bluuebunny/crossref_metadata_2025 huggingface dataset:
Fluid simulations of edge turbulence for stellarators and axisymmetric configurations
Authors: Kleiber R. , Scott B.
Published: October 2005

Nonlinear electromagnetic fluid simulations in a flux tube are used to compute the edge turbulence for a family of axisymmetric configurations with different rotational transform profiles (ι) and the stellarator Wendelstein 7-X (W7-X) [Grieger et al., Plasma Physics and Controlled Nuclear Fusion Research, 1990 (International Atomic Energy Agency, Vienna, 1991), Vol. 3, p. 525]. The influence of the ι profile on anomalous transport and the strength of zonal flows in these axisymmetric equilibria are studied and the results are connected to simulations for the W7-X equilibrium. A strong decrease in transport is found by increasing ι or switching the sign of the shear from tokamak-(ι′<0) to stellarator-like (ι′>0). The effect of pressure-induced changes in the W7-X equilibrium geometry on the transport at fixed parameters is studied and a decrease in the transport following changes in the zonal flows is found.
Long-wave Marangoni instability in a binary-liquid layer with deformable interface in the presence of Soret effect: Linear theory
Authors: Podolny A. , Oron A. , Nepomnyashchy A. A.
Published: October 2005

We investigate the long-wave Marangoni instability in a binary-liquid layer in the limit of a small Biot number B. The surface deformation and the Soret effect are both taken into account. It is shown that the problem is characterized by two distinct asymptotic limits for the disturbance wave number k, k∼B1∕4 and k∼B1∕2, which are caused by the action of two instability mechanisms, namely, the thermocapillary and solutocapillary effects. The asymptotic limit of k∼B1∕2 is novel and is not known for pure liquids. A diversity of instability modes is revealed. Specifically, a new long-wave oscillatory mode is found for sufficiently small values of the Galileo number.
Carrier capture before entering into a semiconductor quantum dot as a dominant pathway for the reduction of emission efficiency
Authors: Lee E. G. , Kim M. D. , Lee D. , Kim S. G.
Published: October 2005

To study the carrier reduction pathway for quantum dots (QDs), we have measured carrier lifetimes and photoluminescence spectra both at 10 K and at higher temperatures. We found that the carriers captured in QDs are robust and are not lost to nearby defects, even at elevated temperature, and that the lower emission efficiency of QDs with defects compared to the corresponding defect-free QDs is due to the capture of carriers to defects before entering into the QDs.
K
H
+
Ti
co-doped NaAlH4 for high-capacity hydrogen storage
Authors: Wang Ping , Kang Xiang-Dong , Cheng Hui-Ming
Published: October 2005

A method for preparation of Ti-doped NaAlH4 with high hydrogen capacity was developed, in which the NaH∕Al mixture was mechanically milled with a catalytic amount of KH together with metallic Ti. The addition of KH was found to result in a pronounced improvement in the dehydriding performance of the Na3AlH6∕NaH+Al step. As a result, the practical cycling hydrogen capacity has been markedly enhanced from 3.3wt% for the Ti-doped hydride to 4.7wt% for KH+Ti co-doped material. Moreover, the pronounced enhancement on hydrogen capacity arising upon adding KH was observed to persist in the following dehydrogenation∕hydrogenation cycles. Structural investigation shows that the addition of KH has led to a lattice expansion. Moreover, it was found that the enthalpy change of the Na3AlH6∕NaH+Al decomposition step underwent a considerable decrease upon adding KH. Therefore, the observed property improvement may be ascribed to a favorable thermodynamic adjustment arising upon the addition of KH.
In-line sensor for accurate rf power measurements
Authors: Gahan D. , Hopkins M. B.
Published: October 2005

An in-line sensor has been constructed with 50Ω characteristic impedance to accurately measure rf power dissipated in a matched or unmatched load with a view to being implemented as a rf discharge diagnostic. The physical construction and calibration technique are presented. The design is a wide band, hybrid directional coupler/current-voltage sensor suitable for fundamental and harmonic power measurements. A comparison with a standard wattmeter using dummy load impedances shows that this in-line sensor is significantly more accurate in mismatched conditions.
Influence of Al∕N flux ratio during nucleation layer growth on the structural properties of AlN grown on sapphire by molecular beam epitaxy
Authors: Fälth J. F. , Davidsson S. K. , Liu X. Y. , Andersson T. G.
Published: October 2005

AlN nucleation and buffer layers have been grown with different Al∕N flux ratio by molecular beam epitaxy on sapphire. Thick AlN on top of a nucleation layer grown with Al∕N flux ratio=1.0 exhibited deep hexagonal holes (diameter 100–200 nm, density ∼109cm−2). Investigation of the nucleation layer surface revealed that the holes were formed already during the nucleation. The formation of holes in AlN buffer layers could be avoided by using a N-rich (Al∕N=0.5) nucleation layer. It is demonstrated that the holes in AlN buffer layers can be effectively avoided choosing a N-rich nucleation layer growth and then switch to Al∕N flux ratio =1.0 for buffer layer growth. The two-step AlN growth gave high quality AlN, with excellent crystalline quality and smooth surface.
Controllable charge storage in quantum dots with independent tuning of electric fields
Authors: Gill K. S. , Moskovitz N. , Wang L.-C. , Sherwin M. S. , Badolato A. , Gerardot B. , Petroff P.
Published: October 2005

Electrons and holes are loaded into ensembles of InAs∕GaAs quantum dots using a sequence of near-infrared optical pulses and voltage biases. The number and sign of charge carriers is completely determined by one of the voltage biases in the sequence. The injected charge remains stored in the dots for at least 10s for a range of independently varied growth-direction electric fields and is detected by purely electrical means. The storage is robust to temperatures exceeding 80K.
Real-time x-ray studies of Mo-seeded Si nanodot formation during ion bombardment
Authors: Ozaydin Gozde , Özcan Ahmet S. , Wang Yiyi , Ludwig Karl F. , Zhou Hua , Headrick Randall L. , Siddons D. Peter
Published: October 2005

The formation of self-organized Si nanostructures induced by Mo seeding during normal incidence Ar+ ion bombardment at room temperature is reported. Silicon surfaces without Mo seeding develop only power-law roughness during 1000eV ion bombardment at normal incidence, in agreement with scaling theory expectations of surface roughening. However, supplying Mo atoms to the surface during ion bombardment seeds the development of highly correlated, nanoscale structures (“dots”) that are typically 3nm high with a spatial wavelength of approximately 30nm. With time, these saturate and further surface roughening is dominated by the growth of long-wavelength corrugations.
Parametric downconversion via cascaded optical nonlinearities in an aperiodically poled MgO:LiNbO3 superlattice
Authors: Guo H. C. , Qin Y. Q. , Tang S. H.
Published: October 2005

Quasi-phase-matched parametric downconversion via cascaded optical nonlinearities in an aperiodically poled MgO:LiNbO3 superlattice was studied in theory and experiment. Due to the cascading effect and the abundant reciprocal structure in an aperiodic optical superlattice, multiple-wavelength parametric downconversion in a wide spectrum range can be obtained. Enhancement of the conversion efficiency and output stability through coupling of two nonlinear processes is demonstrated. The result also reveals that the cascaded parametric downconversion process can be used to efficiently downconvert the fundamental wavelength to a longer wavelength of the infrared region. The process can be additionally served as an efficient mechanism to enhance THz wave propagation in a nonlinear optical medium.
A manifestation of the Ostwald step rule: Molecular-dynamics simulations and free-energy landscape of the primary nucleation and melting of single-molecule polyethylene in dilute solution
Authors: Larini L. , Leporini D.
Published: October 2005

The paper presents numerical results from extensive molecular-dynamics simulations of the crystallization process of a single polyethylene chain with N=500 monomers. The development of the ordered structure is seen to proceed along different routes involving either the global reorganization of the chain or, alternatively, well-separated connected nuclei. No dependence on the thermal history was observed at the late stages of the crystallization. The folding process involves several intermediate ordered metastable states, in strong analogy with the experiments, and ends up in a well-defined long-lived lamella with ten stems of approximately equal length, arranged into a regular, hexagonal pattern. This behavior may be seen as a microscopic manifestation of the Ostwald step rule. Both the metastable states and the long-lived one are evidenced as the local minima and the global one of the free-energy landscape, respectively. The study of the microscopic organization of the lamella evidenced that the two caps are rather flat, i.e., the loops connecting the stems are short. Interestingly, annealing the chain through the different metastable states leaves the average number of monomers per loop nearly unchanged. It is also seen that the chain ends, the so-called cilia, are localized on the surface of the lamella, in agreement with the experiments, and that structural fluctuations take place on the lamella surface, as noted by recent Monte Carlo simulations. The study of the melting process evidences that the degree of hysteresis is small.
Indistinguishable single photons from a single-quantum dot in a two-dimensional photonic crystal cavity
Authors: Laurent S. , Varoutsis S. , Le Gratiet L. , Lemaître A. , Sagnes I. , Raineri F. , Levenson A. , Robert-Philip I. , Abram I.
Published: October 2005

We report on the spontaneous emission of a single-quantum dot embedded in a two-dimensional photonic crystal cavity. The resonant coupling between the dot and the strongly localized optical mode significantly shortens the spontaneous emission lifetime, so that the coherence time of the emitted photons is dominated by radiative effects: The emitted photons are indistinguishable, with a mean wave-packet overlap as high as 72%.
Unusual electromechanical effects in organic semiconductor Schottky contacts: Between piezoelectricity and electrostriction
Authors: Dennler Gilles , Lungenschmied Christoph , Sariciftci Niyazi Serdar , Schwödiauer Reinhard , Bauer Siegfried , Reiss Howard
Published: October 2005

The converse electromechanical response in an organic Schottky contact follows a power law dependence S∝Vα of the mechanical strain S versus the applied voltage V, with an exponent α=1.5, in between linear piezoelectricity and quadratic electrostriction. The experimental result is discussed within the frame of a model, where the Coulomb attraction between charged impurities present in the depletion zone of the Schottky contact and the charges accumulated in the metal at the interface with the semiconductor is considered. Electromechanical responses of such devices appear to be of fundamental interest for the investigation of nonuniform electric field distributions and for potential practical applications as electromechanical transducers.
Gallium nitride microcavities formed by photoenhanced wet oxidation
Authors: Peng L.-H. , Lu C.-Y. , Wu W.-H. , Wang S.-L.
Published: October 2005

We report the formation of gallium nitride (GaN) microcavities by manipulating a photoenhanced oxidation rate difference between the polar and nonpolar crystallographic planes of GaN. When immersed in a buffered acetic (CH3COOH) electrolyte of pH∼6.2 at room temperature, it is shown that the photo-oxidation can proceed at a rate that is one order of magnitude slower on the nonpolar plane of {11¯00}GaN than on the polar plane of {0001¯}GaN due to the reduced surface field action. Gallium nitride microcavities bounded by optically smooth {11¯00} and {11¯03} facets can thus be preferentially formed on the c-plane sapphire substrate after dissolving the oxide layer. The optical properties of these GaN hexagonal cavities reveal characteristic peaks of whispering gallery modes in resonance with the GaN band edge emission spectrum. A typical cavity Q factor of 103 is observed in these GaN microcavities due to a reduced optical scattering loss in the wet chemical reaction process.
Minimum volume of long liquid bridges between noncoaxial, nonequal diameter circular disks under lateral acceleration
Authors: Meseguer J. , Espino J. L. , Cuerva A. , Sanz-Andrés A.
Published: October 2005

The stability limit of minimum volume and the breaking dynamics of liquid bridges between nonequal, noncoaxial, circular supporting disks subject to a lateral acceleration were experimentally analyzed by working with liquid bridges of very small dimensions. Experimental results are compared with asymptotic theoretical predictions, with the agreement between experimental results and asymptotic ones being satisfactory.
A TRAIL receptor-dependent synthetic lethal relationship between
MYC
activation and
GSK3β/FBW7
loss of function
Authors: Rottmann Sabine , Wang Yan , Nasoff Marc , Deveraux Quinn L. , Quon Kim C.
Published: October 2005

The
MYC
protooncogene is frequently deregulated in human cancers. Here, by screening a kinase-directed library of small inhibitory RNAs, we identify glycogen synthase kinase 3β (
GSK3
β) as a gene whose inactivation potentiates TNF-related apoptosis-inducing ligand death receptor-mediated apoptosis specifically in MYC-overexpressing cells. Small inhibitory RNA-induced silencing of
GSK3
β prevents phosphorylation of MYC on T58, thereby inhibiting recognition of MYC by the E3 ubiquitin ligase component FBW7. Attenuating the GSK3β–FBW7 axis results in stabilization of MYC, up-regulation of surface levels of the TNF-related apoptosis-inducing ligand death receptor 5, and potentiation of death receptor 5-induced apoptosis
in vitro
and
in vivo
. These results identify GSK3β and FBW7 as potential cancer therapeutic targets and MYC as a critical substrate in the GSK3β survival-signaling pathway. The results also demonstrate paradoxically that MYC-expressing tumors might be treatable by drug combinations that increase rather than decrease MYC oncoprotein function.
Dendrite-specific remodeling of
Drosophila
sensory neurons requires matrix metalloproteases, ubiquitin-proteasome, and ecdysone signaling
Authors: Kuo Chay T. , Jan Lily Y. , Jan Yuh Nung
Published: October 2005

During neuronal maturation, dendrites develop from immature neurites into mature arbors. In response to changes in the environment, dendrites from certain mature neurons can undergo large-scale morphologic remodeling. Here, we show a group of
Drosophila
peripheral sensory neurons, the class IV dendritic arborization (C4da) neurons, that completely degrade and regrow their elaborate dendrites. Larval dendrites of C4da neurons are first severed from the soma and subsequently degraded during metamorphosis. This process is controlled by both intracellular and extracellular mechanisms: The ecdysone pathway and ubiquitin-proteasome system (UPS) are cell-intrinsic signals that initiate dendrite breakage, and extracellular matrix metalloproteases are required to degrade the severed dendrites. Surprisingly, C4da neurons retain their axonal projections during concurrent dendrite degradation, despite activated ecdysone and UPS pathways. These results demonstrate that, in response to environmental changes, certain neurons have cell-intrinsic abilities to completely lose their dendrites but keep their axons and subsequently regrow their dendritic arbors.
Lineage tracing and characterization of insulin-secreting cells generated from adult pancreatic acinar cells
Authors: Minami Kohtaro , Okuno Masaaki , Miyawaki Kazumasa , Okumachi Akinori , Ishizaki Katsuhiko , Oyama Kazunobu , Kawaguchi Miho , Ishizuka Nobuko , Iwanaga Toshihiko , Seino Susumu
Published: October 2005

Although several studies have suggested that insulin-secreting cells can be generated
in vitro
from cells residing in adult exocrine pancreas, neither the origin of these cells nor their precise insulin secretory properties was obtained. We show here that insulin-secreting cells can be derived from adult mouse pancreatic exocrine cells by suspension culture in the presence of EGF and nicotinamide. The frequency of insulin-positive cells was only 0.01% in the initial preparation and increased to ≈5% in the culture conditions. Analysis by the Cre/loxP-based direct cell lineage tracing system indicates that these newly made cells originate from amylase/elastase-expressing pancreatic acinar cells. Insulin secretion is stimulated by glucose, sulfonylurea, and carbachol, and potentiation by glucagon-like peptide-1 also occurs. Insulin-containing secretory granules are present in these cells. In addition, we found that the enzymatic dissociation of pancreatic acini itself leads to activation of EGF signaling, and that inhibition of EGF receptor kinase blocks the transdifferentiation. These data demonstrate that pancreatic acinar cells can transdifferentiate into insulin-secreting cells with secretory properties similar to those of native pancreatic β cells, and that activation of EGF signaling is required in such transdifferentiation.
Functional food science and substrate metabolism
Authors: Saris W. H. M. , Asp N. G. L. , Björck I. , Blaak E. , Bornet F. , Brouns F. , Frayn K. N. , Fürst P. , Riccardi G. , Roberfroid M. , Vogel M.
Published: October 2005

The present review addresses the role of food constituents in the aetiology of metabolic conditions and chronic diseases, mostly related to energy metabolism and substrate regulation, such as obesity and non-insulin-dependent diabetes mellitus. Second, attention is paid to malnutrition, a major cause of mortality and morbidity in developing countries, which may be a cause of concern in Europe because of the increasing number of elderly people in the population. Finally, the role of diet during exercise, a condition of enormous substrate demands, is evaluated. Based on a critical evaluation of the existing knowledge in the literature, implications for future research in relation to functional foods are discussed.
Optimizing the use of electrophysiology in the diagnosis of chronic inflammatory demyelinating polyneuropathy: a study of 20 cases
Authors: Rajabally Yusuf A. , Jacob Saiju , Hbahbih Majed
Published: October 2005

Abstract  Current electrophysiologic criteria for chronic inflammatory demyelinating polyneuropathy (CIDP) are highly specific but poorly sensitive. The required extensiveness and best practical way of performing nerve conduction studies to achieve optimal sensitivity remain unknown. We here initially retrospectively analyzed the motor nerve conduction study results of 20 consecutive patients with a clinical diagnosis of CIDP (four performed prior to, and 16 after, treatment initiation) to assess the sensitivity of six published sets of criteria (Nicolas et al., 2002; Thaisetthawatkul et al., 2002; Ad Hoc Subcommittee of the American Academy of Neurology AIDS Taskforce, 1991; Magda et al., 2003; Hughes et al., 2001; Saperstein et al., 2001), as well as four combinations (Nicolas et al., 2002; Ad Hoc Subcommittee of the American Academy of Neurology AIDS Taskforce, 1991; Hughes et al., 2001; Saperstein et al., 2001, each individually combined with Thaisetthawatkul et al., 2002). Sensitivity was highest for the combination of Nicolas et al. (2002) and Thaisetthawatkul et al. (2002) (100%). We then determined the sensitivity of this combined criteria, using five different, hypothetical, nerve conduction study protocols, applied retrospectively to the neurophysiologic data of our 20 patients (exclusive upper limb studies with proximal stimulations; exclusive lower limb studies; full forearm and foreleg studies without proximal stimulations; right‐sided studies with proximal stimulations; and left‐sided studies with proximal stimulations). The findings showed that exhaustive upper limb or, alternatively, four‐limb forearm and foreleg testing would have proved considerably more sensitive than unilateral or lower limb studies to achieve an electrophysiologic diagnosis of CIDP.
Different expressions of BDNF, NT3, and NT4 in muscle and nerve after various types of peripheral nerve injuries
Authors: Omura Takao , Sano Michio , Omura Kumiko , Hasegawa Tomohiko , Doi Mitsuhito , Sawada Tomokazu , Nagano Akira
Published: October 2005

Abstract  The changes in the expression of brain‐derived neurotrophic factor (BDNF), neurotrophin‐3 (NT‐3), and neurotrophin‐4 (NT‐4) in the rat neuromuscular system as a result of three different types of sciatic nerve injuries have been evaluated. The changes in mRNA and protein levels for BDNF, NT‐3, and NT‐4 in the soleus muscle and sciatic nerve were assessed 4–28 days after sciatic nerve transection (neurotmesis), sciatic nerve crush (axonotmesis), and mild acute compression (neurapraxia). BDNF mRNA levels increased dramatically with nerve transection in the soleus muscle and the sciatic nerve 7–14 days after injury, whereas the changes were low in other types of injury. The changes of protein levels for BDNF were also similar. The mRNA and the protein levels of NT‐3 in the soleus muscle did not show any significant difference. The mRNA for NT‐4 in the soleus muscle decreased from 4 to 14 days after sciatic nerve transection, and the protein level was also minimum 14 days after sciatic nerve transection. Our results indicate that the neurotrophic factors in the neuromuscular system could play a role in differentiating peripheral nerve injury.
Patterns of P‐glycoprotein activity in the nervous system during vincristine‐induced neuropathy in rats
Authors: Balayssac David , Cayre Anne , Authier Nicolas , Bourdu Sophie , Penault‐Llorca Frederique , Gillet Jean Pierre , Maublant Jean , Eschalier Alain , Coudore François
Published: October 2005

Abstract  Vincristine (VCT) is a neurotoxic agent and also a substrate of multidrug resistance (MDR) transporters such as P‐glycoprotein (P‐gp) and MDR‐associated proteins 1 and 2 (MRP1 and MRP2). These proteins are expressed in the central and peripheral nervous systems (CNS and PNS) and normally protect these structures against the harmful effects of VCT. The aim of this study was to elucidate the paradoxical relation between the MDR transporters and the VCT neurotoxicity. With a validated rat model of VCT‐induced neuropathy, (1) the expressions of mdr1a (P‐gp), mdr1b (P‐gp), mrp1 (MRP1), and mrp2 (MRP2) genes were assessed by quantitative real‐time polymerase chain reaction, and (2) the transporter activity was monitored using a radioactive tracer, 99mTc‐sestamibi, in the CNS and PNS. The results showed higher expression of mdr1a and mdr1b genes (×3 and ×35, respectively) in the brain than in the spinal ganglia in both control and treated animals. Transporter activity was higher (×10) in the CNS than in the PNS. Hence, P‐gp protection may be lower in the PNS than in the CNS, and this may be responsible for the peripheral neurotoxicity of P‐gp substrates. VCT treatment increased expression of the mdr1a gene in the CNS and PNS (both ×1.7), mrp1 gene in the PNS (×1.7), and transporter activity in both the CNS and the PNS (×4 and ×8, respectively). This transporter induction may induce adverse effects when analgesic drugs are administered to treat neuropathic pain.
Agmatine treatment and vein graft reconstruction enhance recovery after experimental facial nerve injury
Authors: Berenholz Leonard , Segal Shmuel , Gilad Varda H. , Klein Collen , Yehezkeli Eyal , Eviatar Ephraim , Kessler Alex , Gilad Gad M.
Published: October 2005

Abstract The rate of nerve regeneration is a critical determinant of the degree of functional recovery after injury. Here, we sought to determine whether treatment with the neuroprotective compound, agmatine, with or without nerve reconstruction utilizing a regional autogenous vein graft would accelerate the rate of facial nerve regeneration. Experiments compared the following seven groups of adult male rats: (A) Intact untreated controls. (B) Sham operation with interruption of the nerve blood supply (controls). (C) Transection of the mandibular branch of the facial nerve (generating a gap of 3 mm) followed by saline treatment. (D) Nerve transection with unsutured autogenous vein (external jugular) graft reconstruction plus saline treatment. (E) Nerve transection with sutured vein graft approximation (coaptation of the proximal and distal nerve stumps) plus saline. (F) Nerve transection with sutured vein graft followed by agmatine treatment (four daily intraperitoneal injections of 100 mg/kg agmatine sulfate). (G) Nerve transection with unsutured vein graft followed by agmatine treatment. Functional recovery, as assessed by grading vibrissae movements and by recording nerve conduction velocity and numbers of regenerated axons, indicated that either vein reconstruction or agmatine treatment resulted in accelerated and more complete recovery as compared with controls. But best results were observed in animals that underwent combined treatment, i.e., vein reconstruction plus agmatine injection. We conclude that agmatine treatment can accelerate facial nerve regeneration and that agmatine treatment together with autogenous vein graft offers an advantageous alternative to other facial nerve reconstruction procedures.
Elevated CO2 reduces disease incidence and severity of a red maple fungal pathogen via changes in host physiology and leaf chemistry
Authors: Mcelrone Andrew J. , Reid Chantal D. , Hoye Katherine A. , Hart Elizabeth , Jackson Robert B.
Published: October 2005

Atmospheric CO2 concentrations are predicted to double within the next century. Despite this trend, the extent and mechanisms through which elevated CO2 affects plant diseases remain uncertain. In this study, we assessed how elevated CO2 affects a foliar fungal pathogen, Phyllosticta minima, of Acer rubrum growing in the understory at the Duke Forest free‐air CO2 enrichment experiment in Durham, North Carolina. Surveys of A. rubrum saplings in the 6th, 7th, and 8th years of the CO2 exposure revealed that elevated CO2 significantly reduced disease incidence, with 22%, 27%, and 8% fewer saplings and 14%, 4%, and 5% fewer leaves infected per plant in the three consecutive years, respectively. Elevated CO2 also significantly reduced disease severity in infected plants in all years (e.g. mean lesion area reduced 35%, 50%, and 10% in 2002, 2003, and 2004, respectively). To assess the mechanisms underlying these changes, we combined leaf structural, physiological and chemical analyses with growth chamber studies of P. minima growth and host infection. In vitro exponential growth rates of P. minima were enhanced by 17% under elevated CO2, discounting the possibility that disease reductions were because of direct negative effects of elevated CO2 on fungal performance. Scanning electron micrographs (SEM) verified that conidia germ tubes of P. minima infect A. rubrum leaves by entering through the stomata. While stomatal size and density were unchanged, stomatal conductance was reduced by 21–36% under elevated CO2, providing smaller openings for infecting germ tubes. Reduced disease severity under elevated CO2 was likely due to altered leaf chemistry and reduced nutritive quality; elevated CO2 reduced leaf N by 20% and increased the C : N ratio by 20%, total phenolics by 15%, and tannins by 14% (P<0.05 for each factor). The potential dual mechanism we describe here of reduced stomatal opening and altered leaf chemistry that results in reduced disease incidence and severity under elevated CO2 may be prevalent in many plant pathosystems where the pathogen targets the stomata.
The influence of landscape structure on occurrence, abundance and genetic diversity of the common frog, Rana temporaria
Authors: Johansson Markus , Primmer Craig R. , Sahlsten Jonas , Merilä Juha
Published: October 2005

Human‐caused habitat destruction and modification constitute one of the largest threats to population persistence and biodiversity, and are also suspected to be the major cause behind the global decline of amphibian populations. We assessed the potential role of agriculture‐related habitat fragmentation on population size and genetic variability in the common frog (Rana temporaria) by recording the occurrence, population density and genetic diversity in three geographically disparate regions in Sweden – each containing landscapes of high and low agricultural activity – and related these to landscape variables extracted from digital maps. We found a highly significant region‐by‐landscape interaction in occurrence, population density and genetic diversity revealing a reversed response to agriculture from south to north: while the effects of agriculture on R. temporaria populations were negative in the south, there were no effects in the central region, whereas positive effects were observed in the north. Spatial autocorrelation analyses of genetic data revealed that populations in high agricultural activity areas were more isolated than populations in low activity areas both in the southern and central regions of Sweden. Landscape diversity showed a strong positive correlation with both density and occurrence of frogs in Sweden as a whole, as well as in the southern region. Also, negative effects of roads and positive effects of ditches on genetic diversity were found in the south. Overall, these results suggest clear but regionally opposite effects of habitat structure on the population size and genetic diversity of amphibian populations. This means that the management strategy aiming to maximize the size and genetic diversity of local common frog populations, and perhaps also those of other amphibian populations, should account for regional differences in existing land‐use patterns.
Case studies: orthopaedic surgery in adult patients with haemophilia A with inhibitors
Authors: GODDARD N.
Published: October 2005

Summary.  Whilst orthopaedic surgery in haemophilia patients without inhibitors is now relatively common in specialized centres, until recently there have been only a few sporadic instances of surgery having been undertaken on patients with inhibitors. The availability of recombinant activated factor VII (rFVIIa) for haemostatic cover during surgery allows procedures to be performed that previously may not have been considered possible. Complications associated with thrombosis are rare in haemophilia patients with inhibitors, but bleeding complications remain a concern. Globally, experience of performing orthopaedic surgery in these patients is increasing and many successful outcomes have been reported. However, more knowledge relating to the incidence and type of bleeding complications liable to be encountered, together with further information about appropriate rescue treatment, would be valuable. Data relating to long‐term follow‐up after surgery would be useful, as would a comparison of outcomes between haemophilia patients with and without inhibitors. Optimal dosing regimens for rFVIIa as surgical cover are still to be determined and further information is required relating to the cost effectiveness of rFVIIa in surgery. Further study should address these issues.
Managing acute bleeds in the patient with haemophilia and inhibitors: options, efficacy and safety
Authors: VON DEPKA M.
Published: October 2005

Summary.  The options available for treating the patient with haemophilia and inhibitors undergoing surgery or with other acute bleeds include high‐dose factor VIII (FVIII) (human or porcine), prothrombin complex concentrates (PCCs), activated PCCs (aPCCs), recombinant activated factor VII (rFVIIa), and factor replacement combined with immunoadsorption or immunosuppression. Human FVIII is effective in patients with low‐titre inhibitors. Porcine FVIII is currently not available, and PCCs and aPCCs, although effective, have been associated with a high incidence of adverse events. Immunoadsorption and immunosuppression offer excellent long‐term solutions, but the duration of these techniques makes them less attractive for use in acute settings. Recombinant FVIIa has demonstrated excellent efficacy and safety, even in patients refractory to other therapies.
Relationship between SPRY and B30.2 protein domains. Evolution of a component of immune defence?
Authors: Rhodes David A. , De Bono Bernard , Trowsdale John
Published: October 2005

SPRY and B30.2 are homologous domains which can be identified in 11 protein families encoded in the human genome. These include cell surface receptors of the immunoglobulin super‐family (BTNs), negative regulators of the JAK/STAT pathway (SOCS‐box SSB1–4) and proteins encoded by the numerous TRIM genes. Collectively, proteins containing SPRY and B30.2 domains cover a wide range of functions, including regulation of cytokine signalling (SOCS), RNA metabolism (DDX1, hnRNPs), intracellular calcium release (RyR receptors), immunity to retroviruses (TRIM5alpha) as well as regulatory and developmental processes (HERC1, Ash2L). In order to clarify the evolutionary relationship between the two domains, we compiled a curated database of SPRY and B30.2‐domain sequences. We show that while SPRY domains are evolutionarily ancient, B30.2 domains, found in BTN and TRIM proteins, are a more recent evolutionary adaptation, comprising the combination of SPRY with an additional domain, PRY. The combination of SPRY and PRY to produce B30.2 domains may have been selected and maintained as a component of immune defence.
Selective inhibition by rottlerin of macropinocytosis in monocyte‐derived dendritic cells
Authors: Sarkar Kakali , Kruhlak Michael J. , Erlandsen Stanley L. , Shaw Stephen
Published: October 2005

We present here the analysis of fluid‐phase endocytosis (FPE) in human blood monocytes and monocyte‐derived dendritic cells (MDDC) facilitated by our serendipitous identification of rottlerin as an efficient inhibitor of dendritic cell FPE (IC50 of 0·4 µM). Rottlerin was found to be an excellent tool for FPE analysis: rapid‐acting, irreversible and selective for FPE (as opposed to receptor‐mediated endocytosis) at concentrations of 3 µM and below. The inhibitory effect was not due to toxicity or visible change in membrane ruffles, but affects on cytoskeletal reorganization were evident in MDDC treated with relevant rottlerin concentrations during adhesion. A marked increase in FPE was observed in 1 hr interleukin (IL)‐4 and granulocyte macrophage‐colony stimulating factor (GM‐CSF)‐stimulated monocytes. Moreover, rottlerin inhibited the augmented FPE of 1‐day cytokine treated monocytes and their augmented ability to induce T cell proliferative responses to tetanus toxoid. We conclude that rottlerin is a useful tool for investigating FPE and its functional importance.
NK cell activity in tuberculosis is associated with impaired CD11a and ICAM‐1 expression: a regulatory role of monocytes in NK activation
Authors: Schierloh Pablo , Alemán Mercedes , Yokobori Noemí , Alves Leandro , Roldán Nicolás , Abbate Eduardo , Sasiain María del C. , De La Barrera Silvia
Published: October 2005

Although the role of natural killer (NK) cells in mycobacterial infections is unclear, it has been postulated that they contribute to protective immunity through the production of interferon (IFN)‐γ. In this study, we evaluate the effect of interleukin (IL)‐10, IL‐15 and IL‐18 on NK lytic activity through the expression of CD16, CD11a and CD69 molecules and the induction of IFN‐γ production in patients with tuberculosis (TB) and healthy individuals (N). Our results showed an impairment of NK lytic activity and a gradual down‐regulation of costimulatory and adhesion molecules on NK cells which were dependent on the severity of the disease. NK lytic activity was increased by exogenous IL‐15 and IL‐18 in both TB and N, and by neutralization of endogenous IL‐10 only in TB; IL‐15 and IL‐18 increased CD69 receptor expression, while anti‐IL‐10 up‐regulated CD16 and CD11a expression in TB. Mycobacterium tuberculosis reduced the number of intracellular adhesion molecule (ICAM)‐1+ CD14+ cells, but in the presence of IL‐15, IL‐18 and anti‐IL‐10 its expression was up‐regulated. In cells from TB patients, the observed effects of IL‐15 and IL‐18 on NK function were not dependent on IL‐10 modulation of the surface expression of activator/adhesion molecules. In the absence of monocytes, IL‐10 activated NK cells, suggesting an indirect effect on their function. Furthermore, in TB patients the depletion of monocytes increased the production of IFN‐γ by NK cells. Therefore, monocytes from TB patients regulated the NK function involving IL‐10 which, through an indirect mechanism, led to the down‐regulation of costimulatory/adhesion molecules and/or IFN‐γ production.
Augmented induction of CD8+ cytotoxic T‐cell response and antitumour resistance by T helper type 1‐inducing peptide
Authors: Kikuchi Takeshi , Uehara Shuichiro , Ariga Haruyuki , Tokunaga Takeshi , Kariyone Ai , Tamura Toshiki , Takatsu Kiyoshi
Published: October 2005

The effector CD8+ T cells recognize major histocompatibility complex (MHC) class I binding altered self‐peptides expressed in tumour cells. Although the requirement for CD4+ T helper type 1 (Th1) cells in regulating CD8+ T cells has been documented, their target epitopes and functional impact in antitumour responses remain unclear. We examined whether a potent immunogenic peptide of Mycobacterium tuberculosis eliciting Th1 immunity contributes to the generation of CD8+ T cells and to protective antitumour immune responses to unrelated tumour‐specific antigens. Peptide‐25, a major Th epitope of Ag85B from M. tuberculosis preferentially induced CD4+ Th1 cells in C57BL/6 mice and had an augmenting effect on Th1 generation for coimmunized unrelated antigenic peptides. Coimmunization of mice with Peptide‐25 and ovalbumin (OVA) or Peptide‐25 and B16 melanoma peptide [tyrosinase‐related protein‐2 (TRP‐2)] for MHC class I led to a profound increase in CD8+ T cells specific for OVA and TRP‐2 peptides, respectively. This heightened response depended on Peptide‐25‐specific CD4+ T cells and interferon‐γ‐producing T cells. In tumour protection assays, immunization with Peptide‐25 and OVA resulted in the enhancement of CD8+ cytotoxic cell generation specific for OVA and the growth inhibition of EL‐4 thymoma expressing OVA peptide leading to the tumour rejection. These phenomena were not achieved by immunization with OVA alone. Peptide‐25‐reactive Th1 cells counteractivated dendritic cells in the presence of Peptide‐25 leading them to activate and present OVA peptide to CD8+ cytotoxic T cells.
Salmonella porins induce a sustained, lifelong specific bactericidal antibody memory response
Authors: Secundino Ismael , López‐Macías Constantino , Cervantes‐Barragán Luisa , Gil‐Cruz Cristina , Ríos‐Sarabia Nora , Pastelin‐Palacios Rodolfo , Villasis‐Keever Miguel Angel , Becker Ingeborg , Puente José Luis , Calva Edmundo , Isibasi Armando
Published: October 2005

We examined the ability of porins from Salmonella enterica serovar typhi to induce a long‐term antibody response in BALB/c mice. These porins triggered a strong lifelong production of immunoglobulin G (IgG) antibody in the absence of exogenous adjuvant. Analysis of the IgG subclasses produced during this antibody response revealed the presence of the subclasses IgG2b, IgG1, IgG2a and weak IgG3. Despite the high homology of porins, the long‐lasting anti‐S. typhi porin sera did not cross‐react with S. typhimurium. Notably, the antiporin sera showed a sustained lifelong bactericidal‐binding activity to the wild‐type S. typhi strain, whereas porin‐specific antibody titres measured by enzyme‐linked immunosorbent assay (ELISA) decreased with time. Because our porin preparations contained the outer membrane proteins C and F (OmpC and OmpF), we evaluated the individual contribution of each porin to the long‐lasting antibody response. OmpC and OmpF induced long‐lasting antibody titres, measured by ELISA, which were sustained for 300 days. In contrast, although OmpC induced sustained high bactericidal antibody titres for 300 days, postimmunization, the bactericidal antibody titre induced by OmpF was not detected at day 180. These results indicate that OmpC is the main protein responsible for the antibody‐mediated memory bactericidal response induced by porins. Taken together, our results show that porins are strong immunogens that confer lifelong specific bactericidal antibody responses in the absence of added adjuvant.
Two different polyketide synthase genes are required for synthesis of zearalenone in Gibberella zeae
Authors: Kim Yong‐Tae , Lee Ye‐Ryun , Jin Jianming , Han Kap‐Hoon , Kim Hun , Kim Jin‐Cheol , Lee Theresa , Yun Sung‐Hwan , Lee Yin‐Won
Published: October 2005

Zearalenone (ZEA) is a polyketide mycotoxin produced by some species of Gibberella/Fusarium and causes hyperestrogenic syndrome in animals. ZEA occurs naturally in cereals infected by Gibberella zeae in temperate regions and threatens animal health. In this study, we report on a set of genes that participate in the biosynthesis of ZEA in G. zeae. Focusing on the non‐reducing polyketide synthase (PKS) genes of the G. zeae genome, we demonstrated that PKS13 is required for ZEA production. Subsequent analyses revealed that a continuous, 50 kb segment of DNA carrying PKS13 consisted of three additional open reading frames that were coexpressed as a cluster during the condition for ZEA biosynthesis. These genes, in addition to PKS13, were essential for the ZEA biosynthesis. They include another PKS gene (PKS4) encoding a fungal reducing PKS; zearalenone biosynthesis gene 1 (ZEB1), which shows a high similarity to putative isoamyl alcohol oxidase genes; and ZEB2 whose deduced product carries a conserved, basic‐region leucine zipper domain. ZEB1 is responsible for the chemical conversion of β‐zearalenonol (β‐ZOL) to ZEA in the biosynthetic pathway, and ZEB2 controls transcription of the cluster members. Transcription of these genes was strongly influenced by different culture conditions such as nutrient starvations and ambient pH. Furthermore, the same set of genes regulated by ZEB2 was dramatically repressed in the transgenic G. zeae strain with the deletion of PKS13 or PKS4 but not in the ZEB1 deletion strain, suggesting that ZEA or β‐ZOL may be involved in transcriptional activation of the gene cluster required for ZEA biosynthesis in G. zeae. This is the first published report on the molecular characterization of genes required for ZEA biosynthesis.
RepB protein of an Agrobacterium tumefaciens Ti plasmid binds to two adjacent sites between repA and repB for plasmid partitioning and autorepression
Authors: Chai Yunrong , Winans Stephen C.
Published: October 2005

Plasmids of Agrobacterium tumefaciens replicate using the products of the repABC operon, which are highly conserved among plasmids and some chromosomes of the alpha‐Proteobacteria. The products of repA and repB direct plasmid partitioning, while the repC gene encodes a replication initiator protein. The transcription of the repABC operon of tumour inducing (Ti) plasmids is both negatively autoregulated by the RepA and RepB proteins, and positively regulated by TraR. In the present study, we have identified a fourth gene (repD) in the repABC operon of an octopine‐type Ti plasmid. repD is 78 codons in length, and maps between repA and repB genes. A repD–lacZ protein fusion demonstrated that repD is strongly expressed. Two identical binding sites for the RepB protein were found within the repD coding sequence, and these sites are required for plasmid stability and for maximal repression of repABC transcription. RepA protein enhances the binding of RepB at these binding sites, just as RepB increases the affinity of RepA for binding sites at the repABC P4 promoter. We propose that RepA and RepB form complexes that bind both sites, possibly causing a loop that is important for repression of the repABC operon. Binding at one or both sites may also be required for accurate plasmid partitioning.
Genesis of large siliceous stromatolites at Frying Pan Lake, Waimangu geothermal field, North Island, New Zealand
Authors: JONES BRIAN , RENAUT ROBIN W. , KONHAUSER KURT O.
Published: October 2005

Lilypad stromatolites, up to 3 m long and 1·5 m wide, were found to be actively growing in the shallow marginal waters of Frying Pan Lake and its outflow channel. These stromatolites, composed of Phormidium (> 90%), Fischerella, and a variety of other microbes, develop through a series of distinct growth stages. Dark green microbial mats cover the floor of the outflow channel and give rise to columns of various sizes and shapes in the shallower marginal waters. Once the columns reach the water level, the mats spread laterally to form a lilypad stromatolite. The lilypads are characterized by a raised, dark green rim, 4–5 mm high, that encircles a flat interior covered with a distinctive orange‐red mat. The microbes forming the columns and lilypad plate are being actively silicified. The stromatolites are formed of: (i) flat‐lying Phormidium filaments (P‐laminae), (ii) upright filaments of Phormidium that are commonly associated with Fischerella (U‐laminae), and (iii) mucus, diatoms and pyrite framboids (M‐laminae). P‐laminae dominate most of the columns, with tripartite cycles of P‐, U‐, to M‐laminae being found mostly in the upper parts of the stromatolites. The transition from the P‐ to U‐laminae is marked by a change in the growth pattern of the Phormidium and branching of Fischerella, which was probably triggered by a change in environmental conditions. In the Frying Pan Lake outflow channel, this change may be related to fluctuations in water level and flow rates that are caused by periods of heavy rain, seasonal changes, long‐term variations in rainfall, and/or the unique 40‐day hydrological cycle that exists between Frying Pan Lake and Inferno Crater, which is a nearby hydrothermal crater lake.
Tissue‐specific expression of stabilized SOLITARY‐ROOT/IAA14 alters lateral root development in Arabidopsis
Authors: Fukaki Hidehiro , Nakao Yoko , Okushima Yoko , Theologis Athanasios , Tasaka Masao
Published: October 2005

Auxin is important for lateral root (LR) initiation and subsequent LR primordium development. However, the roles of tissue‐specific auxin signaling in these processes are poorly understood. We analyzed transgenic Arabidopsis plants expressing the stabilized mutant INDOLE‐3 ACETIC ACID 14 (IAA14)/SOLITARY‐ROOT (mIAA14) protein as a repressor of the auxin response factors (ARFs), under the control of tissue‐specific promoters. We showed that plants expressing the mIAA14‐glucocorticoid receptor (GR) fusion protein under the control of the native IAA14 promoter had the solitary‐root/iaa14 mutant phenotypes, including the lack of LR formation under dexamethasone (Dex) treatment, indicating that mIAA14‐GR is functional in the presence of Dex. We then demonstrated that expression of mIAA14‐GR under the control of the stele‐specific SHORT‐ROOT promoter suppressed LR formation, and showed that mIAA14‐GR expression in the protoxylem‐adjacent pericycle also blocked LR formation, indicating that the normal auxin response mediated by auxin/indole‐3 acetic acid (Aux/IAA) signaling in the protoxylem pericycle is necessary for LR formation. In addition, we demonstrated that expression of mIAA14‐GR under either the ARF7 or the ARF19 promoter also suppressed LR formation as in the arf7 arf19 double mutants, and that IAA14 interacted with ARF7 and ARF19 in yeasts. These results strongly suggest that mIAA14‐GR directly inactivates ARF7/ARF19 functions, thereby blocking LR formation. Post‐embryonic expression of mIAA14‐GR under the SCARECROW promoter, which is expressed in the specific cell lineage during LR primordium formation, caused disorganized LR development. This indicates that normal auxin signaling in LR primordia, which involves the unknown ARFs and Aux/IAAs, is necessary for the establishment of LR primordium organization. Thus, our data show that tissue‐specific expression of a stabilized Aux/IAA protein allows analysis of tissue‐specific auxin responses in LR development by inactivating ARF functions.