bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of rifampicin on the pharmacokinetics and pharmacodynamics of nateglinide in healthy subjects
Authors: Niemi Mikko , Backman Janne T. , Neuvonen Mikko , Neuvonen Pertti J.
Published: September 2003

Aims  Our aim was to investigate the effects of rifampicin on the pharmacokinetics and pharmacodynamics of nateglinide, a novel short‐acting antidiabetic drug.

Methods  In a randomized crossover study with two phases, 10 healthy volunteers took 600 mg rifampicin or placebo orally once daily for 5 days. On day 6 of both phases, they ingested a single 60 mg dose of nateglinide. Plasma nateglinide and blood glucose concentrations were measured for up to 7 h postdose.

Results   Rifampicin decreased the mean AUC(0,7 h) of nateglinide by 24% (range 5–53%; P = 0.0009) and shortened its half‐life (t1/2) from 1.6 to 1.3 h (P = 0.001). However, the peak plasma nateglinide concentration (Cmax) remained unchanged. The AUC(0,7 h) of the M7 metabolite of nateglinide was decreased by 19% (P = 0.002) and its t1/2 was shortened from 2.1 to 1.6 h by rifampicin (P = 0.008). Rifampicin had no significant effect on the blood glucose‐lowering effect of nateglinide.

Conclusions   Rifampicin modestly decreased the plasma concentrations of nateglinide probably by inducing its oxidative biotransformation. In some patients, rifampicin may reduce the blood glucose‐lowering effect of nateglinide.
Population pharmacokinetics of liposomal daunorubicin in children
Authors: Hempel Georg , Reinhardt Dirk , Creutzig Ursula , Boos Joachim
Published: September 2003

Aims  To investigate the population pharmacokinetics of daunorubicin in children after administration of liposomal daunorubicin (Daunoxome®).

Methods   Plasma samples from 19 children with relapsed acute myeloic leukaemia and five children with other malignancies were collected. Daunoxome® was administered as a 1‐ to 2.5 h infusion with doses ranging from 30 to 60 mg m−2. Overall, 214 samples were analysed for daunorubicin using capillary electrophoresis, and population pharmacokinetic modelling was performed using NONMEM.

Results   The data were best described by a one compartment model. Inclusion of interoccasion variability in the model (16.7% for clearance) improved strongly the precision of the estimates. The inclusion of body surface area or height as a covariate decreased interindividual variability. However, the best fit was obtained using the absolute dose, and when weight was included as a covariate for clearance (CL) and volume of distribution (V ). The final parameter estimates were: CL 6.41 ml h−1 kg−1± 0.5 51% and V 65.4 ml kg−1 ± 0.5 27% (population mean ± 0.5 interindividual variability). The area under the curve at a dose of 60 mg m−2 was 231 mg l −1h.

Conclusions   In comparison with free daunorubicin, Daunoxome® shows a low volume of distribution, a lower clearance and a lower interindividual variability in these parameters. This might be advantageous in reducing the variability in exposure to the drug.
Twenty‐four‐hour activity and consistency of activity of levocetirizine and desloratadine in the skin
Authors: Purohit Ashok , Melac Michel , Pauli Gabrielle , Frossard Nelly
Published: September 2003

Aim  Levocetirizine, the active enantiomer of cetirizine, and desloratadine, the active metabolite of loratadine, are two recently introduced anti‐H1 agents. We set out to compare their antihistaminic activity in the skin for 24 h in a double‐blind, randomized cross‐over trial.

Methods  The skin reaction to histamine administered by prick tests (100 mg ml−1) was measured by the surface areas of weals and flares for 24 h [before treatment, 0.5, 1, 2, 3, 4, 6, 8, 10, 12 and 24 h after a single dose of levocetirizine (5 mg), desloratadine (5 mg) or placebo] in 18 healthy volunteers (34.8 ± 9.4 years; 14 women). The areas under the curves (AUC) of the weal and flare areas as a function of time were compared by anova.

Results  A highly significant overall treatment effect (P < 0.0001) was observed and both weals and flares were inhibited. The pairwise comparisons showed that the activity of levocetirizine and desloratadine was significantly superior to that of placebo (P < 0.0001), and the activity of levocetirizine was significantly superior to that of desloratadine (P < 0.0001). ‘Total’ weal inhibition (≥ 95%) occurred only with levocetirizine. Median values of maximal weal inhibition were 44.2% with placebo, 55.0% with desloratadine and 100% with levocetirizine. The time to maximal weal inhibition was 4 h (median value) for all three study drugs, but scattered over a wider range for desloratadine (3–24 h) than levocetirizine (2–4 h). With desloratadine, five of 18 (28%) subjects reached weal inhibition of at least 70% at between 3 and 10 h, whereas with levocetirizine all subjects [18/18 (100%)] reached this level of weal inhibition at between 1 and 3 h. The median duration of 70% weal inhibition was zero with placebo and desloratadine, and was 21.4 h with levocetirizine (P < 0.0001 between the three study drugs, and P < 0.0001 between the two active drugs). No uncommon adverse events were reported, and no subject withdrew from the study due to an adverse event.

Conclusion  This study shows that the activity of levocetirizine in suppressing skin reactivity to histamine was clearly superior to that of desloratadine for 24 h after a single dose. In addition, its activity was more consistent and lasted longer.
Determinants of trapping block of N‐methyl‐d‐aspartate receptor channels
Authors: Bolshakov K. V. , Gmiro V. E. , Tikhonov D. B. , Magazanik L. G.
Published: September 2003

Open channel blockers of NMDA receptors interact with the channel gate in different ways. Compounds like MK‐801 and phencyclidine exhibit pronounced trapping block, whereas 9‐aminoacridine and tetrapentylammonium cannot be trapped. Some blockers such as memantine and amantadine exhibit intermediate properties, so called ‘partial trapping’. To analyze the determinants of trapping we have synthesized a series of mono‐ and dicationic derivatives of phenylcyclohexyl. The blocking action of these compounds as well as that of amantadine has been studied on native NMDA receptors of hippocampal pyramidal neurons. Use‐dependence and kinetics of the blockade have been analyzed to estimate the degree of trapping. Dimensions of the blocking molecules apparently do not correlate with their trapping. However, the degree of trapping is voltage‐dependent and correlates with the kinetics of unblock. For instance, amantadine behaved as non‐trapping blocker at positive voltages, but demonstrated significant trapping at negative voltages. The data may be explained by the model in which the NMDA receptor channel has two binding sites: the shallow and deep ones. Binding to the deep but not to the shallow site allows trapping of the blockers.
Hydroxyurea transport across the blood–brain and blood–cerebrospinal fluid barriers of the guinea‐pig
Authors: Dogruel M. , Gibbs J. E. , Thomas S. A.
Published: September 2003

Hydroxyurea is used in the treatment of HIV infection in combination with nucleoside analogues, 2′3′‐didehydro‐3′deoxythymidine (D4T), 2′3′‐dideoxyinosine or abacavir. It is distributed into human CSF and is transported from the CSF to sub‐ependymal brain sites, but its movement into the brain directly from the blood has not been studied. This study addressed this by a brain perfusion technique in anaesthetized guinea‐pigs. The carotid arteries were perfused with an artificial plasma containing [14C]hydroxyurea (1.6 μm) and a vascular marker, [3H]mannitol (4.6 nm). Brain uptake of [14C]hydroxyurea (8.0 ± 0.9%) was greater than [3H]mannitol (2.4 ± 0.2%; 20‐min perfusion, n = 8). CSF uptake of [14C]hydroxyurea (5.6 ± 1.5%) was also greater than [3H]mannitol (0.9 ± 0.3%; n = 4). Brain uptake of [14C]hydroxyurea was increased by 200 μm hydroxyurea, 90 μm D4T, 350 μm probenecid, 25 μm digoxin, but not by 120 μm hydroxyurea, 16.5–50 μm D4T, 90 μm 2′3′‐dideoxyinosine or 90 μm abacavir. [14C]Hydroxyurea distribution to the CSF, choroid plexus and pituitary gland remained unaffected by all these drugs. The metabolic half‐life of hydroxyurea was > 15 h in brain and plasma. Results indicate that intact hydroxyurea can cross the brain barriers, but is removed from the brain by probenecid‐ and digoxin‐sensitive transport mechanisms at the blood–brain barrier, which are also affected by D4T. These sensitivities implicate an organic anion transporter (probably organic anion transporting polypeptide 2) and possibly p‐glycoprotein in the brain distribution of hydroxyurea and D4T.
Attenuated 5‐HT1A receptor signaling in brains of suicide victims: involvement of adenylyl cyclase, phosphatidylinositol 3‐kinase, Akt and mitogen‐activated protein kinase
Authors: Hsiung Shu‐chi , Adlersberg Mella , Arango Victoria , Mann J. John , Tamir Hadassah , Liu Kuo‐peing
Published: September 2003

Positron emission tomography studies in major depression show reduced serotonin (5‐HT)1A receptor antagonist‐binding potentials in many brain regions including occipital cortex. The functional meaning of this observation in terms of signal transduction is unknown. We used postmortem brain samples from depressed suicide victims to examine the downstream effectors of 5‐HT1A receptor activation. The diagnosis was established by means of psychological autopsy using Diagnostic and Statistical Manual of Mental Disorders (DSM) III‐R criteria. Measurements of [35S]GTPγS binding to Gαi/o in the occipital cortex of suicide victims and matched controls revealed a blunted response in suicide subjects and a decrease in the coupling of 5‐HT1A receptor to adenylyl cyclase. No significant group differences were detected in the expression levels of Gαi/o, Gαq/11 or Gαs proteins, or in the activity of cAMP‐dependent protein kinase A. Studies of a parallel transduction pathway downstream from 5‐HT1A receptor activation demonstrated a decrease in the activity of phosphatidylinositol 3‐kinase and its downstream effector Akt, as well as an increase in PTEN (phosphatase and tensin homolog deleted on chromosome 10), the phosphatase that hydrolyzes phosphatidylinositol 3,4,5‐triphosphate. Finally, the activation of extracellular signal‐regulated kinases 1 and 2 was attenuated in suicide victims. These data suggest that the alterations in agonist‐stimulated 5‐HT1A receptor activation in depressed suicide victims are also manifest downstream from the associated G protein, affecting the activity of second messengers in two 5‐HT1A receptor transduction pathways that may have implications for cell survival.
Differential effects of phencyclidine application on secretogranin II expression in organotypic slices of rat prefrontal cortex
Authors: Hinterhoelzl Josef K. , Salimi Kayvon , Humpel Christian , Singewald Nicolas , Adlassnig Christine , Fischer‐Colbrie Reiner , Fleischhacker Wolfgang W. , Marksteiner Josef
Published: September 2003

Phencyclidine (PCP) is a non‐competitive NMDA glutamate receptor antagonist that induces psychotomimetic effects in humans and experimental animals. Chronic PCP exposure elicits signs of persistently altered frontal brain activity and related behaviors which are also seen in patients with schizophrenia. Secretogranin II (sg II) belongs to the chromogranin family of proteins that exist in large dense core vesicles in nervous tissue. In the brain, 90% of sg II is processed to the small peptide secretoneurin. We previously detected differential effects of single‐dose and subchronic PCP administration on sg II expression in the rat prefrontal cortex (PFC). In the present study, we applied PCP to organotypic PFC slices. PCP application for 28 h induced decreased tissue and culture medium secretoneurin content. In contrast, incubation with the adenylate cyclase activator forskolin caused significantly increased secretoneurin levels after 8 h. PCP for 4 h followed by 24 h without PCP resulted in increased culture medium secretoneurin content but no change in tissue levels. sg II mRNA expression was decreased after 28 h PCP application in cortical neurons. Immunohistochemical and TUNEL staining profiles indicated that the alterations were not due to neurodegeneration. PCP for 5 days changed neither the secretoneurin tissue or culture medium levels, nor the sg II mRNA expression. These results demonstrate that PCP modulates sg II expression in PFC tissue in the absence of afferent inputs and that the nature of these changes is dependent upon the duration of exposure to and/or withdrawal from PCP.
Protective effects of lysophosphatidic acid (LPA) on chronic ethanol‐induced injuries to the cytoskeleton and on glucose uptake in rat astrocytes
Authors: Tomás Mónica , Lázaro‐Diéguez Francisco , Durán Juan M. , Marín Pilar , Renau‐Piqueras Jaime , Egea Gustavo
Published: September 2003

Ethanol induces severe alterations in membrane trafficking in hepatocytes and astrocytes, the molecular basis of which is unclear. One of the main candidates is the cytoskeleton and the molecular components that regulate its organization and dynamics. Here, we examine the effect of chronic exposure to ethanol on the organization and dynamics of actin and microtubule cytoskeletons and glucose uptake in rat astrocytes. Ethanol‐treated cells cultured in either the presence or absence of fetal calf serum showed a significant increase in 2‐deoxyglucose uptake. Ethanol also caused alterations in actin organization, consisting of the dissolution of stress fibres and the appearance of circular filaments beneath the plasma membrane. When lysophosphatidic acid (LPA), which is a normal constituent of serum and a potent intercellular lipid mediator with growth factor and actin rearrangement activities, was added to ethanol‐treated astrocytes cultured without fetal calf serum, it induced the re‐appearance of actin stress fibres and the normalization of 2‐deoxyglucose uptake. Furthermore, ethanol also perturbed the microtubule dynamics, which delayed the recovery of the normal microtubule organization following removal of the microtubule‐disrupting agent nocodazole. Again, pre‐treatment with LPA prevented this alteration. Ethanol‐treated rodent fibroblast NIH3T3 cells that constitutively express an activated Rho mutant protein (GTP‐bound form) were insensitive to ethanol, as they showed no alteration either in actin stress‐fibre organization or in 2‐deoxyglucose uptake. We discuss the putative signalling targets by which ethanol could alter the cytoskeleton and hexose uptake and the cytoprotective effect of LPA against ethanol‐induced damages. The latter opens the possibility that LPA or a similar non‐hydrolysable lipid derivative could be used as a cytoprotective agent against the noxious effects of ethanol.
Scaling exponents for energy transport and dissipation in binary vibro-fluidized granular beds
Authors: Wildman R. D. , Huntley J. M.
Published: September 2003

A binary three-dimensional highly fluidized vibrated granular bed has been investigated for the first time using positron emission particle tracking. Packing fraction distributions and granular temperature profiles are calculated for each species and the response to changes in the amplitude of vibration and the number of grains are determined. It is found that the binary system, though supporting two separate granular temperature profiles, responds to changes in vibration velocity in a broadly similar fashion to a monosized granular bed. This assessment is supported by an analysis of the steady-state energy input/dissipation rate balance equation, which contains terms describing the collisional dissipation between like and unlike grains. However, this theory also suggests that if one fraction dominates over another then the two phases could show different scaling relationships between the granular temperature of each phase and the base peak velocity.
Meissner state of high-Tc oxide thin films observed by scanning superconducting quantum interference device microscopy
Authors: Iguchi I. , Takeda T. , Sugimoto A. , Imaizumi T. , Haibara H. , Kawai T.
Published: September 2003

The magnetic level of the Meissner state in high-Tc oxide thin films is investigated using scanning superconducting quantum interference device microscopy. We find that the Meissner level observed is not uniquely determined and shifts with the temperature and depends on the doping level of individual oxide films. The result at higher temperature may be interpreted by a grain-coupled model which reflects the granular nature of high-Tc oxides and is useful for evaluation of high-Tc film quality.
Turbulent patches in a stratified shear flow
Authors: Fernando H. J. S.
Published: September 2003

The behavior of an isolated turbulent patch generated within the sheared interface between two counter-flowing fluid layers of different densities was investigated experimentally. This flow configuration permitted investigations of stratified shear flows with Rig⩾1, where Rig is the background gradient Richardson number. The turbulent patch was generated within the interface by an oscillating grid. The measurements in the presence and absence of shear under otherwise identical forcing and stratification conditions showed that the background shear significantly increases the patch size when Rig→1. This observation is consistent with the theoretical results that turbulence within a patch can interact with mean shear and enhance turbulence production when Rig<Ric, where Ric=O(1) is a critical Richardson number, and that below Rig∼1 shear across the patch boundaries can enhance local mixing. Both of these mechanisms can increase the size of a sheared turbulent patch beyond its mean shear-free counterpart. The opposite is observed at Rig>Ric, where gravitational collapse compounded with deformation by background shear causes a decrease of the patch size.
Short-wavelength stability analysis of thin vortex rings
Authors: Hattori Y. , Fukumoto Y.
Published: September 2003

The linear stability of thin vortex rings are studied by short-wavelength stability analysis. The modified Hill–Schrödinger equation for vortex rings, which incorporates curvature effect, is derived. It is used to evaluate growth rates analytically. The growth rates are also evaluated by numerical calculation and they agree well with analytical values for small ε which is the ratio of core radius to ring radius. Two types of vortex rings are considered: Kelvin’s vortex ring and a Gaussian vortex ring. For Kelvin’s vortex ring the maximum first-order growth rate is found to be 165256ε. For the Gaussian vortex ring the first-order growth rate is large in the skirts of the vortex core. The first-order instability is significant for both vortex rings.
Disorder–induced localized states in InAs/GaAs multilayer quantum dots
Authors: Gurioli M. , Sanguinetti S. , Grilli E. , Guzzi M. , Taddei S. , Vinattieri A. , Colocci M. , Frigeri P. , Franchi S.
Published: September 2003

We have investigated in detail the dependence of the photoluminescence decay times in stacked quantum dot (QD) structures, showing that they strongly depend on the emission energy. We propose that the dispersion of the lifetimes has to be related to the presence of vertical disorder in the quantum dot column. Due to the disorder the energy distribution of the carrier extended states shrinks and localized states are created in the tails. This idea is supported by a theoretical model, which takes into account the presence of a vertical disorder along the QD columns.
Monitoring the formation of Sb nanocrystals in SiO2 by grazing incidence x-ray techniques
Authors: Dekadjevi D. T. , Wiemer C. , Spiga S. , Ferrari S. , Fanciulli M. , Pavia G. , Gibaud A.
Published: September 2003

We investigate the formation, crystallinity, size, and depth distribution of Sb nanoclusters in thin SiO2 matrix by grazing incidence x-ray diffraction (GIXRD) and reflectivity (GIXRR). The complementarity of these two techniques reveals the formation of Sb nanocrystals after a rapid thermal treatment at 1000 °C and their depth distribution. The implantation profile is found to have its maximum centered in the middle of the SiO2 layer. After thermal treatment, the Sb atom redistribution, monitored by the variation in the electron density profile obtained by GIXRR, corresponds to the formation of metallic Sb nanoclusters, as confirmed by transmission electron microscopy (TEM) and GIXRD. The cluster distribution within the SiO2 layer presents a maximum at the center of the layer and their average diameter is 67±3 Å. The results are in agreement with TEM analyses.
Long-wavelength optical phonon properties of ternary MgZnO thin films
Authors: Chen J. , Shen W. Z.
Published: September 2003

Far-infrared (FIR) reflection measurements have been employed to study the long-wavelength optical phonon properties in cubic MgZnO thin films grown by reactive electron beam evaporation on sapphire substrates. The frequencies of the optical phonons with T2 symmetry are obtained by calculating the FIR reflection spectra using a multioscillator model and Kramers–Kronig dispersion analysis. The modified random-element-isodisplacement model has been used to analyze the long-wavelength optical mode behavior in both cubic and hexagonal MgZnO alloys. It is found that cubic MgZnO exhibits a two-mode behavior, while for hexagonal MgZnO, the E1 mode displays a two-mode behavior and the A1 mode a one-mode behavior. The effects of structural transition on the optical phonon frequency, optical mode behavior, and force constant have also been clearly revealed.
Thermoelectric cooling at cryogenic temperatures
Authors: Harutyunyan S. R. , Vardanyan V. H. , Kuzanyan A. S. , Nikoghosyan V. R. , Kunii S. , Wood K. S. , Gulian A. M.
Published: September 2003

Experimental results demonstrating Peltier cooling below 10 K are reported, using crystals of the thermoelectric cerium hexaboride (CeB6). Direct measurements of the Peltier cooling showed δT up to ∼0.2 K in magnitude at T∼4–5 K. All three kinetic parameters: resistivity (ρ), heat conductivity (k), and Seebeck coefficient (S), characterizing the thermoelectric figure of merit ZT=S2T/ρk, were measured, giving high-confidence results.
Infrared passbands from fractal slit patterns on a metal plate
Authors: Wen Weijia , Yang Z. , Xu Gu , Chen Yonghai , Zhou Lei , Ge Weikun , Chan C. T. , Sheng Ping
Published: September 2003

We show that a fractal pattern of submicron wide slits, etched on a 0.1-μm-thick gold film, exhibit multiple pass and stop bands in the wavelength regime of 2–200 μm. In the midinfrared regime, the passbands show ∼36% transmission (three orders of magnitude higher than the reference), and the stop bands exhibit ∼80% reflection. In the far infrared regime, the passband transmittances are 25%, 29%, and 14%, respectively, at wavelengths of 34, 62, and 111 μm. These transmittances are rather high in view of the fact that supporting substrate is itself only about 40% transmitting, and a control pattern of holes with similar void-to-metal ratio is 3000 times less transmitting in all frequencies. We attribute the high transmittance from subwavelength slits to geometric resonances.
Effects of long-term irrigation with reclaimed water on soils of the Northern Adelaide Plains, South Australia
Authors: Stevens D. P. , McLaughlin M. J. , Smart M. K.
Published: September 2003

On a small scale, reclaimed water (RCW) use has been practised on the Northern Adelaide Plains (NAP) horticultural districts for more than 28 years. The RCW has had approximately 1.7 times the salinity and twice the sodium absorption ratio (SAR) of bore water commonly used for irrigation in the district. Recently, a large-scale reclamation scheme has been commissioned which could eventually supply approximately 30 GL of RCW to over 250 growers on the NAP. This study compared historical water quality and time of use data with physico-chemical properties of soil cores taken from sites where reclaimed (RCW-irrigated) or bore water had been used for irrigation, or sites that had not been irrigated (virgin). The aim was to determine if current farming practices irrigating with RCW could, now or in the future, lead to a decrease in yields through detrimental increases in soil salinity, sodicity, and boron (B) concentrations, and to determine if these changes were significantly different from bore-irrigated or virgin sites. Data suggested that changes in soil salinity and B concentration from RCW use would not decrease yields. However, changes in soil SAR had the potential to restrict drainage and consequently increase salinity; although a more functional critical SAR value for the NAP soils needs to be defined to assess this potential. These findings suggest that farming methods, in the 1967–95 period, did not address the physico-chemical changes associated with the use of more sodic RCW. Considering the future scale of RCW use, the SAR of the irrigation water may need to be decreased and/or appropriate farming methods developed and practised with the use of RCW to protect these soils for future horticultural activities. A low cost soil test, using a simple 1 : 5 soil : water extract was compared with accepted soil extracts (for assessing detrimental physico-chemical soil changes) and is proposed as a grower management tool to assist in monitoring the physico-chemical changes of the NAP soils.
Using novel variation in Brassica species to reduce agricultural inputs and improve agronomy of oilseed rape—a case study in pod shatter resistance
Authors: Morgan Colin , Bavage Adrian , Bancroft Ian , Bruce David , Child Robin , Chinoy Catherine , Summers Jacky , Arthur Eddie
Published: September 2003

Oilseed rape is a very undeveloped crop with regard to efficiency of production and the agronomic practice used to maximize its potential. The genetic potential to modify oilseed rape is limited by the narrow genetic base found within the breeding gene pool, resulting in limited novel variation available for exploitation. Novel variation is, however, present in wild diploid ancestors of oilseed rape and has been made available by developing synthetic Brassica napus. This is illustrated through the use of this material to develop an understanding of pod shattering which is one of the most agronomically important characteristics of the crop. Through a variety of approaches it is shown how progress has been made to understand this trait and how this understanding is being used to improve the crop such that efficiency of production will be enhanced.
Cyberkelp: an integrative approach to the modelling of flexible organisms
Authors: Denny Mark W. , Hale Ben B.
Published: September 2003

Biomechanical models come in a variety of forms: conceptual models; physical models; and mathematical models (both of the sort written down on paper and the sort carried out on computers). There are model structures (such as insect flight muscle and the tendons of rats' tails), model organisms (such as the flying insect,Manduca sexta), even model systems of organisms (such as the communities that live on wave–swept rocky shores). These different types of models are typically employed separately, but their value often can be enhanced if their insights are integrated. In this brief report we explore a particular example of such integration among models, as applied to flexible marine algae. A conceptual model serves as a template for the construction of a mathematical model of a model species of giant kelp, and the validity of this numerical model is tested using physical models. The validated mathematical model is then used in conjunction with a computer–controlled tensile testing apparatus to simulate the loading regime placed on algal materials. The resulting information can be used to create a more precise mathematical model.
Dehydroascorbate Uptake Activity Correlates with Cell Growth and Cell Division of Tobacco Bright Yellow-2 Cell Cultures
Authors: Horemans Nele , Potters Geert , De Wilde Leen , Caubergs Roland J.
Published: September 2003

Recently, ascorbate (ASC) concentration and the activity of a number of enzymes from the ASC metabolism have been proven to correlate with differences in growth or cell cycle progression. Here, a possible correlation between growth and the activity of a plasma membrane dehydroascorbate (DHA) transporter was investigated. Protoplasts were isolated from a tobacco (Nicotiana tabacum) Bright Yellow-2 cell culture at different intervals after inoculation and the activity of DHA transport was tested with 14C-labeled ASC. Ferricyanide (1 mm) or dithiothreitol (1 mm) was included in the test to keep the external 14C-ASC in its oxidized respectively reduced form. Differential uptake activity was observed, correlating with growth phases of the cell culture. Uptake of DHA in cells showed a peak in exponential growth phase, whereas uptake in the presence of dithiothreitol did not. The enhanced DHA uptake was not due to higher endogenous ASC levels that are normally present in exponential phase because preloading of protoplasts of different ages did not affect DHA uptake. Preloading was achieved by incubating cells before protoplastation for 4 h in a medium supplemented with 1 mm DHA. In addition to testing cells at different growth phases, uptake of DHA into the cells was also followed during the cell cycle. An increase in uptake activity was observed during M phase and the M/G1 transition. These experiments are the first to show that DHA transport activity into plant cells differs with cell growth. The relevance of the data to the action of DHA and ASC in cell growth will be discussed.
Electrical Potentials of Plant Cell Walls in Response to the Ionic Environment
Authors: Shomer Ilan , Novacky Anton J. , Pike Sharon M. , Yermiyahu Uri , Kinraide Thomas B.
Published: September 2003

Electrical potentials in cell walls (ψWall) and at plasma membrane surfaces (ψPM) are determinants of ion activities in these phases. The ψPM plays a demonstrated role in ion uptake and intoxication, but a comprehensive electrostatic theory of plant-ion interactions will require further understanding of ψWall. ψWall from potato (Solanum tuberosum) tubers and wheat (Triticum aestivum) roots was monitored in response to ionic changes by placing glass microelectrodes against cell surfaces. Cations reduced the negativity of ψWall with effectiveness in the order Al3+ > La3+ > H+ > Cu2+ > Ni2+ > Ca2+ > Co2+ > Cd2+ > Mg2+ > Zn2+ > hexamethonium2+ > Rb+ > K+ > Cs+ > Na+. This order resembles substantially the order of plant-root intoxicating effectiveness and indicates a role for both ion charge and size. Our measurements were combined with the few published measurements of ψWall, and all were considered in terms of a model composed of Donnan theory and ion binding. Measured and model-computed values for ψWall were in close agreement, usually, and we consider ψWall to be at least proportional to the actual Donnan potentials. ψWall and ψPM display similar trends in their responses to ionic solutes, but ions appear to bind more strongly to plasma membrane sites than to readily accessible cell wall sites. ψWall is involved in swelling and extension capabilities of the cell wall lattice and thus may play a role in pectin bonding, texture, and intercellular adhesion.
A Developmental Response to Pathogen Infection in Arabidopsis
Authors: Korves Tonia M. , Bergelson Joy
Published: September 2003

We present evidence that susceptible Arabidopsis plants accelerate their reproductive development and alter their shoot architecture in response to three different pathogen species. We infected 2-week-old Arabidopsis seedlings with two bacterial pathogens, Pseudomonas syringae and Xanthomonas campestris, and an oomycete, Peronospora parasitica. Infection with each of the three pathogens reduced time to flowering and the number of aerial branches on the primary inflorescence. In the absence of competition, P. syringae and P. parasitica infection also increased basal branch development. Flowering time and branch responses were affected by the amount of pathogen present. Large amounts of pathogen caused the most dramatic changes in the number of branches on the primary inflorescence, but small amounts of P. syringae caused the fastest flowering and the production of the most basal branches. RPS2 resistance prevented large changes in development when it prevented visible disease symptoms but not at high pathogen doses and when substantial visible hypersensitive response occurred. These experiments indicate that phylogenetically disparate pathogens cause similar changes in the development of susceptible Arabidopsis. We propose that these changes in flowering time and branch architecture constitute a general developmental response to pathogen infection that may affect tolerance of and/or resistance to disease.
The importance of business process clarification within the virtual enterprise
Authors: Sackett Peter , Rose Thomas , Adamson Veronica
Published: September 2003

This paper describes the innovative generic business process set (GBPS) model and how this may be used as a functional template for small‐ and medium‐sized enterprises (SMEs) participating in a virtual enterprise. The authors provide specific emphasis on the use of information communication and technology (ICT) in business applications and show how the model can be used as a medium for lifelong learning and workforce development. The SME business model introduced identifies and describes 52 validated specific business processes, the GBPS. A framework and methodology for the application of the model in entrepreneurial firms are provided. Emerging ICT applications are also an integral part of business operations. Using the GBPS, the identification of training needs is directly related to the activities of the business. This approach overcomes the problem, inherent in SMEs and owner‐managed businesses, of a reluctance to endorse training because it is not clearly relevant to entrepreneurial business operations. The same model can be used as a gateway into an e‐learning programme designed for the virtual business environment via a low overhead and easy to implement process.
Hazards Education for Youth: A Quasi‐Experimental Investigation
Authors: Ronan Kevin R. , Johnston David M.
Published: September 2003

No experimental research has examined the hypothesized benefits of hazards education programs for youth in helping to increase community resilience. This preliminary study followed on from correlational studies and examined the role these programs play in helping increase child and family problem‐ and emotion‐focused coping. Children (n= 219) were randomly assigned, based on classroom, to a condition. The “usual condition” consisted of a reading and discussion program. The “emergency management” condition consisted of the usual condition combined with emergency‐management‐focused teaching and increased interaction between youth and home. Factors assessed included both problem‐ and emotion‐focused factors: knowledge of mitigation and emergency response activities, family and home hazard adjustments, hazard‐related fears, emotion‐focused coping ability, and perceptions of parents' hazard‐related fears. Overall, the results supported the role for hazards education programs in increasing resilience in youth and at home. In particular, large intervention produced effect sizes were seen for both child‐ and parent‐reported hazard adjustments. Significant interactions provided additional support for the role of an emergency management focus in the problem‐focused areas of (1) both child‐ and parent‐reported hazard adjustments and (2) increased hazards‐based knowledge in the youth. These initial findings provide a continuing foundation for further research in this emerging area. Discussion considers the role for such programs in the future.
Properties of Au and Ag Schottky diodes prepared on undoped n-ZnO
Authors: Polyakov A. Y. , Smirnov N. B. , Kozhukhova E. A. , Vdovin V. I. , Ip K. , Norton D. P. , Pearton S. J.
Published: September 2003

Electrical properties of Au and Ag Schottky diodes prepared on epiready (0001)Zn surfaces of bulk n-ZnO crystals with electron concentration close to 1017 cm−3 were studied after various surface cleaning treatments. The lowest reverse currents were obtained with simple cleaning of the surface in organic solvents while additional etching of the surface in concentrated HCl or HNO3 substantially increased the reverse current without giving any clear advantages in the ideality factor of the forward current–voltage characteristics or in the accuracy of capacitance–voltage characteristics and deep level spectra measurements. The properties of both the Au and the Ag Schottky diodes were seriously degraded by heating them in vacuum to temperatures higher than about 365 K but the mechanisms of degradation seem to be different for the two metals.
Deposition pressure dependence of internal stress in TiN films deposited by filtered cathodic vacuum arc
Authors: Cheng Y. H. , Tay B. K.
Published: September 2003

TiN films were deposited by an off-plane double bend filtered cathodic vacuum arc technique. The composition, structure, and surface morphology of the films were characterized by x-ray photoelectron spectroscopy, x-ray diffraction, and atomic force microscopy, respectively. Internal stress was determined by a substrate bending method. The influence of the deposition pressure on the composition, structure, and internal stress of the films was studied systematically. At a deposition pressure of 1×10−5 Torr, the films are composed of single α-TiN0.30 phase with fairly low internal stress, and the atomic ratio of N to Ti is 0.32. As the deposition pressure increases to 5×10−5 Torr, the N/Ti ratio increases to 0.56, and the films are composed of a mixture of hexagonal α-TiN0.30 and cubic TiN0.90. The formation of TiN0.90 phase and the mismatch of these two kinds of phases contribute to a dramatic increase of internal stress in the films. The increase of deposition pressure to 2×10−4 Torr results in the formation of stoichiometric TiN films with single TiN phase, which corresponds to slightly lower internal stress. However, a further increase of deposition pressure results in a continuous increase in the N/Ti ratio and the formation of overstoichiometric films. The incorporation of excess N atoms in the films accounts for the further increase of internal stress.
X-ray photoelectron spectroscopy and secondary electron yield analysis of Al and Cu samples exposed to an accelerator environment
Authors: Rosenberg R. A. , McDowell M. W. , Ma Q. , Harkay K. C.
Published: September 2003

It is well known that exposure to an accelerator environment can cause “conditioning” of the vacuum chamber surfaces. In order to understand the manner in which the surface structure might influence the production of gases and electrons in the accelerator, such surfaces should be studied both before and after exposure to accelerator conditions. Numerous studies have been performed on representative materials prior to being inserted into an accelerator, but very little has been done on materials that have “lived” in the accelerator for extended periods. In the present work, we mounted Al and Cu coupons at different positions in a section of the Advanced Photon Source storage ring and removed them following exposures ranging from 6 to 18 months. X-ray photoelectron spectroscopy (XPS) of the surface was performed before and after exposure. Changes were observed that depended on the location and whether the coupon was facing the chamber interior or chamber wall. These results will be presented and compared to XPS and secondary electron yield data obtained from laboratory measurements meant to simulate the accelerator conditions.
Atomic layer deposition of zirconium silicate films using zirconium tetra-tert-butoxide and silicon tetrachloride
Authors: Kim Won-Kyu , Kang Sang-Woo , Rhee Shi-Woo
Published: September 2003

A new precursor combination (SiCl4 and Zr(OtC4H9)4) was used to deposit Zr silicate with Zr(OtC4H9)4 as a zirconium source and oxygen source at the same time. SiCl4 and Zr(OtC4H9)4 have higher vapor pressures than their counterpart, ZrCl4 and tetra-n-butyl orthosilicate (TBOS), and it was expected that the cycle time would be shorter. The deposition temperature of the new combination was about 150 °C lower than that of ZrCl4 and TBOS. The film was zirconium rich while it was silicon rich with ZrCl4 and TBOS. Growth rate (nm/cycle), composition ratio [Zr/(Zr+Si)], and chlorine impurity were decreased with increasing deposition temperature from 125 to 225 °C. The composition ratio of the film deposited at 225 °C was 0.53 and the chlorine content was about 0.4 at. %. No carbon was detected by x-ray photoelectron spectroscopy.
From metallurgical coatings to surface engineering
Authors: Sproul William D.
Published: September 2003

The history of the Vacuum Metallurgy Division (VMD), which is now the Advanced Surface Engineering Division (ASED), of the American Vacuum Society is reviewed briefly. The focus of the VMD moved from vacuum melting of materials to metallurgical coatings. The division sponsored two conferences, the Conference on Vacuum Metallurgy and the International Conference on Metallurgical Coatings. As the interest in vacuum metallurgy eventually subsided, interest grew in the deposition of metallurgical coatings. However, the emphasis at the Metallurgical Coatings conference has changed from just depositing coatings to surface engineering of a component. Today, the challenge is to use the tools of surface engineering with advances in deposition technology such as high-power pulsed sputtering. To align itself with the changing interests of the majority of its members, the VMD changed its name to the ASED.
Role of third bodies in friction and wear of protective coatings
Authors: Singer I. L. , Dvorak S. D. , Wahl K. J. , Scharf T. W.
Published: September 2003

The literature on protective tribological coatings often focuses on correlations with measurable coating properties (composition, structure, and mechanical) but ignores the mechanisms of friction and wear. In fact, long-lived coatings often survive because of third bodies that form inside the moving contact. This article reviews earlier studies of third body processes carried out by mainly ex situ methods and reports more recent studies investigating third body processes using in situ techniques. Direct evidence that third bodies control friction and wear processes has been obtained with a tribometer incorporating in situ optical microscopy and Raman spectroscopy. Videotapes and Raman spectra of the sliding contact were recorded during reciprocating sliding tests performed in both dry and humid air with transparent hemispheres (glass or sapphire). Third body processes were correlated directly to friction and wear behavior of three low friction coatings: amorphous Pb–Mo–S; diamond-like carbon (DLC); and annealed boron carbide. In all three cases, the friction behavior could be explained in terms of the relative motion between a transfer film on the hemisphere and the wear track. With amorphous Pb–Mo–S, the transfer film was MoS2; with DLC, it was a graphite-like carbon; and with annealed boron carbide, it was either a mix of H3BO3 and carbon (at μ=0.08) or, when the H3BO3 wore away, carbon alone (at μ=0.2). Friction rises with Pb–Mo–S and DLC in humid air were ascribed to a change in interfacial shear strength; friction spikes and fluctuations with DLC were associated with periodic loss of transfer film thickness. For all three coatings, interfacial sliding between transfer film and wear track on coating was the dominant velocity accommodation mode.
Nucleation theory and the early stages of thin film growth
Authors: Ratsch C. , Venables J. A.
Published: September 2003

A review is given of nucleation and growth models as applied to the earliest stages of thin film growth. Rate equations, kinetic Monte Carlo, and level set simulations are described in some detail, with discussion of remaining uncertainties, in particular the functional form of the so-called capture numbers in rate equations. Recent examples are given of sub-monolayer nucleation at surface defects, attachment-limited capture, and Ostwald ripening. The experimental literature is cited, and experiment–theory comparisons are made where possible. Emphasis is given to fast computational models that can span a large range of length and time scales, which might be further developed in the direction of on-line process control.
Photoinduced anisotropy of second-harmonic generation from azobenzene-modified alkylsiloxane monolayers
Authors: Yi Y. W. , Furtak T. E. , Farrow M. J. , Walba D. M.
Published: September 2003

Noncontact alignment of liquid crystal displays offers the advantage of reduced contamination and minimal surface charging. This approach also provides a means of reversible alignment after a device has been assembled. With this objective we have synthesized self-assembled monolayers based on dimethylaminoazobenzene units covalently attached to a glass surface by means of a short alkylsiloxane anchor, a derivatized version of methyl red (d-MR). The resulting architecture favors an orientation in which the axis of the azobenzene group should be nearly parallel to the surface with an isotropic azimuthal distribution. Under illumination with polarized light the trans–cis isomerization and subsequent relaxation serves to wiggle the molecule into an orientation perpendicular to the treatment polarization. We have tested this scenario using optical second harmonic generation and supporting optical techniques. We are able to identify a surface order parameter that characterizes the photoalignment of the azobenzene group, and have shown that the treatment illumination promotes the formation of H aggregates of the azobenzene species. We have also demonstrated that the treated d-MR layer successfully aligns a nematic liquid crystal.
Anomalous Nitrogen Isotope Ratio in Comets
Authors: Arpigny Claude , Jehin Emmanuël , Manfroid Jean , Hutsemékers Damien , Schulz Rita , Stüwe J. A. , Zucconi Jean-Marc , Ilyin Ilya
Published: September 2003

High-resolution spectra of the CN
B
2
∑
+
–
X
2
∑
+
(0,0) band at 390 nanometers yield isotopic ratios for comets C/1995 O1 (Hale-Bopp) and C/2000 WM1 (LINEAR) as follows: 165 ± 40 and 115 ± 20 for
12
C/
13
C, 140 ± 35 and 140 ± 30 for
14
N/
15
N. Our N isotopic measurements are lower than the terrestrial
14
N/
15
N = 272 and the ratio for Hale-Bopp from measurements of HCN, the presumed parent species of CN. This isotopic anomaly suggests the existence of other parent(s) of CN, with an even lower N isotopic ratio. Organic compounds like those found in interplanetary dust particles are good candidates.
Use of Genetic Profiling in Leprosy to Discriminate Clinical Forms of the Disease
Authors: Bleharski Joshua R. , Li Huiying , Meinken Christoph , Graeber Thomas G. , Ochoa Maria-Teresa , Yamamura Masahiro , Burdick Anne , Sarno Euzenir N. , Wagner Manfred , Röllinghoff Martin , Rea Thomas H. , Colonna Marco , Stenger Steffen , Bloom Barry R. , Eisenberg David , Modlin Robert L.
Published: September 2003

Leprosy presents as a clinical and immunological spectrum of disease. With the use of gene expression profiling, we observed that a distinction in gene expression correlates with and accurately classifies the clinical form of the disease. Genes belonging to the leukocyte immunoglobulin-like receptor (LIR) family were significantly up-regulated in lesions of lepromatous patients suffering from the disseminated form of the infection. In functional studies, LIR-7 suppressed innate host defense mechanisms by shifting monocyte production from interleukin-12 toward interleukin-10 and by blocking antimicrobial activity triggered by Toll-like receptors. Gene expression profiles may be useful in defining clinical forms of disease and providing insights into the regulation of immune responses to pathogens.
A Yankee in King Gustav's Court
Authors: Brenner Sydney
Published: September 2003

How to Win the Nobel Prize
An Unexpected Life in Science. by J. Michael Bishop. Harvard University Press, Cambridge, MA, 2003. 287 pp., illus. $27.95, £18.50, €27.95. ISBN 0-674-00880-4.

Offering more than an account of his path to Stockholm, Bishop weaves together an autobiography and histories of efforts to control infectious diseases and to identify and control the causes of cancer.