showing 36 of ~574560 from 574555 documents
false
1989
Coefficients de diffusion de traceurs dans les melanges de PS avec poly(o-methylstyrene), poly(p-methylstyrene et un copolymere statistique p-m-methylstyrene
Probable exclusion of juvenile neuronal ceroid lipofuscinosis in a fetus at risk: an interim report.
1989
In a family with two children affected by juvenile neuronal ceroid lipofuscinosis (JNCL) an attempt was made at the prenatal diagnosis of the disorder. The following tissues from the fetus at risk were investigated by electron microscopy and were found to be free of fingerprint profiles and curvilinear bodies, typical for JNCL: uncultivated amniotic fluid cells, lymphocytes isolated from fetal blood, and fetal skin biopsy specimens. The child was born at the 34th week of gestation and was clinically normal at the age of 15 months. Postnatally, lymphocytes (isolated at the age of 6 and 15 months) and skin tissue (taken at the age of 15 months) were found to be morphologically normal. It is h…
Interesting synthetic routes from the reinvestigation of the reaction of the M(CO)6 (M=Cr, Mo and W) species with KOH
1989
Reinvestigation of the reaction of M(CO)6 (M=Cr, Mo or W) with KOH has been found to provide a very convenient route to the K[M2H(CO)10] compounds (M=Cr, Mo or W). The reaction involving Cr(CO)6 yields new potassium derivatives containing [Cr2(CO)10]2− and [HCr(CO)5]− species; also K[Cr2D(CO)10] is produced from the Cr(CO)6/KOD interaction in C2D5OD. The reaction involving two different group 6 metal carbonyls yields [MM′(CO)10(μ-H)]− (MM′=CrMo, CrW or WMo) species as their K+ and PPN+ [bis(triphenylphosphine)iminium] salts.
Interleukin-4 induces secretion of CSF for granulocytes and CSF for macrophages by peripheral blood monocytes.
1989
Abstract T cells are known to interact cooperatively with monocytes to produce Colony-Stimulating Factors (CSF), although T cell-mediated signals leading to CSF secretion by monocytes are not completely understood. We have made use of Northern blot hybridization and specific bioassays to study the effects of the T cell product interleukin-4 (IL-4) on monocyte CSF expression. The results suggest a previously unrecognized role of IL-4 as a CSF inducer since exposure of monocytes to IL-4 resulted in accumulation of transcripts for granulocyte-CSF (G-CSF) and macrophage-CSF (M-CSF). Consequently, IL-4-activated monocytes released factors in their culture supernatants biologically and antigenica…
ChemInform Abstract: Heterocyclic Photorearrangements. Photochemical Behaviour of Some 3,5-Disubstituted 1,2,4-Oxadiazoles in Methanol at 254 nm.
1989
Photochemical behaviour of some 3,5-disubstituted 1,2,4-oxadiazoles in methanol at 254 nm has been investigated. Ring photoisomerization to the 1,3,4-oxadiazole heterocycle or formation of open chain compounds involving the nucleophilic solvent was shown to depend on the nature and the position of the substituent. Photoinduced ring closure into the benzimidazole system, involving a 3-N-phenylamino side chain sequence and a photolytic intermediate of the oxadiazole heterocycle, is also reported.
Thermal irreversibility in optically labeled low-temperature glasses.
1989
We present an investigation of irreversible features of thermal broadening of persistent spectral holes. The investigation is based on temperature-cycling hole-burning experiments performed with a variety of organic glasses doped with rather different probe molecules. The results show a rich temperature dependence. They can, however, be interpreted in terms of the well-known spectral diffusion models, in which we introduced a freezing condition to account for thermal irreversiblity. There is a tunneling regime for low temperatures and an activated regime for high temperatures. In the tunneling regime the broadening is linear in T; in the activated regime it increases with ${T}^{3/2}$ and lo…
Solar neutrino oscillation parameters and the broken R parity majoron
1989
Matter-enhanced neutrino-oscillation parameters can be probed in a variety of conventional experiments in supergravity models where the small neutrino mass arises from spontaneous R-parity violation. A combined analysis of astrophysical and laboratory limits tends to exclude regions of oscillation parameters where the high-energy neutrinos are adiabatically converted. This suggests the possibility of a large reduction in the pp and /sup 7/Be neutrino flux even for a mildly reduced /sup 8/B neutrino flux, thus stressing the importance of gallium experiments.
Mobility, interdiffusion, and tracer diffusion in lattice-gas models of two-component alloys
1989
The transport properties of lattice-gas models of alloys with two particle species are studied. The numbers of the particles and vacancies are conserved, and the two particle species have different exchange rates with the vacancies. The mobility and interdiffusion is described by the linear Onsager theory of transport. The Onsager coefficients are estimated from numerical simulations of the mobilities. A recently proposed relation between the Onsager coefficients of the random-alloy model is verified. The interdiffusion of the two species is directly monitored in the simulations; it is well described by the estimated Onsager coefficients. The results on interdiffusion are compared with simu…
Neutron powder diffraction study in the mixed molecular system (NaCN)1−x(KCN)x
1989
A detailed structural analysis of (NaCN${)}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$(KCN${)}_{\mathrm{x}}$ mixed crystals with x=0.02, 0.19, and 0.95 was performed by neutron powder diffraction. The structural parameters of the cubic phases were refined, applying a model of preferred orientations. Different noncubic low-temperature phases were observed for x=0.02 and 0.95. For x=0.02 the antiferroelectric ordering of ${\mathrm{CN}}^{\mathrm{\ensuremath{-}}}$ dipoles at low temperatures is accompanied by significant alkali-alkali and alkali-${\mathrm{CN}}^{\mathrm{\ensuremath{-}}}$ sublattice shifts. Structural data are presented together with previous results for mixed crystals with x=0.59 and…
ChemInform Abstract: The Allyl Ester as Carboxy-Protecting Group in the Stereoselective Construction of Neuraminic Acid Glycosides.
1989
The application of the allyl-ester moiety as protecting principle for the carboxy group of N-acetylneuraminic acid is described. Peracetylated allyl neuraminate 2 is synthesized by reacting the caesium salt of the acid 1 with allyl bromide. Treatment of 2 with HCl in AcCl or with HF/pyridine gives the corresponding 2-chloro or 2-fluoro derivatives 3 and 4, respectively (Scheme 1). In the presence of Ag2CO3, the 2-chloro carbohydrate 3 reacts with di-O-isopropylidene-protected galactose 5 to give the 2–6 linked disaccharide with the α-D-anomer 6a predominating (α-D/β-D = 6:1; Scheme 2). Upon activation of the 2-fluoro derivative 4 with BF3 · Et2O, the β-D-anomer 6b is formed preferentially (…
ChemInform Abstract: Regioselective Proton-Catalyzed Diarylmethylation of Indoles with 9H-Xanthydrol, Dibenzosuberenol, and Bis(4-dimethylaminophenyl…
1989
3-Isopropylindole (4) is xanthenylated both at N-1 (stereocontrolled major reaction), C-2, and on the phenyl nucleus of the indole skeleton by xanthydrol (1). Other carbinols such as dibenzosuberenol (2) and bis[4-dimethylaminophenyl]methanol (3) with lower electrophilic SN1 activities than 1 do not react with 4 but do react very selectively with simple methylindoles to form diarylmethylated derivatives.
Asymmetrische Hetero-Diels-Alder-Reaktionen in wäßriger Lösung unter Verwendung von Aminosäureestern als chiralen Auxiliaren
1989
(R)- und (S)-Aminosaure-methylester-hydrochloride bilden mit Formaldehyd in THF/Wasser-Gemischen Iminium-Ionen, die als elektronenarme Dienophile mit Cyclopentadien, 1,3-Cyclohexadien und Alkyl-substituierten Butadienen bereits bei 0°C Hetero-Diels-Alder-Reaktionen eingehen. Die Cycloaddukte werden mit hohen Ausbeuten im Multigrammasstab und mit Diastereomerenverhaltnissen (bis zu 93:7) gebildet, die mit anderen chiralen Aminen bisher nicht erreicht werden konnten. Mit Hilfe von NOE-Experimenten werden die absoluten Konfigurationen der Hauptdiastereomeren zugeordnet. Aus den Phenylglycin- und den Serin-Derivaten konnen die chiralen Hilfsgruppen mittels hydrogenolytischer Methoden bzw. unter…
Zur Regiochemie von [4 + 2]-Cycloadditionen mit Methylpyrano[3,4-b]indol-3-onen und unsymmetrischen Dienophilen
1989
Die methylierten Pyrano[3,4-b]indol-3-one 1a, 1b reagieren mit acyclischen, unsymmetrischen CC-Dienophilen nach einer Diels-Alder-Reaktion/CO2-Extrusion zu selektiv funktionalisierten Carbazolen 2. In Abhangigkeit von der Struktur der Reaktionspartner wird keine oder geringe bis hohe Regioselektivitat festgestellt. Diethylmesoxalat reagiert mit 1a, 1b regioselektiv zu neuen 2,3-difunktionalisierten Indolen 4a, 4b, die aus einer regiokontrollierten [4 + 2]-Cycloaddition und Cycloreversion resultieren, wobei Pyrano[3,4-b]indoldicarbonsaure-diethylester 3a, 3b als Intermediate auftreten durften. Regiochemistry of [4 + 2] Cycloadditions with Methylpyrano[3,4–b]indol-3-ones and Unsymmetric Dieno…
Considerable deficits in the detection performance of the cat after lesion of the suprasylvian visual cortex
1989
The ability of two cats to discriminate between two geometrical outline patterns in the presence of superimposed structured background was tested before and after bilateral removal of the lateral suprasylvian visual areas (PMLS, PLLS, AMLS, ALLS, part of area 7). There were mild deficits when patterns and background were kept stationary; these deficits may be due to a partial undercutting of areas 17, 18 and 19. However, there was a severe impairment in performance when the patterns were moving on a stationary background which may be due to loss of the suprasylvian visual areas. Movement of the background relative to the figure resulted in an intermediate detection deficit.
Eye Muscle Antibodies in Endocrine Exophthalmos
1989
Serum samples were obtained from 65 patients with endocrine exophthalmos class I-V. In 33/65 patients who were treated either with prednisone or with ciclosporin, blood was sampled before, during and after therapy. Antibodies against eye muscle were determined during the course of immunosuppressive therapy in order to have an objective parameter of the therapeutic effect. To ascertain the specificity of the reaction both eye and abdominal muscles were used as antigens in an ELISA system. Both IgG and IgM antibodies were detected. In 45/65 patients (71%) eye muscle antibodies were positive before starting therapy. Antibodies were mostly detected in patients with active disease. Patients with…
Begleitende Inhaltsstoffe in 22 OTC-Fischöl- und Lebertranpräparaten: Cholesterin, Schwermetalle und Vitamin A
1989
Fischolkapseln werden von selbstmedizierenden Patienten in zunehmendem Mase eingenommen. Hier wurde der Frage nachgegangen, ob 22 kommerziell erhaltliche Fischol- und Lebertranzubereitungen Begleitsubstanzen enthalten, deren Menge unter Umstanden nachteilig fur den Patienten sein konnten. Gemessen wurden: Cholesterin mit der Gaschromatographie, Schwermetalle mittels Atomabsorption und Vitamin A mit der hochauflosenden Flussigkeitschromatographie (HPLC). Sowohl der Cholesterin-als auch der Schwermetallgehalt lagen in unbedenklichen Bereichen. Der Vitamin-A-Gehalt von Lebertrankapseln wurde jedoch in Mengen gefunden, bei denen schwangere Frauen die Dosierungsempfehlungen der Hersteller nicht …
A Mössbauer cryostat equipped with a Gifford McMahon cryocooler
1989
A new cryostat for Mossbauer spectroscopic measurements has been developed around a cryogenerator of the Gifford McMahon type operating with helium gas in a closed circuit. Both source and absorber can be cooled to about 30K and the unwanted vibrations caused by the helium compression/expansion cycle have been limited to approximately 0.05–0.06 mms−1.
Generalized prequojections and bounded maps
1989
YOLK SAC deL TESTICOLO. Raro caso con metastasi retroperitoneale
1989
Gli Autori riportano un caso di tumore primitivo del testicolo (Yolk Sac Tumor) e metastasi gigante retroperitoneale e sindrome virilizzante associata
The new nuclide225U
1989
In the bombardment of a 270μg/cm 2 180Hf target with48 Ca projectiles at a primary beam energy of E/A=4.24 MeV/u the new nuclide225U was produced. The experiment was performed at the velocity filter SHIP. 225U was found to decay by α emission with Eα=(7880 ±20) keV (≈90%), (7830±20) keV (≈10%) and has a half-life ofT 1/2=(80 −20 +40 ms).
Optimal Reporting of Predictions
1989
Abstract Consider a problem in which you and a group of other experts must report your individual predictive distributions for an observable random variable X to some decision maker. Suppose that the report of each expert is assigned a prior weight by the decision maker and that these weights are then updated based on the observed value of X. In this situation you will try to maximize your updated, or posterior, weight by appropriately choosing the distribution that you report, rather than necessarily simply reporting your honest predictive distribution. We study optimal reporting strategies under various conditions regarding your knowledge and beliefs about X and the reports of the other e…
Spin, helicity and flavour patterns in exclusive decays of bottom mesons into baryon-antibaryon pairs
1989
I use the constituent quark model to calculate the exclusive decays of bottom mesons into ground state baryon-antibaryon pairs mediated by the weakb→c and b→u transitions. TheW-exchange contributions to these decays are found to be negligible. For theW-decay contributions I find that the simple colour-flavour structure of the 1/2+ and 3/2+ ground state baryons together with the current-current nonleptonic Hamiltonian leads to many simple and testable predictions. Notable among these is the predicted vanishing of decays involving 3/2+ baryons as in\(\overline {B^0 } (B^ - ) \to 3/2^ + \overline {1/2^ + } \) and\(\overline {B^0 } (B^ - ) \to 3/2^ + \overline {3/2^ + } \). An experimental veri…
Non-linear Intestinal Absorption Kinetics of Cefadroxil in the Rat
1989
Abstract Absorption of Cefadroxil in a selective intestinal absorption area (the proximal third of the small intestine) of the anaesthetized rat, at seven initial perfusion concentrations, ranging from 0·01 to 10·0 mg mL−1, is shown to be a non-linear transport mechanism. With the aid of computer-fitting procedures based on differential and integrated forms of Michaelis-Menten equation, Vm and Km values of 36·7–37·3 mg h−1 and 12·0–13·0 mg, respectively, were found. The statistical parameters were better than those obtained both for first-order and for combined Michaelis-Menten and first-order kinetics. There is no evidence for substantial passive diffusion processes. The results reported h…
Response of tumour red blood cell flux to hyperthermia and/or hyperglycaemia.
1989
Laser Doppler flowmetry has been applied to subepidermal rat tumours during localized ultrasound hyperthermia and/or moderate, short-term hyperglycaemia. Blood glucose levels were elevated 4-fold by continuous i.v. infusion of D-glucose (4.8 g/kg/60 min). To determine whether the effects of hyperglycaemia on tumour blood flow involved increased rates of glycolysis and lactic acid production, galactose, a sugar not metabolized by the tumour, was administered using the same dose schedule. Hyperglycaemia was accompanied by a 3-fold increase in blood lactate levels and a slight hypervolaemic haemodilution without any significant systematic changes of the arterial blood pressure or respiratory b…
Psychotherapie und ihre Wirksamkeit bei chronischen Schmerzzuständen
1989
Der Paradigmenwechsel bei Schmerz von einem linear-kausalen zu einem kybernetischen Modell fuhrte zu einer verstarkten Berucksichtigung der Erforschung seelischer Faktoren in der Genese und Aufrechterhaltung chronischer Schmerzzustande. Dadurch entwickelte sich ein zunehmendes Interesse an der Wirksamkeit psychotherapeutischer Verfahren bei Patienten mit chronischem Schmerz. Die Arbeit gibt einen Uberblick uber die heute am haufigsten eingesetzten Psychotherapieverfahren (Hypnose, Entspannungsverfahren, verhaltensthera-peutische Verfahren, psychoanalytisch orientierte Verfahren), ihre theoretischen Ansatze, ihre Durch-fuhrung sowie ihre bisher nachgewiesene Wirksamkeit. Die psychoanalytisch…
In vivo assembly of chromatin on pBR322 sequences cloned into yeast plasmids
1989
Abstract In order to study the in vivo assembly of chromatin on prokaryotic DNA templates, we have transformed yeast cells with plasmids pAJ50 and pRB58, which contain pBR322 sequences. In both cases nucleosomes are assembled in vivo on pBR322 DNA, although the nucleosomes are not homogeneous in size. To explore whether there is any preference for nucleosome assembly along pBR322 sequences, we have used an indirect end labeling method. The results indicate that most nucleosomes are placed at random on pBR322, although the probability for histone octamers to interact with some short regions is somewhat reduced. These regions coincide with sequences in which the frequency distribution of nucl…
Verwertbarkeit verschiedener Cysteinderivate bei langfristiger parenteraler Ernährung
1989
Utilization of cysteine derivatives for parenteral nutrition was established by means of nitrogen balance of growing rats. N,N-bis-acetylcystine and bisacetyl-glycyl-cystine were not utilized as substrates. N-acetylcysteine, glutathione disulfide, and L-thiazolidine-(4)-carboxylic acid gave evidence as suitable cysteine sources for parenteral nutrition.
High-level secretion of tumor necrosis factor-alpha contributes to hematopoietic failure in hairy cell leukemia [see comments]
1989
Hairy cell leukemia (HCL) is frequently associated with severe pancytopenia. The authors detected high levels of tumor necrosis factor (TNF)-alpha in the bone marrow serum of patients with HCL and found anti-TNF-alpha neutralizing monoclonal antibodies (MoAbs) to be able to enhance hematopoiesis of HCL patients in in vitro colony assays. As potent producers of TNF-alpha, hairy cells could be identified, thus implicating the malignant population in the pathogenesis of hematopoietic failure due to inappropriate secretion of this cytokine.
Sugar specific cellular lectins of Phallusia mamillata hemocytes: Purification, characterization and evidence for cell surface localization
1989
Cellular lectins (CLs) of Phallusia mamillata were demonstrated in protein preparations obtained by salt fractionation from hemocytes sonicated in a suitable medium. Since the lectins from the precipitated fraction bind sugars containing D-galactosyl groups, they were purified by affinity chromatography on Sepharose. SDS-PAGE under reducing conditions showed that CLs are formed of two components of apparent MWs approximately 36,900 and 35,090 and thus differ from serum lectins (SLs) (MW about 62,200). The "shrinkage" observed when SLs were examined under nonreducing conditions suggest the presence of intrachain disulphide bonds which can affect the molecular structure of the SLs. CL-SL diff…
Microstructure of a Discotic Polymer as Revealed by Electron Diffraction and High-Resolution Imaging
1989
Time-differential Mössbauer emission spectroscopy: Development of a new spectrometer and first results
1989
A spectrometer for time-differential Mossbauer spectroscopy was developed with a high count rate capability, a good time resolution, and a flexible data handling. Chemical and physical aftereffects following the57Co decay were studied within the cobalt doped systems Turnbulls blue and ZnS.
Quasi-free electron scattering in a relativistic model of the nucleus
1989
Longitudinal and transverse response functions of quasi-free electron scattering have been calculated in mean field approximation for a relativisticσ-ω model, including non-linearities in theσ-field. As a consequence of the completely consistent and fully relativistic treatment of wave functions and current operators, gauge invariance is perfectly satisfied throughout the calculation. The results indicate that models with the same nuclear bulk properties lead to similar response functions within 10%. Our results agree with the experimental data for12C and238U, but cannot describe the longitudinal response in the Ca-Fe region. Predictions for208Pb are given for comparison with future experim…
The new neutron-rich isotope228Rn
1989
2 pages, 1 table, 2 figures.-- PACS nrs.: 23.90.+w; 27.90.+b.-- Section: Short Notes.
How to best return the value of a function
1989
COMPRESSION OF ENVELOPE SOLITONS IN NONLINEAR ELECTRICAL LINES
1989
Resume : La propagation des solitons enveloppe dans les lignes non lineaires de transmission electrique et de transmission Josephson est etudiee sous l'aspect theorique et en simulation numerique. Dans l'approximation des milieux continus et la limite des faibles amplitudes, les equations caracteristiques de ces lignes se ramenent a l'equation NLS . La solution "a deux solitons enveloppe" se propage parfaitement dans les lignes considerees avec des phenomenes de recurrence et de compression d'enveloppe. Ceci est observe egalement pour des profils d'excitation non solution de NLS, ce qui est d'un grand interet pour les applications pratiques.
Characterization of the muscarine receptors involved in the modulation of serotonin release from the vascularly perfused small intestine of guinea pi…
1989
Isolated small intestinal segments of the guinea pig were arterially perfused and the release of 5-hydroxytryptamine (5-HT) and its metabolite 5-hydroxyindoleacetic acid (5-HIAA) into the portal venous effluent measured by HPLC with electrochemical detection. Test substances were applied via the arterial perfusion medium. McN-A-343, pilocarpine and oxotremorine inhibited concentration-dependently the outflow of 5-HT and 5-HIAA. Pirenzepine (0.03-0.1 mumol/l) which can discriminate between M1 and M2-receptor subtypes antagonized completely this inhibitory effect. In the presence of 1 mumol/l tetrodotoxin (TTx), all three muscarine receptor agonists increased the outflow of 5-HT and 5-HIAA. O…