cssi/SciSciGPT-SciSciNet huggingface dataset:
Dysregulation of Na+/K+ ATPase by amyloid in APP+PS1 transgenic mice.

The pathology of Alzheimer's disease (AD) is comprised of extracellular amyloid plaques, intracellular tau tangles, dystrophic neurites and neurodegeneration. The mechanisms by which these various pathological features arise are under intense investigation. Here, expanding upon pilot gene expression studies, we have further analyzed the relationship between Na+/K+ ATPase and amyloid using APP+PS1 transgenic mice, a model that develops amyloid plaques and memory deficits in the absence of tangle formation and neuronal or synaptic loss. We report that in addition to decreased mRNA expression, there was decreased overall Na+/K+ ATPase enzyme activity in the amyloid-containing hippocampi of the APP+PS1 mice (although not in the amyloid-free cerebellum). In addition, dual immunolabeling revealed an absence of Na+/K+ ATPase staining in a zone surrounding congophilic plaques that was occupied by dystrophic neurites. We also demonstrate that cerebral Na+/K+ ATPase activity can be directly inhibited by high concentrations of soluble Aβ. The data suggest that the reductions in Na+/K+ ATPase activity in Alzheimer tissue may not be purely secondary to neuronal loss, but may results from direct effects of amyloid on this enzyme. This disruption of ion homeostasis and osmotic balance may interfere with normal electrotonic properties of dendrites, blocking intraneuronal signal processing, and contribute to neuritic dystrophia. These results suggest that therapies aimed at enhancing Na+/K+ ATPase activity in AD may improve symptoms and/or delay disease progression.
Update in Pain Medicine for Primary Care Providers: A Narrative Review, 2010–2012

Objective This manuscript reviews peer-reviewed literature published from 2010–2012 relevant to the management of chronic pain in the primary care setting. Design Narrative review of peer-reviewed literature. Methods We searched MEDLINE, PubMed, and reference lists and queried expert contacts for English-language studies related to the management of chronic noncancer pain in adult patients in primary care settings. One investigator reviewed all eligible studies for relevance, and 47 studies were reviewed by all authors and rated according to their impact on 1) primary care clinical practice, 2) policy, 3) research, and 4) quality of study methods. Through iterative discussion, nine articles were selected for detailed review and discussion. Results We present articles in six topic areas: interventional pain management; opioid dose and risk of overdose death; neuropathic pain; yoga for chronic low back pain; cognitive behavioral therapy; and systematic approaches to treating back pain. We discuss implications for pain management in primary care. Conclusions There is growing evidence for the risks, benefits, and limitations of the multiple modalities available to primary care providers for the management of chronic pain. The dissemination and implementation of the evidence from these studies as well as novel system-level interventions warrant additional study and support from clinicians, educators, and policy makers.
Diffusion in type A zeolites: New insights from old data

Abstract The extensive kinetic data accumulated, over many years, from a series of experimental studies of the kinetics of adsorption/desorption of a wide range of different sorbates in type A zeolites are reviewed and analyzed in an attempt to develop a coherent understanding of the behavior of these systems. Kinetic data for large laboratory synthesized crystals and small commercial crystals, measured under similar conditions, have been studied in detail. In well dehydrated crystals the sorption rates are generally controlled by intracrystalline diffusion but exposure to traces of water leads to the development of surface resistance and a pronounced reduction in the sorption rate. Zeolite samples of different origin show widely different sorption rates but the diffusional activation energies (for a given sorbate) are essentially constant. The differences between the different samples appear to be due mainly to differences in the cation distribution caused by differences in the initial dehydration procedure. The ideal cation distribution (in 5A) in which all window sites are unoccupied is realized only in very carefully dehydrated samples in which the water was removed slowly at gradually increasing temperature under a high vacuum. In the small commercial 5A crystals many of the windows are blocked, even though all the cations could theoretically be accommodated in the 6-ring sites. This is probably due to cation hydration reactions which are likely to occur when the dehydration conditions are not carefully controlled.
Theory of the rotation of the rigid earth

An analytical theory is developed for the three axes of the triaxial rigid earth (the angular-momentum axis, the figure axis, and the rotational axis). A theory on rigid earth rotation will be important to one on a nonrigid earth, since the latter gives only the ratios between the amplitudes of rigid nutation and those of nonrigid nutation. The present theory is characterized by the use of Andoyer variables, Hori’s averaging method, and a moving reference plane. A comparison with Woolard’s theory shows that 1) the maximum difference in nutation of the angular-momentum axis, calculated from the same constants as Woolard adopted, reaches 0.0017; 2) the maximum discrepancy in Oppolzer terms is 0V0012: and 3) the present theory has no secular term either in the first power of time in the obliquity referred to the fixed ecliptic or in the angle between the figure axis and the rotational axis; both these secular terms appeared in Woolard’s theory and have an effect on the establishment of a reference system. Nutation amplitudes as large as O.OOOl are calculated for all three axes. Use is made of Brown’s theory of the moon as improved by Eckert and of numerical values recommended at the working meeting of the International Astronomical Union held in Washington in September 1974. Any future revision of the lunar theory will not alter the values of the amplitudes of the nutational terms derived here.
Natural killer cell mediated pathogenesis determines outcome of central nervous system infection with Venezuelan equine encephalitis virus in C3H/HeN mice.

TC83 is a human vaccine with investigational new drug status and is used as a prototype Venezuelan equine encephalitis virus for pathogenesis and antiviral research. Differing from other experimental models, the virus causes high titer infection in the brain and 90–100% mortality in the C3H/HeN murine model. To better characterize the susceptibility to disease development in C3H/HeN mice, we have analyzed the gene transcriptomes and cytokine production in the brains of infected mice. Our analysis indicated the potential importance of natural killer cells in the encephalitic disease development. This paper describes for the first time a pathogenic role for natural killer cells in VEEV encephalitis.
The transneuronal transport of horseradish peroxidase in the visual system of the frog, Rana pipiens.

Abstract During the course of experiments designed to study synaptic relationships between the terminals of retinal axons and the various cell populations in the optic tectum of the frog, Rana pipiens , we found that neurons in many of the retinorecipient nuclei, including the tectum, are labeled transneuronally following injections of horseradish peroxidase into the optic nerve. In the optic tectum, particular cell groups are labeled to the extent that their dendrites as well as their somas are filled with reaction product while other cell types, which, on the basis of the location of their somas or dendrites, seem equally likely to receive direct retinal projections, remain free of label. Electron microscopic investigation of the optic tectum reveals that the label is confined to pre- and postsynaptic processes. These results suggest that the transneuronal transport depends on a transfer of horseradish peroxidase from presynaptic terminals to postsynaptic cells rather than on a widespread diffusion of the enzyme through the neuropil followed by a selective uptake by particular cell groups. These results also suggest that only some of the tectal cell groups which receive direct retinal projections may be transneuronally labeled. The transneuronal transport of horseradish peroxidase is useful since it reveals the morphology as well as the location of at least some of the retinorecipient cells. Moreover, the robust nature of this phenomenon makes the frog a good choice for future studies of the mechanism of transneuronal transport.
Differential activity in rats as a function of deprivation, stimulus change, and recording method.

The effects of stimulus changes on activity in 20 food-deprived and 20 nondeprived adult rats were studied using a photo-relay method, direct observation, and bar-press rate. Differences in activity as measured by the photo-cells and differences in bar-presses were significant (p < .001) for stimulation, deprivation, and the interactions. Ss in the stimulus change groups had the highest activity counts, their most frequent single behavior being exploration. The results confirmed the utility of the photo-relay system of measurement, demonstrated that stimulus change differentially affected the activity of deprived and nondeprived Ss, and supported the conclusion that stimulation sensitized S to its internal state to which it then reacted.
Reply to "Comment on 'Superconducting phases of Bi and Ga induced by deposition on a Ni sublayer' "

van Hulst et al. interpret our results on Ni/Bi thin films as due to (102)-oriented bulk Bi crystal structure instead of the possible fcc structure that we had interpreted as the structure of these films. They attribute the superconductivity in these films to surface phenomena in such films. It was pointed out here that the observed superconductivity in Ni/Bi is a bulk phenomenon and is not consistent with van Hulst's model, as seen by our results on resistivity vs temperature, band structure seen in tunneling, critical field, conductance peaks, energy gap, etc.
Optimization metrics for the design of filament array-based linear force transducers

Dense, planar arrays consisting of molecular motors and their complementary filaments have been proposed for the bottom-up construction of a hybrid actuator. The following design metrics were established to quantify filament array quality defined as efficiency of force transduction along a single direction: number density, spatial distribution, orientation distribution. Theoretical models describing the inherent randomness involved in manipulating nanoscale filament structures were used to determine achievable optimums for each design metric. These optimization limits were then validated by analyzing fabricated unipolar filament arrays based on the microtubule-kinesin system.
The Hartree approximation as a high-density limit☆

Abstract By doing a formal series expansion of the partition function in terms of the inverse of the chemical potential associated with baryon number conservation, μ, it is shown that the dominant terms for large baryon density correspond to the Hartree, or mean-field, approximation.
MEC1-Dependent Redistribution Of The SIR3 Silencing Protein from Telomeres to DNA Double Strand Breaks

The yeast Sir2/3/4p complex is found in abundance at telomeres, where it participates in the formation of silent heterochromatin and telomere maintenance. Here, we show that Sir3p is released from telomeres in response to DNA double-strand breaks (DSBs), binds to DSBs, and mediates their repair, independent of cell mating type. Sir3p relocalization is S phase specific and, importantly, requires the DNA damage checkpoint genes MEC1 and RAD9. MEC1 is a homolog of ATM, mutations in which cause ataxia telangiectasia (A-T), a disease characterized by various neurologic and immunologic abnormalities, a predisposition for cancer, and a cellular defect in repair of DSBs. This novel mode by which preformed DNA repair machinery is mobilized by DNA damage sensors may have implications for human diseases resulting from defective DSB repair.
Styrax and its Refractive Index

IN the issue of NATURE for February 2, Mr. A. Mallock requests information on styrax. I am able to supply the following information: The styrax best suited for the mounting of diatoms is obtained from the Oriental sweet gum tree (Liquid-ambar orientalis). This tree is native to the southwestern portion of Asia Minor. The balsam is a pathological secretion from the wood and inner bark. After the tree has been injured and the secretion has collected on the injured surface, the inner bark is removed and boiled in sea water—the balsam being skimmed from the surface.
Direct antioxidant properties of creatine.

Abstract Creatine is the most popular supplement proposed to be an ergogenic aid. There is some evidence in the literature that creatine supplementation increases lean body mass, muscular strength, and sprint power. However, the efficacy of creatine has not been consistent, and the potential mechanisms are unresolved. While limited evidence that suggests that creatine could possess an antioxidant effect this has not been tested directly. Because oxidants such as free radicals can affect muscle fatigue and protein turnover, it is important to know whether creatine can neutralize free radicals and other reactive oxygen species. We tested the hypothesis that creatine would remove superoxide anions (O•−2), peroxynitrite (OONO−), hydrogen peroxide, and lipid peroxides (t-butyl hydroperoxide). We also determined whether creatine displayed a significant antioxidant scavenging capacity (ASC) using 2,2′-azino-bis(3-ethylbenzothiazolamine-6-sulfonic acid) (ABTS+) quenching as a marker. Creatine did not significantly reduce levels of hydrogen peroxide or lipid peroxidation. In contrast, creatine displayed a significant ability to remove ABTS+, O•−2, and OONO− when compared with controls. Creatine quenching of ABTS+ was less than physiological levels of reduced glutathione (0.375 mM). To our knowledge, this is the first evidence that creatine has the potential to act as a direct antioxidant against aqueous radical and reactive species ions.
Hemodynamic consequences of acute occlusion of the superior mesenteric artery.

Abstract The hemodynamic events produced by acute occlusion of the superior mesenteric artery were studied in 15 dogs and the results obtained contrasted with findings in a control series of 11 animals. Acute occlusion of the superior mesenteric artery caused a reduction in cardiac index after 60 minutes, whereas arterial pressure increased for the first 5 minutes and was reduced after 11/2 hours. Systemic vascular resistance showed a sustained and progressive increase. Blood flow in the left anterior descending coronary, renal and common carotid arteries showed short-lived initial increases followed by a progressive decrease in each regional circulation.
Thoughts Addressed to an Analytical Thomist

De croyance juive, l'A. se propose d'etablir un dialogue avec le thomisme analytique sur la question de la preuve de l'existence de Dieu et sur la question de la predication en respectant Dieu. Distinguant les connexions conceptuelles d'une theorie philosophique des notions proprement religieuses d'etre transcendant et etre necessaire, d'une part, et soulignant l'incommensurabilite des langages ordinaire et religieux, d'autre part, l'A. montre que ni la theologie negative de Maimonide ni le discours analogique de Saint Thomas d'Aquin n'apportent de solution au probleme des attributs de Dieu
Increased unrecognized coronary heart disease and sudden deaths in rheumatoid arthritis: A population-based cohort study

Objective To examine the risk of clinical coronary heart disease (CHD) in patients with rheumatoid arthritis (RA) compared with age- and sex-matched non-RA subjects, and to determine whether RA is a risk factor for CHD after accounting for traditional CHD risk factors. Methods We assembled a population-based incidence cohort of 603 Rochester, Minnesota residents ages ≥18 years who first fulfilled the American College of Rheumatology (ACR) 1987 criteria for RA between January 1, 1955 and January 1, 1995, and 603 age- and sex-matched non-RA subjects. All subjects were followed up through their complete inpatient and outpatient medical records, beginning at age 18 years until death, migration, or January 1, 2001. Data were collected on CHD events and traditional CHD risk factors (diabetes mellitus, hypertension, dyslipidemia, body mass index, smoking) using established diagnostic criteria. CHD events included hospitalized myocardial infarction (MI), unrecognized MI, coronary revascularization procedures, angina pectoris, and sudden CHD deaths. Conditional logistic regression and Cox regression models were used to estimate the risk of CHD associated with RA, both prior to and following RA diagnosis, after adjusting for CHD risk factors. Results During the 2-year period immediately prior to fulfillment of the ACR criteria, RA patients were significantly more likely to have been hospitalized for acute MI (odds ratio [OR] 3.17, 95% confidence interval [95% CI] 1.16–8.68) or to have experienced unrecognized MIs (OR 5.86, 95% CI 1.29–26.64), and less likely to have a history of angina pectoris (OR 0.58, 95% CI 0.34–0.99) compared with non-RA subjects. After the RA incidence date, RA patients were twice as likely to experience unrecognized MIs (hazard ratio [HR] 2.13, 95% CI 1.13–4.03) and sudden deaths (HR 1.94, 95% CI 1.06–3.55) and less likely to undergo coronary artery bypass grafting (HR 0.36, 95% CI 0.16–0.80) compared with non-RA subjects. Adjustment for the CHD risk factors did not substantially change the risk estimates. Conclusion Patients with RA have a significantly higher risk of CHD when compared with non-RA subjects. RA patients are less likely to report symptoms of angina and more likely to experience unrecognized MI and sudden cardiac death. The risk of CHD in RA patients precedes the ACR criteria–based diagnosis of RA, and the risk cannot be explained by an increased incidence of traditional CHD risk factors in RA patients.
Surveillance of Pancreatic Cancer Patients after Surgical Resection

There are no clear recommendations to guide posttreatment surveillance in patients with pancreatic cancer. Our goal was to describe the posttreatment surveillance patterns in patients undergoing curative-intent resection for pancreatic cancer. We used Surveillance, Epidemiology, and End Results (SEER)–Medicare linked data (1992–2005) to identify CT scans and physician visits in patients with pancreatic cancer who underwent curative resection (n = 2393). Surveillance began 90 days after surgery, and patients were followed for 2 years at 6-month intervals. Patients were censored if they died, experienced recurrence of disease, or entered hospice. A total of 2045 patients survived uncensored to the beginning of the surveillance period. CT scan use decreased from 20.9% of patients in month 4 to 6.4% in month 27. There was no temporal pattern in CT use to suggest regular surveillance. Twenty-three percent of patients did not receive a CT scan in the year after surgery, increasing to 42% the second year. Patients who underwent adjuvant therapy and patients diagnosed in later years had higher CT scan use over the surveillance periods. Most patients visited both a primary care physician and a cancer specialist in each 6-month surveillance period. Patients who visited cancer specialists were more likely to have any CT scan and to be scanned more frequently. Current surveillance patterns after resection for pancreatic cancer reflect the lack of established guidelines, implying a need for evaluation and standardization of surveillance protocols. The lack of a temporal pattern in CT testing suggests that most were obtained to evaluate symptoms rather than for routine surveillance.
Multiple sources of alkanes in Quaternary oceanic sediment of Antarctica

Normal alkanes (n-C13n-C36), isoprenoid hydrocarbons (i-C15, i-C16, i-C18, i-C19, and i-C20) triterpanes (C27C32), and (C27C29) are present in low concentrations offshore Antarctica in near-surface, Quaternary sediment of the Wilkes Land continental margin and of the western Ross Sea. The distributions of these hydrocarbons are interpreted relative to possible sources and processes. The hydrocarbons appear to be mixtures of primary and recycled material from marine and terrigenous sources. The n-alkanes are most abundant and are characterized by two distinct populations, one of probable marine origin and the other likely from terrigenous, vascular plant sources. Because the continent of Antarctica today is devoid of higher plants, the plant-derived hydrocarbons in these offshore sediments probably came from wind-blown material and recycled Antarctic sediment that contains land-plant remains from an earlier period of time. Isoprenoid hydrocarbons are partially recycled and mainly of marine origin; the dominance of pristane over phytane suggests oxic paleoenvironmental conditions. Both modern and ancient triterpanes and steranes are present, and the distribution of these indicates a mixture of primary and recycled bacterial, algal, and possible higher-plant materials. Although the sampled sediments were deposited during the Quaternary, they apparently contain a significant component of hydrocarbons of pre-Quaternary age.
CONTINUUM ASPECTS OF RF GRADIENT ACCELERATION OF PLASMA

A quasi-one-dimensional model of acceleration of a continuum plasma by r- f electric field gradient forces is examined. The conditions imposed on the electric field in order to effect sonic transitions are given. The case of isentropic flow is treated, and departure from the particle model is indicated for pressure> 100 mu and temperatures approx equal = 0.1 ev.
Differential contribution of A-type potassium currents in shaping neuronal responses to synaptic input

Neurons receive input from thousands of excitatory and inhibitory synapses, but they are not merely passive receivers and transmitters of information. The intrinsic properties of neurons, and more specifically the collection of ion channels expressed, influence a cell's excitability and integration processes. The role of different voltage-dependent transient (A-type) and persistent (delayed rectifier) potassium currents in shaping the activity of neurons in response to synaptic input is not well understood. We developed a biophysical model incorporating realistic synaptic input [1] to investigate the specific roles played by distinct A-type potassium channels encoded by different genes, namely Shaker/Kv1 and Shal/Kv4. We find that these two channel types, which are functionally distinguished by their inactivation properties, exert different control mechanisms on the transitions between rest and repetitive spiking in neurons. Bifurcation analysis is used to characterize the influence of each channel and the overall behavior of the membrane as a function of the relative presence of the two A-type channels. We found that the influence of each channel type depends on the resting potential of the neuron, suggesting that modulation and/or network states may shift their relative contribution. For example, at a particular membrane potential, Shal/Kv4 channels are more likely to mediate delays to first spike in response to excitatory input. Overall, this work increases our understanding of the interaction between intrinsic properties and synaptic input in creating neuronal response profiles. Further, we provide a link between relative gene expression and bifurcation structures in dynamical systems modeling neuronal membranes.
The Herpes Simplex Virus Type 1 Transactivator ICP0 Mediates Aberrant Intracellular Localization of the Viral Helicase/Primase Complex Subunits

The infected cell polypeptide 0 (ICP0) protein of herpes simplex virus type 1 (HSV-1) is a promiscuous transactivator. When expressed by transfection, ICP0 forms spherical structures in the nucleus. Using a double-label immunofluorescence assay, we have found that the HSV-1 helicase/primase complex subunits accumulate within ICP0 structures in cotransfected cells. This phenomenon was also observed in cells coexpressing ICP0 and UL6, a protein thought to be involved in the cleavage and/or packaging of viral genomes. ICP0 structures were found to be proteinaceous by immunoelectron microscopy. These results suggest that ICP0 may interact nonspecifically with a variety of viral proteins.
Orthogonal rotation algorithms

The quartimax and varimax algorithms for orthogonal rotation attempt to maximize particular simplicity criteria by a sequence of two-factor rotations. Derivations of these algorithms have been fairly complex. A simple general theory for obtaining “two factor at a time” algorithms for any polynomial simplicity criteria satisfying a natural symmetry condition is presented. It is shown that the degree of any symmetric criterion must be a multiple of four. A basic fourth degree algorithm, which is applicable to all symmetric fourth degree criteria, is derived and applied using a variety of criteria. When used with the quartimax and varimax criteria the algorithm is mathematically identical to the standard algorithms for these criteria. A basic eighth degree algorithm is also obtained and applied using a variety of eighth degree criteria. In general the problem of writing a basic algorithm for all symmetric criteria of any specified degree reduces to the problem of maximizing a trigonometric polynomial of degree one-fourth that of the criteria.
Heterocycles from ketenimines XI. Oxindoles

The reaction of ketenimines with heterocyclic N-oxides yields N-substituted oxindoles. Hydrolysis of these adducts or acid work-up of the original reaction mixtures leads directly to oxindoles in which the nitrogen atom is unsubstituted.
Transient modeling and analysis of a passive liquid-feed DMFC

A two-dimensional, transient, multi-phase, multi-component model has been developed for a liquid-feed DMFC delivery system including the fuel cell itself. The model considers the mass transport in the feed delivery system attached to the anode inlet of the fuel cell, and the effect of coupled heat and mass transfer under ambient conditions. The results are compared with the existing experimental data with a high level of agreement. The effects of feed methanol concentration in the reservoir and current density on mass transport and performance of DMFC system are revealed. When initial feed concentration in the reservoir decreases, methanol crossover is minimized, but the duration of cell performance is shortened and fuel cell temperature decreases. The anodic overpotential and its increasing rate become higher, while the decreasing rates of solution leftover and methanol concentration in the reservoir become lower. When current density increases, the duration of the cell performance is shortened. While the anodic overpotential and its increasing rate, cell temperature, decreasing rates of methanol crossover, solution leftover and methanol concentration in the reservoir increase.
Thermodynamic changes associated with the formation of aminopolycarboxylate chelates

By emf. measurements of cells of the type Pt-H2, H+, A− (buffer), KCl, Ag-AgCl, and extrapolation of the data to infinite dilution, thermodynamic dissociation constants and metal chelate stability constants have been obtained for ethylenediaminetetraacetic and nitrilotriacetic acid. From measurements of this type made over a series of temperatures, the enthalpy and entropy changes associated with complex formation were calculated. In all cases the enthalpy changes were found to be relatively small, while the entropy contributions to the stability of the chelate compounds were found to be considerably greater. The results are interpreted on the basis of the structures of the compounds, and of present theories of chelate ring formation.
The role of beta-endorphin in the acute motor stimulatory and rewarding actions of cocaine in mice

Rationale Opioid receptor antagonists have been shown to attenuate the rewarding and addictive effects of cocaine. Furthermore, cocaine has been shown to cause the release of beta-endorphin, an endogenous opioid peptide.
Low-energy helium diffraction studies of CO2 overlayers physisorbed on NaCl(001)

Abstract Low-energy helium diffraction experiments have revealed that CO2 physisorbs on NaCl(001) at low temperatures to form distinct phases at low and high coverages. The structures of both phases are commensurate with the underlying NaCl(001) substrate. The low-coverage phase consists of a rectangular 1 × 2 unit mesh whereas the unit mesh of the high-coverage, monolayer phase is 2√2 × 2√2 R45°. The diffraction results and structural models are discussed in relation to recent infrared spectroscopic studies of CO2/NaCl(001).
Real-time color-flow MRI at 3 T using variable-density spiral phase contrast

The purpose of this study was to demonstrate and evaluate the performance of real-time color-flow MRI at 3 T using variable-density spiral (VDS) phase contrast. Spiral phase contrast imaging was implemented within a flexible real-time interactive MRI system that provided continuous image reconstruction and an intuitive user interface. The pulse sequence consisted of a spectral-spatial excitation, bipolar gradient, spiral readout and gradient spoiler. VDSs were utilized to increase spatial and/or temporal resolution relative to uniform-density spirals (UDSs). Parameter choices were guided by specific applications. Sliding window reconstruction was used to achieve a maximum display rate of 40 frames/s. No breath-holding or gating was used. Our results demonstrated that real-time color-flow movies using UDS and VDS provided adequate visualization of intracardiac flow, carotid flow and proximal coronary flow in healthy volunteers. Average aortic outflow velocity measured at the aortic valve plane using VDS was 29.4% higher than that using UDS. Peak velocity measured in the common carotid artery using VDS was 9.8% higher than that using UDS.
The transformation of bayerite into hydrargillite

X-ray and infra-red studies have been made of the ageing of bayerite in water and in potassium aluminate solution for periods of up to 3 months at 30°. They show that transformation of bayerite into hydrargillite occurs slowly in water, and more rapidly in potassium aluminate solution. The seeding of alkali aluminate solution is also investigated in connexion with these results.
Gas-phase fragmentation of di- and tripeptides via ion–molecule reactions with ClPCl+

Abstract The reactivity of the phosphenium ion ClPCl + toward gaseous neutral di- and tripeptides was examined by Fourier transform ion cyclotron resonance mass spectrometry. ClPCl + was found to react with the peptides at collision rate. Extensive fragmentation of the peptides leads to only one (dipeptides) or two (tripeptides) dominant product ions. For each dipeptide, the major product ion has a molecular weight that is 34 u less than that of the dipeptide, i.e. the side chains are retained in the fragment ion. A substantial amount of effort was given to resolve the structure of this product ion, with a focus on the ion ( m/z 98) generated from reaction of Gly–Gly (MW 132) with ClPCl + . The molecular formula of the ion of m/z 98 was determined to be C 4 H 6 NO by exact mass measurements. The relative energies of a variety of isomeric ions with this elemental composition were examined by molecular orbital calculations in order to identify the most likely structures. Collision-activated dissociation experiments, mechanistic considerations, and comparison of calculated adiabatic recombination energies of isomeric ions to that determined experimentally for the unknown ion, led to the assignment of a six-membered, highly unsaturated ring structure to the product ion of m/z 98 of Gly–Gly. This assignment is supported by the finding that the experimentally determined acidity of the unknown ion is in excellent agreement with that calculated for the proposed six-membered structure. The most likely pathway for the formation of this product ion, as well as those obtained for the other dipeptides, involves an electrophilic attack of ClPCl + at the amide carbonyl oxygen of the dipeptide, followed by a hydride shift, proton transfer, and loss of H 2 O and Cl 2 PO · . The very high exothermicity of the initial addition (69 kcal mol −1 , AM1) allows the adduct to form high-energy intermediates (highest estimated to lie at 34 kcal mol −1 above the adduct) during the reaction that is exothermic by about 36 kcal mol −1 overall. An analogous mechanism readily rationalizes the formation of the two major product ions observed for tripeptides. These reactions involve the cleavage of each peptide bond, yielding product ions that contain the intact side chains of two adjacent amino acids. Similar observations were made for the BrPBr + reagent ion. The results presented here suggest that ClPCl + (and BrPBr + ) may provide useful sequence information for peptides.
The profile distribution of zinc in selected soils in Louisiana

Abstract An Investigation was conducted to determine the content and distribution of total and DTPA‐extractable Zn in the genetic horizons of 72 agriculturally important soils from the six major mineral soil areas in Louisiana. The concentration of total Zn appeared to vary more with the clay constituents of the soils and the amount of the element in the parent materials than with soil depth. The majority of the soils had the largest amounts of total Zn in the subsurface horizons. The range in total Zn for all soils and horizons was from 7.0 to 150.0 ppm. The DTPA‐extractable Zn in all of the soils and horizons ranged from 0.08 to 4.22 ppm. In the majority of the soil profiles the highest concentration of extractable Zn was in the surface horizons. There was a decrease in the extractable Zn with increasing soil depth. The alluvial soils along the Ouachita and Mississippi Rivers, and the Mississippi Terrace soil areas contained relatively large amounts of DTPA‐extractable Zn. In some soils the extractable ...
Polarization memory decay spectroscopy of photoexcitations in π -conjugated polymers: Evidence for excimers

We used the technique of ultrafast transient polarized photomodulation in the visible/near-infrared range and polarization memory decay (PMD) spectroscopy to study the primary photoexcitations in films and solutions of two poly(phenylene-vinylene) (PPV) derivatives, namely, 2-methoxy-5-(${2}^{\ensuremath{'}}$-ethylhexyloxy) PPV (MEH-PPV) and 2,5-dioctyloxy PPV (DOO-PPV). We found that the primary photoexcitations in DOO-PPV films and solutions and MEH-PPV solutions are intrachain singlet excitons that show the same PMD across the entire spectrum. In contrast, the ultrafast photoexcitations in MEH-PPV films are of two kinds; these are intrachain excitons with fast PMD kinetics and interchain species with very slow PMD kinetics, which is the property that identifies these photoexcitations as excimers (or interchain charge transfer exciton). We attribute the excimers in MEH-PPV films to the increased interchain coupling due to the tightly packed nanomorphology, which also explains the photoluminescence efficiency decrease and its odd kinetics.
Microkinetic modeling of steady-state NO/H2/O2 on Pt/BaO/Al2O3 NOx storage and reduction monolith catalysts☆

Abstract A steady-state microkinetic model for NO reduction by H 2 and NH 3 in O 2 on alumina supported Pt/BaO monolith catalysts is developed based on the measurements from a parallel experimental study (R. Clayton, M.P. Harold, V. Balakotaiah, Selective catalytic reduction of NO by H 2 in O 2 on Pt/BaO/Al 2 O 3 , Appl. Catal. B: Environ. 81 (3–4) (2008) 161–18). The microkinetic model describes pertinent Pt-catalyzed regeneration chemistry during NOx storage and reduction with H 2 . Kinetic parameters not available from the literatures are estimated to capture the experimental trends and to meet thermodynamic constraints. The kinetic model is incorporated into a short monolith reactor model to simulate the steady-state NH 3 /O 2 , NH 3 /NO and NO/NH 3 /H 2 reaction systems. The predicted conversion and product distribution are in excellent qualitative and good quantitative agreement with the experimental data. Among other features, the model predicts for the three reaction systems the non-linear light-off, and the product selectivity dependencies on temperature and feed composition. The model predicted trends in the species surface coverages with operating conditions help to elucidate the selectivity trends. A sensitivity analysis of the rate constants identified the critical steps in the reaction network. The effects of external mass transfer on the conversions and product distributions are assessed and discussed.
Vector spaces as unions of proper subspaces

In this note, we find a sharp bound for the minimal number (or in general, indexing set) of subspaces of a fixed (finite) codimension needed to cover any vector space V over any field. If V is a finite set, this is related to the problem of partitioning V into subspaces.
Ozone exposure and nitrogen deposition lowers root biomass of ponderosa pine in the San Bernardino Mountains, California

Abstract Decreased root biomass in forest trees in response to anthropogenic pollutants is believed to be one of the first steps in forest health degradation. Although decreased root biomass has been observed in controlled experiments, ozone effects on mature tree roots in natural stands has not previously been documented. Here we report standing root biomass of ponderosa pine at three sites in the San Bernardino Mountains distributed along a known, long-term pollution gradient of ozone and nitrogen deposition. Trees at each site were assessed for foliar ozone injury and below-ground attributes, in addition to other environmental factors known to influence root growth. During the period of peak root growth in the spring, root biomass at the least polluted site was 6–14 times greater than that observed at the most polluted site. Known differences in climatic and edaphic factors among the sites potentially contributing to the observed response were discounted as primary contributors to the response since in most cases the site differences would have driven the patterns of root growth in the opposite direction to that observed. Differences in biotic competitive interactions, also known to affect root growth, did not explain the observed pattern for the same reason. The data suggests that elevated ozone, high nitrogen deposition, and possibly other contributing factors such as soil acidification are primarily responsible for lowering root biomass in ponderosa pine stands in the San Bernardino Mountains.
Supersymmetry-induced non-oblique radiative corrections to atomic parity violation

Abstract We calculate supersymmetry-induced, non-oblique radiative corrections to cesium parity-violation experiments. With the current limits on the masses of the superpartners, these corrections are typically of the order of 10 −3 , relative to the tree level and may be detectable with the improved accuracy of the experiments.
A Strategy for Labeling Tumor Boundaries

We describe a method for labeling tumor boundaries using an enzyme active in the tumor boundary to crosslink a fluorescent-labeled substrate into the boundary. Preliminary in vitro assays are described.
Clinical benefits versus shortcomings of diltiazem once-daily in the chronotherapy of cardiovascular diseases.

Background: The introduction of chronotherapy (that is improving a drugs therapeutic efficacy by paralleling the drugs plasma levels to circadian rhythms) has recently become a focus of interest. Objective: This article addresses the efficacy and potential shortcomings of chronotherapy, and focuses on one specific type of chronotherapy: a novel long-acting diltiazem formulation, DTZ-LA. Methods: We reviewed the literature to assess the clinical benefits and shortcomings associated with DTZ-LA in the management of hypertension and angina. Results/conclusions: The clinical benefits of DTZ-LA outweigh its disadvantages when surrogate outcomes are evaluated, but it still remains to be determined whether chronotherapy benefits hard clinical outcomes. Nonetheless, chronotherapy has the potential to address the cardiovascular triggers that peak in the early morning hours when the preponderance of cardiovascular events occur, as well as providing better target organ protection compared with non-chronotherapeutic ...
Downregulation of telomerase activity in HL60 cells by differentiating agents is accompanied by increased expression of telomerase-associated protein.

Telomerase activity provides a mechanism for the unlimited division potential of neoplastic cells. Induced differentiation of these cells was found to be associated with repression of telomerase activity irrespective of the inducing agent. We have employed a series of sublines of human promyelocytic leukemia line HL60 with differing degrees of resistance to differentiation to determine how tightly the expression of the differentiated phenotype is coupled to the downregulation of telomerase activity and to the expression of the recently identified telomerase-associated protein 1 (TP1). As expected, in the 1,25D3-dihydroxyvitamin D3 (1,25D3)–resistant subclones (20A–100A cells), telomerase activity was not significantly downregulated by 1,25D3 and, in most cases, by all-trans retinoic acid (atRA), to which these cells were cross-resistant, but telomerase activity was repressed by dimethylsulfoxide (DMSO) and phorbol-12-myristate-13-acetate (TPA), to which the sublines were in general sensitive. However, there were exceptions; in some instances telomerase activity was repressed in the absence of the expression of markers of differentiation. Also, there was an inverse relationship between telomerase activity and the cellular levels of TP1 transcripts. We conclude that in HL60 cells downregulation of telomerase is loosely associated with upregulation of differentiation markers and with other cellular changes which include an upregulation of TP1. J. Cell. Biochem. 67:13–23, 1997. © 1997 Wiley-Liss, Inc.
Hospital-Reported Pneumococcal Susceptibility to Penicillin

Geographic variation in drug susceptibility among isolates of Streptococcus pneumoniae has influenced national treatment guidelines for community-acquired pneumonia. Whether individual hospital susceptibility data provide reliable and valid information for providers is unclear. We examined the geographic and temporal variability in hospital-reported rates of pneumococcal susceptibility. We surveyed all 52 hospitals that provided acute adult care in the five counties surrounding Philadelphia and collected data on levels of penicillin susceptibility among all pneumococcal blood isolates from 1998 to 2000. In 1998, pneumococcal nonsusceptibility to penicillin varied from 0% to 67% of all blood isolates across the 33 hospitals with >10 isolates in that year. Hospital location did not correlate with the level of reported pneumococcal susceptibility (p = 0.8). In addition, correlations were not significant in reported pneumococcal susceptibility to penicillin within individual hospitals during the 3 years.
846 — Microtubule-dependent membrane interactions studied in two types of double bilayer membrane systems

Abstract The microtubules consisting of tubulin subunits are ubiquitous cytoskeletal elements implicated in a variety of cellular functions. It is probable that they play an important role in the integration of the membrane processes and in the structural-functional organization in the cells by mediating long-range interactions between membranes, and by functioning as an intermembrane linking system. This suggestion was tested by using two different techniques for studying the interrelationships between two bilayer lipid membranes (BLMs). In both systems evidence for microtubule-assisted interconnections between the membranes was obtained. When electric pulses with amplitude 60–70 mV and duration 30 ms were applied across one of the membranes a displacement in the potential across the other membrane was observed even when the membranes were separated apart. This effect was found only in the presence of microtubules. It was not observed in MES-buffer or in the presence of depolymerized microtubule protein, colchicine-treated tubulin or albumin. On the basis of the data, the suggestion is made that defined configurations of the microtubule fiber networks and bundles may form structural bridges and coupling between membranes. These findings may be related to the role of the microtubules in the processes of information transfer in neurons and other cells.
Brain and plasma levels of testosterone, dihydrotestosterone and estradiol in the one-day-old rat.

Abstract Current evidence indicates that the secretion of testosterone during perinatal life is essential in organizing the male brain which subsequently directs the male pattern of gonadotrophin (GTH) secretion and adult male sexual behavior in the rat. It has been hypothesized that testosterone is converted into estradiol enzymatically in the brain prior to its action. In the absence of testosterone and with the resultant low levels of estradiol, female patterns of gonadotrophin secretion and behavior result. In order to investigate this hypothesis further, the endogenous levels of gonadal steroids in the plasmas and brains of 24–48 hr old male and female rats were determined. Pooled samples were analyzed for testosterone, dihydrotestosterone and estradiol by radioimmunoassay. Testosterone levels in male brain and plasma samples were significantly (10-fold) higher than those in the female brain and plasma samples. Brain levels of estradiol were significantly higher in the male than in the female neonate, while plasma levels were identical. Whether the higher level of estradiol in the male brain is due to enzymatic conversion from testosterone within the brain differences in permeability or some other mechanism cannot be stated at this point. The significantly higher brain levels of both testosterone and estradiol in male neonates do fit the pattern predicted by the present concept of sexual differentiation. Dihydrotestosterone levels in brain and plasma of male rats were about 25% of those of testosterone. However in females the brain levels of dihydrotestosterone were significantly higher than testosterone even though the plasma levels of these hormones were identical. This may reflect a protective mechanism through which permeability of testosterone is lowered in the neonatal female brain during the critical period or simply a functional conversion of testosterone to dihydrotestosterone in the female during this period.
Desulfurization of Real and Model Liquid Fuels Using Light: Photocatalysis and Photochemistry

Ultra-deep desulfurization of liquid fuels is crucial for the environment, longer lifetime of combustion engines, and emerging “green,” sustainable, carbon-neutral fuels for fuel cell applications. Current interest is towards photocatalysis and photochemistry for production of clean fuels and valuable chemicals. This critical Review provides systematization and analysis of studies on photocatalytic, photosensitized, and photochemical desulfurization of liquid fuels in the recent approximately 20 years. Zeolites, single-site photocatalysts, TiO2, and photosensitizers are discussed with their characterization and photocatalytic, photosensitized, and photochemical reaction networks. Pilot-scale photoreactors, kinetics of fuel desulfurization using sunlight, and uses of by-products of photodesulfurization of liquid fuels are covered (181 references).