bluuebunny/crossref_metadata_2025 huggingface dataset:
Synaptic Protein Dynamics in Hibernation
Authors: von der Ohe Christina G. , Garner Craig C. , Darian-Smith Corinna , Heller H. Craig
Published: January 2007

Neurons in hibernating mammals exhibit a dramatic form of plasticity during torpor, with dendritic arbors retracting as body temperature cools and then regrowing rapidly as body temperature rises. In this study, we used immunohistochemical imaging and Western blotting of several presynaptic and postsynaptic proteins to determine the synaptic changes that accompany torpor and to investigate the mechanisms behind these changes. We show torpor-related alterations in synaptic protein localization that occur rapidly and uniformly across several brain regions in a temperature-dependent manner. Entry into torpor is associated with a 50–65% loss of synapses, as indicated by changes in the extent of colocalization of presynaptic and postsynaptic markers. We also show that the loss of synaptic protein clustering occurring during entry into torpor is not attributable to protein loss. These findings suggest that torpor-related changes in synapses stem from dissociation of proteins from the cytoskeletal active zone and postsynaptic density, creating a reservoir of proteins that can be quickly mobilized for rapid rebuilding of dendritic spines and synapses during the return to euthermia. A mechanism of neural plasticity based on protein dissociation rather than protein breakdown could explain the hibernator's capacity for large, rapid, and repeated microstructural changes, providing a fascinating contrast to neuropathologies that are dominated by protein breakdown and cell death.
Polymorphism in an Aqua‐Bridged, Dinuclear 2‐Nitrobenzoate Complex of Cobalt(II)
Authors: Karmakar Anirban , Sarma Rupam J. , Baruah Jubaraj B.
Published: January 2007

Three polymorphs of a dinuclear, aqua‐bridged cobalt complex with the composition [Co2(μ‐OH2)(C5H5N)4(μ‐O2CC6H4‐2‐NO2)2(O2CC6H4‐2‐NO2)2] are identified and the crystal structures are determined by X‐ray crystallography. Selective crystallisation of the polymorphs can be achieved by controlling the reaction conditions as well as the crystallisation processes. The reaction of cobalt(II) acetate tetrahydrate with 2‐nitrobenzoic acid followed by treatment with excesspyridine leads to a mononuclear complex with the composition [Co(H2O)2(C5H5N)2(O2CC6H4‐2‐NO2)2]. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Human papillomavirus testing on self‐sampled cervicovaginal brushes: An effective alternative to protect nonresponders in cervical screening programs
Authors: Bais Aagje G. , van Kemenade Folkert J. , Berkhof Johannes , Verheijen René H.M. , Snijders Peter J.F. , Voorhorst Feja , Babović Milena , van Ballegooijen Marjolein , Helmerhorst Theo J.M. , Meijer Chris J.L.M.
Published: January 2007

Women not attending cervical screening programs are at increased risk of cervical cancer. We investigated in these nonresponders to what extent offering self‐sampling devices for cervicovaginal brushes for high‐risk human papillomavirus (hrHPV) testing would induce participation and, if so, what the yield of precursor (i.e. CIN2 or worse) lesions following self‐sampling would be. In addition, we assessed screening history of participants and costs per detected high‐grade CIN2 or worse (“CIN2+”) lesion in comparison to the regular program in the Netherlands. Nonresponders received a device for hrHPV testing (self‐sampling group, n = 2,546) or an extra recall for conventional cytology (control group, n = 284). The percentage of self‐sampling responders were compared with responders in the recall group. hrHPV positive self‐sampling responders were invited for cytology and colposcopy. CIN2+ yield and costs per detected CIN2+ were evaluated. Active response was higher in the self‐sampling than in the control group (34.2 vs. 17.6%; p < 0.001). hrHPV positive self‐sampling responders were less likely to have a prior screening history than screening participants (p < 0.001), indicating that they are regular nonresponders. hrHPV prevalence was similar (8.0 vs. 6.8%; p = 0.11), but CIN2+ yield was higher in self‐sampling responders compared to screening participants (1.67 vs. 0.97%; OR = 2.93, 95% CI 1.48–5.80; p = 0.0013). Costs per CIN2+ lesion detected via self‐sampling were in the same range as those calculated for conventional cytological screening (€8,836 vs. €7,599). Offering self‐sampling for hrHPV testing in nonresponders is an attractive adjunct to effectively increase population coverage of screening without the adverse effect of markedly increased costs per detected CIN2+ lesion. © 2006 Wiley‐Liss, Inc.
In vivo mutagenicity of vinyl carbamate and ethyl carbamate in lung and small intestine of F1 (Big Blue® × A/J) transgenic mice
Authors: Hernandez Lya G. , Forkert Poh‐Gek
Published: January 2007

Vinyl carbamate (VC) is a metabolite of ethyl carbamate (EC), a chemical found in alcoholic beverages and fermented foods. We undertook this study to: (i) evaluate the ability of both EC and VC to induce gene mutations in lung and various extrapulmonary tissues, and (ii) identify the type of mutations induced by the two compounds in various tissues. F1 (Big Blue® × A/J) transgenic mice harboring the lambda cII transgene were used for identification and quantitation of mutations in vivo. Time‐course studies in lung showed a plateau in mutant frequency (MF) 4 weeks after VC treatment, at which time mutations were fixed and were about 4‐fold higher than in controls. Dose‐dependent increases in MF were detected in the lung and small intestine (SI) after treatment with 15–75 mg/kg, i.p., of VC. VC was mutagenic in the lung and SI at doses of 45, 60 and 75 mg/kg. Sequencing of the cII gene in lung and SI showed that VC induced mainly A:T→G:C transitions and A:T→T:A transversions. EC was also mutagenic in the lung at 500 and 1,000 mg/kg and elicited mainly G:C→A:T transitions. A VC dose of 60 mg/kg elicited a similar level of MF as an EC dose of 1,000 mg/kg. At 4 weeks after treatment, neither VC nor EC elicited mutations in the colon, bone marrow or kidney. These results demonstrated that VC and EC are mutagenic in vivo and affirm that VC is a more potent mutagen than EC. © 2006 Wiley‐Liss, Inc.
Transition rate dependence on the atom charge states, Z
Authors: Ristić V M , Stevanović J M
Published: January 2007

Here are shown two different transition rates, one obtained in the ADK-theory [1,2] and the other one for ADK result with turning point corrected with the Coulomb interaction – let us denote it cADK [1,3], in both cases the changing of charge states Z of atoms was performed. If plotted for the fields from 1012 W/cm2 to 1017 W/cm2 and for Z=1 to Z=10, the two variants give behavior which were not predicted before, Fig. 1 and Fig. 2, showing in the cADK case pick which is not shown in the ADK case. But from results shown on Fig. 3 and Fig. 4, although they are giving only the illustration of the real behavior of the transition rates, the actual situation can be predicted. On Fig. 4 one has results of cADK, and obtains the strongest tunnel effect at 1013 W/cm2, differing from the ADK case (Fig. 3), which gives this effect at 1014 W/cm2, in accordance with our earlier result [1].
Magnetic properties of cobalt and manganese doped ZnO nanowires
Authors: Clavel G. , Pinna N. , Zitoun D.
Published: January 2007

The study focuses on synthesis and characterization of transition‐metal doped zinc oxide (Zn1–x Mx O), which has been theoretically predicted to be ferromagnetic at room temperature. Although this system has been under experimental study for some time, the vast majority of research conducted on this material has been done on bulk crystals or thin films. There are very few reports on the fabrication of one‐dimensional nanostructures of Zn1–x Mx O, and all of these syntheses employ high‐temperature, vapor‐phase methods. While this approach has proven quite effective for the production of a multitude of nanoscale semiconductors, gas‐phase synthesis have considerable limits on nanowire yield and reaction scalability. We present the synthesis and characterization of cobalt‐ or manganese‐doped zinc oxide (Zn1–x Cox O and Zn1–x Mnx O) nanowires grown from a solution phase synthesis.

The article reports the structural and magnetic characterization of the nanowires, the effect of annealing on secondary phase precipitation and on magnetic properties. The dopant concentration was determined by EDX (Energy Dispersive X‐ray) spectroscopy, the dopant distribution by EDX and EPR (Electron Paramagnetic Resonance). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis of platelet activating factor by cholinephospho‐transferase in developing fetal rabbit lung
Authors: Hoffman Dennis R. , Bateman Maureen K. , Johnston John M.
Published: January 2007

Developing fetal lung is a possible source of the platelet activating factor (PAF, 1‐alkyl‐2‐acetyl‐sn‐glycero‐3‐phosphocholine) present in amniotic fluid of women in labor. We have assayed the microsomal activities of a specific enzyme for the de novo synthesis of PAF in developing fetal and neonatal rabbit lung, 1‐alkyl‐2‐acetyl‐glycerol‐dependent dithiothreitol‐insensitive cholinephosphotransferase. The specific activity of this enzyme increased from 0.92 to 3.60 nmol×min−1×mg−1 protein between day 21 and day 31 of gestation. In contrast, during this same period the activity of the PAF‐biosynthetic cholinephos‐photransferase in developing rabbit kidney did not change significantly. The specific activity of the diacyl‐glycerol‐dependent, dithiothreitol‐sensitive cholinephos‐photransferase that catalyzes the final step in phosphatidylcholine biosynthesis was not altered during late gestation in either fetal lung or kidney. Previously, increased amounts of pulmonary PAF had been found during the latter stages of gestation (Hoffman, Truong and Johnston (1986)Biochim. Biophys. Acta 879, 88–96) and may be attributed to increased activity of the PAF biosynthetic enzymes found in this investigation. This elevated level of PAF in fetal lung may serve to facilitate breakdown of glycogen that provides, in part, the carbon and energy source for surfactant biosynthesis. In addition, PAF may be secreted in association with surfactant into amniotic fluid in which it may interact with amnion tissue and subsequently participate in the events associated with the initiation of parturition.
Characterization of porcine omental lipids
Authors: McCluer Robert H. , Evans James E. , Kamarei Ahmad Reza , Williams Marcia A.
Published: January 2007

Porcine omental lipid extracts were fractionated and the major lipid components characterized. Approximately 97% of the chloroform/methanol extract consisted of triglycerides containing primarily 16∶0, 18∶0, 18∶1, and 18∶2 fatty acids. Small quantities of free fatty acids, cholesterol, di‐ and monoglycerides were also detected. The phospholipid fraction, obtained by solvent partition and Unisil column chromatography and characterized by high performance liquid chromatography (HPLC) and HPLC‐mass spectrometry, was found to consist primarily of phosphatidylcholine, sphingomyelin, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol. The neutral glycolipids, isolated by solvent partition and Unisil column chromatography and identified by HPTLC and HPLC, were found to consist primarily of di‐, tri‐and tetraosylceramides. The complex glycolipid fraction, obtained from Folch upper phase solvent partition and characterized by HPTLC and immunoblotting, was found to consist primarily of ganglio‐, globo‐, and neolacto‐ neutral glycolipids and ganglio‐, globo‐, neolacto‐ and fucosylated gangliosides.
Lipids and lipogenic enzymes in adipose tissue of castrated male goats
Authors: Giménez María S. , Ponce de Ascheri Ana M. , Elorza de Orellano María E. , Oliveros Liliana , de Hodara Fanny Zirulnik , Bonomi Mirta R. , Giménez Luis A.
Published: January 2007

Male goats (“Criolla Argentina” breed), castrated at 45 days of age, showed altered lipid metabolism 180 days after castration as compared to control goats. Subcutaneous, perirenal and omental adipose tissues of castrated goats showed increases in fatty acid synthetase, glucose‐6‐phosphate dehydrogenase and NADP‐isocitrate dehydrogenase activities. Castration increased the amount of total lipids and triglycerides, but did not modify the amount of cholesterol, phospholipid and protein in the three types of adipose tissue. The incorporation of [1‐14C]acetate into fatty acids of subcutaneous and perirenal adipose tissue was increased in castrated goats in relation to noncastrated goats. Our results suggest that removal of gonadal steroids increases significantly the rate of lipogenesis in adipose tissue of male goats.
Polyphosphoinositide formation in isolated cardiac plasma membranes
Authors: Kasinathan C. , Xu Z. ‐C. , Kirchberger M. A.
Published: January 2007

Phosphatidylinositol (PtdIns) and phosphatidylinositol 4‐phosphate (PtdIns4P) kinase activities in plasma membranes isolated from canine left ventricle were partially characterized, and their sensitivity to a number of intracellular variables was established. PtdIns and PtdIns4P kinase activities were estimated by the formation of [32P]PtdIns4P and [32P]phosphatidylinositol 4,5‐bisphosphate ([32P]PtdIns(4,5)P2), respectively, when membranes were incubated with [γ‐32P]ATP and 0.1% Triton X‐100. Unlike [32P]‐PtdIns4P formation, [32P]PtdIns(4,5)P2 formation required exogenous (PtdIns4P) substrate. [32P]‐PtdIns4P and [32P]PtdIns(4,5)P2 formation were insensitive to Ca2+ at concentrations ranging from 0.1–30 μM. The hydrolysis of [32P]PtdIns4P was less than 15% under standard assay conditions for measuring its formation, and was unaffected by any of the variables tested. The apparent Km of the PtdIns kinase for ATP was 53±13 (S.E.M.) μM (N=3). ADP inhibited [32P]PtdIns4P formation competitively with respect to ATP, the Ki being 0.4 mM. The data indicate that ADP is a poor competitive inhibitor of PtdIns kinase at the concentrations which are believed to be present intracellularly normally or which may be attained during mild hypoxia provided ATP levels are maintained in the millimolar range. Hence, any response of the myocardium to α‐adrenergic hormones during mild hypoxia would be largely unimpaired by effects of Ca2+ on PtdIns and PtdIns(4,5)P2, or of ADP on PtdIns kinase activity.
Field population biology of citrus whitefly, Dialeurodes citri (Ashmead) (Heteroptera: Aleyrodidae), on oranges in California
Authors: Bellows T. S. , Meisenbacher C.
Published: January 2007

Populations of Dialeurodes citri (Ashmead) on oranges were studied in two orange orchards in southern California, USA, to quantify developmental times and mortalities affecting this species. Four populations were followed in detail for three generations over 2 years, by monitoring the development and survival of 200 individuals in each population. Overall, preimaginal mortality among the generation studied varied from 56 to 94%. No evidence of disease or parasitism was present in the populations, and mortality was likely due to generalist predators. Weather records for the period were typical for the region, and periods of rainfall or elevated temperatures did not show any correlation with periods of mortality in the populations. Overall, the populations have high survival rates for whitefly populations, and this high survival is likely a major contributing factor to their pest status in California orchards. Addition of natural enemies to reduce the survival rates of these populations is proposed as the next course of action in suppressing populations below damaging levels.
The effect of buoyancy on vortex breakdown in a swirling jet
Authors: MOURTAZIN DINA , COHEN JACOB
Published: January 2007

The purpose of this experimental study is to explore the effect of buoyancy on vortex breakdown (VB) in swirling jets. Three non-dimensional parameters govern the flow: the jet exit Reynolds number, the swirl ratio and the Richardson number (buoyancy). The experimental apparatus consists of a vertical swirling water jet which discharges into a large tank. Moderate values of the Reynolds number are used, in the range 150 ≤ Re ≤ 600. Swirl is imparted to the jet in a rotating chamber whereas the temperature difference between the jet and its surroundings is established by passing the jet through a heat exchanger, immersed in a circulating water bath with a controlled temperature. Vector maps of the vertical mid-plane and horizontal cross-sections are obtained by particle image velocimetry (PIV) measurements. It is demonstrated that VB can be effectively suppressed (enhanced) when there is a negative (positive) temperature difference between the jet core and its surrounding fluid. The experimental critical swirl ratio for the appearance of VB is found to be in good agreement with a simple criterion, originally derived by Billant, Chomaz & Huerre (J. Fluid Mech., vol. 376, 1998, p. 183) for isothermal swirling jets and extended here to include buoyancy effects. The transition of VB from a closed bubble to an open cone configuration is mapped in terms of the Reynolds and Richardson numbers. Finally, the effect of the upstream velocity field on the critical rotation rate for the onset of VB and its configuration is exhibited using two different interchangeable rotating chambers.
Morphology of the forced oscillatory flow past a finite-span wing at low Reynolds number
Authors: PARKER K. , VON ELLENRIEDER K. D. , SORIA J.
Published: January 2007

A study of the morphology of the vortical skeleton behind a flapping NACA0030 wing with a finite aspect ratio of 3, is undertaken. The motivation for this work originates with the proposal that thrust can be efficiently produced by flapping aerofoils. The test condition corresponds to a Strouhal number of 0.35, Reynolds number, based on aerofoil chord, of 600 and an amplitude of flapping, equal to the chord length of the wing. This test condition corresponds to the optimal thrust-producing case in infinite-span flapping wings. This study investigates the effect of wing three-dimensionality on the structure of the wake-flow. This is accomplished here, by quantitatively describing the spatio-temporal variations in the velocity, vorticity and Reynolds stresses for the finite-span-wing case.

Preliminary flow visualizations suggest that the presence of wingtip vortices for the three-dimensional-wing case, create a different vortical structure to the two-dimensional-wing case. In the case of a two-dimensional-wing, the flow is characterized by the interaction of leading- and trailing-edge vorticity, resulting in the formation of a clear reverse Kármán vortex street at the selected test condition. In the case of a three-dimensional-wing, the flow exhibits a high degree of complexity and three-dimensionality, particularly in the midspan region. Using phase-averaged particle image velocimetry measurements of the forced oscillatory flow, a quantitative analysis in the plane of symmetry of the flapping aerofoil was undertaken. Using a triple decomposition of the measured velocities, the morphological characteristics of the spanwise vorticity is found to be phase correlated with the aerofoil kinematics. Reynolds stresses in the direction of oscillation are the dominant dissipative mechanism. The mean velocity profiles resemble ajet, indicative of thrust production. Pairs of strong counter-rotating vortices from the leading- and trailing-edge of the aerofoil are shed into the flow at each half-cycle. The large-scale structure of the flow is characterized by constructive merging of spanwise vorticity. The midspan region is populated by cross-sections of interconnected vortex rings.
Mathematics in Context: A Case in Early Nineteenth-Century Korea
Authors: Hoon Jun Yong
Published: January 2007

Argument

This paper aims to show how a nineteenth-century Korean scholar's mathematical study reflects the Korean intellectual environment of his time by focusing on the rule of false double position and the method of root extraction. There were two major trends in Korean mathematics of the early nineteenth century: the first was “Tongsan,” literally “Eastern Mathematics,” which largely depended on Chinese mathematics of the Song and Yuan period adopting counting rod calculation; the second trend was Western mathematics, which was transmitted by the Jesuits and their Chinese collaborators from the late sixteenth century. There was also an intellectual transition in late eighteenth-century Korea when mathematics, which had been of only minor interest for Confucian scholars, became an important part of Confucian pursuits. We can gain an insight into the history of mathematics in Korea by examining and understanding Hong Kil-chu's (1786–1841) mathematical studies and the context of the academic world of his time.
Errors induced by ozone field horizontal inhomogeneities into simulated nadir‐viewing orbital backscatter UV measurements
Authors: Felder Martin , Poli Paul , Joiner Joanna
Published: January 2007

Radiative transfer calculations for nadir‐viewing satellites normally assume the atmosphere to be horizontally homogeneous. Yet it has been shown recently that horizontal gradients can lead to significant errors in satellite infrared and microwave soundings. We extend the methodology to nadir backscatter ultraviolet forward modeling and present a first estimate of the effect's magnitude. The Solar Backscatter Ultraviolet/2 (SBUV/2) instrument, a nadir sounder, serves as our test bed. We find that the RMS error in calculated SBUV radiance induced by ozone inhomogeneities ranges between 0.05 and 0.3% (0.1–0.5%) for the 318 nm (306 and 313 nm) channel. The lower (higher) estimate corresponds to soundings with small (high) solar zenith angle. Occurrence of higher errors, particularly at wavelengths longer than 300 nm, coincides with some of the most interesting atmospheric phenomena like tropopause folds and the south polar ozone hole. This leads to a seasonal variation of the magnitude of the effect. Because of the mostly zonal variability of the ozone distribution, there is also the possibility that biases may be introduced, which is particularly critical if the data are to be assimilated or used to determine trends. The results presented are tested for robustness using different model atmospheres.
Seismic imaging of deep low‐velocity zone beneath the Dead Sea basin and transform fault: Implications for strain localization and crustal rigidity
Authors: ten Brink Uri S. , Al‐Zoubi Abdallah S. , Flores Claudia H. , Rotstein Yair , Qabbani Isam , Harder Steve H. , Keller G. Randy
Published: January 2007

New seismic observations from the Dead Sea basin (DSB), a large pull‐apart basin along the Dead Sea transform (DST) plate boundary, show a low velocity zone extending to a depth of 18 km under the basin. The lower crust and Moho are not perturbed. These observations are incompatible with the current view of mid‐crustal strength at low temperatures and with support of the basin's negative load by a rigid elastic plate. Strain softening in the middle crust is invoked to explain the isostatic compensation and the rapid subsidence of the basin during the Pleistocene. Whether the deformation is influenced by the presence of fluids and by a long history of seismic activity on the DST, and what the exact softening mechanism is, remain open questions. The uplift surrounding the DST also appears to be an upper crustal phenomenon but its relationship to a mid‐crustal strength minimum is less clear. The shear deformation associated with the transform plate boundary motion appears, on the other hand, to cut throughout the entire crust.
Combined time‐series resistivity and geochemical tracer techniques to examine submarine groundwater discharge at Dor Beach, Israel
Authors: Swarzenski P. W. , Burnett W. C. , Greenwood W. J. , Herut B. , Peterson R. , Dimova N. , Shalem Y. , Yechieli Y. , Weinstein Y.
Published: January 2007

A high‐resolution, stationary geophysical and geochemical survey was conducted at Dor Beach, Israel, to examine the shallow coastal hydrogeology and its control on the exchange of submarine groundwater with the shallow Mediterranean Sea. Time‐series resistivity profiles using a new 56 electrode (112‐m long) marine cable produced detailed profiles of the fresh water/salt water interface and the subtle response of this interface to tidal excursions and other forcing factors. Such information, when ground‐truthed with representative pore water salinities and formation resistivity values, can provide unique information of the extent and rates of submarine groundwater discharge (SGD). Time‐series 222Rn measurements of the adjacent coastal water column complemented these geophysical techniques and were modeled to yield integrated advective flow rates across the sediment/water interface, which at Dor Beach ranged from about 0 to 30 cm day−1 (mean = 7.1 cm d−1), depending on the tidal range. Such results suggest that the underlying hydrogeologic framework at Dor is favorable for substantial SGD. Extrapolating these SGD estimates across a 100‐m wide coastal zone implies that the Rn‐derived SGD rate would equal ∼7.1 m3 d−1 per m of shoreline, and that the source of this discharging groundwater is a complex mixture of fresh groundwater derived from the upland Kurkar deposits, as well as locally recycled seawater.
Ice dynamics in the central Greenland Sea
Authors: Wilkinson J. P.
Published: January 2007

Until recently a tongue‐shaped sea ice feature formed over the central Greenland Sea each winter. This tongue, known to generations of Norwegian sealers as “Odden,” sometimes protrudes several hundred kilometres in a northeast direction from the main East Greenland ice edge. Owing to the high wave energy in the Greenland Sea in winter, the formation of sea ice is restricted to locally formed pancake and frazil ice. The Greenland Sea is also a key region for the formation of dense water, and the movement of ice within this tongue will play a crucial role in determining the volume of ice formed over a winter and the subsequent modification to the upper water column through brine drainage. We present results from three drifting “pancake” buoys released in the Odden in 1997. From the analysis of data from these buoys it was found that the ice predominantly moves in a southwesterly direction, but meanders in any direction are possible, and on timescales above 6 hours the surface wind almost exclusively drives the ice dynamics. Results indicate that pancake ice within the Odden drifts at approximately 4% of the wind speed and at about 40 degrees to the right of the wind.
p90 RSK-1 associates with and inhibits neuronal nitric oxide synthase
Authors: Song Tao , Sugimoto Katsuyoshi , Ihara Hideshi , Mizutani Akihiro , Hatano Naoya , Kume Kodai , Kambe Toshie , Yamaguchi Fuminori , Tokuda Masaaki , Watanabe Yasuo
Published: January 2007

Evidence is presented that RSK1 (ribosomal S6 kinase 1), a downstream target of MAPK (mitogen-activated protein kinase), directly phosphorylates nNOS (neuronal nitric oxide synthase) on Ser847 in response to mitogens. The phosphorylation thus increases greatly following EGF (epidermal growth factor) treatment of rat pituitary tumour GH3 cells and is reduced by exposure to the MEK (MAPK/extracellular-signal-regulated kinase kinase) inhibitor PD98059. Furthermore, it is significantly enhanced by expression of wild-type RSK1 and antagonized by kinase-inactive RSK1 or specific reduction of endogenous RSK1. EGF treatment of HEK-293 (human embryonic kidney) cells, expressing RSK1 and nNOS, led to inhibition of NOS enzyme activity, associated with an increase in phosphorylation of nNOS at Ser847, as is also the case in an in vitro assay. In addition, these phenomena were significantly blocked by treatment with the RSK inhibitor Ro31-8220. Cells expressing mutant nNOS (S847A) proved resistant to phosphorylation and decrease of NOS activity. Within minutes of adding EGF to transfected cells, RSK1 associated with nNOS and subsequently dissociated following more prolonged agonist stimulation. EGF-induced formation of the nNOS–RSK1 complex was significantly decreased by PD98059 treatment. Treatment with EGF further revealed phosphorylation of nNOS on Ser847 in rat hippocampal neurons and cerebellar granule cells. This EGF-induced phosphorylation was partially blocked by PD98059 and Ro31-8220. Together, these data provide substantial evidence that RSK1 associates with and phosphorylates nNOS on Ser847 following mitogen stimulation and suggest a novel role for RSK1 in the regulation of nitric oxide function in brain.
15-Deoxyspergualin inhibits eukaryotic protein synthesis through eIF2α phosphorylation
Authors: Ramya T. N. C. , Surolia Namita , Surolia Avadhesha
Published: January 2007

DSG (15-deoxyspergualin), an immunosuppressant with tumoricidal properties, binds potently to the regulatory C-terminal ‘EEVD’ motif of Hsps (heat-shock proteins). In the present study we demonstrate that DSG inhibits eukaryotic protein synthesis by sequestering Hsp70 which is required for maintaining HRI (haem-regulated inhibitor), a kinase of the eIF2α (eukaryotic initiation factor 2α), inactive. DSG stalled initiation of protein synthesis through phosphorylation of HRI and eIF2α. Addition of a recombinant eIF2α (S51A) protein, which lacks the phosphorylation site, lowered the inhibitory potential of DSG in reticulocyte lysate. The inhibitory effect of DSG was also attenuated in HRI knockdown cells. Moreover, exogenous addition of Hsp70 or the peptide ‘EEVD’ reversed the inhibitory effect of DSG. Interestingly, the inhibitory effect of DSG in different mammalian cancer cells was found to negatively correlate with the amount of Hsp70 expressed in the cells, emphasizing the link with Hsp70 in DSG inhibition of eukaryotic translation.
Glutamine gluconeogenesis in the small intestine of 72 h-fasted adult rats is undetectable
Authors: Martin Guy , Ferrier Bernard , Conjard Agnès , Martin Mireille , Nazaret Rémi , Boghossian Michelle , Saadé Fadi , Mancuso Claire , Durozard Daniel , Baverel Gabriel
Published: January 2007

Recent reports have indicated that 48–72 h of fasting, Type 1 diabetes and high-protein feeding induce gluconeogenesis in the small intestine of adult rats in vivo. Since this would (i) represent a dramatic revision of the prevailing view that only the liver and the kidneys are gluconeogenic and (ii) have major consequences in the metabolism, nutrition and diabetes fields, we have thoroughly re-examined this question in the situation reported to induce the highest rate of gluconeogenesis. For this, metabolically viable small intestinal segments from 72 h-fasted adult rats were incubated with [3-13C]glutamine as substrate. After incubation, substrate utilization and product accumulation were measured by enzymatic and NMR spectroscopic methods. Although the segments utilized [13C]glutamine at high rates and accumulated 13C-labelled products linearly for 30 min in vitro, no substantial glucose synthesis could be detected. This was not due to the re-utilization of [13C]glucose initially synthesized from [13C]glutamine. Arteriovenous metabolite concentration difference measurements across the portal vein-drained viscera of 72 h-fasted Wistar and Sprague–Dawley rats clearly indicated that glutamine, the main if not the only gluconeogenic precursor taken up, could not give rise to detectable glucose production in vivo. Therefore we challenge the view that the small intestine of the adult rat is a gluconeogenic organ.
Strong-coupling limit for the ground state of a particle harmonic oscillator interaction
Authors: Carley Holly
Published: January 2007

We consider the quantum Hamiltonian for a particle interacting with a harmonic oscillator, H≔−Δx+A†A+λϕA+λϕ*A†, for various choices of coupling potential ϕ=ϕ(x), where A† and A are creation and annihilation operators, and λ is a parameter to be thought of as large. This operator is a caricature of the polaron Hamiltonian where the quantum field is approximated by a single mode. The large λ corresponds to large coupling between the electron and the field. Let E0(λ) be the infimum of the spectrum of H, and let EP(λ)=inf⟨ψ,Hψ⟩ where the infimum is taken over product states for the electron and oscillator, the oscillator function taken as a coherent state. It is a remarkable fact that EP(λ) is a “good” approximation of E0(λ). More specifically, (EP(λ)−1)⩽E0(λ)⩽EP(λ) for all λ, as observed by Lieb. In this paper we examine this gap EP(λ)−E0(λ) for various choices of ϕ, showing cases where it closes and cases where it does not.
Elastic properties of a-C:N:H films
Authors: Wang Chengbing , Yang Shengrong , Li Hongxuan , Zhang Junyan
Published: January 2007

Dual dc-rf plasma system has been used to deposit hydrogenated carbon nitride (CNx:H) films that exhibit high elastic recovery (75%). Transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectra and Raman spectra were subsequently used to study the microstructure and bonding of the resultant films. The structure of the films from TEM is seen to consist of many particles embedded in an amorphous carbon matrix, and the films can be described as graphitelike or onionlike with interplanar distances of ≈1.15, 1.95, and 3.5Å, as obtained from selected area electron diffraction (SAED). FTIR shows that nitrogen promotes the formation of sp2 CC∕CN aromatic rings in the films. Raman spectra shows two apparent peaks at about 700 and 1200cm−1 in addition to the G and D peaks. Only by adding two extra peaks at approximately 1230 and 1470cm−1 can we deconvolute the Raman spectra of CNx:H in the region of 1000–2000cm−1. Combining TEM and SAED, we attribute the three peaks at about 700, 1200, and 1470cm−1 to fullerene or onion structure. However, the elastic recovery is relatively lower than elastic hydrogenated free carbon nitride films. We think that this is due to the fact that hydrogen is mainly incorporated to sp3 carbon and suppresses cross-linking three-dimensional (3D) network growth.
Preparation and thermoelectric transport properties of high-performance p-type Bi2Te3 with layered nanostructure
Authors: Tang Xinfeng , Xie Wenjie , Li Han , Zhao Wenyu , Zhang Qingjie , Niino Masayuki
Published: January 2007

High performance Bi2Te3 bulk materials with layered nanostructure have been prepared by combining melt spinning technique with spark plasma sintering, and their thermoelectric transport properties are investigated. The electrical conductivity increases greatly and the lattice thermal conductivity decreases significantly with the increase of the roller’s linear speed. These lead to a great improvement in the thermoelectric figure of merit (ZT). The maximum ZT value of 1.35 is obtained at 300K for the sample which is prepared by melt spinning with roller linear speed of 40m∕s. Compared with the zone melting sample, it increases by 73% at the same temperature.
Near-infrared camera in polycrystalline germanium integrated on complementary-metal-oxide semiconductor electronics
Authors: Colace Lorenzo , Masini Gianlorenzo , Cozza Stefano , Assanto Gaetano , DeNotaristefani Francesco , Cencelli Valentino
Published: January 2007

The authors demonstrate a two-dimensional array of Si-integrated photodetectors equipped with readout electronics and operating in the near infrared. The chip is realized in polycrystalline Ge on a silicon complementary metal oxide semiconductor circuitry and includes 512pixels, 64 analog to digital converters, dark current cancellation, and test/calibration facilities. They describe its design, fabrication, characterization, and operation as a near-infrared image sensor.
Anomalous photoluminescence behavior from amorphous Ge quantum dots produced by buffer-layer-assisted growth
Authors: Bhatti A. S. , Antonov V. N. , Swaminathan P. , Palmer J. S. , Weaver J. H.
Published: January 2007

The authors present photoluminescence results from amorphous Ge quantum dots formed using buffer-layer-assisted growth. Their sizes, shapes, and densities were controlled by varying the thickness of the Xe buffer layer, with sizes varying from 2to8nm. A relatively weak signal was observed at ∼3K at ∼0.91eV that was independent of size and was insensitive to laser intensity. Its temperature-dependent magnitude showed a Berthelot-type behavior that they associate with hopping of carriers between radiative tail states and shallow nonradiative states. These findings are similar to those from porous semiconductors.
Development of latent images due to transient free carrier electrons by femtosecond laser pulses and its application to grating shape trimming
Authors: Kawamura Ken-ichi , Otsuka Takukazu , Hirano Masahiro , Kamiya Toshio , Hosono Hideo
Published: January 2007

The effects of prepulse exposure on the threshold energy to encode a micrograting structure on a SiO2 glass surface by a prepulse-postpulse exposure technique using femtosecond (∼150fs pulse duration) laser pulse irradiation were examined by measuring the laser intensity diffracted by the microgratings. It was revealed that prepulse exposure reduces the threshold energy of the postpulse from ∼0.4to∼0.2Jcm−2, which enables to develop a latent image of the free carriers generated by the prepulse with the postpulse. This technique was applied to trim the shape of the micrograting pattern with the prepulse pattern. The role of the prepulse was investigated by comparing the dynamics of the photoexcited carriers in two dielectrics (SiO2 glass and MgO single crystal) that have largely different lifetimes of photoexcited carriers. It was determined that the ultrashort relaxation time of the photoexcited carriers in SiO2 glass limits the time delay of the postpulse to develop a latent image.
Electrical properties of nominally undoped silicon nanowires grown by molecular-beam epitaxy
Authors: Bauer Jan , Fleischer Frank , Breitenstein Otwin , Schubert Luise , Werner Peter , Gösele Ulrich , Zacharias Margit
Published: January 2007

Single undoped Si nanowires were electrically characterized. The nanowires were grown by molecular-beam epitaxy on n+ silicon substrates and were contacted by platinum/iridium tips. I-V curves were measured and electron beam induced current investigations were performed on single nanowires. It was found that the nanowires have an apparent resistivity of 0.85Ωcm, which is much smaller than expected for undoped Si nanowires. The conductance is explained by hopping conductivity at the Si–SiO2 interface of the nanowire surface.
Highly reflective low resistance Ag-based Ohmic contacts on p-type GaN using Mg overlayer
Authors: Jang Ho Won , Son Jun Ho , Lee Jong-Lam
Published: January 2007

A metallization scheme with high reflectance and smooth surface morphology has been developed for obtaining low resistance Ohmic contacts on p-type GaN. Excellent Ohmic characteristics with a specific contact resistivity as low as 9.0×10−6Ωcm2 were obtained by annealing evaporated Ni (10Å)∕Ag (1500Å)∕Mg (500Å) contact at 450°C for 2min in O2 ambient. Additionally, a high reflectance over 80% was observed in the 400–500nm wavelength range. The Mg overlayer suppressed excessive incorporation of oxygen into the Ni and Ag layers during oxidation annealing, leading to high reflectance and smooth surface quality of the Ohmic contact.
Unambiguous identification of the PL-I9 line in zinc oxide
Authors: Müller S. , Stichtenoth D. , Uhrmacher M. , Hofsäss H. , Ronning C. , Röder J.
Published: January 2007

Radioactive In111 atoms implanted into zinc oxide (ZnO) single crystals occupy substitutional Zn lattice sites after annealing to 700°C. The respective photoluminescence (PL) spectra of the samples were monitored while the donor In decayed into stable and isolectronic Cd. The commonly labeled PL-I9 line could be clearly assigned to excitons bound to the donor In. An arising luminescence band centered at 2.85eV was observed with the characteristic lifetime of the isotope, and the origin could be identified as levels of the isoelectronic Cd impurities.
Knowledge, Attitudes, and Practice of Iranian Dentists with Regard to HIV-Related Disease
Authors: Askarian Mehrdad , Mirzaei Kamran , Cookson Barry
Published: January 2007

Of 369 registered dentists in Fars province in Iran, 309 (83.7%) responded to a survey regarding knowledge, attitudes, and practices related to human immunodeficiency virus (HIV) infection. The level of knowledge was low and was correlated with years in practice, hours worked per week, and whether additional work in a governmental dental office was performed; only the last was significantly associated with adherence to relevant infection control recommendations.
Role of Safety-Engineered Devices in Preventing Needlestick Injuries in 32 French Hospitals
Authors: Lamontagne F. , Abiteboul D. , Lolom I. , Pellissier G. , Tarantola A. , Descamps J. M. , Bouvet E.
Published: January 2007

Objectives.

To evaluate safety-engineered devices (SEDs) with respect to their effectiveness in preventing needlestick injuries (NSIs) in healthcare settings and their importance among other preventive measures.

Design.

Multicenter prospective survey with a 1-year follow-up period during which all incident NSIs and their circumstances were reported. Data were prospectively collected during a 12-month period from April 1999 through March 2000. The procedures for which the risk of NSI was high were also reported 1 week per quarter to estimate procedure-specific NSI rates. Device types were documented. Because SEDs were not in use when a similar survey was conducted in 1990, their impact was also evaluated by comparing findings from the recent and previous surveys.

Setting.

A total of 102 medical units from 32 hospitals in France.

Participants.

A total of 1,506 nurses in medical or intensive care units.

Results.

A total of 110 NSIs occurring during at-risk procedures performed by nurses were documented. According to data from the 2000 survey, use of SEDs during phlebotomy procedures was associated with a 74% lower risk (P < .01 ). The mean NSI rate for all relevant nursing procedures was estimated to be 4.72 cases per 100,000 procedures, for a 75% decrease since 1990 (P < .01); however, the decrease in NSI rates varied considerably according to procedure type. Between 1990 and 2000, decreases in the NSI rates for each procedure were strongly correlated with increases in the frequency of SED use (r = 0.88; P < .02).

Conclusion.

In this French hospital network, the use of SEDs was associated with a significantly lower NSI rate and was probably the most important preventive factor.
Morphological transformation in three mammalian cell systems following treatment with 6-nitrochrysene and 6-nitro-benzo[a]pyrene
Authors: Sala M. , Lasne C. , Lu Y.P. , I. Chouroulinkov
Published: January 2007

Two nitroaromatics, 6-nitrobenzo[a]pyrene (6-N-BaP) and 6-nitrochrysene (6-N-CRY), and the corresponding parent hydrocarbons, benzo[a]pyrene (BaP) and chrysene (CRY), were studied in in vitro transformation assays with Syrian hamster embryo (SHE) cells, BALB/3T3 and C3H10T1/2 mouse cell lines. The three cell systems showed different sensitivities to the transforming effects of the chemicals studied, SHE cells being the most efficient, followed by 3T3 cells and the last being C3H1OT1/2 cells. In the SHE cell system all compounds were active. Considering the concentrations (in μM) and the transformation frequency BaP was the most active, followed by 6-N-BaP, 6-N-CRY and CRY. In the BALB/3T3 standard assay and in the C3H10T1/2 assay only BaP was clearly active. When used as initiators 6-N-BaP and 6-N-CRY were inactive in the C3H cell system. In conclusion 6-N-BaP appears less active in in vitro systems than the parent compound BaP; 6-N-CRY is probably negative since it is questionable in vitro and negative in mouse skin.
Phorbol ester-induced formation of clastogenic factor from human monocytes
Authors: Kozumbo Walter J. , Muehlematter D. , Jörg A. , Emerit I.
Published: January 2007

Phorbol-12-myristate-13-acetate (PMA) acts as a tumor promoter on mouse skin. It induces inflammation and leukocyte-mediated clastogenicity which appears to be related to rapid changes in lipid metabolism. To identify lipids possessing clastogenic and/or tumor-promoting properties, we have characterized the metabolism and release of arachidonic acid (AA) and related lipids during the formation of lipophilic clastogenic factors by PMA-treated human monocytes. In 1 h, [ 3 H]AA-labeled monocytes spontaneously released significant amounts of their total radioactivity (4#) which increased nearly 4-fold (15#) with PMA (30 ng/ml) treatment. Eighty-five per cent of extracellular 3 H-label from both control and PMA-treated monocytes was composed of free AA (plus AA-metabolites), while the remaining radioactivity was incorporated in pbospholipids and mono- and diacylglycerols. Treated and non-treated cells released essentially the same kind of metabolites but PMA induced a 3- to 4-fold increase in total amounts. The major products consisted of prostaglandins F 2α and E 2 , thromboxane B 2 , 12-hydroxy-5,8,10-hepta-decatrienoic acid and 5-, 11- and 15-hydroxyeicosatetraenoic acids. PMA also induced increases in the levels of three unidentified products. Neither leukotrienes nor 4-hydroxy-nonenal, a major alkenal degradation product of AA, were found in medium from PMA-treated monocytes. PMA, in contrast to the first-stage tumor promoter calcium ionophore A23187, failed to stimulate the release of platelet activating factor. The increased formation of phorbol ester-induced AA metabolites was proportional to the increase in free extracellular AA. The source of AA from treated and untreated monocytes consisted of cellular phospholipids with phosphatidylcholine and phosphatidylethanoloamine accounting for 85%.
The clonal nature of carcinogen-induced altered foci of γ-glutamyl transpeptidase expression in rat liver
Authors: Weinberg W.C. , Berkwits L. , Iannaccone P.M.
Published: January 2007

The clonality of tumors has been convincingly established. Because it is generally accepted that tumor formation involves a number of steps, it is important to determine which if any of the precursors of tumors are clonal. A series of chimeric rats produced between congenic strains by morulae aggregation were used to establish the cellular composition of foci of γ-glutamyl transpeptidase (-γ-GTP; E.C. 2.3.2.2) expression in liver following initiation with N -nitrosodiethylamine and promotion with phenobarbital. The chimeras were produced between congenic rat strains (PVG and PVG-RT1 a ) genetically distinguished by alleles of the major histocompatibility complex (MHQ. Monoclonal antibodies directed to distinctive class I MHC alloantigens were used to detect patterns of mosaicism in the animals. The parental genotypes present in most visceral tissues could be easily distinguished by our method. Analysis of 499 enzyme-altered foci revealed that 474 were comprised solely of either PVG-RT1 a or PVG cells. Some apparent mixture of cells from the two lineages was observed in 25 lesions, most of which were very small. The observed pattern of distortion of normal patch distribution clearly indicated the expanding and clonal nature of these lesions.
Suppression by methionine and choline of onco-fetal patterns of liver tRNA methyltransferase activities in carcinogen-treated rats
Authors: Wainfan Elsie , Dizik Mark
Published: January 2007

When male Fischer rats were fed Purina chow supplemented with 2% D,L-methionine and 1% choline chloride, the rapid increase in N2-guanine tRNA methyltransferase II (NMG2) activity otherwise seen in response to cancer-promoting doses (0.02% in the diet) of 2-acetylaminofluorene (AAF) was prevented, and the increase in NMG2 activity otherwise caused by carcinogenic doses of AAF (0.06% in the diet) was decreased by 50%. In addition, the return of NMG2 activity to a normal level after completion of a 3-week regimen of 0.06% AAF was accelerated in animals fed the methionine plus choline supplemented diet. As shown earlier in this laboratory, liver tRNA methylating enzyme activities are shifted rapidly to an onco-fetal pattern in rats receiving methyl-deficient diets. This pattern is characterized by selectively elevated NMG2 activity while the activities of other base-specific tRNA methylating enzymes are relatively unchanged. Our combined results indicate that the exogenous supply of methyl groups is a factor in regulating NMG2 activity and can modulate at least one response of animals to carcinogens.