showing 36 of ~574560 from 574555 documents
Determination of benperidol and its reduced metabolite in human plasma by high-performance liquid chromatography and electrochemical detection.
1991
An isocratic high-performance liquid chromatographic method with electrochemical detection for the quantification of benperidol and its suggested reduced metabolite TVX Q 5402 in human plasma is described. The method included a two-step solid-phase extraction on reversed-phase and cation-exchange material, followed by separation on a cyanopropyl silica gel column (5 microns; 250 mm x 4.6 mm I.D.). The eluent was 0.15 M acetate buffer (pH 4.7) containing 25% acetonitrile (w/w). Spiperone served as internal standard. The inclusion of the cation-exchange step provided sample purity higher than those achieved with other methods. After extraction of 1 ml of plasma, concentrations as low as 0.5 n…
Inhibition of calcium entry induced by cularines and isocrasifoline in uterine smooth muscle.
1991
Abstract The effects of nifedipine, papaverine and four benzylisoquinoline alkaloids (cularine, cularidine, celtisine and isocrasifoline) were studied in isolated rat uterus in order to clarify the mechanism of their relaxant action. All the compounds tested completely relaxed KCl-induced contractions and totally or partially inhibited oxytocin-induced rhythmic contractions. Only papaverine acted intracellularly, promoting relaxation of contractile responses induced by oxytocin or vanadate in a Ca 2+ -free medium. In spite of the structural relationship between papaverine and the other alkaloids, the mechanism of their relaxant action is not the same. The activities of cularine derivatives …
Subcellular localization and nucleosome specificity of yeast histone acetyltransferases
1991
We have previously reported [López-Rodas et al. (1989) J. Biol. Chem. 264, 19028-19033] that the yeast Saccharomyces cerevisiae contains four histone acetyltransferases, which can be resolved by ion-exchange chromatography, and their specificity toward yeast free histones was studied. In the present contribution we show that three of the enzymes are nuclear, type A histone acetyltransferases and they are able to acetylate nucleosome-bound histones. They differ in their histone specificity. Enzyme A1 acetylates H2A in chicken nucleosomes, although it is specific for yeast free H2B; histone acetyltransferase A2 is highly specific for H3, and histone acetyltransferase A3 preparations acetylate…
Approche scientifique de la qualité par l'analyse sensorielle et instrumentale
1991
National audience
Three-dimensional simulation of polytropic accretion discs
1991
Three-dimensional simulations of the formation and evolution of accretion discs in close binary systems,realised with the Smoothed Particle Hydrodynamics method to solve the fluid dynamic equations, are presented. Although the runs presented here refer to an ideal gas with different polytropic indexes, and constitute the first stage of more physically complex forthcoming simulations, they nervertheless give some interesting results: the disc structure and dynamics are in agreement with standard models only for small γ-values; as a consequence of the z-resolution it is found that disc formation is inhibited for γ ≥ 1.2, which means that some 2 D simulations of polytropic discs are meaningles…
Proton glass behavior and hopping conductivity in solid solutions of antiferroelectric betaine phosphate and ferroelectric betaine phosphite.
1991
Measurements of the dielectric permittivity are reported for solid solutions of antiferroelectric betaine phosphate and ferroelectric betaine phosphite at frequencies 10 −2 Hz T c the dielectric response is dominated by ac and dc conduction. The 40% sample exhibits pure relational behavior indicative of a transition into an orientational glass state
Inhibition of prolyl hydroxylation and procollagen processing in chick-embryo calvaria by a derivative of pyridine-2,4-dicarboxylate. Characterizatio…
1991
The biochemical and morphological consequences of procollagen prolyl 4-hydroxylase inhibition by pyridine-2,4-dicarboxylic acid (2,4-PDCA) and its diethyl ester (diethyl-2,4-PDC) were studied in chick-embryo calvaria, which predominantly synthesize type I collagen. Half-maximal inhibition of tissue hydroxyproline formation required 650 microM-2,4-PDCA, whereas the Ki with respect to chicken prolyl 4-hydroxylase in vitro was 2 microM. In contrast, half-maximal inhibition was caused by 10 microM-diethyl-2,4-PDC in the intact calvaria, although chicken prolyl 4-hydroxylase in vitro was not inhibited even at 1 mM. The collagenous material produced in the presence of diethyl-2,4-PDC showed an al…
The four dimensional Ising spin glass: A Monte Carlo study (invited)
1991
We describe results of Monte Carlo simulation studies on the Ising spin glass in four dimensions on a hypercubic lattice with nearest neighbor bonds. Studies of the equilibrium static properties show that the system undergoes a genuine phase transition to an ordered spin glass phase. Critical dynamical behavior is analyzed to obtain the dynamic exponent. Finally, we describe results on the spin glass phase, in particular the finite size scaling of the order parameter distribution function, and compare it with existing models of the spin glass phase, namely the droplet model and the Parisi solution for the low temperature phase of the infinite range spin glass.
Reactions of 3-vinylindole derivatives with dienophiles
1991
Reactions of 3-(1-cyclohexenyl)-1,2-dimethylindole (1a) and the 1,2-dihydrocarbazole 1b with some carbo- and heterodienophiles are described. Thus, compound 1a reacts to give ene, Michael-type, and Diels-Alder adducts, depending on the dienophile and reaction conditions. The 3-vinylindole 1b reacts with 4-phenyl-1,2,4-triazoline-3,5-dione or N-phenylmaleimide in a dehydrogenative reaction to yield the fully aromatized carbazole 8.
Ein neues Butenolid ausConyza bonariensis
1991
A New Butenolide from Conyza bonariensis Extraction of aerial parts of Conyza bonariensis and chromatographic separation yielded the new butenolide 1, together with the acetylenic compounds trans-lachnophyllum lactone (2) and cis-lachnophyllum methyl ester (3), and the germacrane alcohol 4.
Role of glycine-82 as a pivot point during the transition from the inactive to the active form of the yeast Ras2 protein
1991
AbstractRas proteins bind either GDP or GTP with high affinity. However, only the GTP-bound form of the yeast Ras2 protein is able to stimulate adenylyl cyclase. To identify amino acid residues that play a role in the conversion from the GDP-bound to the GTP-bound state of Ras proteins, we have searched for single amino acid substitutions that selectively affected the binding of one of the two nucleotides. We have found that the replacement of glycine-82 of the Ras2 protein by serine resulted in an increased rate of dissociation of Gpp(NH)p, a nonhydrolysable analog of GTP, while the GDP dissociation rate was not significantly modified. Glycine-82 resides in a region that is highly conserve…
Nuclear transition rates in μ-catalyzedp-dfusion
1991
Nuclear transition rates in \ensuremath{\mu}-catalyzed p-d fusion have been calculated using numerically converged $^{3}\mathrm{He}$ bound-state and p-d scattering wave functions for the first time. The transition rates for M1 radiative capture in both quartet and doublet initial states have been computed using a model of meson-exchange currents which reproduces the thermal n-d capture cross section, and are in excellent agreement with experiment. The muon internal-conversion rate is in very good agreement with a recent reanalysis of old bubble-chamber measurements. Furthermore, our nonvanishing quartet capture rate resolves the anomaly in the Wolfenstein-Gerstein effect.
Analysis of multilayer adsorption models without screening
1991
A class of recently introduced irreversible multilayer adsorption models without screening is analysed. The basic kinetic process of these models leads to power law behaviour for the decay of the jamming coverage as a function of height. The authors find the exact value for the power law exponent. An approximate analytical treatment of these models and previous Monte Carlo simulations are found to be in good agreement.
Effect of indomethacin on the kinetics of tumour necrosis factor alpha release and tumour necrosis factor alpha gene expression by human blood monocy…
1991
Summary In this investigation we have examined the effects of indomethacin, an inhibitor of the cyclooxygenase pathway of arachidonic acid, upon the kinetics of the release of tumour necrosis factor alpha (TNF) and of the expression of TNF gene by lipopolysaccharide (LPS)-stimulated human blood monocytes (BM). Following stimulation of BM with LPS, TNF was released within 2 h, reached peak values at 8 h and declined at subsequent time-points (24 and 48 h). Indomethacin (10−5 m ) slightly stimulated the production of TNF at 2, 4, and 8 h and prevented the decline of TNF observed at 24 and 48 h. This effect was related to the persistence of TNF synthesis, as demonstrated by kinetics evaluation…
Some observations on the spectrophotometric determination of nitrite using ergonovine-p-dimethylaminobenzaldehyde
1991
Abstract The system ergonovine maleate-p-diethylaminobenzaldehyde in sulfuric acid media is applied to the kinetic-spectrophotometric determination of nitrite ions with competitive precision. The reaction rate is strongly enhanced by the presence of nitrite or ferric ions, being the nitrite in the “promoting” role of the reaction. Linear calibration plots are obtained for nitrite concentration ranges 0.3–2.4 ppm or 0.66–6 ppb. The influence of foreign compounds is also established.
Chronology of early Archaean granite-greenstone evolution in the Barberton Mountain Land, South Africa, based on precise dating by single zircon evap…
1991
We report precise 207Pb/206Pb single zircon evaporation ages for low-grade felsic metavolcanic rocks within the Onverwacht and Fig Tree Groups of the Barberton Greenstone Belt (BGB), South Africa, and from granitoid plutons bordering the belt. Dacitic tuffs of the Hooggenoeg Formation in the upper part of the Onverwacht Group yield ages between 3445 +/- 3 and 3416 +/- 5 Ma and contain older crustal components represented by a 3504 +/- 4 Ma old zircon xenocryst. Fig Tree dacitic tuffs and agglomerates have euhedral zircons between 3259 +/- 5 and 3225 +/- 3 Ma in age which we interpret to reflect the time of crystallization. A surprisingly complex xenocryst population in one sample documents …
Paleontología y ambientes del Triásico Medio en el sector noroccidental de la cordillera ibérica (provs. de Soria y Guadalajara, España)
1991
El Triásico Medio del sector noroccidental de la Cordillera Ibérica está compuesto por dos formaciones carbonáticas, que se corresponden con la unidad carbonática superior del Muschelkalk, y que hacia el NW pasan lateralmente a una formación terrígena. El registro fósil se encuentra en ambos tipos de formaciones. Tanto el estudio tafonómico como sedimentológico, permiten inferir la presencia de elementos acumulados que podrían corresponder a asociaciones autóctonas, compuestas en su mayoría por bivalvos infaunales de medios marinos someros y sometidos a fuerte influencia de terrígenos. Se caracterizan en la zona tres asociaciones faunísticas: 1. Asociación CostatoriaLyriomyophoria, que apar…
An introduction to the cognitive therapy of evaluation-[1]
1991
Abstract This paper introduces a new cognitive therapy which is evolving from the theoretical background of general semantics theory. This therapy is being tested since 1985 with several samples, the results being favorable and promising. Nevertheless, only its theoretical rational and clinical background will be introduced. Subsequently, the cognitive therapy of evaluation will be defined, and its main therapeutic ingredients described; finally, its differences and similarities with current cognitive therapies will be highlighted.
The concept of major depression. II. Agreement between six competing operational definitions in 600 psychiatric inpatients.
1991
Six operational definitions of the concept of major depression were submitted to empirical evaluation in 600 psychiatric inpatients. Special attention was given to the comparison of major depression in DSM-III-R and ICD-10. The data base created by a polydiagnostic interview revealed relevant classificatory differences between the six definitions under study. Sources of different diagnostic base rates were: inclusion or omission of anhedonia as an obligatory mood criterion; minimal number of syndrome criteria required for the syndrome diagnosis; different width and reference points of time criteria; exclusion rules for co-existing schizophrenic symptoms and for previous nonaffective and man…
Chromosome 5 abnormalities in acute lymphoblastic leukemia
1991
Abstract We report two cases of acute lymphoblastic leukemia with involvement of chromosome 5. One of them showed a del(5)(q13q33) in a 5-year-old boy who had previously received antineoplastic chemotherapy for an L1-ALL that had been diagnosed nine months before. The other one showed a t(5;7)(q12–13;q36) together with a t(8;14)(q24;q32) and a der(1) in a 66-year-old man with an L3-ALL. Both chromosome 5 aberrations are interpreted as evolutionary events. In the first case, it was secondary to chemotherapy treatment; in the second, an evolutionary chromosome rearrangement, considering the translocation between chromosomes 8 and 14 as the primary cytogenetic event.
Myxosporea parasites in roach, Rutilus rutilus (Linnaeus), from four lakes in central Finland
1991
Ten myxosporean species belonging to three families were found in roach, Rutilus rutilus (Linnaeus), obtained in 1985 and 1986 from four lakes in central Finland which are connected to each other, but differ in water quality. One of the lakes is polluted by paper and pulp mill effluent, two are eutrophic and one is oligotrophic and still in its natural state. Eight species were found in all the lakes. The most common species were Myxidium rhodei Leger, 1905, Myxobolus muelleri Butschli, 1882 and Myxobolus pseudodispar Gorbunova, 1936 with prevalences varying between 66–80, 16–31 and 32–59%, respectively, in the four lakes. The largest difference in myxosporean prevalence between lakes was f…
High-j bands in 173Ir
1991
Abstract High-spin states in rotational bands associated with the 11 2 − [505] , 1 2 − [541] and 1 2 + [660] Nilsson orbits have been observed in the previously unknown 173Ir nucleus using the 144Sm(32S,p2n) reaction at 163 MeV. The B(M1; I → I − 1)/B(E2; I → I −2) ratios have been extracted for the 11 2 − [505] band and compared with predictions of the semiempirical model by Donau and Frauendorf. The quasineutron band crossing frequencies and alignment gains are discussed in terms of the CSM model. Calculations for equilibrium deformations suggest different deformations for the three bands observed.
O(αs2) corrections to high-qT polarized gauge boson production at hadron colliders
1991
Abstract We report first results on O(αs2) corrections to the parity conserving structure functions that describe high-qT polarized gauge boson production in hadron collisions. We present some numerical results for polarized W+ production at the Tevatron p p collider. In particular we find that the relation A0=A2 between the longitudinal and transverse interference structure functions no longer holds true at next-to-leading order (NLO). We calculate the NLO corrections to this relation.
Influence on the phase transitions of barium titanate of the manganese valency, introduced as a substituant in the titanium site
1991
Abstract A small amount of manganese introduced in BaTiO3 modifies strongly the vibrational and electronic properties of the pure compound. Dielectric response and EPR measurements are reported in order to study the influence of the manganese valency on the ferroelectric-paraelectric phase transition.
Efficient evaluation for a subset of recursive queries
1991
Abstract We consider the efficient evaluation of recursive queries in logic databases where the queries are expressed using a Datalog program (function-free Horn-clause program) that contains only regularly or linearly recursive predicates. Using well-known results on graph traversal, we develop an efficient algorithm for evaluating relations defined by a binary-chain program. We also present a transformation by which the evaluation of a subset of queries involving nonbinary relations can be reduced to the evaluation of binary-chain queries. This transformation is guided by the choice of bound arguments in the query, and the bindings are propagated through the program so that in the evaluat…
Cycloaddition of benzothiete and electron-deficient nitriles
1991
The o-quinoid 8π electron system 2, generated by thermal ring opening of benzothiete (1), enters regio-specific [8π + 2π] cycloaddition reactions with electron-deficient nitriles 3a-d, yielding the 4H-1,3-benzothiazines 4a-d. A competitive dimerization of 1 leads to 1,5-dibenzo[b,f]dithiocin (5). Depending on the nitrile further competitive or subsequent reactions (2 + 3b 7b, 2 + 3d 4d 8d) can occur. The cycloadducts 10e and 11e gained from 3e anticipate a primary cleavage of 3e to methylisothiocyanate 9e which reacts at the CN double bond as well as at the CS double bond.
Classical electromagnetic radiation in noninertial reference frames
1991
Customarily electromagnetic radiation is defined with reference to some inertial laboratory frame. But such a definition is too narrow to be applicable to questions concerning accelerated observers,e.g. why an accelerated observer does not receive radiation from a co-accelerating charge. It is shown in this paper that a radiation concept introduced for inertial observers by Rohrlich and Teitelboim allows an extension to noninertial (accelerating and rotating) reference frames in a natural way. The generalized concept is explicitly dependent on the proper acceleration and the rotation of the observer’s laboratory frame. The case of radiation due to an accelerated point charge is treated in f…
Pnoepyga immaculata n. sp., eine neue bodenbewohnende Timalie aus dem Nepal-Himalaya
1991
Pnoepyga immaculata n. sp. lebt im Areal der beiden anderenPnoepyga-Artenalbiventer (Hodgson 1837) undpusilla Hodgson 1845 und wurde durch ihren markant abweichenden Territorialgesang entdeckt. Sie besitzt eine kurze silberhelle Strophe aus kurzen, in gleichmasigen Abstanden gereihten Pfiff-Elementen, die in der Frequenz leicht abfallt. Neben der Stimme liegen die wesentlichen diagnostischen Merkmale nach jetzigem Kenntnisstand gegenuber sympatrischenalbiventer in wenig groserem Schnabel, der Fleckenlosigkeit von Oberseite, Kopf und Flugeldecken, gegenuberpusilla in den groseren Korperabmessungen, gegenuber sympatrischenalbiventer undpusilla im schwachen grunlichen Schimmer der Oberseite un…
Diels-Alder-Reaktionen von Vinylindolen mit Arin und 1,4-Benzochinonen: Neue potentielle DNA-Interkalatoren
1991
Diels-Alder reactions of 2- and 3-vinylindoles with aryne, 1,4-benzo- and 1,4-naphtho-quinone lead to new six-ring annellated carbazoles. Molecular modeling studies predict that the compounds with coplanar framework are able to intercalate with the B-DNA.
Some glutathione-related enzymic activities in skeletal muscle and myocardium of the rat : adaptations to endurance training
1991
1-Naphthyl Acetate-Dependent Medium Acidification by Zea mays L. Coleoptile Segments
1991
Zea mays L. cv INRA 5a coleoptile segments ecidify the incubation medium on the addition of 1-naphthyl acetate (1-NA). The buffering capacity of the bathing solution increases during 1-NA stimulated medium acidification. The solution bathing the 1-NA treated coleoptile segment was analyzed by high performance liquid chromatography. A considerable amount of acetic acid was detected in the bathing solution used to measure 1-NA-dependent medium acidification. For the first time, the data demonstrate directly the release of acetic acid from 1-NA. The extent of medium acidification was proportional to 1-NA concentration. Simultaneous measurement of medium acidification and acetate content upon a…
Emission of thermal dileptons in ultrarelativistic heavy-ion collisions
1991
Abstract The emission of thermal dileptons from a quark-gluon plasma and hot pion gas formed in a collision of heavy nuclei, is studied in the framework of hydrodynamics. Thermal rates are compared with the estimates of rates for Drell-Yan production. Dependence on the mass number and impact parameter of colliding nuclei, and the collision energy is considered.
The cognitive therapy of evaluation: Therapeutic techniques-[2]
1991
Abstract The main aim of this paper is to introduce the techniques used in cognitive therapy of evaluation. The Cognitive therapy of evaluation is being developed from the theoretical background of general semantics theory and it is a therapy based on language as an instrument of cognitive processes, and on the role it plays, through word-facts identification, in the development and treatment of emotional problems. The main techniques developed (abstraction orders and the extensional devices) and other therapeutic issues are introduced and explained.
Salt effects on the protonation of l-histidine and l-aspartic acid: a complex formation model
1991
Abstract Protonation constants of l -histidine (histidinate: his − ) and l -aspartic acid (aspartate: asp 2− ) were determined potentiometrically, using the (H + ) glass electrode, in aqueous tetraethylammonium iodide (Et 4 NI), calcium chloride and sodium chloride solutions, at 0 −3 and 10 ⩽, T ⩽, 45 ° C. Differences in protonation constants determined in different salt media were explained by a complex formation model and, according to this model, the presence of the following species was hypothesized: Ca(his) + , CaH(his) 2+ , CaH 2 (his) 3+ Na(his) 0 , H 3 (his)X + , H 2 (his)X 0 , Et 4 N(his) 0 , Et 4 NH(his) + , Ca(asp) 0 , CaH(asp) + , CaH 2 (asp) 2+ , Na(asp) − , NaH(asp) 0 , H 3 (a…
Brauer's fixed-point-formula as a consequence of Thompson's order-formula
1991
Social overwintering and food distribution in the bank vole Clethrionomys glareolus
1991
We studied overwintering in the bank vole Clethrionomys glareolus in four 0.5 ha enclosures in an abandoned field in central Finland in the winter 1987/88. In two of the enclosures food was offered evenly distributed over the whole enclosed area (Even Enclosures = EE), in the two others food was offered in one feeding patch with four feeding chambers 2 m apart (Patchy Enclosures = PE). Food was provided in about the same amount in both enclosures. The experiment commenced in early October, with 13 females and 11 males in EEs and 12 + 13 voles in PEs. After two months the voles in the PEs were concentrated around the feeding patches. Territoriality was not observed in EEs, instead the voles …