bluuebunny/crossref_metadata_2025 huggingface dataset:
Textural Characterisation of Iron-Promoted Raney Nickel Catalysts Synthesised by Mechanical Alloying
Authors: Salmones J. , Zeifert B. , Cabañas-Moreno J.G. , Aguilar-Rios G. , Rojas F. , Ramirez-Cuesta A.J.
Published: October 2002

Mesoporous binary AlxNiy and ternary AlxNiyFez Raney-type catalysts were synthesised by a two-step procedure involving two main processes, i.e. (i) mechanical metal alloying and (ii) alkaline aluminium leaching. Pure metallic powders of Al, Ni and Fe (if required) were first mechanically alloyed in an attrition mill and then subjected to KOH leaching to selectively remove part of the aluminium atoms. After a slow drying process, a fine, nanostructured slit-shaped material was obtained. Substrate characterisation involved studies by atomic absorption (AA), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS) in the SEM and nitrogen physisorption. An intermetallic β- or B2-(AlNi) phase with a metastable bcc crystalline structure was formed as a non-equilibrium phase after the metal alloying process. Because of aluminium removal, the β-(AlNi) phase was transformed into the more stable nickel fcc structure. In this work, some important physico-chemical properties of binary (Al–Ni) and ternary (Al–Ni–Fe) catalysts, with especial attention to textural properties adduced from nitrogen physisorption, are presented and discussed.
A New Approach to Seismic Isolation: Possible Application in Space Structures
Authors: Tatemichi Ikuo , Kawaguchi Mamoru
Published: October 2002

Pendulum is one of the basic methods of seismic isolation. In this paper, full-scale tests using a floor isolated by a pendulum system, model tests of paddle isolators, and analytical studies on pendulum isolators applied in high-rise buildings and space structures were described. Isolating device with long period such as 4 second may be realized in a relatively simple way if pendulum isolators are used. Also clarified was that when pendulum isolators are adopted in space structures, they would reduce vertical response induced by input horizontal load quite efficiently.
Form Finding and Analysis of Tension Structures by Dynamic Relaxation
Authors: Barnes Michael R.
Published: October 2002

The paper describes numerical procedures, based on the method of dynamic relaxation with kinetic damping, for the form finding, analysis and fabrication patterning of wide-span cable nets and grid shells, uniform or variably prestressed fabric membranes and battened membrane roofs. The historical development of the method is briefly reviewed and a full description is then given which accounts for cable or strut elements, membrane elements and spline beam elements. All of these elements are implemented in their natural stiffness form allowing for gross geometrical and material non-linearities, with automatic controls to ensure stablility and convergence of the method.
Feasibility Study of a Wind-Powered Pumped-Storage Hydroelectric System
Authors: Cheng Edmond D. H.
Published: October 2002

To provide a realistic basis of determining the viability of a wind-powered pumped-storage hydroelectric system at a potential site, an evaluation technique has been developed to determine the ideal combination of models and quantities of various wind energy conversion systems under consideration. Basically, this approach uses a synthesized wind speed time series to simulate the operation of a wind-powered pumped-storage hydroelectric system at a potential wind farm. An application of this approach is presented.
Wind farm Planning Evaluation: Case Study in Sardinia Combining Engineering, Community and Landscape Requirements
Authors: Delitala A. , Marini M. , Satta A. , Spanedda F.
Published: October 2002

The present study reviews for Planners a procedure for developing a wind farm, starting from consideration of wind features and site morphology, and progressing to costs and environmental constraints. The procedure is applied to a test case in Sardinia.
Blade and Shaft Crack Detection Using Torsional Vibration Measurements Part 2: Resampling to Improve Effective Dynamic Range
Authors: Maynard Kenneth P. , Trethewey Martin
Published: October 2002

The primary goal of the development project was to demonstrate the feasibility of detecting changes in blade bending natural frequencies (such as those associated with a blade crack) on a turbine using non-contact, non-intrusive measurement methods. The approach was to set up a small experimental apparatus, develop a torsional vibration detection system, and maximize the dynamic range and the signal to noise ratio. The results of the testing and analysis clearly demonstrated the feasibility of using torsional vibration to detect the change in natural frequency of a blade due to a change in stiffness such as those associated with a blade crack. However, it was found that harmonics of shaft operating speed, created as an unwanted artifact of the measurement method, resulted in spectral regions in which the effective dynamic range was inadequate to detect low-level torsional vibration associated with the natural frequencies. The loss of effective dynamic range was due to the “skirts” created by the sampling window. Application of order resampling, followed by frequency resampling, to the torsional vibration waveform increased the effective dynamic range and improved the ability to identify shaft torsional and blade bending natural frequencies.
Contributions to the Climate Change Debate
Authors: Mathieson Mikel
Published: October 2002

The greenhouse hypothesis, the reasons for the present global warming and the merits of the Kyoto Protocol are subject to heated debate. Whereas some question what bizarre relations between science and government have allowed politicians to treat a highly controversial hypothesis as though it were proven, others supply the public and the politicians with what appears akin to propaganda in the name of science.
An Assessment of Validation Experiments Conducted on Computer Models of Global Climate Using the General Circulation Model of the UK'S Hadley Centre
Authors: Courtney Richard S
Published: October 2002

The Intergovernmental Panel on Climate Change (IPCC) has accepted that output from the Hadley Centre transient climate model is “evidence” that man-made global warming is occurring. This paper explains that the model output only indicates that the Hadley Centre climate model does not emulate climate changes in the real world. The IPCC and the Hadley Centre have presented the GCM model's input data as being its output. This proclamation is not true and contravenes the principle of science that hypothesis are tested against observed data.
Sound Transmission Loss of Thick Perforated Panels
Authors: Chen K. T. , Jan S. H.
Published: October 2002

A study is reported of the sound transmission loss of perforated panels. The study includes a theoretical analysis and measurement by means of sound intensity.

The predicted transmission loss is similar to that measured above 630 Hz. The maximum discrepancy is less than 2 dB. The perforation in a thick panel is found to reduce the coincidence effect at the critical frequency.
Control of Acoustical Quality of Indoor Spaces: Thorough Analysis of the Influence of Façade Typologies
Authors: Barbaro Salvatore , Caracausi Rosario , Rapin Jean Marie
Published: October 2002

Building shape is of prime importance with regard to the acoustic aspects of achieving adequate indoor environmental quality. This paper presents experimental results obtained in a measurement programme carried out at CSTB, using reduced-scale models. The objectives were to identify the architectural forms of façades' best for noise mitigation, and to address the influence of façade architecture on indoor acoustic quality. Many façade typologies have been assessed in different situations involving combinations of structural and architectural elements, such as balustrades, balconies, loggias, etc. A systematic simulation of real configurations (buildings in front of one another, stacked or contiguous rooms, L or U buildings, etc.) contributes to developing our knowledge of sound propagation and insulation effects for improvement of urban dwellings.
Vibration and Sound Radiation from Plates Excited by Piezoelectric Actuators
Authors: Chong F. , Lee Y. Y. , Ng C. F.
Published: October 2002

Theoretical analysis of the vibration of plates excited by piezoelectric actuators is presented in this paper. The geometric non-linear finite element model and the loading model of the piezoelectric actuators were developed for non-linear analysis. It is found that non-linear analysis is more accurate than linear analysis for large displacement vibration. A comparison of the results of the numerical model with experiment results shows that the numerical model and the computer program are correct. The vibration excited by piezoelectric actuators is also compared with the sound radiation generated by actuators.
Prediction of the Reduction of Impact Vibration in Raised Access Floors
Authors: Chiang C. M. , Lin F. M. , Chung S. C. , Chung C. M.
Published: October 2002

This study describes a prediction model for the impact vibration of raised access floors by a Finite Element Method (FEM) numerical analysis. The residual ratio of the natural frequency of the peak wave is 1.3% and the residual ratio of the maximum vibration acceleration is 0.8%, which indicates the accuracy in application of the numerical model. With the validated numerical model, this study evaluates the influence on the vibration of various construction parameters. It is shown that the panel material, bracing, and panel thickness may reduce the impact vibration.
Case Study of Building Diagnostics: Acoustic Post-Occupancy Evaluation of Buildings in Tropical Climates
Authors: Ribeiro M. , Kortchmar L. , Slama J. G.
Published: October 2002

A re-examination of traditional procedures for evaluation of occupied buildings, marrying objective evaluation and subjective judgement of acoustic quality, has pointed to a wide range of areas where architectural planning could be improved. Systematic methods were used to assess acoustical problems: interviews, technical observation, objective measurements, and computer simulation. From an extensive report of the findings, some results of a survey in Rio de Janeiro, a typical tropical region in Brazil, are highlighted. Data obtained from the reaction to environmental noise and those related to building acoustics are considered. The results underscore the importance of adequate architectural planning in regard to climate conditions and particular social-cultural and economic characteristics.
Inter-Laboratory Test of Sound Insulation Measurements on Heavy Walls: Part II — Results of Main Test
Authors: Meier A. , Schmitz A. , Raabe G.
Published: October 2002

This second part, of a two part paper, presents and analyses the results of an Inter-Laboratory Test (ILT) for a heavy single leaf wall. Significant differences were found in the measured sound reduction index (SRI) for the participating laboratories. These differences were not caused by the measurement technique. During the ILT the damping of the test wall in terms of the total loss factor in each laboratory was measured in addition to other measurements.

The damping of the test element was controlled by the design of the transmission suite supporting walls. It is shown that the results of the damping measurements can be used to reduce the variations of SRI. Other influences of the transmission suite such as flanking transmission are also discussed. It is found that the principle reason for the differences in the sound reduction index is the type of construction of the transmission suite.

From this study suggestions for the improvement in the reliability of sound insulation measurements are given, which could provide improvements in standardisation.
An Investigation into the Reproducibility Values of the European Inter-Laboratory Test for Lightweight Walls
Authors: Smith R.S. , Pompoli R. , Fausti P.
Published: October 2002

In an inter-laboratory test programme (ILT) for the measurement of airborne sound insulation of lightweight walls, reproducibility values of up to 12dB were obtained from the sound reduction index measured in 21 participating laboratories. These high reproducibility values were for a test structure composed of lightweight plasterboard panels, forming a double wall, mounted on separate metal ‘C’ channels.

This paper presents possible reasons for the large reproducibility values for the double wall using experimental investigations and theoretical models using Statistical Energy Analysis (SEA). Whilst the sound reduction index(SRI) does take into account the different test wall areas and reverberation times of the respective laboratories involved, some factors which may influence the measured SRI values are not.

It is suggested that the principle factor which may have effected the SRI values of this test programme for the double wall was the lining material of the test aperture in the various laboratories which can provide a flanking transmission path between both sides of the double wall. Other factors are discussed which may also play a contributory role in causing differences in the measured SRI values such as sill/reveal size, aspect ratio, panel-channel connections and workmanship.
Development of Generalised Boundary Conditions for the Buckling of Composite Panel
Authors: Khong P.W.
Published: October 2002

This paper gives details of theoretical investigations into the buckling behaviour of uniformly compressed rectangular composite panel with the two unloaded edges elastically restrained. The theoretical elastic buckling analysis employs a semi-numerical approach, the finite strip method. This general method of approach is to postulate a fifth degree polynomial function which describe the buckled form of the panel. Based on the principle of minimum potential energy, the strain energies of the restraining medium along the unloaded edges are evaluated in term of matrix form. This elastic restraint stiffness matrix can be added directly onto the existing stiffness matrix. To utilize the Rayleigh-Ritz method, coefficients in the deflection series are evaluated. Hence the elastic buckling stiffness of the composite panel are obtained.
Parametric Study of Tendon Profiles in Prestressed Steel Plate Girder
Authors: Ronghe G. N. , Gupta L. M.
Published: October 2002

The concept of prestressing steel structures has only recently been widely considered, despite a long and successful history of prestressing concrete members. Several analytical studies of prestressed steel plate girder were reported in the literature, but much of that work was not studied with reference to different parameters like tendon profile, eccentricity, partial span to full span ratio, prestressing force, load carrying capacity etc. associated with prestressing.

This paper examines analytically a comparative study of various tendon configurations and prestressing parameters on over all analysis and design of prestressed steel plate girder. The output from the computer Program for analysis and design of steel plate girder prestressed with different tendon configurations are compared among each other. As a Case-study, a prototype model of Prestressed Steel Testing Frame with straight tendon has been designed, constructed and tested in the laboratory for its safe load carrying capacity and maximum deflection.
Inhibition by acharan sulphate of angiogenesis in experimental inflammation models
Authors: Ghosh Ajoy Kumar , Hirasawa Noriyasu , Lee Yeon Sil , Kim Yeong Sik , Shin Kuk Hyun , Ryu Nama , Ohuchi Kazuo
Published: October 2002

The effects of acharan sulphate, a glycosaminoglycan isolated from the giant African snail Achatina fulica, on angiogenesis in the granulation tissue were analysed using an air pouch‐type carrageenin‐induced inflammation model in rats and a cotton thread‐induced inflammation model in mice.

In the carrageenin‐induced inflammation model in rats, intra‐pouch injections of acharan sulphate (5 and 50 μg) inhibited the pouch fluid accumulation and the granulation tissue formation as well as the angiogenesis in the granulation tissue at day 6 in a dose‐dependent manner.

The inhibitory effects of acharan sulphate at 50 μg on the pouch fluid accumulation and the leucocyte infiltration into the pouch fluid was not so effective as that of the cyclo‐oxygenase inhibitor indomethacin at 100 μg, but the inhibitory effects of acharan sulphate at 50 μg on the granulation tissue formation and angiogenesis in the granulation tissue were almost the same as those of indomethacin at 100 μg.

Acharan sulphate did not affect levels of vascular endothelial growth factor (VEGF) in the granulation tissue and in the pouch fluid at day 6, but indomethacin significantly lowered them.

In the cotton thread‐induced inflammation model in mice, injections of acharan sulphate (10 μg) at the site of the cotton thread implantation inhibited the granulation tissue formation and angiogenesis as indomethacin (20 μg) did. Acharan sulphate (10 μg) did not affect levels of VEGF in the cotton thread‐induced granulation tissue at day 5, but indomethacin (20 μg) significantly lowered them.

In culture of human vascular endothelial cells, acharan sulphate at 10 and 100 μg ml−1 inhibited VEGF‐induced capillary tube formation.

These findings suggest that the inhibitory effect of acharan sulphate on angiogenesis in carrageenin‐ and cotton thread‐induced granulation tissues is not due to the inhibition of VEGF protein induction, but is due to the inhibition of VEGF‐induced vascular tube formation.

British Journal of Pharmacology (2002) 137, 441–448. doi:10.1038/sj.bjp.0704886
Presynaptic internal Ca2+ stores contribute to inhibitory neurotransmitter release onto mouse cerebellar Purkinje cells
Authors: Bardo Scott , Robertson Brian , Stephens Gary J
Published: October 2002

Miniature inhibitory postsynaptic currents (mIPSCs) were recorded in mouse Purkinje cells in the presence of 1 μM tetrodotoxin (TTX). Under these conditions, which eliminated Ca2+ influx through voltage‐dependent Ca2+ channels (VDCCs), the contribution of Ca2+ stores to spontaneous GABA release was examined.

The plant alkaloid ryanodine acts as an inhibitor of endoplasmic reticulum ryanodine‐sensitive Ca2+ release channels (ryanodine receptors) at low micromolar concentrations. Ryanodine effects were confined to a subpopulation of cells tested. At 10 μM ryanodine, 4/12 cells showed a significant increase in mean mIPSC frequency of +19.6±4.0% (n=4).

The sarco/endoplasmic reticulum Ca2+‐ATPase (SERCA) pump inhibitor cyclopiazonic acid (CPA) produced a more robust effect. In 8/10 cells, 25 μM CPA caused a significant increase in mean mIPSC frequency; the mean increase being +26.0±3.0% (n=8). Similar results were seen with thapsigargin (1–2 μM), another SERCA pump inhibitor.

Ruthenium red (RuR) has been proposed to either act directly on the release machinery or block Ca2+ pumps on internal stores. At 10 μM RuR, all cells showed a rapid, large increase in mean mIPSC frequency of +90.4±16.4% (n=9). This increase was greater than that seen by agents known to modulate Ca2+ stores and was more consistent with a direct action. At this concentration, RuR also occluded the effects of CPA.

For all reagents, there were no obvious effects on mean mIPSC amplitude. However, the effects on mIPSC frequency were consistent with a presynaptic action and indicate that Ca2+ stores may contribute to spontaneous GABA release onto mouse Purkinje cells.

British Journal of Pharmacology (2002) 137, 529–537. doi:10.1038/sj.bjp.0704901
Significance and statistical errors in the analysis of DNA microarray data
Authors: Brody James P. , Williams Brian A. , Wold Barbara J. , Quake Stephen R.
Published: October 2002

DNA microarrays are important devices for high throughput measurements of gene expression, but no rational foundation has been established for understanding the sources of within-chip statistical error. We designed a specialized chip and protocol to investigate the distribution and magnitude of within-chip errors and discovered that, as expected from theoretical expectations, measurement errors follow a Lorentzian-like distribution, which explains the widely observed but unexplained ill-reproducibility in microarray data. Using this specially designed chip, we examined a data set of repeated measurements to extract estimates of the distribution and magnitude of statistical errors in DNA microarray measurements. Using the common “ratio of medians” method, we find that the measurements follow a Lorentzian-like distribution, which is problematic for subsequent analysis. We show that a method of analysis dubbed ”median of ratios“ yields a more Gaussian-like distribution of errors. Finally, we show that the bootstrap algorithm can be used to extract the best estimates of the error in the measurement. Quantifying the statistical error in such measurements has important applications for estimating significance levels, clustering algorithms, and process optimization.
Parallel processing of serial movements in prefrontal cortex
Authors: Averbeck Bruno B. , Chafee Matthew V. , Crowe David A. , Georgopoulos Apostolos P.
Published: October 2002

A key idea in Lashley's formulation of the problem of serial order in behavior is the postulated neural representation of all serial elements before the action begins. We studied this question by recording the activity of individual neurons simultaneously in small ensembles in prefrontal cortex while monkeys copied geometrical shapes shown on a screen. Monkeys drew the shapes as sequences of movement segments, and these segments were associated with distinct patterns of neuronal ensemble activity. Here we show that these patterns were present during the time preceding the actual drawing. The rank of the strength of representation of a segment in the neuronal population during this time, as assessed by discriminant analysis, predicted the serial position of the segment in the motor sequence. An analysis of errors in copying and their neural correlates supplied additional evidence for this code and provided a neural basis for Lashley's hypothesis that errors in motor sequences would be most likely to occur when executing elements that had prior representations of nearly equal strength.
Diversity, topographic differentiation, and positional memory in human fibroblasts
Authors: Chang Howard Y. , Chi Jen-Tsan , Dudoit Sandrine , Bondre Chanda , van de Rijn Matt , Botstein David , Brown Patrick O.
Published: October 2002

A fundamental feature of the architecture and functional design of vertebrate animals is a stroma, composed of extracellular matrix and mesenchymal cells, which provides a structural scaffold and conduit for blood and lymphatic vessels, nerves, and leukocytes. Reciprocal interactions between mesenchymal and epithelial cells are known to play a critical role in orchestrating the development and morphogenesis of tissues and organs, but the roles played by specific stromal cells in controlling the design and function of tissues remain poorly understood. The principal cells of stromal tissue are called fibroblasts, a catch-all designation that belies their diversity. We characterized genome-wide patterns of gene expression in cultured fetal and adult human fibroblasts derived from skin at different anatomical sites. Fibroblasts from each site displayed distinct and characteristic transcriptional patterns, suggesting that fibroblasts at different locations in the body should be considered distinct differentiated cell types. Notable groups of differentially expressed genes included some implicated in extracellular matrix synthesis, lipid metabolism, and cell signaling pathways that control proliferation, cell migration, and fate determination. Several genes implicated in genetic diseases were found to be expressed in fibroblasts in an anatomic pattern that paralleled the phenotypic defects. Finally, adult fibroblasts maintained key features of
HOX
gene expression patterns established during embryogenesis, suggesting that
HOX
genes may direct topographic differentiation and underlie the detailed positional memory in fibroblasts.
Adenoviral gene transfer of endothelial nitric-oxide synthase (eNOS) partially restores normal pulmonary arterial pressure in eNOS-deficient mice
Authors: Champion Hunter C. , Bivalacqua Trinity J. , Greenberg Stanley S. , Giles Thomas D. , Hyman Albert L. , Kadowitz Philip J.
Published: October 2002

It has been shown that mice deficient in the gene coding for endothelial nitric-oxide synthase (eNOS) have increased pulmonary arterial pressure and pulmonary vascular resistance. In the present study, the effect of transfer to the lung of an adenoviral vector encoding the eNOS gene (AdCMVeNOS) on pulmonary arterial pressure and pulmonary vascular resistance was investigated in eNOS-deficient mice. One day after intratracheal administration of AdCMVeNOS to eNOS
−/−
mice, there was an increase in eNOS protein, cGMP levels, and calcium-dependent conversion of
l
-arginine to
l
-citrulline in the lung. The increase in eNOS protein and activity in eNOS
−/−
mice was associated with a reduction in mean pulmonary arterial pressure and pulmonary vascular resistance when compared with values in eNOS-deficient mice treated with vehicle or a control adenoviral vector coding for β-galactosidase, AdCMVβgal. These data suggest that
in vivo
gene transfer of eNOS to the lung in eNOS
−/−
mice can increase eNOS staining, eNOS protein, calcium-dependent NOS activity, and cGMP levels and partially restore pulmonary arterial pressure and pulmonary vascular resistance to near levels measured in eNOS
+/+
mice. Thus, the major finding in this study is that
in vivo
gene transfer of eNOS to the lung in large part corrects a genetic deficiency resulting from eNOS deletion and may be a useful therapeutic intervention for the treatment of pulmonary hypertensive disorders in which eNOS activity is reduced.
Pyrimethamine and WR99210 exert opposing selection on dihydrofolate reductase from
Plasmodium vivax
Authors: Hastings Michele D. , Sibley Carol Hopkins
Published: October 2002

Plasmodium vivax
is a major public health problem in Asia and South and Central America where it is most prevalent. Until very recently, the parasite has been effectively treated with chloroquine, but resistance to this drug has now been reported in several areas. Affordable alternative treatments for vivax malaria are urgently needed. Pyrimethamine-sulfadoxine is an inhibitor of dihydrofolate reductase (DHFR) that has been widely used to treat chloroquine-resistant
Plasmodium falciparum
malaria. DHFR inhibitors have not been considered for treatment of vivax malaria, because initial trials showed poor efficacy against
P. vivax. P. vivax
cannot be grown in culture; the reason for its resistance to DHFR inhibitors is unknown. We show that, like
P. falciparum
, point mutations in the
dhfr
gene can cause resistance to pyrimethamine in
P. vivax
. WR99210 is a novel inhibitor of DHFR, effective even against the most pyrimethamine-resistant
P. falciparum
strains
.
We have found that it is also an extremely effective inhibitor of the
P. vivax
DHFR, and mutations that confer high-level resistance to pyrimethamine render the
P. vivax
enzyme exquisitely sensitive to WR99210. These data suggest that pyrimethamine and WR99210 would exert opposing selective forces on the
P. vivax
population. If used in combination, these two drugs could greatly slow the selection of parasites resistant to both drugs. If that is the case, this novel class of DHFR inhibitors could provide effective and affordable treatment for chloroquine- and pyrimethamine-resistant vivax and falciparum malaria for many years to come.
Size-dependent life-history traits promote catastrophic collapses of top predators
Authors: De Roos André M. , Persson Lennart
Published: October 2002

Catastrophic population collapses such as observed in many exploited fish populations have been argued to result from depensatory growth mechanisms (i.e., reduced reproductive success at low population densities, also known as Allee effect). Empirical support for depensation from population-level data is, however, hard to obtain and inconclusive. Using a size-structured, individual-based model we show that catastrophic population collapses may nonetheless be an intrinsic property of many communities, because of two general aspects of individual life history: size- and food-dependent individual growth and individual mortality decreasing with body size. Positive density dependence, characteristic for depensatory growth mechanisms and catastrophic behavior, results as a direct and robust consequence of the interplay between these individual life-history traits, which are commonly found in many species.
Antiviral and antitumor peptides from insects
Authors: Chernysh Sergey , Kim S. I. , Bekker G. , Pleskach V. A. , Filatova N. A. , Anikin V. B. , Platonov V. G. , Bulet Philippe
Published: October 2002

Insects can rapidly clear microbial infections by producing a variety of immune-induced molecules including antibacterial and/or antifungal peptides/polypeptides. In this report, we present the isolation, structural characterization, and biological properties of two variants of a group of bioactive, slightly cationic peptides, referred to as alloferons. Two peptides were isolated from the blood of an experimentally infected insect, the blow fly
Calliphora vicina
(Diptera), with the following amino acid sequences: HGVSGHGQHGVHG (alloferon 1) and GVSGHGQHGVHG (alloferon 2). Although these peptides have no clear homologies with known immune response modifiers, protein database searches established some structural similarities with proteins containing amino acid stretches similar to alloferon.
In vitro
experiments reveal that the synthetic version of alloferon has stimulatory activities on natural killer lymphocytes, whereas
in vivo
trials indicate induction of IFN production in mice after treatments with synthetic alloferon. Additional
in vivo
experiments in mice indicate that alloferon has antiviral and antitumoral capabilities. Taken together, these results suggest that this peptide, which has immunomodulatory properties, may have therapeutic capacities. The fact that insects may produce cytokine-like materials modulating basic mechanisms for human immunity suggests a source of anti-infection and antitumoral biopharmaceuticals.
Ultrafast ligand rebinding in the heme domain of the oxygen sensors FixL and Dos: General regulatory implications for heme-based sensors
Authors: Liebl Ursula , Bouzhir-Sima Latifa , Négrerie Michel , Martin Jean-Louis , Vos Marten H.
Published: October 2002

Heme-based oxygen sensors are part of ligand-specific two-component regulatory systems, which have both a relatively low oxygen affinity and a low oxygen-binding rate. To get insight into the dynamical aspects underlying these features and the ligand specificity of the signal transduction from the heme sensor domain, we used femtosecond spectroscopy to study ligand dynamics in the heme domains of the oxygen sensors FixL from
Bradyrhizobium japonicum
(FixLH) and Dos from
Escherichia coli
(DosH)
.
The heme coordination with different ligands and the corresponding ground-state heme spectra of FixLH are similar to myoglobin (Mb). After photodissociation, the excited-state properties and ligand-rebinding kinetics are qualitatively similar for FixLH and Mb for CO and NO as ligands. In contrast to Mb, the transient spectra of FixLH after photodissociation of ligands are distorted compared with the ground-state difference spectra, indicating differences in the heme environment with respect to the unliganded state. This distortion is particularly marked for O
2
. Strikingly, heme–O
2
recombination occurs with efficiency unprecedented for heme proteins, in ≈5 ps for ≈90% of the dissociated O
2
. For DosH–O
2
, which shows 60% sequence similarity to FixLH, but where signal detection and transmission presumably are quite different, a similarly fast recombination was found with an even higher yield. Altogether these results indicate that in these sensors the heme pocket acts as a ligand-specific trap. The general implications for the functioning of heme-based ligand sensors are discussed in the light of recent studies on heme-based NO and CO sensors.
Experimental autoimmune encephalomyelitis mobilizes neural progenitors from the subventricular zone to undergo oligodendrogenesis in adult mice
Authors: Picard-Riera Nathalie , Decker Laurence , Delarasse Cécile , Goude Karine , Nait-Oumesmar Brahim , Liblau Roland , Pham-Dinh Danielle , Evercooren Anne Baron-Van
Published: October 2002

The destiny of the mitotically active cells of the subventricular zone (SVZ) in adult rodents is to migrate to the olfactory bulb, where they contribute to the replacement of granular and periglomerular neurons. However, these adult neural progenitors also can be mobilized in periventricular white matter and triggered to differentiate into astrocytes and oligodendrocytes in response to lysolecithin-induced demyelination. To mimic the environmental conditions of multiple sclerosis, we assessed the proliferation, migration, and differentiation potential of adult SVZ progenitor cells in response to experimental autoimmune encephalomyelitis (EAE) in mice. Inflammation and demyelination were observed in all mouse brains after EAE induction. EAE induced cell proliferation throughout the brain and especially within the lesions. Proliferating cells were neural progenitors, astrocytes, and oligodendrocyte precursors. EAE enhanced the migration of SVZ-derived neural progenitors to the olfactory bulb and triggered their mobilization in the periventricular white matter. The mobilized cells gave rise to neurons, astrocytes, and oligodendrocytes in the olfactory bulb but essentially to astrocytes and oligodendrocytes in the lesioned white matter. Our data indicate that the adult mouse SVZ is a source of newly generated oligodendrocytes and thus may contribute, along with oligodendrocyte precursors, to the replacement of oligodendrocytes in inflammatory demyelinating diseases of the central nervous system such as multiple sclerosis.
The two GAF domains in phosphodiesterase 2A have distinct roles in dimerization and in cGMP binding
Authors: Martinez Sergio E. , Wu Albert Y. , Glavas Natalie A. , Tang Xiao-Bo , Turley Stewart , Hol Wim G. J. , Beavo Joseph A.
Published: October 2002

Cyclic nucleotide phosphodiesterases (PDEs) regulate all pathways that use cGMP or cAMP as a second messenger. Five of the 11 PDE families have regulatory segments containing GAF domains, 3 of which are known to bind cGMP. In PDE2 binding of cGMP to the GAF domain causes an activation of the catalytic activity by a mechanism that apparently is shared even in the adenylyl cyclase of Anabaena, an organism separated from mouse by 2 billion years of evolution. The 2.9-Å crystal structure of the mouse PDE2A regulatory segment reported in this paper reveals that the GAF A domain functions as a dimerization locus. The GAF B domain shows a deeply buried cGMP displaying a new cGMP-binding motif and is the first atomic structure of a physiological cGMP receptor with bound cGMP. Moreover, this cGMP site is located well away from the region predicted by previous mutagenesis and structural genomic approaches.
High efficiency genetic modification of hair follicles and growing hair shafts
Authors: Saito Norimitsu , Zhao Ming , Li Lingna , Baranov Eugene , Yang Meng , Ohta Yukinori , Katsuoka Kensei , Penman Sheldon , Hoffman Robert M.
Published: October 2002

A technique for genetic modification of hair follicles was developed which results in efficient alteration of the hair shaft phenotype. High-level
in vivo
transgene expression was maintained in hair follicles such that growing hair shafts were phenotypically altered. Mouse anagen skin fragments, maintained in histoculture, were genetically modified at high efficiency with adenoviral-GFP. The histocultured skin fragments were treated with collagenase which made hair follicles accessible to the adenoviral GFP gene, allowing high-efficiency transduction. These skin fragments were subsequently grafted on to nude mice where GFP was readily visualized in as many as 75% of hair follicles. Most follicles produced GFP-fluorescent growing hair shafts. This technique has produced efficient genetic modification of the hair shaft.
β2 nicotinic acetylcholine receptor subunit modulates protective responses to stress: A receptor basis for sleep-disordered breathing after nicotine exposure
Authors: Cohen Gary , Han Zhi-Yan , Grailhe Régis , Gallego Jorge , Gaultier Claude , Changeux Jean-Pierre , Lagercrantz Hugo
Published: October 2002

Nicotine exposure diminishes the protective breathing and arousal responses to stress (hypoxia). By exacerbating sleep-disordered breathing, this disturbance could underpin the well established association between smoking and the increased risk of sudden infant death syndrome. We show here that the protective responses to stress during sleep are partially regulated by particular nicotinic acetylcholine receptors (nAChRs). We compared responses of sleeping wild-type and mutant mice lacking the β2 subunit of the nAChR to episodic hypoxia. Arousal from sleep was diminished, and breathing drives accentuated in mutant mice indicating that these protective responses are partially regulated by β2-containing nAChRs. Brief exposure to nicotine significantly reduced breathing drives in sleeping wild-type mice, but had no effect in mutants. We propose that nicotine impairs breathing (and possibly arousal) responses to stress by disrupting functions normally regulated by β2-containing, high-affinity nAChRs.
A method for the generation of combinatorial antibody libraries using pIX phage display
Authors: Gao Changshou , Mao Shenlan , Kaufmann Gunnar , Wirsching Peter , Lerner Richard A. , Janda Kim D.
Published: October 2002

For more than a decade, phage displayed combinatorial antibody libraries have been used to generate and select a wide variety of antibodies. We previously reported that the phage coat proteins pVII and pIX could be used to display the heterodimeric structure of the antibody Fv region. Herein, aspects of this technology were invoked and extended to construct a large, human single-chain Fv (scFv) library of 4.5 × 10
9
members displayed on pIX of filamentous bacteriophage. Furthermore, the diversity, quality, and utility of the library were demonstrated by the selection of scFv clones against six different protein antigens. Notably, more than 90% of the selected clones showed positive binding for their respective antigens after as few as three rounds of panning. Analyzed scFvs were also found to be of high affinity. For example, kinetic analysis (BIAcore) revealed that scFvs against staphylococcal enterotoxin B and cholera toxin B subunit had a nanomolar and subnanomolar dissociation constant, respectively, affording affinities comparable to, or exceeding that, of mAbs obtained from immunization. High specificity was also attained, not only between very distinct proteins, but also in the case of the
Ricinus communis
(“ricin”) agglutinins (RCA
60
and RCA
120
), despite >80% sequence homology between the two. The results suggested that the performance of pIX-display libraries can potentially exceed that of the pIII-display format and make it ideally suited for panning a wide variety of target antigens.
Sphingoid base synthesis is required for oligomerization and cell surface stability of the yeast plasma membrane ATPase, Pma1
Authors: Wang Qiongqing , Chang Amy
Published: October 2002

The plasma membrane H
+
-ATPase, Pma1, is an essential and long-lived integral membrane protein. Previous work has demonstrated that the Pma1-D378N mutant is a substrate for endoplasmic reticulum (ER)-associated degradation and causes a dominant negative effect on cell growth by preventing ER export of wild-type Pma1. We now show that Pma1-D378N is ubiquitylated, and it heterooligomerizes with wild-type Pma1, resulting in ubiquitylation and ER-associated degradation of wild-type Pma1. In temperature-sensitive
lcb1-100
cells, defective in sphingoid base synthesis, Pma1 fails to oligomerize. At 30°C,
lcb1-100
is a suppressor of
pma1-D378N
because wild-type Pma1 fails to heterooligomerize with Pma1-D378N; wild-type Pma1 moves to the cell surface, indicating that oligomerization is not required for delivery to the plasma membrane. Even in the absence of Pma1-D378N, wild-type Pma1 is ubiquitylated and it undergoes internalization from the cell surface and vacuolar degradation at 30°C in
lcb1-100
cells. At 37°C in
lcb1-100
cells, a more severe defect occurs in sphingoid base synthesis, and targeting of newly synthesized Pma1 to the plasma membrane is impaired. These data indicate requirements for sphingolipids at three discrete stages: Pma1 oligomerization at the ER, targeting to the plasma membrane, and stability at the cell surface.
Metapopulation dynamics and spatial heterogeneity in cancer
Authors: González-García Isabel , Solé Ricard V. , Costa José
Published: October 2002

With the advent of drugs targeting specific molecular defects in cancerous cells [Gorre, M. E.,
et al
. (2001)
Science
293, 876–880], it is important to understand the degree of genetic heterogeneity present in tumor cell populations and the rules that govern microdiversity in human cancer. Here, we first show that populations with different genotypes in genes influencing cell growth and programmed cell death coexist in advanced malignant tumors of the colon, exhibiting microsatellite instability. Detailed, physical mapping of the diverse populations shows them to be arranged in small, intermingling areas, resulting in a variegated pattern of diversity. Using computational modeling of the experimental data, we find that the coexistence between similar competitors is enhanced, instead of deterred, by spatial dynamics [Hanski, I. (1999)
Metapopulation Dynamics
(Oxford Univ. Press, New York)]. The model suggests a simple and plausible scenario for the generation of spatial heterogeneity during tumor progression. The emergence and persistence of the patterns of diversity encountered in the tumors can be generated without a need to invoke differences in mutation rates, neutrality of interactions, or separated time scales. We posit that the rules that apply to spatial ecology and explain the maintenance of diversity are also at work in tumors and may underlie tumor microheterogeneity.
Alpha-fetoprotein, the major fetal serum protein, is not essential for embryonic development but is required for female fertility
Authors: Gabant Philippe , Forrester Lesley , Nichols Jennifer , Van Reeth Thierry , De Mees Christelle , Pajack Bernard , Watt Alistair , Smitz Johan , Alexandre Henri , Szpirer Claude , Szpirer Josiane
Published: October 2002

The alpha-fetoprotein gene (
Afp
) is a member of a multigenic family that comprises the related genes encoding albumin, alpha-albumin, and vitamin D binding protein. The biological role of this major embryonic serum protein is unknown although numerous speculations have been made. We have used gene targeting to show that AFP is not required for embryonic development. AFP null embryos develop normally, and individually transplanted homozygous embryos can develop in an AFP-deficient microenvironment. Whereas mutant homozygous adult males are viable and fertile, AFP null females are infertile. Our analyses of these mice indicate that the defect is caused by a dysfunction of the hypothalamic/pituitary system, leading to anovulation.
Direct stimulation of transcription by negative cofactor 2 (NC2) through TATA-binding protein (TBP)
Authors: Cang Yong , Prelich Gregory
Published: October 2002

Negative cofactor 2 (NC2) is an evolutionarily conserved transcriptional regulator that was originally identified as an inhibitor of basal transcription. Its inhibitory mechanism has been extensively characterized; NC2 binds to the TATA-binding protein (TBP), blocking the recruitment of TFIIA and TFIIB, and thereby inhibiting preinitiation complex assembly. NC2 is also required for expression of many yeast genes
in vivo
and stimulates TATA-less transcription in a
Drosophila in vitro
transcription system, but the mechanism responsible for the NC2-mediated stimulation of transcription is not understood. Here we establish that yeast NC2 can directly stimulate activated transcription from TATA-driven promoters both
in vivo
and
in vitro
, and moreover that this positive role requires the same surface of TBP that mediates the NC2 repression activity. On the basis of these results, we propose a model to explain how NC2 can mediate both repression and activation through the same surface of TBP.
Low atmospheric CO
2
levels during the Permo- Carboniferous glaciation inferred from fossil lycopsids
Authors: Beerling D. J.
Published: October 2002

Earth history was punctuated during the Permo-Carboniferous [300–250 million years (Myr) ago] by the longest and most severe glaciation of the entire Phanerozoic Eon. But significant uncertainty surrounds the concentration of CO
2
in the atmosphere through this time interval and therefore its role in the evolution of this major prePleistocene glaciation. Here, I derive 24 Late Paleozoic CO
2
estimates from the fossil cuticle record of arborsecent lycopsids of the equatorial Carboniferous and Permian swamp communities. Quantitative calibration of Late Carboniferous (330–300 Myr ago) and Permian (270–260 Myr ago) lycopsid stomatal indices yield average atmospheric CO
2
concentrations of 344 ppm and 313 ppm, respectively. The reconstructions show a high degree of self-consistency and a degree of precision an order of magnitude greater than other approaches. Low CO
2
levels during the Permo-Carboniferous glaciation are in agreement with glaciological evidence for the presence of continental ice and coupled models of climate and ice-sheet growth on Pangea. Moreover, the Permian data indicate atmospheric CO
2
levels were low 260 Myr ago, by which time continental deglaciation was already underway. Positive biotic feedbacks on climate, and geotectonic events, therefore are implicated as mechanisms underlying deglaciation.
Pipsqueak and GAGA factor act in concert as partners at homeotic and many other loci
Authors: Schwendemann Alexander , Lehmann Michael
Published: October 2002

The
Drosophila
GAGA factor (GAF) controls transcription and other chromosome functions by altering chromatin structure. We found that a second GAGA-binding protein of
Drosophila
, Pipsqueak (Psq), can directly bind to GAF and is associated with GAF
in vivo
. Genetic interaction studies provide evidence that Psq and GAF act together in the transcriptional activation and silencing of homeotic genes. A complete colocalization of Psq and GAF on polytene interphase chromosomes and mitotic chromosomes suggests that the two proteins cooperate as general partners not only at homeotic loci, but also at hundreds of other chromosomal sites.