak dependence on the shape and size distribution of the grains, and typically ranges from 0.85 for rounded grain surfaces to one for the sharpest ones. The scaling corrections of exactly solvable models suggest the possibility of slightly smaller values due to other smoothing effects of the surface images. The crossover length rc provides a reasonable estimate of the average grain size in all model systems, including the cases of wide grain size distributions. In Kardar-Parisi-Zhang growth, very different values of α2 are obtained, ranging from 0.4 for the films with smoothest surfaces to values in the range 0.1≲α2≲0.2 for systems with large cliffs separating the grains. Possible applications to real systems which show this crossover with similar exponents are discussed.
Conservation laws in Skyrme-type models
Authors: Adam C. , Sánchez-Guillén J. , Wereszczyński A.
Published: March 2007

The zero curvature representation of Zakharov and Shabat [V. E. Zakharov and A. B. Shabat, Soviet Phys. JETP 34, 62 (1972)] has been generalized recently to higher dimensions and has been used to construct nonlinear field theories which are integrable or contain integrable submodels. The Skyrme model, for instance, contains an integrable subsector with infinitely many conserved currents, and the simplest Skyrmion with baryon number 1 belongs to this subsector. Here we use a related method, based on the geometry of target space, to construct a whole class of theories which are integrable or contain integrable subsectors (where integrability means the existence of infinitely many conservation laws). These models have three-dimensional target space, like the Skyrme model, and their infinitely many conserved currents turn out to be Noether currents of the volume-preserving diffeomorphisms on target space. Specifically for the Skyrme model, we find both weak and strong integrability conditions, where the conserved currents form a subset of the algebra of volume-preserving diffeomorphisms in both cases, but this subset is a subalgebra only for the weak integrable submodel.
Gradients for two-component quasirelativistic methods. Application to dihalogenides of element 116
Authors: van Wüllen Christoph , Langermann Norbert
Published: March 2007

The authors report the implementation of geometry gradients for quasirelativistic two-component Hartree-Fock and density functional methods using either the zero-order regular approximation Hamiltonian or spin-dependent effective core potentials. The computational effort of the resulting program is comparable to that of corresponding nonrelativistic calculations, as it is dominated by the evaluation of derivative two-electron integrals, which is the same for both types of calculations. Besides the implementation of derivatives of matrix elements of the one-particle Hamiltonian with respect to nuclear displacements, the calculation of the derivative exchange-correlation energy for the open shell case involves complicated expressions because of the noncollinear approach chosen to define the spin density. A pilot application to dihalogenides of element 116 shows how spin-orbit coupling strongly affects the chemistry of the superheavy p-block elements. While these molecules are bent at a scalar-relativistic level, spin-orbit coupling is so strong that only the 7p3∕2 atomic orbitals of element 116 are involved in bonding, which favors linear molecular geometries for dihalogenides with heavy terminal halogen atoms.
Time-of-flight mass spectrometry for time-resolved measurements
Authors: Blitz Mark A. , Goddard Andrew , Ingham Trevor , Pilling Michael J.
Published: March 2007

A time-resolved time-of-flight mass spectrometer (TOF-MS) that can simultaneously monitor multiple species on the millisecond time scale has been constructed. A pulsed photolysis laser is used to initiate reaction, and then via a pinhole the reaction mixture is sampled by the TOF-MS. The ions are created by photoionization via either a discharge lamp or a pulsed laser. Comparison between the two ionization sources showed that the laser is at least an order of magnitude more efficient, based on the time to accumulate the data. Also, unlike the continuous lamp the pulsed laser is not mass limited. Frequency tripling the 355nm output of a Nd:YAG laser provided a convenient laser ionization source. However, using a dye laser provided an equally intense laser ionization source with the ability to tune the vacuum ultraviolet (vuv) light. To show the versatility of the system the kinetics of the reaction of SO and ClSO radicals with NO2 were simultaneously measured, and using the dye laser the vuv light was tuned to 114nm in order to observe H2CO being formed from the reaction between CH3CO and O2.
Micropatterned silicone elastomer substrates for high resolution analysis of cellular force patterns
Authors: Cesa Claudia M. , Kirchgeßner Norbert , Mayer Dirk , Schwarz Ulrich S. , Hoffmann Bernd , Merkel Rudolf
Published: March 2007

Cellular forces are closely related to many physiological processes, including cell migration, growth, division, and differentiation. Here, we describe newly developed techniques to measure these forces with high spatial resolution. Our approach is based on ultrasoft silicone elastomer films with a regular microstructure molded into the surface. Mechanical forces applied by living cells to such films result in elastomer deformation which can be quantified by video microscopy and digital image processing. From this deformation field forces can be calculated. Here we give detailed accounts of the following issues: (1) the preparation of silicon wafers as molds for the microstructures, (2) the fabrication of microstructured elastomer substrates, (3) the in-depth characterization of the mechanical properties of these elastomers, (4) the image processing algorithms for the extraction of cellular deformation fields, and (5) the generalized first moment tensor as a robust mathematical tool to characterize whole cell activity. We present prototype experiments on living myocytes as well as on cardiac fibroblasts and discuss the characteristics and performance of our force measurement technique.
High-power operation of diode edge-pumped, composite all-ceramic Yb:Y3Al5O12 microchip laser
Authors: Tsunekane Masaki , Taira Takunori
Published: March 2007

A solid-state laser material of composite all-ceramic Yb:Y3Al5O12 is applied as a source of a high-power, diode edge-pumped microchip laser. 520W quasi-continuous-wave and 414W continuous-wave (cw) output powers were obtained from the 3.7-mm-diameter, Yb doped ceramic core with a 200μm thickness. The cw output power densities of 3.9kW∕cm2 and 0.19MW∕cm3 in the core area and volume, respectively, are the highest for an active-mirror solid-state laser. The maximum thermal stress in the ceramic core is estimated to be 384MPa at the noncooled surface and is twice the tensile strength of single-crystal Y3Al5O12.
Effects of carbon nanotubes on electro-optical characteristics of liquid crystal cell driven by in-plane field
Authors: Jeon Sang Youn , Shin Seung Hwan , Jeong Seok Jin , Lee Seung Hee , Jeong Seok Ho , Lee Young Hee , Choi Hyun Chul , Kim Kyeong Jin
Published: March 2007

Homogeneously aligned nematic liquid crystal (LC) cells doped with carbon nanotubes (CNTs) driven by an in-plane field were fabricated and their electro-optic characteristics were investigated. The effective cell retardation values showed no difference between doped and undoped LC cells in the absence of electric field. However, in the presence of electric field, it was smaller in the CNT-doped cell than in the undoped cell, resulting in the decrease of transmittance. Furthermore, the CNT-doped cell exhibited a slight increase in the driving voltage due to the increase of the twist elastic constant (K22) and the decrease in the decay response time due to the decrease in the rotational viscosity (γ) and γ∕K22 compared to the undoped cell.
Predictions of thermoelastic stress in a broad-area semiconductor laser
Authors: Cox B. P. , Smith W. R.
Published: March 2007

The coupling of electrical, optical, and thermal effects in broad-area semiconductor lasers has been investigated using a multilateral mode mathematical model. Numerical solutions for the active layer temperature rise are input into the thermal source terms of elasticity equations, leading to the prediction of the thermoelastic stresses which occur in regions of high defect concentration. The magnitude of this prediction is compared with the size of other stresses reported elsewhere in experimental observations of the degraded facet of broad-area devices.
Path Dependency and the Implementation of Environmental Regulation
Authors: Kirk Elizabeth A , Reeves Alison D , Blackstock Kirsty L
Published: March 2007

The authors examine the implementation of environmental regulation and demonstrate that path dependency, created largely by resource constraints, narrows the range of options for implementing regulation. It also magnifies the impact of the institutional history of the regulatory body and the impact of the disciplinary commitments of those working within the regulatory body on the implementation process. It is shown that the result is that those involved in the implementation process are unable to consider all possible routes to implementation but, rather, only a relatively few ‘manageable’ options for the regulation of particular activities. The arguments are examined in the context of implementation of the Water Framework Directive 2000 (WFD) in Scotland. In particular the authors focus on the regulation of diffuse pollution under the WFD and on the role played by the Scottish Environment Protection Agency in that regulation.
Immigrant Entrepreneurship, Institutional Discrimination, and Implications for Public Policy: A Case Study in Toronto
Authors: Teixeira Carlos , Lo Lucia , Truelove Marie
Published: March 2007

Immigration since World War 2 has been a primary engine of economic, social, and cultural change in Canada. Two of its important characteristics have been its ‘urban’ character and the non-European origins of immigrants since the 1960s. The Toronto Census Metropolitan Area (CMA) has been a major destination for those immigrants who have entered the self-employed sector of the economy in ever-larger numbers. The authors focus on the barriers and challenges experienced by the Polish, Portuguese, Caribbean, Korean, and Somali immigrants in the establishment and operation of their businesses in the Toronto CMA. With information collected through key-informant interviews, a questionnaire survey, and focus groups, it is found that, despite the Canadian commitment to multiculturalism at all levels of government, visible-minority entrepreneurs still confront more barriers in their business practice than do non-visible-minority entrepreneurs, with access to financing being a persistent problem. Given the increasingly multicultural nature of major Canadian cities and the acknowledged role of immigrants as an engine of economic growth, the authors identify barriers to entrepreneurship among immigrants as an area of clear concern both for policymakers and for scholars, and suggest solutions to address this concern.
Towards Sustainability: Is Integrated Appraisal a Step in the Right Direction?
Authors: Kidd Sue , Fischer Thomas B
Published: March 2007

The authors examine the role of integrated appraisal as a tool for promoting sustainable development and good governance, and the potential tensions that may exist between these two objectives. Drawing upon experience in the United Kingdom, it is argued that an undue emphasis on governance issues may compromise the rigour of integrated-appraisal methodologies and result in a loss of focus upon sustainability concerns, particularly those related to environmental matters. This framework of ideas is explored further with reference to the development of an integrated Appraisal Toolkit for the North West region of England. Ways in which integrated appraisal can retain its place within the suite of environmental assessment tools as a way of supporting more sustainable patterns of development, and at the same time contributing to good governance, are discussed.
Examination of basement membrane components associated with the bovine seminiferous tubule basal lamina
Authors: Glattauer Veronica , Irving-Rodgers Helen F. , Rodgers Raymond J. , Stockwell Sally , Brownlee Alan G. , Werkmeister Jerome A. , Ramshaw John A. M.
Published: March 2007

Immunohistology has been used to examine the distribution of certain components of the basement membrane (BM) associated with bovine spermatogonial germ cells that are located within the seminiferous tubules. Histology was performed on testis tissue from Brahman cattle (Bos indicus) of three different age groups: pre-pubescent (4–6 months), juvenile (8–10 months) and adult (18–24 months) animals. There were no major changes in the BM composition apparent between these three age groups, except for certain lectin staining. These data suggest that the predominant collagen type IV component may have an α3 and α4 composition, although other chains, including the α5 and α6 chains, were also present. Possibly the main laminin type present was laminin 121 (α1β2γ1), although other variants were also present. Both nidogen-1 and perlecan, which are normal BM components, were also found as part of the seminiferous tubule BM. Interstitial collagens, such as type I, III and VI collagens, were found in the peritubular space, but were not part of the BM itself, although type VI collagen was most visible in the peritubular zone adjacent to the tubules. Examination of the BM with a range of lectins gave strong staining for (glcNAc)2 entities, weak positive staining for α-l-fuc, but little or no staining for α-galNAc and (glcNAc)3 at all ages, whereas staining for α-gal, β-gal(1→3)galNAc and α-man showed developmental changes.
Influence of hyaluronic acid synthesis and cumulus mucification on bovine oocyte in vitro maturation, fertilisation and embryo development
Authors: Gutnisky Cynthia , Dalvit Gabriel C. , Pintos Laura N. , Thompson Jeremy G. , Beconi Martha T. , Cetica Pablo D.
Published: March 2007

During cumulus–oocyte complex (COC) maturation, cumulus expansion involves the deposition of mucoelastic compounds, especially hyaluronic acid, synthesised from glucose via the hexosamine biosynthesis pathway. The aim of the present study was to determine the effects of uridine monophosphate (UMP) and 6-diazo-5-oxo-l-norleucine (DON), inhibitors of hyaluronic acid synthesis, during bovine oocyte in vitro maturation (IVM) on cumulus expansion, glucose uptake, protein synthesis, cumulus cell number, meiotic maturation, cleavage rate and subsequent embryo development. A further aim of the study was to examine the effect of hyaluronic acid on sperm capacitation and acrosome reaction in relation to the capacity of COCs to be fertilised in vitro. A low correlation between glucose uptake and degree of cumulus expansion was observed. Total and partial inhibition of cumulus expansion was observed with DON and UMP, respectively, and was accompanied by a decrease in glucose uptake with DON. Total protein content and cumulus cell number per COC increased during IVM, but was unaffected by the presence of DON or UMP, as was oocyte meiotic maturation. Rates of cleavage and blastocyst development decreased in oocytes matured with DON and UMP, although this inhibition was reversed when the in vitro fertilisation (IVF) medium contained heparin. Hyaluronic acid induced capacitation and the acrosome reaction, and in IVF medium prevented the inhibition of cleavage and blastocyst development by DON in a similar fashion to heparin. Hyaluronic acid synthesis during cumulus mucification contributes to the penetration and fertilisation of bovine oocytes, most likely by facilitating the processes of capacitation and acrosome reaction. Mucification during IVM is independent of cumulus cell proliferation, COC protein content, oocyte meiotic maturation and subsequent developmental competence once fertilised.
Paternal care in the mound-building mouse reduces inter-litter intervals
Authors: Féron Christophe , Gouat Patrick
Published: March 2007

In many rodent species males display paternal behaviour. The primary reported effect of this paternal care is to increase pup survival. In mammal females, pregnancy and lactation are energetically demanding, especially when they are concurrent in post-partum reproduction. To face this energy requirement, females generally lengthen the duration of their post-partum pregnancy. In the present study we tested whether paternal care could affect this duration in the monogamous mound building mouse Mus spicilegus. In this species, females have a short reproductive life that does not exceed 4 months. Reduction of inter-delivery latencies would then be an efficient way to increase reproductive success. In a male removal experiment, we showed that inter-delivery latency was shortened by male presence. Moreover, behavioural estimations of paternal involvement were correlated with inter-delivery latency. The longer the male spent inside the nest the shorter the inter-delivery latency. In the mound-building mouse, the female might be able to monopolise the parental care of a single male, which could be important for the evolution of monogamy. The characteristics of first reproduction as compared to post-partum reproduction suggest that it may contribute to the formation of a strong and exclusive social bond between the reproductive partners.
Crossing barriers in transplantation
Authors: Bashyam Hema
Published: March 2007

In 1978, Jonathan Sprent and Robert Korngold proved that graft-versus-host disease (GVHD) is caused by donor T cells that attack the host's non-MHC antigens. T cell depletion of donor grafts has since become a staple of transplantation strategies to combat leukemia and other inherited blood disorders.
Appropriateness of Upper Gastrointestinal Endoscopy in Children: A Retrospective Study
Authors: Jantchou Prévost , Schirrer Jacques , Bocquet Alain
Published: March 2007

Background:

Upper gastrointestinal endoscopy (UGIE) is appropriate in many situations in adults and children. Recommendations for UGIE use in children were published recently by the French‐language Paediatric Hepatology, Gastroenterology, and Nutrition Group (GFHGNP).

Patients and Methods:

We retrospectively reviewed the 293 UGIE procedures undertaken in 251 children between January 1, 2001 and June 30, 2003 by 2 senior endoscopists. The UGIE procedures were categorized as appropriate or inappropriate based on GFHGNP recommendations, and diagnostic efficiency was compared in the 2 groups with the χ2 test followed by multivariate logistic regression analysis.

Results:

Of the 293 UGIE procedures, 52 (17.7%) were considered inappropriate. Diagnostic efficiency was 51% in the appropriate group versus 17.3% in the inappropriate group (odds ratio, 4.2; 95% CI, 2–8.7; P < 10−3). The proportion of appropriate UGIE procedures was higher among inpatients than outpatients (odds ratio, 2.51; 95% CI, 1.24–5.08; P = 0.01). Inappropriate reasons for performing UGIE included isolated failure to thrive and follow‐up after neonatal esophagogastroduodenitis. Nine inappropriate UGIE procedures contributed useful information: ulcerative esophagitis in 1 patient, hemorrhagic esophagitis in 4 patients, duodenitis in 1 patient, and malabsorption in 3 patients caused in 1 case by cow's milk allergy and in 2 cases to fully documented celiac disease.

Conclusions:

UGIE was usually performed appropriately in our pediatric hospital. Inappropriate UGIE procedures were more common in outpatients than in admitted patients. Awareness of the recommendations for appropriate UGIE use needs to be improved among office‐based and hospital‐based physicians.
Long‐term Treatment With Autologous Red Blood Cells Loaded With Dexamethasone 21–Phosphate in Pediatric Patients Affected by Steroid‐dependent Crohn Disease
Authors: Castro M , Rossi L , Papadatou B , Bracci F , Knafelz D , Ambrosini MI , Calce A , Serafini S , Isacchi G , D'Orio F , Mambrini G , Magnani M
Published: March 2007

Background:

Inflammatory bowel disease (IBD) present in childhood in 15% to 25% of cases. The aim of therapy in children is not only to guarantee normal growth but also to prevent relapse and to maintain remission. Steroids are effective to induce remission; however, resistance, dependency, and irreversible side effects can develop. The aim of this study was to determine whether treatment with repeated infusions of autologous red blood cells (RBCs) loaded with dexamethasone 21‐phosphate (Dex 21‐P) is safe and allows maintenance of long‐term remission in children with steroid‐dependent Crohn disease (CD).

Patients and Methods:

Eighteen consecutive pediatric patients who met the inclusion criteria were admitted to the study. Infusions of autologous RBCs loaded with Dex 21‐P were performed every 4 weeks; the mean duration of treatment was 24 months. At the beginning of treatment and after 6, 12, and 24 months, we performed clinical evaluation according to the Pediatric Crohn Disease Activity Index (pCDAI). Assessment of body mass indexamethasone and bone mineral density by means of computerized bone mineralometry‐dual energy x‐ray absorptiometry, endoscopic evaluation, and hematic morning cortisol determination were also performed.

Results:

During treatment, the mean pCDAI significantly decreased (P < 0.05); 78% of patients discontinued steroids. Determination of morning cortisol showed suppression only on the first day after infusion, followed by normalization of values. Endoscopic findings showed remission in 44% of patients. None of the patients experienced serious side effects.

Conclusions:

These data suggest that repeated infusions of RBCs loaded with Dex 21‐P can be safe and useful to maintain long‐term remission in pediatric patients with moderately active CD.
Reversal of Liver Cirrhosis: A Desirable Clinical Outcome and Its Pathogenic Background
Authors: Bortolotti Flavia , Guido Maria
Published: March 2007

Cirrhosis is the final stage of chronic liver damage of various etiologies. It used to be considered an irreversible lesion, but enormous advances in our understanding of hepatic cellular and molecular biology in the past 2 decades have challenged this view. There is now substantial evidence that cirrhosis can be a reversible process. This concept is supported by an increasing number of clinical reports showing the disappearance of cirrhotic lesions from liver biopsies taken from patients cured of their liver disease. The reversal of cirrhosis usually occurs in patients with short‐lived liver disease, after the successful treatment of the underlying liver damage. Recently, however, we observed the spontaneous reversal of cirrhosis after the loss of hepatitis B viremia in 2 men, 21 and 28 years old, who had developed cirrhosis as young children. Several questions and controversial issues concerning the definition of advanced cirrhosis, the limitations of liver biopsy (eg, sampling, interpretation error), and the applicability of noninvasive methods to the assessment of fibrosis, are being addressed. Future prospects include the possibility of antifibrotic therapy to prevent fibrosis or favor its degradation.
Community‐based Case‐Control Study of Childhood Chronic Abdominal Pain: Role of Selected Laboratory Investigations
Authors: Soon Gordon S , Saunders Norman , Ipp Moshe , Sherman Philip M , Macarthur Colin
Published: March 2007

Objective:

To compare laboratory investigation results in children with chronic abdominal pain and in healthy control children. Our hypothesis was that parasitic infection was not a causal factor for chronic abdominal pain and that there would be no difference in leukocyte count, hemoglobin level, or erythrocyte sedimentation rate (ESR) between the 2 groups.

Patients and Methods:

Children with chronic abdominal pain and healthy control children (5–15 years) were recruited from the practices of 6 primary care pediatricians in Toronto, Canada. Stool samples were analyzed for ova and parasites, and serum samples were used to estimate leukocyte count, hemoglobin, and ESR. A standardized questionnaire was used to gather social, demographic, and clinical information.

Results:

A total of 157/200 children (79%) provided samples. Children with chronic abdominal pain were more likely to be female than were control children. Stool samples were positive for parasitic infection in 15 children, with no difference in prevalence between children with chronic abdominal pain (6/87; 7%) and healthy control children (9/70; 13%); P = 0.28). The mean (standard deviation) leukocyte count in children with chronic abdominal pain was 7.4 × 109/L (2.03), compared with 8.3 × 109/L (1.82) in healthy control children. No child had a leukocyte count above 20 × 109/L. The mean (SD) hemoglobin in children with chronic abdominal pain was 131 g/L (8.4), compared with 130 g/L (9.2) in healthy control children. Last, the median ESR in children with chronic abdominal pain was 5 mm/hour, compared with 3 mm/hour in control children.

Conclusions:

The study findings suggest that in the absence of alarming symptoms and signs, parasitic infection is not a causal factor for chronic abdominal pain and that routine screening tests (leukocyte count, hemoglobin, ESR) are not useful.
Prenatal Molecular Diagnosis of Inherited Cholestatic Diseases
Authors: Jung Camille , Driancourt Catherine , Baussan Christiane , Zater Mokhtar , Hadchouel Michelle , Meunier‐Rotival Michèle , Guiochon‐Mantel Anne , Jacquemin Emmanuel
Published: March 2007

Objectives:

Progressive familial intrahepatic cholestasis (PFIC) and to a lesser extent, Alagille syndrome, often lead to end‐stage liver disease during childhood. We report our experience of DNA‐based prenatal diagnosis of PFIC1–3 and Alagille syndrome.

Patients and Methods:

Four molecular antenatal diagnoses were performed in 3 PFIC families and 17 in 11 Alagille syndrome families. DNA was isolated from chorionic villus or cultured amniocyte samples from women, without pregnancy complications.

Results:

All four foetuses with a family history of PFIC1, 2, or 3 were heterozygous for an ATP8B1, ABCB11, or ABCB4 mutation and pregnancies were continued. Three of the infants were healthy after birth, and 1 premature infant, who had an ABCB4 mutation, experienced transient neonatal cholestasis. Among the families with a history of de novo JAG1 mutation, none of the foetuses was mutated, versus 40% of those with a history of familial mutation. Of 4 pregnant women with a JAG1‐mutated foetus, 3 cut short their pregnancy and 1 gave birth to a child with overt Alagille syndrome.

Conclusions:

Molecular antenatal diagnosis of PFIC1–3 and Alagille syndrome is reliable because clinical outcome after birth corresponded to molecular foetal data.
The design and analysis of field studies to estimate catch‐and‐release mortality
Authors: POLLOCK K. H. , PINE W. E.
Published: March 2007

Abstract  The practice of catch and release (CR) as a fisheries management tool to reduce fishing mortality is widely applied in both freshwater and marine fisheries, whether from shifts in angler attitudes related to harvest or from the increasing use of harvest restrictions such as closed seasons or length limits. This approach assumes that for CR fishing policies to benefit the stock, CR will result in much lower mortality than would otherwise occur. There are many challenges in the design of CR studies to assess mortality, and in many practical settings it is difficult to obtain accurate and precise estimates. The focus of this article is on the design and quantitative aspects of estimating CR mortality, the need for a comprehensive approach that explicitly states all components of CR mortality, and the assumptions behind these methods. A general conceptual model for CR mortality that is applicable to containment and tagging‐based studies with a slight modification is presented. This article reviews the design and analysis of containment and tagging studies to estimate CR mortality over both the short and long term and then compares these two approaches. Additionally, the potential population‐level impacts of CR mortality are discussed. A recurring theme is the difficulty of designing studies to estimate CR mortality comprehensively and the need for additional research into both statistical model development and field study design.
Using a bioenergetic model to assess growth reduction from catch‐and‐release fishing and hooking injury in rainbow trout, Oncorhynchus mykiss
Authors: MEKA J. M. , MARGRAF F. J.
Published: March 2007

Abstract  A bioenergetic model was used to predict the potential effects of feeding cessation caused by catch‐and‐release capture and a reduction in feeding efficiency from hooking injuries on rainbow trout, Oncorhynchus mykiss (Walbaum), growth in southwest Alaska, USA. Simulations indicated that a 1‐day feeding cessation for a rainbow trout captured one to two times during summer months resulted in deviations from expected growth of −3% to −15%. To represent debilitating hooking injuries, the proportion of the maximum feeding potential was decreased by 5–50% resulting in deviations from expected growth of −9% to −164%. Simulated growth effects were most prominent from captures during months when salmon eggs and flesh constituted the majority of the trout diet. Simulated growth effects from reduced foraging efficiency were most prominent when hooking injuries occurred early in the fishing season. These simulations suggest that rainbow trout are most vulnerable to decreases in growth when salmon are abundant and spawning and, coincidentally, during the months when most fishing occurs.
Post‐release mortality of bonefish, Albula vulpes, exposed to different handling practices during catch‐and‐release angling in Eleuthera, The Bahamas
Authors: DANYLCHUK A. J. , DANYLCHUK S. E. , COOKE S. J. , GOLDBERG T. L. , KOPPELMAN J. B. , PHILIPP D. P.
Published: March 2007

Abstract  Bonefish, Albula spp., are popular sportfish that inhabit shallow nearshore environments in tropical and subtropical seas. Although catch and release is a common voluntary practice for anglers seeking bonefish, the post‐release fate of bonefish is poorly understood. Gastrically implanted acoustic transmitters were used to assess the short‐term (<48 h) and long‐term (>48 h) post‐release mortality of bonefish, Albula vulpes (Linnaeus), in Eleuthera, The Bahamas, subjected to gentle handling (quick retrieval, 0–15 s of air exposure and brief handling time) or rough handling (longer retrieval, 30–60 s of air exposure and extended handling time). Of the 12 fish captured and released, one was preyed upon by two lemon sharks, Negaprion brevirostris (Poey), within the first hour post‐release, and this fish was handled roughly. The transmitter from another bonefish was found on the substratum 2 days post‐release near the site at which the fish was originally caught. Of the remaining 10 fish, all were tracked and alive for at least 13 days and up to 24 days, suggesting that the negative impacts of catch‐and‐release angling that lead to mortality for bonefish likely occur within minutes post‐release.
Voluntary catch‐and‐release can generate conflict within the recreational angling community: a qualitative case study of specialised carp, Cyprinus carpio, angling in Germany
Authors: ARLINGHAUS R.
Published: March 2007

Abstract  Because of low fishing mortality that results from catch‐and‐release angling for carp, Cyprinius carpio L, it is counterintuitive that voluntary catch‐and‐release (vC&R) of this species induces conflicts within the angling community. Originally motivated by animal welfare concerns, vC&R is today probably as or more strongly criticised within the angling community itself than it is intersectorally. This study reviews the institutional treatment of C&R in Germany and explores within a sociological conflict model the conflicting views surrounding vC&R, specifically in specialised carp angling. It is argued that the intrasectoral (i.e. among angler groups) conflicts around vC&R fishing may divide the recreational angling community, which in turn may weaken the coherence of the entire angling sector. Restricting the opportunity to practice vC&R also can have important social and biological implications, which suggest a rethinking on the current treatment of vC&R recreational angling in Germany.
The PI3K‐Akt pathway promotes microtubule stabilization in migrating fibroblasts
Authors: Onishi Keisuke , Higuchi Maiko , Asakura Tomoko , Masuyama Norihisa , Gotoh Yukiko
Published: March 2007

Directed cell migration is controlled by extracellular cues such as growth factors/chemokines and extracellular matrix. In a migrating cell, a subset of microtubules becomes stabilized, and this stabilization is implicated in the establishment and maintenance of cell polarity. It is still not fully understood, however, how extracellular cues regulate the dynamics of microtubules. Here we show that the PI3K‐Akt signaling pathway plays a pivotal role in growth factor regulation of microtubule stability. Treatment of NIH 3T3 fibroblasts with platelet‐derived growth factor (PDGF) increases the amount of stabilized microtubules, and this increase is abrogated by the addition of a PI3K inhibitor or by expression of a dominant‐negative form of Akt (DN‐Akt), but not by the addition of a MEK inhibitor. Expression of an active form of Akt slightly increases the bulk amount of stabilized microtubules. Stabilization of microtubules induced in edge cells in the wounded monolayer culture is also attenuated by the PI3K inhibitor treatment or by expression of DN‐Akt. Given that Akt is activated at the leading edge of a migrating cell and plays an essential role in directed cell migration, these results reveal a novel mechanism linking extracellular cues to directed cell migration, namely Akt regulation of microtubule stability.
Combined ecological niche modelling and molecular phylogeography revealed the evolutionary history of Hordeum marinum (Poaceae) — niche differentiation, loss of genetic diversity, and speciation in Mediterranean Quaternary refugia
Authors: JAKOB SABINE S. , IHLOW ALEXANDER , BLATTNER FRANK R.
Published: March 2007

The Hordeum marinum species group consists of two annual grasses of western Eurasian saline meadows or marshes. The two grasses split in the Quaternary about two million years ago. Hordeum marinum and the diploid of Hordeum gussoneanum (2×) co‐occur throughout the Mediterranean basin, while the autotetraploid cytotype of H. gussoneanum (4×) overlaps with its diploid progenitor geographically only in the utmost Eastern Mediterranean, extending from there eastwards into Asia. Using chloroplast sequences of the trnL‐F region, six newly developed chloroplast microsatellite loci, ecological predictive models based on climate data, and the present geographical distribution of the two species we analysed differentiation processes in the H. marinum group. The chloroplast data indicated clear differences in the history of both species. For H. marinum we found a subdivision between genetically variable populations from the Iberian Peninsula and the more uniform populations from the remaining Mediterranean. As an explanation, we assume Pleistocene fragmentation of an earlier widespread population and survival in an Iberian and a Central Mediterranean glacial refuge. Chloroplast variation was completely absent within the cytotypes of H. gussoneanum, indicating a severe and recent genetic bottleneck. Due to this lack of chloroplast variation only the combination of ecological habitat modelling with molecular data analyses allowed conclusions about the history of this taxon. The distribution areas of the two cytotypes of H. gussoneanum overlap today in parts of Turkey, indicating an area with similar climate conditions during polyploid formation. However, after its origin the polyploid cytotype underwent a pronounced ecological shift, compared to its diploid progenitor, allowing it to colonize mountainous inland habitats between the Mediterranean basin and Afghanistan. The extant sympatric occurrence of H. marinum and H. gussoneanum 2× in the Mediterranean region is interpreted as a result of secondary contact after fast Holocene range expansion out of different ice age refugia.
Population genetic consequences of geographic disjunction: a prairie plant isolated on Great Lakes alvars
Authors: HAMILTON J. A. , ECKERT C. G.
Published: March 2007

Species may often exhibit geographic variation in population genetic structure due to contemporary and historical variation in population size and gene flow. Here, we test the predictions that populations on the margins of a species’ distribution contain less genetic variation and are more differentiated than populations towards the core of the range by comparing patterns of genetic variation at five microsatellite loci between disjunct and core populations of the perennial, allohexaploid herbGeum triflorum. We sampled nine populations isolated on alvar habitat within the eastern Great Lakes region in North America, habitats that include disjunct populations of several plant species, and compared these to 16 populations sampled from prairie habitat throughout the core of the species’ distribution in midwestern Canada and the USA. Alvar populations exhibited much lower within‐population diversity and contained only a subset of alleles found in prairie populations. We detected isolation by distance across the species’ range and within alvar and prairie regions separately. As predicted, genetic differentiation was higher among alvar populations than among prairie populations, even after controlling for the geographic distance between sampled populations. Low diversity and high differentiation can be accounted for by the greater contemporary spatial isolation of alvar populations. However, the genetic structure of alvar populations may also have been influenced by postglacial range expansion and contraction. Our results are consistent with alvar populations being founded during an expansion of prairie habitat during the warmer, hypsithermal period ∼5000bpand subsequently becoming stranded on isolated alvar habitat as the climate grew cooler and wetter.
PrpJ, a PP2C‐type protein phosphatase located on the plasma membrane, is involved in heterocyst maturation in the cyanobacterium Anabaena sp. PCC 7120
Authors: Jang Jichan , Wang Li , Jeanjean Robert , Zhang Cheng‐Cai
Published: March 2007

Protein phosphatases play important roles in the regulation of cell growth, division and differentiation. The cyanobacterium Anabaena PCC 7120 is able to differentiate heterocysts specialized in nitrogen fixation. To protect the nitrogenase from inactivation by oxygen, heterocyst envelope possesses a layer of polysaccharide and a layer of glycolipids. In the present study, we characterized All1731 (PrpJ), a protein phosphatase from Anabaena PCC 7120. prpJ was constitutively expressed in both vegetative cells and heterocysts. Under diazotrophic conditions, the mutant ΔprpJ (S20) did not grow, lacked only one of the two heterocyst glycolipids, and fragmented extensively at the junctions between developing cells and vegetative cells. No heterocyst glycolipid layer could be observed in the mutant by electron microscopy. The inactivation of prpJ affected the expression of hglEA and nifH, two genes necessary for the formation of the glycolipid layer of heterocysts and the nitrogenase respectively. PrpJ displayed a phosphatase activity characteristic of PP2C‐type protein phosphatases, and was localized on the plasma membrane. The function of prpJ establishes a new control point for heterocyst maturation because it regulates the synthesis of only one of the two heterocyst glycolipids while all other genes so far analysed regulate the synthesis of both heterocyst glycolipids.
Different gene expression patterns of sucrose‐starch metabolism during pollen maturation in cytoplasmic male‐sterile and male‐fertile lines of rice
Authors: Kong Jin , Li Zhong , Tan Yan‐Ping , Wan Cui‐Xiang , Li Shao‐Qing , Zhu Ying‐Guo
Published: March 2007

Starch biosynthesis, a very critical event during pollen development, is not well understood in terms of gene regulation and intracellular controls. Using the rice HL‐type cytoplasmic male sterile (HL‐CMS) line with starch deficiency in pollen and two related male‐fertile lines (Oryza sativa L.), we have studied two specific developmental stages: ‘early’, that is, before or during pollen mitosis I, without starch accumulation, and ‘late’, the actively starch‐filling postpollen mitosis I phase. Real‐time reverse transcription‐PCR analysis showed temporal changes in the expression patterns of six metabolic genes involved in the sucrose–starch pathway, i.e. sucrose synthase (EC 2.4.1.13), Rsus3; acid invertase (EC 3.2.1.26), OSINV2; phosphoglucomutase (EC 5.4.2.2), OsPGM; uridine diphosphate‐glucose pyrophosphorylase (EC 2.7.7.9), OsUGP; a subunit of adenosine diphosphate‐glucose pyrophosphorylase (AGPase) (EC 2.2.7.2), OsAGPL3; soluble starch synthase (EC 2.4.1.21), OsSSI and three transporter genes [sucrose transporter, OsSUT3; hexose transporter, OSMST7 and plasma membrane H+‐adenosine triphosphatase (ATPase) (EC 3.6.1.35), OSA2]. Regarding metabolic enzyme activities, lower activity of sucrose synthase was detected at ‘late’ compared with ‘early’ stage in the three rice lines; invertase and other downstream enzymes had higher activities at ‘late’ stage in male‐fertile but not male‐sterile lines. Meanwhile, significantly reduced sugars and ATP levels were detected at ‘early’ and ‘late’ stages in male‐sterile compared with male‐fertile tissues. Furthermore, transgenic data showed that AGPase gene can stimulate starch accumulation in pollen of male‐sterile host lines, showing the importance of AGPase in the metabolic pathway. Taken together, these data suggest that the combined effects of the reduced energy supply and sugar levels in starch biosynthesis may lead to the observed temporal changes in gene expression, and eventually to pollen sterility.