bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative Analysis of Thin Films by dc Arc Optical Emission Spectroscopy
Authors: Hogrefe Arnold W. , Lowry Robert K.
Published: September 2005

dc arc optical emission spectroscopy was investigated as a quantitative method for measuring compositions of thin films commonly used in fabricating semiconductor devices. Thin films studied were nickel-chromium, phosphorus-silicon dioxide, and silicon-aluminum. Film samples were obtained by direct deposition onto ordinary graphite electrodes mounted in vacuum deposition chambers. Standards for each film were prepared by evaporating series of synthetic solutions approximating film compositions onto electrode tips, or by preparing appropriately weighed mixed powder standards. Calibration curves were established by burning multiple sets of these standard electrodes in a 15-A dc arc and plotting the intensity ratios for selected atomic lines of the analyte elements. Correlation of emission results with atomic absorption, electron microprobe, and gravimetric analysis showed absolute agreement to within ±3% for nickel-chromium, ± 0.3% for phosphorus-silicon dioxide, and ±0.2% for silicon-aluminum. Maximum relative percent error was 5, 10, and 12.5%, respectively. This technique has proved to be a rapid convenient process control tool in the manufacture of microelectronic devices.
Measurement of Electronic and Resonance Raman Spectra from the Same Gas Matrix or Thin Film Sample
Authors: Scheuermann W. , Nakamoto K.
Published: September 2005

A new method is described to measure effective electronic absorption spectra by means of the Raman spectrometer. The spectra originate from the same sample spot of a gas matrix or thin film that was used for the Raman measurement. The influence of the substrate material and the angle of incidence was investigated. Octaethylporphinatocobalt (II) was used to demonstrate the method. It was observed that the α and β absorption bands shift as much as 700 cm−1 depending on sample preparation, thermal treatment, and the resulting physical state. A variation of the angle of incidence from α = 45° to α = 20° had no influence on the position of the α and β bands. Five significantly different resonance Raman spectra were recorded with 514.5 nm excitation. It was found that the relative intensities of the Raman bands were dependent on the position of the β band with respect to the frequency of the exciting radiation. This result led to the conclusion that Raman band intensities should only be correlated with an effective electronic absorption spectrum obtained from the same sample spot.
Effect of External Magnetic Field on the Volatilization of Elements in the dc Arc
Authors: Fakhry A. A. , Eid M. A. , Hashem M. S.
Published: September 2005

In the present investigation opposing magnetic fields are applied to the free burning carbon arc with a silicate sample (granodiorite) in its anode crater. The magnetic field promoted the selective volatilization of the elements present in the sample. As a result, a depression in the spectral line intensities of Mn, Ti, Th, and Fe as well as the background was observed. At the same time the intensity of the spectral lines of Ag, Ge, Pb, In, and Cu is enhanced. The latter elements are of great significance since they are used as pathfinders for gold.
A Flame Chemiluminescence Method for the Determination of Sulfide and its Application to the Determination of Sulfur in Mild Steel, Carbon Steel, and Cast Iron
Authors: Hamouda A. A. , Kirkbright G. F. , Mounce R. P.
Published: September 2005

A study has been made of the determination of sulfide by generation of hydrogen sulfide from acidified sample solutions followed by measurement of the chemiluminescence of the S2 species produced on introduction of the H2S into an argon-hydrogen flame. The technique is simple to perform and results in considerable increase in the absolute detection limit for sulfur compared to that obtained on aspiration of aqueous solutions of sulfide into the flame. A method has been developed to allow application of the technique to the determination of sulfur in samples of mild steel, carbon steel, and cast iron.
Measurement Procedures for Characterization of High Voltage Spark Sources
Authors: Scheeline Alexander , Coleman David M. , Walters John P.
Published: September 2005

Procedures are presented for calibration of electronic adjustable waveform capacitor discharge spark sources. Both individual component measurements and system measurements are discussed. Characterization of components and subsystems involved in capacitor charging, spark formation, and discharge current control is described. Specific measurement devices and techniques are discussed, and precision requirements for various degrees of characterization of both components and systems are given. Application of the characterization procedures to routine source monitoring and to source development are also presented.
Accuracy and Optimization of the Two Polarization Technique for Obtaining the Optical Constants from Attenuated Total Reflection Measurements
Authors: Hirschfeld Tomas
Published: September 2005

The relative error of the optical constants determined by attenuated total reflectance at two polarizations and the same incidence angle is calculated as a function of the reflectance errors by a perturbation method. The variations in the error as a function of the incidence angle are then plotted for various values of the optical constants. The experimental accuracy is optimized by either shallow incidence angles and low index optics or by high index optics in the close vicinity of the critical angle. In either case, the number of reflections should be chosen to give strong attenuation. Under optimum conditions, the method gives reasonably good accuracies.
Modulation Techniques in Polarization Spectroscopy
Authors: Jensen H. P. , Schellman J. A. , Troxell T.
Published: September 2005

Optical calculi for anistropic media are reviewed and extended for use in a phase-modulation spectrophotometer. It is demonstrated under which conditions signals proportional to linear and circular dichroisms may be collected, and how artifacts may be introduced from either the optical systems or the medium itself. Finally, conversions among the optical calculi in use are tabulated and discussed.
Evaluation of Commercial Energy Dispersion X-Ray Analyzers for Water Pollution
Authors: Birks L. S. , Gilfrich J. V.
Published: September 2005

Seven typical commercial energy dispersion x-ray analyzers were evaluated for application to the measurement of elemental concentration in polluted water. Sensitivity and detection limits were measured on single- (or dual-) element standards. Results for 400-sec counting intervals indicate that the better energy dispersive analyzers have limits of detection between 10 and a few hundred µg/cm2. Many pollutants in natural water are present at >10 ppb, which means that adequate material can be obtained from 100 to 1000 ml samples; some elements of interest such as Cd and Sn are generally present at <1 ppb, which makes practical detection marginal for the energy dispersion method. When x-ray calibration curves were prepared from individual-element gravimetric standards and used to analyze multiple-element samples (also prepared gravimetrically), the agreement between x-ray and gravimetric results showed an average relative deviation of 16%.
Continuum Source Atomic Fluorescence of Arsenic
Authors: Heithmar E. M. , Plankey F. W.
Published: September 2005

Although continuum sources in atomic fluorescence spectrometry have been thought to be of little use for studies below 200 nm, a high pressure xenon arc continuum source has proved to be effective for exciting arsenic at 189.0, 193.7, and 197.2 nm. To enable good atomization characteristics and a constant signal for wavelength scans, a commercially prepared mixture of arsine in H2 was used as the sample. A wavelength scan is presented, comparisons of sensitivities at various wavelengths are shown, and some indication of the quenching characteristics of Ar and N2 are included in this work. Analytical studies show that the 189.0 nm line has the greatest sensitivity and when this line is used in conjunction with the 235.0 nm line, a dynamic range of approximately 700 is expected. The detection limit in terms of mass flow of As, is found to be about 0.5 ng/s at the 189.0 nm line.
Spectral Evaluation of Windowless Argon Discharge Vacuum Ultraviolet Lamps for Matrix Isolation Spectroscopy
Authors: Andrews Lester , Tevault David E. , Smardzewski Richard R.
Published: September 2005

Windowless argon discharge tubes used as resonance lamps in matrix isolation experiments produced strong argon resonance radiation at 1048 and 1067 Å, and at low pressures, the Ar+ resonance doublet at 920 and 932 Å made a major contribution to the vacuum ultraviolet spectrum. At discharge pressures below 60 µ, the relative intensities of the 1048, 1067 Å argon resonance doublet are reversed in favor of the 1067 Å line, although the Ar+ resonance lines are substantially increased relative to the neutral atom emissions.
Correlation Readout System for a Photodiode Array Spectrometer Applied to Inductively Coupled Plasma Emission Spectroscopy
Authors: Betty K. R. , Horlick Gary
Published: September 2005

A hardware cross-correlator has been developed as a readout system for a photodiode array spectrometer. With this system a reference spectrum is stored in a transient recorder and used as an electronic correlation mask for the detection and measurement of the same spectral signal. The correlator is described and then applied to the detection of Ca and Cr emission signals from an inductively coupled plasma source. The applicability of this correlator to the detection of a specific spectral pattern in the presence of a more complex partially overlapping spectral signal is also illustrated.
Investigations of the Determination of Phosphorus in Organic Media by Atomic Absorption Heated Graphite Atomizer
Authors: Vigler Mildred S. , Strecker Arthur , Varnes Arthur
Published: September 2005

The analysis of phosphorus in organic compounds used as product additives has been investigated. It has been found necessary to change the organic phosphorus to inorganic phosphorus before measuring it by atomic absorption spectrophotometry. In the determination of tricresyl phosphate in gasoline the gasoline is ashed on magnesium sulfonate. The tricresyl phosphate is converted to Mg2P2O7 and subsequently dissolved in nitric acid, diluted to desired concentration, and then injected into the heated graphite furnace. A calibration curve is made from gasoline containing a known phosphorus content to give a range of 1 to 10 ppm. Twenty-five microliters of the knowns and unknown are injected on 10 µl of a 1% solution of lanthanum nitrate on the graphite tube. An alkyl phenyl phosphite additive is diluted in dimethylformamide to bring it into solution in the range of 1 to 10 ppm phosphorus. A portion is ashed on magnesium oxide with the addition of 1 ml of 30% hydrogen peroxide. The Mg2P2O7 is dissolved in nitric acid, then diluted to the calibration curve range. It is injected into the heated graphite furnace in the presence of 10 µl of a 1% lanthanum nitrate solution.
Homocysteine and heart failure: a review of investigations from the Framingham Heart Study
Authors: Sundström Johan , Vasan Ramachandran S.
Published: September 2005

High plasma homocysteine levels are associated with a moderately increased risk of cardiovascular disease, particularly of atherosclerotic events. We review the association of plasma homocysteine with heart failure, with a specific focus on a series of previously published investigations from the community-based Framingham Heart Study that evaluated the relations of plasma homocysteine levels with overt heart failure, and with its key antecedents, echocardiographic left ventricular (LV) mass and hypertension. In the Framingham sample, higher plasma homocysteine levels were associated with increased risk of new-onset heart failure in both men and women, with a more continuous and graded relation being observed in women. A positive relation between homocysteine and LV mass was observed in women, but not in men; this may underlie the stronger relations of homocysteine to heart failure risk in women. Plasma homocysteine was not associated with hypertension incidence prospectively in either sex. The relations of increased homocysteine to heart failure (in both sexes) and to greater LV mass (in women) noted in the Framingham sample should be confirmed in other community-based samples. Secondary analyses of heart failure outcomes in ongoing randomized clinical trials may provide insights into whether lowering of plasma homocysteine levels is associated with a reduction in LV mass and/or a reduction of heart failure risk.
Vitamin B12 deficiency is the dominant nutritional cause of hyperhomocysteinemia in a folic acid-fortified population
Authors: Green Ralph , Miller Joshua W.
Published: September 2005

Prevalence rates for folate deficiency and hyperhomocysteinemia have been markedly reduced following the introduction of folic acid fortification in the United States. We report the prevalence of hyperhomocysteinemia in a population of community-dwelling elderly Latinos in the post-folic acid fortification era. We measured homocysteine, total vitamin B
Homocysteine, folic acid and vitamin B12 in relation to pre- and postnatal health aspects
Authors: Obeid Rima , Herrmann Wolfgang
Published: September 2005

Studies linking hyperhomocysteinemia (HHCY) and B-vitamin deficiency to some health aspects in children have been accumulating. Low B-vitamin status inearly life, even as early as the time of conception, may endanger the potential for new life and may negatively influence the health of the offspring. Early abortion, pregnancy complications and poor pregnancy outcomes have been linked to elevated concentrations of total plasma homocysteine (tHcy) and low folate or vitamin B
Homocysteine in relation to cognitive performance in pathological and non-pathological conditions
Authors: Teunissen Charlotte E. , van Boxtel Martin P. J. , Jolles Jellemer , de Vente Jan , Vreeling Fred , Verhey Frans , Polman Chris H. , Dijkstra Christine D. , Blom Henk J.
Published: September 2005

Elevated serum homocysteine has been associated with increased risk of Alzheimer's disease. Furthermore, elevated homocysteine levels are related to cognitive dysfunction in the elderly. The aim of the present study was to explore the disease specificity of the relation between serum total homocysteine levels and cognitive function. For this, we summarize data from several studies on homocysteine levels in both normal and pathological conditions performed in our laboratories and evaluate possible mechanisms of effects of elevated homocysteine levels in the central nervous system. Total homocysteine levels were measured in serum of: 1) healthy aging individuals; 2) patients with Alzheimer's and Parkinson's disease and patients with other cognitive disorders; and 3) patients with multiple sclerosis. Increased serum homocysteine concentration was related to worse cognitive performance over a 6-year period in the normal aging population (r=−0.36 to −0.14, p<0.01 for the Word learning tests; r=0.76, p<0.05 for the Stroop Colored Word test). Homocysteine was only increased in patients with Parkinson's disease on L-Dopa therapy (18.9 vs. 16.5μmol/L in healthy controls), and not in dementia patients. Homocysteine was elevated in patients with progressive multiple sclerosis (15.0μmol/L, n=39, compared to 12.0 μmol/L in 45 controls) and correlated to both cognitive and motor function (r=−0.33 and −0.33, p<0.05, respectively). The relationship between homocysteine and cognitive function in non-pathological and pathological situations indicates that changes in its levels may play a role in cognitive functioning in a broad spectrum of conditions.
Bradykinin-Induced Functional Competence and Trafficking of the δ-Opioid Receptor in Trigeminal Nociceptors
Authors: Patwardhan Amol M. , Berg Kelly A. , Akopain Armen N. , Jeske Nathaniel A. , Gamper Nikita , Clarke William P. , Hargreaves Kenneth M.
Published: September 2005

Peripheral opioid analgesia is increased substantially after inflammation. We evaluated the hypothesis that an inflammatory mediator, bradykinin (BK), evokes functional competence of the δ-opioid receptor (DOR) for inhibiting trigeminal ganglia (TG) sensory neurons. We also evaluated whether BK evokes trafficking of the DOR to the plasma membrane. Rat TG cultures were pretreated with BK (10 μm) or vehicle, and the effects of DOR agonists ([d-Pen2,5]-enkephalin or [d-Ala2,d-Leu5]-enkephalin) on BK (10μm)/prostagladin E2 (PGE2; 1 μm)-stimulated immunoreactive calcitonin gene-related peptide (iCGRP) release or PGE2 (1 μm)-stimulated cAMP accumulation were measured. The effect of BK treatment on opioid receptor trafficking was evaluated by DOR immunohistochemistry, cell-surface DOR biotinylation, and live imaging of neurons transfected with mDOR–green fluorescent protein. BK pretreatment rapidly and significantly increased DOR agonist inhibition of evoked iCGRP release and cAMP accumulation. These effects of BK pretreatment were blocked by a B2receptor antagonist (HOE-140; 10μm) or a protein kinase C (PKC) inhibitor [bisindolymaleimide (BIS); 1μm]. Moreover, BK treatment rapidly and significantly increased the accumulation of DOR in the plasma membrane. However, BK-induced trafficking of DOR was not reversed by pretreatment with BIS, nor was trafficking evoked by application of a PKC activator PMA (200 nm). These data suggest that BK, in a PKC-dependent manner, induces rapid functional competence of DOR for inhibiting TG nociceptors and in a PKC-independent manner rapidly induces trafficking of DOR to the plasma membrane. These findings indicate that exposure to certain inflammatory mediators rapidly alters the signaling properties and neuronal localization of DOR, possibly contributing to peripheral opioid analgesia.
Quantitative Investigation of Connections of the Prefrontal Cortex in the Human and Macaque using Probabilistic Diffusion Tractography
Authors: Croxson Paula L. , Johansen-Berg Heidi , Behrens Timothy E. J. , Robson Matthew D. , Pinsk Mark A. , Gross Charles G. , Richter Wolfgang , Richter Marlene C. , Kastner Sabine , Rushworth Matthew F. S.
Published: September 2005

The functions of prefrontal cortex (PFC) areas are constrained by their anatomical connections. There is little quantitative information about human PFC connections, and, instead, our knowledge of primate PFC connections is derived from tracing studies in macaques. The connections of subcortical areas, in which white matter penetration and hence diffusion anisotropy are greatest, can be studied with diffusion-weighted imaging (DWI) tractography. We therefore used DWI tractography in four macaque and 10 human hemispheres to compare the connections of PFC regions with nine subcortical regions, including several fascicles and several subcortical nuclei. A distinct connection pattern was identified for each PFC and each subcortical region. Because some of the fascicles contained connections with posterior cortical areas, it was also possible to draw inferences about PFC connection patterns with posterior cortical areas. Notably, it was possible to identify similar circuits centered on comparable PFC regions in both species; PFC regions probably engage in similar patterns of regionally specific functional interaction with other brain areas in both species. In the case of one area traditionally assigned to the human PFC, the pars opercularis, the distribution of connections was not reminiscent of any macaque PFC region but, instead, resembled the pattern for macaque ventral premotor area. Some limitations to the DWI approach were apparent; the high diffusion anisotropy in the corpus callosum made it difficult to compare connection probability values in the adjacent cingulate region.
Integrated Neural Representations of Odor Intensity and Affective Valence in Human Amygdala
Authors: Winston Joel S. , Gottfried Jay A. , Kilner James M. , Dolan Raymond J.
Published: September 2005

Arousal and valence are proposed to represent fundamental dimensions of emotion. The neural substrates for processing these aspects of stimuli are studied widely, with recent studies of chemosensory processing suggesting the amygdala processes intensity (a surrogate for arousal) rather than valence. However, these investigations have assumed that a valence effect in the amygdala is linear such that testing valence extremes is sufficient to infer responses across valence space. In this study, we tested an alternative hypothesis, namely that valence responses in the amygdala are nonlinear. Using event-related functional magnetic resonance imaging, we measured amygdala responses to high- and low-concentration variants of pleasant, neutral, and unpleasant odors. Our results demonstrate that the amygdala exhibits an intensity-by-valence interaction in olfactory processing. In other words, the effect of intensity on amygdala activity is not the same at all levels of valence. Specifically, the amygdala responds differentially to high (vs low)-intensity odor for pleasant and unpleasant smells but not for neutral smells. This implies that the amygdala codes neither intensity nor valence per se, but a combination that we suggest reflects the overall emotional value of a stimulus.
AnAplysiaType 4 Phosphodiesterase Homolog Localizes at the Presynaptic Terminals ofAplysiaNeuron and Regulates Synaptic Facilitation
Authors: Park Hyungju , Lee Jin-A , Lee Changhoon , Kim Min-Jeong , Chang Deok-Jin , Kim Hyoung , Lee Seung-Hee , Lee Yong-Seok , Kaang Bong-Kiun
Published: September 2005

The cAMP-dependent signaling pathway is critically involved in memory-related synaptic plasticity. cAMP-specific type 4 phosphodiesterases (PDE4) play a role in this process by regulating the cAMP concentration. However, it is unclear how PDE4 is involved in regulating synaptic plasticity. To address this issue inAplysiasensory-to-motor synapses, we identified a long isoform of the PDE4 homolog inAplysia kurodai(apPDE), with genetic and biochemical properties similar to those of mammalian PDE4s. Furthermore, apPDE is localized to the membrane and presynaptic region. Both apPDE overexpression and knock-down impaired short- and long-term facilitation, indicating that an appropriate expression level of apPDE in synaptic regions is required for normal synaptic facilitation. By using fluorescence resonance energy transfer-based measurement ofin vivoprotein kinase A (PKA) activation, we found that the PKA activation by 5-hydroxytryptamine (5-HT) was impaired in both apPDE-overexpressed and knock-down synapses. Analogous to the inhibition of apPDE by RNA interference, chronic rolipram treatment before 5-HT stimulation also impaired the PKA activation by 5-HT, suggesting that regulation of the synaptic cAMP level by PDE4 is critical for normal synaptic facilitation. Together, we suggest that PDE4s localized in the synapses play a critical role in regulating the optimum cAMP level required for normal synaptic plasticity.
Separate Spatial Scales Determine Neural Activity-Dependent Changes in Tissue Oxygen within Central Visual Pathways
Authors: Thompson Jeffrey K. , Peterson Matthew R. , Freeman Ralph D.
Published: September 2005

The relationship between oxygen levels and neural activity in the brain is fundamental to functional neuroimaging techniques. We have examined this relationship on a fine spatial scale in the lateral geniculate nucleus (LGN) and visual cortex of the cat using a microelectrode sensor that provides simultaneous colocalized measurements of oxygen partial pressure in tissue (tissue oxygen) and multiunit neural activity. In previous work with this sensor, we found that changes in tissue oxygen depend strongly on the location and spatial extent of neural activation. Specifically, focal neural activity near the microelectrode elicited decreases in tissue oxygen, whereas spatially extended activation, outside the field of view of our sensor, yielded mainly increases. In the current study, we report an expanded set of measurements to quantify the spatiotemporal relationship between neural responses and changes in tissue oxygen. For the purpose of data analysis, we develop a quantitative model that assumes that changes in tissue oxygen are composed of two response components (one positive and one negative) with magnitudes determined by neural activity on separate spatial scales. Our measurements from visual cortex and the LGN are consistent with this model and suggest that the positive response spreads over a distance of 1–2 mm, whereas the negative component is confined to a few hundred micrometers. These results are directly relevant to the mechanisms that generate functional brain imaging signals and place limits on their spatial properties.
Regulation of Ventral Surface Chemoreceptors by the Central Respiratory Pattern Generator
Authors: Guyenet Patrice G. , Mulkey Daniel K. , Stornetta Ruth L. , Bayliss Douglas A.
Published: September 2005

The rat retrotrapezoid nucleus (RTN) contains neurons described as central chemoreceptors in the adult and respiratory rhythm-generating pacemakers in neonates [parafacial respiratory group (pfRG)]. Here we test the hypothesis that both RTN and pfRG neurons are intrinsically chemosensitive and tonically firing neurons whose respiratory rhythmicity is caused by a synaptic feedback from the central respiratory pattern generator (CPG). In halothane-anesthetized adults, RTN neurons were silent below 4.5% end-expiratory (e-exp) CO2. Their activity increased linearly (3.2 Hz/1% CO2) up to 6.5% (CPG threshold) and then more slowly to peak ∼10 Hz at 10% CO2. Respiratory modulation of RTN neurons was absent below CPG threshold, gradually stronger beyond, and, like pfRG neurons, typically (42%) characterized by twin periods of reduced activity near phrenic inspiration. After CPG inactivation with kynurenate (KYN), RTN neurons discharged linearly as a function of e-exp CO2(slope, +1.7 Hz/1% CO2) and arterial pH (threshold, 7.48; slope, 39 Hz/pH unit). In coronal brain slices (postnatal days 7–12), RTN chemosensitive neurons were silent at pH 7.55. Their activity increased linearly with acidification up to pH 7.2 (17 Hz/pH unit at 35°C) and was always tonic.

In conclusion, consistent with their postulated central chemoreceptor role, RTN/pfRG neurons encode pH linearly and discharge tonically when disconnected from the rest of the respiratory centersin vivo(KYN treatment) andin vitro.In vivo, RTN neurons receive respiratory synchronous inhibitory inputs that may serve as feedback and impart these neurons with their characteristic respiratory modulation.
Two Antiphase Oscillations Occur in Each Suprachiasmatic Nucleus of Behaviorally Split Hamsters
Authors: Yan Lily , Foley Nicholas C. , Bobula Jessica M. , Kriegsfeld Lance J. , Silver Rae
Published: September 2005

The suprachiasmatic nuclei (SCNs) control circadian rhythms of numerous behavioral and physiological responses. In hamsters, constant light causes “splitting” of circadian rhythms, such that a single daily bout of activity separates into two components, 12 h apart, with antiphase circadian oscillations in the left and right SCN. Given the phenotypic and functional heterogeneity of the SCN, in which ventrolateral but not dorsomedial neurons are retinorecipient, we asked how these two compartments respond to the constant lighting conditions that produce splitting, using three different phase markers of neuronal activity: PER1 (Period 1), c-FOS, and pERK (phosphorylated extracellular signal-regulated kinase). We report the emergence of a coherent novel network in which each side of the SCN exhibits two antiphase oscillating subregions, here termed “core-like” and “shell-like,” in addition to the known antiphase oscillation between the right and left SCN. The novel SCN response entails a coherent rhythm in a core-like region of the SCN, which otherwise is not cycling. A mathematical model is presented, and this model interprets the observed changes in the proportion of in-phase and antiphase populations of SCN oscillators and suggests novel testable hypotheses. Finally, the functional significance of this network was explored by investigating the adjacent hypothalamus. Activation of the paraventricular nucleus is in-phase with the ipsilateral core-like SCN, whereas activation of the lateral subparaventricular zone is in-phase with the ipsilateral shell-like SCN, pointing to a multiplicity of SCN output signals. These results suggest a neural basis for internal coincidence of SCN oscillators, and a novel mechanism of plasticity in SCN neural networks and outputs.
Hyperpolarization-Activated Cyclic Nucleotide-Gated Cation Channels Regulate Auditory Coincidence Detection in Nucleus Laminaris of the Chick
Authors: Yamada Rei , Kuba Hiroshi , Ishii Takahiro M. , Ohmori Harunori
Published: September 2005

Coincidence detection of bilateral acoustic signals in nucleus laminaris (NL) is the first step in azimuthal sound source localization in birds. Here, we demonstrate graded expression of hyperpolarization-activated cyclic nucleotide-gated (HCN) cation channels along the tonotopic axis of NL and its role in the regulation of coincidence detection. Expression of HCN1 and HCN2, but not HCN3 or HCN4, was detected in NL. Based on measurement of both subtype mRNA and protein, HCN1 varied along the tonotopic axis and was minimal in high-characteristic frequency (CF) neurons. In contrast, HCN2 was evenly distributed. The resting conductance was larger and the steady-state activation curve ofIhwas more positive in neurons of middle to low CF than those of high CF, consistent with the predominance of HCN1 channels in these neurons. Application of 8-Br-cAMP or noradrenaline generated a depolarizing shift of theIhvoltage activation curve. This shift was larger in neurons of high CF than in those of middle CF. The shift in the activation voltage ofIhdepolarized the resting membrane, accelerated the EPSP time course, and significantly improved the coincidence detection in neurons of high CF, suggesting thatIhmay improve the localization of sound sources.
Mechanism of Positive Allosteric Modulators Acting on AMPA Receptors
Authors: Jin Rongsheng , Clark Suzanne , Weeks Autumn M. , Dudman Joshua T. , Gouaux Eric , Partin Kathryn M.
Published: September 2005

Ligand-gated ion channels involved in the modulation of synaptic strength are the AMPA, kainate, and NMDA glutamate receptors. Small molecules that potentiate AMPA receptor currents relieve cognitive deficits caused by neurodegenerative diseases such as Alzheimer's disease and show promise in the treatment of depression. Previously, there has been limited understanding of the molecular mechanism of action for AMPA receptor potentiators. Here we present cocrystal structures of the glutamate receptor GluR2 S1S2 ligand-binding domain in complex with aniracetam [1-(4-methoxybenzoyl)-2-pyrrolidinone] or CX614 (pyrrolidino-1,3-oxazino benzo-1,4-dioxan-10-one), two AMPA receptor potentiators that preferentially slow AMPA receptor deactivation. Both potentiators bind within the dimer interface of the nondesensitized receptor at a common site located on the twofold axis of molecular symmetry. Importantly, the potentiator binding site is adjacent to the “hinge” in the ligand-binding core “clamshell” that undergoes conformational rearrangement after glutamate binding. Using rapid solution exchange, patch-clamp electrophysiology experiments, we show that point mutations of residues that interact with potentiators in the cocrystal disrupt potentiator function. We suggest that the potentiators slow deactivation by stabilizing the clamshell in its closed-cleft, glutamate-bound conformation.
Camphor Activates and Strongly Desensitizes the Transient Receptor Potential Vanilloid Subtype 1 Channel in a Vanilloid-Independent Mechanism
Authors: Xu Haoxing , Blair Nathaniel T. , Clapham David E.
Published: September 2005

Camphor is a naturally occurring compound that is used as a major active ingredient of balms and liniments supplied as topical analgesics. Despite its long history of common medical use, the underlying molecular mechanism of camphor action is not understood. Capsaicin and menthol, two other topically applied agents widely used for similar purposes, are known to excite and desensitize sensory nerves by acting on two members of transient receptor potential (TRP) channel superfamily: heat-sensitive TRP vanilloid subtype 1 (TRPV1) and cold-sensitive TRP channel M8, respectively. Camphor has recently been shown to activate TRPV3, and here we show that camphor also activates heterologously expressed TRPV1, requiring higher concentrations than capsaicin. Activation was enhanced by phospholipase C-coupled receptor stimulation mimicking inflamed conditions. Similar camphor-activated TRPV1-like currents were observed in isolated rat DRG neurons and were strongly potentiated after activation of protein kinase C with phorbol-12-myristate-13-acetate. Camphor activation of rat TRPV1 was mediated by distinct channel regions from capsaicin, as indicated by camphor activation in the presence of the competitive inhibitor capsazepine and in a capsaicin-insensitive point mutant. Camphor did not activate the capsaicin-insensitive chicken TRPV1. TRPV1 desensitization is believed to contribute to the analgesic actions of capsaicin. We found that, although camphor activates TRPV1 less effectively, camphor application desensitized TRPV1 more rapidly and completely than capsaicin. Conversely, TRPV3 current sensitized after repeated camphor applications, which is inconsistent with the analgesic role of camphor. We also found that camphor inhibited several other related TRP channels, including ankyrin-repeat TRP 1 (TRPA1). The camphor-induced desensitization of TRPV1 and block of TRPA1 may underlie the analgesic effects of camphor.
Eye–Hand Coordination during Learning of a Novel Visuomotor Task
Authors: Sailer Uta , Flanagan J. Randall , Johansson Roland S.
Published: September 2005

We investigated how gaze behavior and eye–hand coordination change when subjects learned a challenging visuomotor task that required acquisition of a novel mapping between bimanual actions and their visual sensory consequences. By applying isometric forces and torques to a rigid tool held freely between the two hands, subjects learned to control a cursor on a computer screen to hit successively displayed targets as quickly as possible. The learning occurred in stages that could be distinguished by changes in performance (target–hit rate) as well as by gaze behavior and eye–hand coordination. In a first exploratory stage, the hit rate was consistently low, the cursor position varied widely, and gaze typically pursued the cursor. In a second skill acquisition stage, the hit rate improved rapidly, and gaze fixations began to mark predictively desired cursor positions, indicating that subjects started to program spatially congruent eye and hand motor commands. In a third skill refinement stage, performance continued to improve gradually, and gaze shifted directly toward the target. We suggest that during the exploratory stage, the learner attempts to establish basic mapping rules between manual actions and eye-movement commands. In this process, subjects may establish correlations between hand motor commands and their visual sensory consequences, primarily in fovea-anchored, gaze-centered coordinates, and correlations between recent hand motor commands and eye motor commands. The established mapping rules are then implemented and refined in the skill acquisition and refinement stages.
Acute γ-Secretase Inhibition Improves Contextual Fear Conditioning in the Tg2576 Mouse Model of Alzheimer's Disease
Authors: Comery Thomas A. , Martone Robert L. , Aschmies Suzan , Atchison Kevin P. , Diamantidis George , Gong Xiaohai , Zhou Hua , Kreft Anthony F. , Pangalos Menelas N. , Sonnenberg-Reines June , Jacobsen J. Steven , Marquis Karen L.
Published: September 2005

Transgenic mice (Tg2576) overexpressing the Swedish mutation of the human amyloid precursor protein display biochemical, pathological, and behavioral markers consistent with many aspects of Alzheimer's disease, including impaired hippocampal function. Impaired, hippocampal-dependent, contextual fear conditioning (CFC) is observed in mice as young as 20 weeks of age. This impairment can be attenuated after treatment before training with the phosphodiesterase-4 inhibitor rolipram (0.1 mg/kg, i.p.). A rolipram-associated improvement is also observed in the littermate controls, suggesting that the effect of rolipram is independent of β-amyloid. Acute treatment before training (but not after training or before testing) with the γ-secretase inhibitor (GSI)N-[N-(3,5-difluorophenacetyl)-l-alanyl]-S-phenylglycine-t-butylester (DAPT), at a dose that reduces brain concentrations of β-amyloid (100 mg/kg), attenuates the impairment in 20- to 65-week-old Tg2576 mice. Importantly, DAPT had no effect on performance of control littermates. These data are supportive of a role of β-amyloid in the impairment of CFC in Tg2576 mice. Furthermore, they suggest that acute treatment with GSI may provide improved cognitive functioning as well as disease-modifying effects in Alzheimer's disease.
α2-Adrenoceptor Stimulation Transforms Immune Responses in Neuritis and Blocks Neuritis-Induced Pain
Authors: Romero-Sandoval E. Alfonso , McCall Charles , Eisenach James C.
Published: September 2005

Neuropathic pain may be primarily driven by immune responses in peripheral nerves. Peripherally released catecholamines may exacerbate neuropathic pain and also modulate immune responses in a complex and sometimes opposing manner by actions on multiple adrenoceptor subtypes. We showed previously that injection of the α2-adrenoceptor agonist clonidine at the site of peripheral nerve injury reduces pain behavior and local tissue pro-inflammatory cytokine content in rats. The current study used a model of acute inflammatory neuritis to test the efficacy and mechanisms of action ofα2-adrenoceptor stimulation to reduce pain. Zymosan, injected on the sciatic nerve, caused hypersensitivity to mechanical stimuli ipsilateral to injection and contralaterally, so-called mirror image pain. Ipsilateral hypersensitivity was inhibited dose-dependently by perineural injection of clonidine. Zymosan increased leukocyte number at the site of injection 3 d later as well as their content of interleukin 1α (IL-1α), IL-1β, and IL-6. Perineural clonidine prevented both the increase in leukocyte number and cytokine expression induced by zymosan. Additionally, clonidine reduced the capacity of leukocytes to express pro-inflammatory cytokines as assessed by treatment of cellsex vivowith lipopolysaccharide, whereas no repression of IL-10 production occurred. Clonidine reduced the number of macrophages and lymphocytes as well as their expression of tumor necrosis factor α. All of the effects of clonidine were prevented by coadministration of anα2A-adrenoceptor-preferring antagonist. These results suggest that α2-adrenoceptor stimulation transforms cytokine gene expression, especially in macrophages and lymphocytes from a pro- to an anti-inflammatory profile in the setting of neuritis, likely relieving neuritis-induced pain by this mechanism.
Konzeption, Herstellung und funktionelle Prüfung eines neuartigen Kontaktrefraktometers (Planning, Construction and Functional Evaluation of a New-Type Contact Refractometer)
Authors: Zirk Kai , Pötzschke Harald
Published: September 2005

Ein neueres Refraktometrieverfahren nutzt die Verschiebung der zeitlichen Phasenlage orthogonaler Feldstärkekomponenten, die ein polarisierter Lichtstrahl im Innern eines optisch dichteren Messkörpers bei einer Totalreflexion an der Grenzfläche zum optisch dünneren Messgut erfährt. Mit kleinstmöglichen Bauteilen traditioneller Herstelltechnik wurde ein entsprechendes Kontaktrefraktometer zur Bestimmung der Glukose in wässrigen Lösungen miniaturisiert gefertigt. Dessen Konzeption, Aufbau und Funktionsweise wird beschrieben, außerdem werden Messergebnisse von experimentellen Aufbauten und dem Refraktometer präsentiert.
Structural variations of Cr-doped (Y,REE)AlO3 perovskites
Authors: Cruciani Giuseppe , Matteucci Francesco , Dondi Michele , Baldi Giovanni , Barzanti Andrea
Published: September 2005

The crystal structure of ten different Y, REE (REE: rare earth elements) perovskite-type aluminates, doped with chromium, has been investigated by means of synchrotron powder diffraction in order to assess the crystallographic modifications related to varying the lanthanide ions. The symmetry change from orthorhombic (Y, Yb—Sm) to rhombohedral (Nd and Pr) has been confirmed. The anomalous behaviour of the unit cell parameters (in the Pnma setting, b and c contract while a expands as a function of the ‘lanthanide contraction’) has been clarified on the basis of changes in coordination number of the site containing the Y and lanthanide ion: this varies from approximately eight-fold in Yb-, Er-, Ho-, Y-, and Dy-orthoaluminates to nine-fold (or larger) in Gd-, Eu-, and Sm-orthoaluminates to twelve-fold (as in the archetypal cubic structure) in rhombohedral perovskites (Nd and Pr). The coordination number appears about two units greater in orthoaluminates with respect to the corresponding orthoferrites and an inverse correlation between the average bond distance of the Y, REE site and that of the octahedral Al (and Cr) hosting site has been observed.
Cu2MnMIVS4 (MIV = Si, Ge, Sn) — analysis of crystal structures and tetrahedra volumes of normal tetrahedral compounds
Authors: Bernert Thomas , Pfitzner Arno
Published: September 2005

The crystal structures of the normal tetrahedral compounds Cu2MnSiS4, Cu2MnGeS4, and Cu2MnSnS4 are presented. The structures were refined from single crystal X-ray data. Cu2MnSiS4 and Cu2MnGeS4 crystallize in the space group Pmn21 in a wurtzite type superstructure. The refinement of Cu2MnSiS4 converged to R = 0.0214 and wR2 = 0.0477. The redetermination of Cu2MnGeS4 converged to R = 0.0281, wR2 = 0.0739. The tetrahedra volumes of the coordination polyhedra of the cations in these compounds are calculated and compared with those of Cu2MnSnS4 (redetermination, spacegroup I-42m, sphalerite type superstructure, R = 0.0146, wR2 = 0.0425). In the wurtzite type structures the tetrahedra volumes differ significantly for different cations while they differ only in a small range in the sphalerite type structure.
Psychosocial and Environmental Correlates of Adolescent Sedentary Behaviors
Authors: Norman Gregory J. , Schmid Béatrice A. , Sallis James F. , Calfas Karen J. , Patrick Kevin
Published: September 2005

Objective. To determine correlates of sedentary behaviors in adolescents through the examination of psychosocial and environmental variables.

Method. The study used a cross-sectional design to evaluate an ethnically diverse clinic-based sample of 878 adolescents who were 11 to 15 years old. Bivariate and multivariate analyses were stratified by gender to assess correlates of sedentary behaviors occurring on the most recent nonschool day (television viewing, computer video games, sitting listening to music, and talking on the phone).

Results. For girls, age, family support, television/video rules, and hills in the neighborhood were associated with sedentary behaviors. Furthermore, psychological constructs such as self-efficacy, enjoyment, change strategies, and pros and cons of change emerged as correlates of sedentary behaviors. A moderator effect revealed that the proportion of girls in the low-BMI group decreased with increased self-efficacy, whereas the proportion of girls in the high-BMI group did not vary significantly by self-efficacy. For boys, age, ethnicity, BMI, cons of change, and self-efficacy were associated with sedentary behaviors.

Conclusions. This study provides evidence of factors associated and not associated with adolescent sedentary behaviors. Similar to physical activity, measures of specific psychosocial constructs of sedentary behavior demonstrated important associations. The results highlight the need for additional examination of the correlates of sedentary behavior to determine which correlates are mechanisms of behavior change.
Association of Consumption of Fried Food Away From Home With Body Mass Index and Diet Quality in Older Children and Adolescents
Authors: Taveras Elsie M. , Berkey Catherine S. , Rifas-Shiman Sheryl L. , Ludwig David S. , Rockett Helaine R.H. , Field Alison E. , Colditz Graham A. , Gillman Matthew W.
Published: September 2005

Objectives. Rates of overweight have increased dramatically among children in the United States. Although an increase in consumption of food prepared away from home has paralleled overweight trends, few data exist relating food prepared away from home to change in BMI in children. The goals of this study were to (1) examine the cross-sectional and longitudinal associations between consumption of fried foods away from home (FFA) and BMI and (2) examine the cross-sectional associations between intake of FFA and several measures of diet quality.

Methods. We studied a cohort of 7745 girls and 6610 boys, aged 9 to 14 years, at baseline in 1996. We obtained BMI from self-reported height and weight, measures of diet quality from a food frequency questionnaire, and weekly servings of FFA during the previous year. We performed linear regression analyses to assess the longitudinal associations between change in consumption of FFA on change in BMI, using data from three 1-year periods from 1996 through 1999. We also related consumption of FFA with intake of selected foods and nutrients at baseline.

Results. In cross-sectional analyses, adjusting for potential confounders, mean (SE) BMI was 19.1 (0.13) among children who ate FFA “never or <1/week,” 19.2 (0.13) among those who responded “1 to 3 times/week,” and 19.3 (0.18) among those who responded “4 to 7 times/week.” In longitudinal multivariate models, increasing (over 1 year) consumption of FFA “never or <1/week” to “4 to 7/week” was associated with increasing BMI (β = 0.21 kg/m2; 95% confidence interval: 0.03–0.39) compared with those with low consumption of FFA at baseline and 1 year later. At baseline, frequency of eating FFA was associated with greater intakes of total energy, sugar-sweetened beverages, and trans fat, as well as lower consumption of low-fat dairy foods and fruits and vegetables.

Conclusions. These data suggest that older children who consume greater quantities of FFA are heavier, have greater total energy intakes, and have poorer diet quality. Furthermore, increasing consumption of FFA over time may lead to excess weight gain.