Next-to-leading order renormalization of the $\Delta B=2$ operators in the static theory

1996

The renormalization, at the next-to-leading order in $\alpha_s$, of the $\Delta B=2$ operators at the lowest order in the heavy quark expansion, namely in the static theory, is computed taking into account previously missed contributions. These operators are relevant for the calculation of the $B^0$--$\bar B^0$ mixing on the lattice.

Canal transportation caused by a new instrumentation technique and three standard techniques

1996

The ability of three different enlarging techniques (balanced force concept, step-back, and recapitulation) and a prototype system to maintain the original canal path during root canal preparation were compared, in vitro, with a theoretical ideally prepared root canal. Measurements were made at the concave and convex sides of the canal at four different levels (1, 4, 5, and 7 mm from apical, respectively). Simulated root canals embedded in clear casting resin and an enlarging computer-supported device were used for this study. The results showed that none of the enlarging techniques used in this study was able to prepare a canal ideally. The prototype system, at level 1, showed an ideal amo…

Selective killing of human monocytes and cytokine release provoked by sphingomyelinase (beta-toxin) of Staphylococcus aureus.

1996

The best-known activity of Staphylococcus aureus sphingomyelinase C, alias beta-toxin, is as a hemolysin that provokes hot-cold lysis of erythrocytes which contain substantial amounts of sphingomyelin in the plasma membrane. Sheep erythrocytes are most susceptible, and we found that one hemolytic unit, representing the toxin concentration that elicits 50% hemolysis of 2.5 X 10(8) erythrocytes per ml, corresponds to 0.05 enzyme units or to approximately 0.25 microg of sphingomyelinase per ml. The cytotoxic action of beta-toxin on nucleated cells has not been described in any detail before, and the present investigation was undertaken to fill this information gap. We now identify beta-toxin a…

Pythium deliense causing severe damping-off of cucumber seedlings and its biological control by soil bacteria

1996

Abstract Pythium deliense Meurs was isolated from cucumber plant debris and was found to be highly pathogenic to cucumber seedlings, causing severe damping-off disease. The fungus however was completely inhibited by a soil bacterium SU-48.1. In vitro and in vivo studies reveal that the disease can be controlled by using this bacterium. The details of the parasitic fungus, the antagonism between the fungus and the bacteria, and the biological control of the disease, are described in this article.

Tracking the evolution of warning signals

1996

EVOLUTIONARYstudies are hampered by a lack of experimental ways in which to test past events such as the origination of aposematism1–7, whereby unpalatable or poisonous prey signal their unprofitability, often by being warningly coloured. Inexperienced predators do learn to avoid unpalatable prey as a result of such signals8–10, but in addition there may be an inherited cautiousness about attacking when common or conspicuous warning signals are evident11–16. As current predators are not naive in the evolutionary sense, it is still not resolved3–7,17,18 whether aposematism originated only in aggregations of prey19,20 or among solitary prey as well21–23. Here we explore this controversy in ev…

Die nicht-invasive Messung der mittleren zerebralen O2-Sättigung des Hämoglobins

1996

Photoemission of spinpolarized electrons from strained GaAsP

1996

Strained layer GaAs.95P.05 photo cathodes are presented, which emit electron beams spinpolarized to a degree of P = 75% typically. Quantum yields around QE = 0.4% are observed routinely. The figure of merit P2 × QE = 2.3 × 10−3 is comparable to that of the best strained layer cathodes reported in literature. The optimum wavelength of irradiating light around 830 nm is in convenient reach of Ti:sapphire lasers or diode lasers respectively. The cathodes are produced using MOCVD-techniques. A GaAs.55P.45-GaAs.85P.15 superlattice structure prevents the migration of dislocations from the substrate and bottom layers to the strained overlayer. The surface is protected by an arsenic layer so that n…

The Serum Protein α2-HS Glycoprotein/Fetuin Inhibits Apatite Formation in Vitro and in Mineralizing Calvaria Cells

1996

We present data suggesting a function of alpha2-HS glycoproteins/fetuins in serum and in mineralization, namely interference with calcium salt precipitation. Fetuins occur in high serum concentration during fetal life. They accumulate in bones and teeth as a major fraction of noncollagenous bone proteins. The expression pattern in fetal mice confirms that fetuin is predominantly made in the liver and is accumulated in the mineralized matrix of bones. We arrived at a hypothesis on the molecular basis of fetuin function in bones using primary rat calvaria osteoblast cultures and salt precipitation assays. Our results indicate that fetuins inhibit apatite formation both in cell culture and in …

Morphogenesis in leaf and single-cell cultures of mature Juniperus oxycedrus

1996

Single cells were mechanically isolated from leaf-derived callus of mature Juniperus oxycedrus L. These cells divided and gave rise to callus when plated on medium containing growth regulators. Best plating efficiency was obtained on a modified Schenk and Hildebrandt medium supplemented with 0.6 micro M 2,4-dichlorophenoxyacetic acid and 100 mg l(-1) casein hydrolyzate. Although single-cell-derived callus showed poor morphogenic potential, both adventitious shoots and embryogenic tissues differentiated from the callus. We also achieved induction of somatic embryogenesis in leaf explants of mature J. oxycedrus trees cultured in the presence of 6.0 or 10.0 micro M 2,4-dichlorophenoxyacetic ac…

Heuristics and Memory Strategies Used by Mathematicians

1996

The study of the cognitive processes involved in learning and acquisition of technically complex material is a main focus of interest for basic and applied research. Our research program tries to identh memory aids and heuristic training strategies useful for improving mathematics performance. Part of the effectiveness of a course, designed by taking into account knowledge about the cognitive system, has to do with the development of an adequate relationship with the belief system of the learner. As a first step in that direction, we present a survey of the opinions of a group of mathematicians about the dd€iculty of their subjecr matter, the strategies they use spontaneously to overcome di…

Hepatitis G virus: an old, but newly discovered hepatotropic virus--is it of interest for the nephrologist?

1996

Leukocyte flow properties, polymorphonuclear membrane fluidity, and cytosolic Ca2+ content in subjects with vascular atherosclerotic disease with and…

1996

The aim of this research was the evaluation of white blood cell (WBC) filtration, reflecting WBC flow properties, polymorphonuclear cell membrane fluidity, and cytosolic Ca 2+ content in subjects with vascular atherosclerotic disease (VAD) and in VAD subjects with noninsulin-dependent diabetes mellitus (NIDDM), in good hemodynamic balance. The authors examined WBC filtration (unfractionated, mononuclear [MN], polymorphonu clear [PMN] cells), using the St. George Filtrometer and considering, respectively, the initial relative flow rate (IRFR) and the clogging rate (CR); the PMN membrane fluidity, employing the fluorescent probe TMA-DPH and calculating the fluorescence polarization degree; a…

Secoiridoids and Xanthones fromGentianella nitida

1996

From Gentianella nitida twelve known metabolites were isolated and identified by HPLC-UV and/or by spectroscopic methods as secologanoside, amaroswerin, amarogentin (secoiridoids), isoorientin (C-glucosylflavone), mangiferin, demethylbellidifolin 8-O-glucoside, norswertianine 1-O-glucoside, swertianine 1-O-primeveroside, swertianine 8-O-glucoside, norswertianine, demethylbellidifolin, and swertianine (xanthone glycosides and aglycones). Secologanoside is reported here for the first time in Gentianaceae species ; the antioxidant mangiferin was obtained as the major compound in good yield.

Microradiography and confocal laser scanning microscopy applied to enamel lesions formed in vivo with and without fluoride varnish treatment

1996

The aim of the present investigation was to combine 2 techniques suitable for lesion characterization: quantitative microradiography (TMR) and confocal laser scanning microscopy (CLSM) on in vivo induced lesions with and without a fluoride varnish (Duraphat(R)) treatment. Orthodontic bands were attached to premolars to be extracted for orthodontic reasons to induce enamel caries on the buccal surfaces. In the caries development part of the study, 1 tooth of each pair received at the start 1 topical application with the fluoride varnish Duraphat(R), the contralateral tooth serving as untreated control. All teeth were extracted after 4 weeks. In the caries progression part, the premolars were…

Chromatographic determination of caffeine in pharmaceutical formulations using micellar mobile phases

1996

An HPLC procedure is described for the determination of caffeine in pharmaceutical preparations. A Spherisorb octadecylsilane ODS-2 C18 analytical column and spectrophotometric detection at 273 nm were used. The chromatographic behaviour of caffeine with different micellar eluents containing sodium dodecyl sulphate (SDS) is described. The determination of caffeine in pharmaceutical preparations was performed by use of a mobile phase containing 0.05 M sodium dodecylsulphate (SDS) and 1.5% propanol at pH7. At a 6.0 μg mL−1 concentration level the peak area and peak height repeatability were 2.6 and 2.4%, respectively. The application of the proposed method to the analysis of five pharmaceutic…

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1996

The major new developments in electron crystallography and high resolution imaging of organic molecules are discussed. The aim is to show that the recent rapid advances in computer technology have made it possible to analyze molecules at a level or resolution which was impossible less than a decade ago, thus bringing the concept of molecular design to produce specific physical properties much nearer to realization

Colorimetric susceptibility testing for Aspergillus fumigatus: comparison of menadione-augmented 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazo…

1996

Two colorimetric methods that use Alamar Blue or 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) for assaying the in vitro activities of antifungal agents have been described. We report that both tests performed similarly when the antifungal activity of amphotericin B against Candida albicans was determined. However, only the MTT test generated interpretable data when Aspergillus fumigatus was used.

Trapping of Different Lipase Conformers in Water-Restricted Environments

1996

Based on a recently reported strategy to rationally activate lipolytic enzymes for use in nonaqueous media [Mingarro, I., et al. (1995) Proc. Natl. Acad. Sci. U.S.A. 92, 3308-3312], we compared the behavior in water-restricted environments of activated vs nonactivated forms of different lipases toward their natural substrates, triacylglycerols. To this end, nine lipases from varied origins (mammalian, fungal, and bacterial) were assayed using simple acidolyses as nonaqueous model reactions. The experimental results for several (though not all) lipases, discussed in the light of current structural and functional information, were collectively consistent with a model where, depending on the "…

Cancer consequences of the Chernobyl accident in Europe outside the former USSR: A review

1996

The accident which occurred during the night of April 25-26, 1986 in reactor 4 of the Chernobyl nuclear power plant in the Ukraine released considerable amounts of radioactive substances into the environment. Outside the former USSR, the highest levels of contamination were recorded in Bulgaria, Austria, Greece and Romania, followed by other countries of Central, Southeast and Northern Europe. Studies of the health consequences of the accident have been carried out in these countries, as well as in other countries in Europe. This report presents the results of a critical review of cancer studies of the exposed population in Europe, carried out on the occasion of the 10th anniversary of the …

Rapid-rate transcranial magnetic stimulation of left dorsolateral prefrontal cortex in drug-resistant depression.

1996

Summary Background Lesion and neuroimaging studies suggest that left prefrontal lobe dysfunction is pathophysiologically linked to depression. Rapid-rate transcranial magnetic stimulation (rTMS) to prefrontal structures has a lateralised effect on mood in normal volunteers, and several preliminary studies suggest a beneficial effect of rTMS on depression. However, adequately controlled studies have not been conducted. Methods We have studied the effects of focal rTMS on the depressive symptoms in 17 patients with medication-resistant depression of psychotic subtype. The study was designed as a multiple cross-over, randomised placebo-controlled trial. Sham rTMS and stimulation of different c…

Cross-talk between Different Enhancer Elements during Mitogenic Induction of the Human Stromelysin-1 Gene

1996

Platelet-derived growth factor (PDGF) induces the expression of human stromelysin-1, a matrix metalloproteinase involved in tumor invasion and metastasis. Here it is shown that stromelysin-1 gene induction by PDGF depends on Ras and involves three previously identified promoter elements (the stromelysin-1 PDGF-responsive element (SPRE) site, the two head-to-head polyomavirus enhancer A-binding protein-3 (PEA3) sites, and the activator protein-1 (AP-1) binding site). During mitogenic induction, these responsive elements appear to be organized in two independent transcriptional units, SPRE-AP-1 and PEA3-AP-1, which result from specific element cross-talking. Interestingly, expression of a dom…

Virtual Compton Scattering off Spin-Zero Particles at Low Energies

1996

We discuss the low-energy behavior of the virtual Compton scattering amplitude off a spin-zero target. We first compare various methods of obtaining a low-energy expression based either on the soft-photon approximation or the use of Ward-Takahashi identities. We point out that structure-dependent terms are defined with respect to a low-energy approximation of the pole terms which commonly is separated from the full amplitude. We derive a general expression for the structure-dependent terms in an expansion in terms of the momenta $k_1$ and $k_2$ of the initial and final virtual photon, respectively, up to and including terms of order ${\cal O}(k^4)$. At order ${\cal O}(k^2)$ two terms appear…

Bacillus thuringiensis crystal proteins CRY1Ab and CRY1Fa share a high affinity binding site in Plutella xylostella (L.).

1996

The future success of Bacillus thuringiensis based insecticides depends in part on our ability to prevent insects from developing resistance against their insecticidal crystal proteins. Two recent papers indicated cross-resistance between Cry1A proteins and Cry1Fa in two different insect species (Tabashnik et al., 1994, Appl. Environ. Microbiol. 60, 4627-4629; Gould et al., 1995, J. Econ. Entomol. 88, 1545-1559). Brush border membrane vesicles were prepared from Plutella xylostella and used in binding assays with 125I-labeled trypsin-activated crystal proteins. Competition experiments showed that Cry1Fa competed with Cry1Ab for a same binding site, though the latter still bound to a differe…

A gas chromatography-olfactometric study of cooked cured ham-impact of sodium nitrite

1996

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Quantitative analysis of new potent flavour compounds in Burgundy pinot noir wines

1996

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Identification and sensory evaluation of the character-impact compounds of goat cheese flavour

1996

1 SUMMARY The volatile compounds of various goat cheeses have been isolated in order to identify the character-impact odorants by a combination of instrumental analyses and sensory studies. Different extraction procedures have been studied in order to obtain a volatile fraction representative of the cheeses. The most representative extract, as determined by sensory evaluation, has been submitted to GC-MS and to GC-olfactometry, using the aroma extract dilution analysis (AEDA) method. The volatile fatty acids have been found to be the most important compounds for the characteristic goat flavour. Among them, branched-chain fatty acids ( e.g. , 4-methyloctanoic and 4-ethyloctanoic) have been f…

Relationships between odorous intensity and partition coefficients of delta-decalactone, diacetyl and butyric acid in model emulsions

1996

International audience

Interaction of prion protein mRNA with CBP35 and other cellular proteins: possible implications for prion replication and age-dependent changes.

1996

Abstract A study of the intracellular distribution of prion protein (PrP) in N2a neuroblastoma cells which had been infected with prions (ScN2a cells) revealed that most PrP is present in the cytoplasm. However, a significant amount of PrP is also present in the nucleus (predominantly in the nucleoli) of these cells, as analyzed by confocal laser scanning microscopy. By contrast, no PrP could be detected in the nucleus of uninfected N2a cells. The steady-state level of PrP mRNA did not markedly differ between the two cell strains. Likewise, no changes were found in the rate of transcription and in the half-life of PrP mRNA. A number of cellular proteins, among them the nuclear lectin CBP35,…

Production of representative champagne extracts for olfactory analysis

1996

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Interactions of beta-lactoglobulin with flavour compounds

1996

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Pore-forming toxins trigger shedding of receptors for interleukin 6 and lipopolysaccharide.

1996

Cleavage of membrane-associated proteins with the release of biologically active macromolecules is an emerging theme in biology. However, little is known about the nature and regulation of the involved proteases or about the physiological inducers of the shedding process. We here report that rapid and massive shedding of the interleukin 6 receptor (IL-6R) and the lipopolysaccharide receptor (CD14) occurs from primary and transfected cells attacked by two prototypes of pore-forming bacterial toxins, streptolysin O and Escherichia coli hemolysin. Shedding is not induced by an streptolysin O toxin mutant which retains cell binding capacity but lacks pore-forming activity. The toxin-dependent c…

Supersymmetric Unification with Radiative Breaking of R-parity

1996

We show how R-parity can break spontaneously as a result of radiative corrections in unified N=1 supergravity models. We illustrate this with a concrete rank-four unified model, where the spontaneous breaking of R-parity is accompanied by the existence of a physical majoron. We determine the resulting supersymmetric particle mass spectrum and show that R-parity-breaking signals may be detectable at LEP200.

Black Hole Evaporation by Thermal Bath Removal

1996

We study the evaporation process of 2D black holes in thermal equilibrium when the incoming radiation is turned off. Our analysis is based on two different classes of 2D dilaton gravity models which are exactly solvable in the semiclassical aproximation including back-reaction. We consider a one parameter family of models interpolating between the Russo-Susskind-Thorlacius and Bose-Parker-Peleg models. We find that the end-state geometry is the same as the one coming from an evaporating black hole formed by gravitational collapse. We also study the quantum evolution of black holes arising in a model with classical action $S = {1\over2\pi} \int d^2x \sqrt{-g} (R\phi + 4\lambda^2e^{\beta\phi}…

Analysis of four potent odorants in Burgundy chardonnay wines : partial quantitative descriptive sensory analysis and optimization of simultaneous ex…

1996

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Hydrodynamical Description of 200 A GeV/c S+Au Collisions: Hadron and Electromagnetic Spectra

1996

We study relativistic S+Au collisions at 200 A GeV/c using a hydrodynamical approach. We test various equations of state (EOSs), which are used to describe the strongly interacting matter at densities attainable in the CERN-SPS heavy ion experiments. For each EOS, suitable initial conditions can be determined to reproduce the experimental hadron spectra; this emphasizes the ambiguity between the initial conditions and the EOS in such an approach. Simultaneously, we calculate the resulting thermal photon and dielectron spectra, and compare with experiments. If one allows the excitation of resonance states with increasing temperature, the electro-magnetic signals from scenarios with and witho…

Le formalisme algébrique U(p+1) adapté aux modes de pliage des molécules tétraédriques.

1996